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Synchronous variation in demographic parameters across species increases the risk of simultaneous local extinction, which lowers the probability of subsequent recolonization. Synchrony therefore tends to destabilize meta‐populations and meta‐communities. Quantifying interspecific synchrony in demographic parameters, like abundance, survival, or reproduction, is thus a way to indirectly assess the stability of meta‐populations and meta‐communities. Moreover, it is particularly informative to identify environmental drivers of interspecific synchrony because those drivers are important across species. Using a Bayesian hierarchical multisite multispecies mark–recapture model, we investigated temporal interspecific synchrony in annual adult apparent survival for 16 common songbird species across France for the period 2001–2016. Annual adult survival was largely synchronous among species (73%, 95% credible interval [47%–94%] of the variation among years was common to all species), despite species differing in ecological niche and life history. This result was robust to different model formulations, uneven species sample sizes, and removing the long‐term trend in survival. Synchrony was also shared across migratory strategies, which suggests that environmental forcing during the 4‐month temperate breeding season has a large‐scale, interspecific impact on songbird survival. However, the strong interspecific synchrony was not easily explained by a set of candidate weather variables we defined a priori. Spring weather variables explained only 1.4% [0.01%–5.5%] of synchrony, while the contribution of large‐scale winter weather indices may have been stronger but uncertain, accounting for 12% [0.3%–37%] of synchrony. Future research could jointly model interspecific variation and covariation in breeding success, age‐dependent survival, and age‐dependent dispersal to understand when interspecific synchrony in abundance emerges and destabilizes meta‐communities. [ABSTRACT FROM AUTHOR]

Recently, considerable attention has been paid to animal adaptations to anthropogenic environments, such as foraging in burned areas where plants are promoted to regenerate by anthropogenic burning. However, among primates, reports on the utilization of resources that are available immediately after burning have been limited to a few primate species. In this study, we investigated and compared the activity budgets and food categories of a group of patas monkeys (Erythrocebus patas) in freshly burned areas by comparing them with those in previously burned areas and unburned areas. We also assessed the proportion of time spent in the freshly burned area before and after the fire: GPS collars were fitted to five of the six adults in the group, and their patterns when they traveled toward freshly burned and unburned feeding areas were compared. Patas monkeys spent more time in freshly burned areas after the fire, and they visited such areas mostly for feeding, particularly on roasted seeds of Cissus populnea. Furthermore, patas monkeys traveled faster and in a more synchronized way toward freshly burned areas. This "apparent goal-directed" travel began at least 1 h before arriving. Results indicate that the group recognized freshly burned areas as valuable, and the monkeys were able to travel in a goal-directed manner to them despite their variable locations. We suggest that smoke from freshly burned areas provides a visual cue with which to orient to the burned areas. Our results also support the notion that some primates are flexible enough to adapt to and benefit from anthropogenic environmental changes. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate whether temporal synchrony processing deficits remain when normal visual acuity is restored in adults with unilateral anisometropic amblyopia. Methods: We recruited 14 clinically treated anisometropic amblyopes (mean age 23.17 ± 2.53 years) with best‐corrected visual acuity ≤ 0.1 logMAR and 15 age‐matched emmetropes (mean age 24.40 ± 1.92 years) with normal vision to participate in our experiment. We presented two pairs of flicking Gaussian dots (1 Hz) as visual stimuli: one pair of dots was synchronous (reference), and the other pair of dots was asynchronous (signal). Subjects were asked to determine the position of the asynchronous pair. We applied the constant stimuli method to measure the temporal synchrony threshold under monocular and dichoptic viewing conditions. There were eight temporal phase lags in the asynchronous pair. The minimum degree of the temporal phase at which a participant can discriminate a signal pair is defined as the temporal synchrony threshold. Results: Under monocular viewing conditions where both the reference and signal pairs were presented to one eye, the temporal synchrony thresholds of previous amblyopic eyes and fellow eyes were not significantly different (p = 0.15). Under dichoptic viewing conditions where both the reference and signal pairs were dichoptically presented to both eyes, the temporal synchrony threshold in the treated anisometropic amblyopes was significantly higher than that of the controls (119.34 ± 20.43 vs. 99.78 ± 16.60 ms, p = 0.009). There was no significant correlation between the monocular and dichoptic viewing conditions in the treated amblyopes (r = −0.22, p = 0.94). Conclusions: Temporal synchrony discrimination is abnormal under dichoptic but not under monocular visual stimulation in treated anisometropic amblyopes with normalised visual acuity. [ABSTRACT FROM AUTHOR]

Autism Spectrum Disorder is a highly heritable condition characterized by sociocommunicative difficulties, frequently entailing language atypicalities that extend to infants with a familial history of autism. The developmental mechanisms underlying these difficulties remain unknown. Detecting temporal synchrony between the lip movements and the auditory speech of a talking face and selectively attending to the mouth support typical early language acquisition. This preliminary eye-tracking study investigated whether these two fundamental mechanisms atypically function in infant siblings. We longitudinally tracked the trajectories of infants at elevated and low-likelihood for autism in these two abilities at 4, 8, and 12 months (n = 29). We presented two talking faces (synchronous and asynchronous) while recording infants' gaze to the talker's eyes and mouth. We found that infants detected temporal asynchronies in talking faces at 12 months regardless of group. However, compared to their typically developing peers, infants with an elevated likelihood of autism showed reduced attention to the mouth at the end of the first year and no variations in their interest to this area across time. Our findings provide preliminary evidence on a potentially atypical trajectory of reduced mouth-looking in audiovisual speech during the first year in infant siblings, with potential cascading consequences for language development, thus contributing to domain-general accounts of emerging autism. • Temporal synchrony detection and mouth-looking in speech boost language acquisition. • Infants with a familial history of autism show group-level language atypicalities. • We predict that atypicalities may also occur in the mechanisms underlying language. • We found no evidence of reduced temporal asynchrony detection in infant siblings. • And preliminary evidence of reduced mouth-preference in infant siblings at 12 months. [ABSTRACT FROM AUTHOR]

Resting-state fMRI studies have shown that multiple functional networks, which consist of distributed brain regions that share synchronised spontaneous activity, co-exist in the brain. As these resting-state networks (RSNs) have been thought to reflect the brain's intrinsic functional organization, intersubject variability in the networks’ spontaneous fluctuations may be associated with individuals’ clinical, physiological, cognitive, and genetic traits. Here, we investigated resting-state fMRI data along with extensive clinical, lifestyle, and genetic data collected from 37,842 UK Biobank participants, with the object of elucidating intersubject variability in the fluctuation amplitudes of RSNs. Functional properties of the RSN amplitudes were first examined by analyzing correlations with the well-established between-network functional connectivity. It was found that a network amplitude is highly correlated with the mean strength of the functional connectivity that the network has with the other networks. Intersubject clustering analysis showed the amplitudes are most strongly correlated with age, cardiovascular factors, body composition, blood cell counts, lung function, and sex, with some differences in the correlation strengths between sensory and cognitive RSNs. Genome-wide association studies (GWASs) of RSN amplitudes identified several significant genetic variants reported in previous GWASs for their implications in sleep duration. We provide insight into key factors determining RSN amplitudes and demonstrate that intersubject variability of the amplitudes primarily originates from differences in temporal synchrony between functionally linked brain regions, rather than differences in the magnitude of raw voxelwise BOLD signal changes. This finding additionally revealed intriguing differences between sensory and cognitive RSNs with respect to sex effects on temporal synchrony and provided evidence suggesting that synchronous coactivations of functionally linked brain regions, and magnitudes of BOLD signal changes, may be related to different genetic mechanisms. These results underscore that intersubject variability of the amplitudes in health and disease need to be interpreted largely as a measure of the sum of within-network temporal synchrony and amplitudes of BOLD signals, with a dominant contribution from the former.

The visual attentional blink can be substantially reduced by delivering a task‐irrelevant sound synchronously with the second visual target (T2), and this effect is further modulated by the semantic congruency between the sound and T2. However, whether the cross‐modal benefit originates from audiovisual interactions or sound‐induced alertness remains controversial, and whether the semantic congruency effect is contingent on audiovisual temporal synchrony needs further investigation. The current study investigated these questions by recording event‐related potentials (ERPs) in a visual attentional blink task wherein a sound could either synchronize with T2, precede T2 by 200 ms, be delayed by 100 ms, or be absent, and could be either semantically congruent or incongruent with T2 when delivered. The behavioral data showed that both the cross‐modal boost of T2 discrimination and the further semantic modulation were the largest when the sound synchronized with T2. In parallel, the ERP data yielded that both the early occipital cross‐modal P195 component (192–228 ms after T2 onset) and late parietal cross‐modal N440 component (424–448 ms) were prominent only when the sound synchronized with T2, with the former being elicited solely when the sound was further semantically congruent whereas the latter occurring only when that sound was incongruent. These findings demonstrate not only that the cross‐modal boost of T2 discrimination during the attentional blink stems from early audiovisual interactions and the semantic congruency effect depends on audiovisual temporal synchrony, but also that the semantic modulation can unfold at the early stage of visual discrimination processing. [ABSTRACT FROM AUTHOR]

Flexibility and robustness of multisensory temporal recalibration is paramount for maintaining perceptual constancy of the surrounding natural world. Different environments impart various impediments, distances and routes that alter the propagation times of sight and sound cues comprising a multimodal event. One's ability to rapidly calibrate and account for these external variations allows for maintained perception of synchrony which is crucial for coherent and consistent perception. The two common paradigms used to compare precision of temporal processing between experimental and control groups, the simultaneity judgment (SJ) and temporal order judgment (TOJ) tasks, often use supra-threshold stimuli. However, few studies have specifically examined the effects of normalizing stimulus intensities to participant's unisensory detection thresholds. The current project presented multiple combinations of auditory and visual stimulus intensity levels, based on individual detection thresholds, during a TOJ and a SJ task. While no effect of stimulus intensity was found on temporal sensitivity or perceived temporal synchrony, there was a significant difference in point of subjective simultaneity (PSS) measures between tasks. In addition, PSS estimates were audio-leading, rather than visual-leading as previously reported, suggesting that exposure to the particular combinations of stimulus intensity levels used influenced temporal synchrony perception. Overall, these results support the use of supra-threshold stimuli in TOJ and SJ tasks as a way of minimizing the confound from differences in unisensory processing. [ABSTRACT FROM AUTHOR]

Protecting water quality at catchment scales is complicated by the high spatiotemporal variability in water chemistry. Consequently, determining pollutant sources requires costly monitoring strategies to diagnose causes and guide management solutions. However, recent studies have shown that spatial patterns in water chemistry can be persistent at catchment scales, potentially allowing identification of pollution sources and sinks with just a few sampling campaigns. Here, we tested a new method to quantify spatial persistence (SP) of water chemistry patterns with data from synoptic samplings in 22 headwater subcatchments within a 375 km2 catchment in western France (March 2018 to July 2019). This new method to quantify SP reduces dependence on long‐term metrics such as flow‐weighted concentrations, which are usually uncertain or unavailable. We applied the method to 16 ecologically relevant water quality parameters, including soluble reactive phosphorus, nitrate, and dissolved organic carbon. The results showed an average SP of 0.68 among parameters during the study period. For most parameters, SP was higher during the high‐flow winter period but lower and more variable during the low‐flow summer period. We found that the SP ultimately depended on the ratio between the temporal and spatial coefficients of variation (variance explained: 70%) rather than the temporal synchrony among subcatchments (variance explained: 4%). These results demonstrate that in these temperate catchments, synoptic sampling during the high‐flow winter period allows efficient identification of source and sink subcatchments, while more frequent samplings are needed to characterize ecological conditions at low flow. Key Points: We found high spatial persistence of water chemistry, despite high spatiotemporal variability in water chemistrySpatial persistence of water chemistry is primarily determined by the ratio between spatial and temporal variabilityA single synoptic sampling during the high‐flow season allows efficient identification of source and sink subcatchments [ABSTRACT FROM AUTHOR]

The embodiment approach has shown that motor neural networks are involved in the processing of action verbs. There is developmental evidence that embodied effects on verb processing are already present in early years. Yet, the ontogenetic origin of this motor reuse in action verbs remains unknown. This longitudinal study investigates the co-occurrence of manual verbs and actions during mother-child daily routines (free play, bathing, and dining) when children were 1 to 2 (Group 1) and 2 to 3 (Group 2) years old. Eight mother-child dyads were video-recorded in 3-month intervals across 12 months (27 recording hours), and the timing of verbs and manual actions (21,876 entries) were coded by independent observers. Results showed that the probability of matched verb-action co-occurrences were much higher (0.80 and 0.77) than that of random co-occurrences (0.13 and 0.15) for Group 1 and Group 2, respectively. The distributions of the verb-action temporal intervals in both groups were quite symmetrical and skewed with the peak corresponding to both 0.00 s synchronic intervals (8% of the cases) and the shortest +5 s interval (40% of the cases). Mother-led instances occurred in both groups whereas child-led instances were restricted to Group 2. Mothers pragmatically aligned their verbal productions, since they repeatedly used (74%) those verbs they shared with their children’s repertoire (31%). In conclusion, the early multisensory communicative and manipulative scene affords grounding of verb meanings on the ongoing actions, facilitating verb-action pairing in the realm of social interactions, providing a new dimension to the prevailing solipsistic approach to embodiment.

Studies on binocular combination and rivalry show that short-term deprivation strengthens the contribution of the deprived eye in binocular vision. However, whether short-term monocular deprivation affects temporal processing per se is not clear. To address this issue, we conducted a study to investigate the effect of monocular deprivation on dichoptic temporal synchrony. We tested ten adults with normal vision and patched their dominant eye with an opaque patch for 2.5 h. A temporal synchrony paradigm was used to measure if temporal synchrony thresholds change as a result of monocular pattern deprivation. In this paradigm, we displayed two pairs of Gaussian blobs flickering at 1 Hz with either the same or different phased- temporal modulation. In Experiment 1, we obtained the thresholds for detecting temporal asynchrony under dichoptic viewing configurations. We compared the thresholds for temporal synchrony between before and after monocular deprivation and found no significant changes of the interocular synchrony. In Experiment 2, we measured the monocular thresholds for detecting temporal asynchrony. We also found no significant changes of the monocular synchrony of either the patched eye or the unpatched eye. Our findings suggest that short-term monocular deprivation induced-plasticity does not influence monocular or dichoptic temporal synchrony at low temporal frequency.

Studies on binocular combination and rivalry show that short-term deprivation strengthens the contribution of the deprived eye in binocular vision. However, whether short-term monocular deprivation affects temporal processing per se is not clear. To address this issue, we conducted a study to investigate the effect of monocular deprivation on dichoptic temporal synchrony. We tested ten adults with normal vision and patched their dominant eye with an opaque patch for 2.5 h. A temporal synchrony paradigm was used to measure if temporal synchrony thresholds change as a result of monocular pattern deprivation. In this paradigm, we displayed two pairs of Gaussian blobs flickering at 1 Hz with either the same or different phased- temporal modulation. In Experiment 1, we obtained the thresholds for detecting temporal asynchrony under dichoptic viewing configurations. We compared the thresholds for temporal synchrony between before and after monocular deprivation and found no significant changes of the interocular synchrony. In Experiment 2, we measured the monocular thresholds for detecting temporal asynchrony. We also found no significant changes of the monocular synchrony of either the patched eye or the unpatched eye. Our findings suggest that short-term monocular deprivation induced-plasticity does not influence monocular or dichoptic temporal synchrony at low temporal frequency. [ABSTRACT FROM AUTHOR]

Temporal coordination of vocal exchanges between mothers and their infants emerges from a developmental process that relies on the ability of communication partners to co-coordinate and predict each other’s turns. Consequently, the partners engage in communicative niche construction that forms a foundation for language in human infancy. While robust universals in vocal turn-taking have been found, differences in the timing of maternal and infant vocalizations have also been reported across cultures. In this study, we examine the temporal structure of vocal interactions in 38 mother–infant dyads in the first two years across two cultures—American and Lebanese—by studying observed and randomized distributions of vocalizations, focusing on both gaps and overlaps in naturalistic 10-min vocal interactions. We conducted a series of simulations using Kolmogorov–Smirnov (K–S) tests to examine whether the observed responsivity patterns differed from randomly generated simulations of responsivity patterns in both Arabic and English for mothers responding to infants and for infants responding to mothers. Results revealed that both mothers and infants engaged in conversational alternation, with mothers acting similarly across cultures. By contrast, significant differences were observed in the timing of infant responses to maternal utterances, with the Lebanese infants’ tendency to cluster their responses in the first half-second after the offset of the Lebanese mothers’ utterances to a greater extent than their American counterparts. We speculate that the results may be due to potential phonotactic differences between Arabic and English and/or to differing child-rearing practices across Lebanese and American cultures. The findings may have implications for early identification of developmental disorders such as autism spectrum disorders within and across cultures.

The eastern North American monarch butterfly population shows a long-term population decline. While it is hypothesized that forest loss on the wintering grounds and milkweed loss throughout the breeding range are responsible for the observed decline, there is much less certainty regarding the factors driving year-to-year variation around the current population level. Using 15 years of butterfly count data, we used a community-based approach to delineate the stage of the annual cycle during which population limiting factors are most strongly acting. We compared annual fluctuations in size of the breeding population of monarch butterflies in Canada to fluctuations in 13 additional butterfly species which either migrate long distances to Canada or are resident but breed in similar habitats to the monarch. We show that the breeding population of monarchs in southern Canada shows a higher degree of synchrony with other long-distance migrants than with breeding residents, and that annual fluctuations of all migrant butterflies show a positive correlation with the number of 21°C days during spring migration and re-colonization. Further, we found that size of the monarch breeding population shows a higher degree of synchrony with the size of the following winter population than with the size of the previous winter population. Combined, our results suggest that the monarch population in Canada is limited by factors acting during spring migration, and that weather plays an important role in the ability of the monarch to successfully re-colonize and breed in the northern portion of their summer range each year. A predicted increase in temperature in the early spring, combined with continued loss of breeding and wintering habitat, has the potential to limit the reproductive capacity of monarchs and their ability to recover from population lows.

Temporal coordination of vocal exchanges between mothers and their infants emerges from a developmental process that relies on the ability of communication partners to co-coordinate and predict each other's turns. Consequently, the partners engage in communicative niche construction that forms a foundation for language in human infancy. While robust universals in vocal turn-taking have been found, differences in the timing of maternal and infant vocalizations have also been reported across cultures. In this study, we examine the temporal structure of vocal interactions in 38 mother–infant dyads in the first two years across two cultures—American and Lebanese—by studying observed and randomized distributions of vocalizations, focusing on both gaps and overlaps in naturalistic 10-min vocal interactions. We conducted a series of simulations using Kolmogorov–Smirnov (K–S) tests to examine whether the observed responsivity patterns differed from randomly generated simulations of responsivity patterns in both Arabic and English for mothers responding to infants and for infants responding to mothers. Results revealed that both mothers and infants engaged in conversational alternation, with mothers acting similarly across cultures. By contrast, significant differences were observed in the timing of infant responses to maternal utterances, with the Lebanese infants' tendency to cluster their responses in the first half-second after the offset of the Lebanese mothers' utterances to a greater extent than their American counterparts. We speculate that the results may be due to potential phonotactic differences between Arabic and English and/or to differing child-rearing practices across Lebanese and American cultures. The findings may have implications for early identification of developmental disorders such as autism spectrum disorders within and across cultures. [ABSTRACT FROM AUTHOR]

Recent research undertaken in Mediterranean pine forests suggests that the establishment of Pinus pinea L. and Pinus pinaster Ait. natural regeneration is determined by different spatial and temporal factors. In this context, we analyzed the establishment and success of natural regeneration in these two species and we examined the hypothesis that the spatial pattern of natural regeneration depends on adult tree presence, density or stand composition, while temporal patterns are typically driven by climatic conditions. For the purposes of the experiment we used 1936 plots of 0.02 ha established in mixed and pure forests of P. pinea and P. pinaster in the Northern Plateau of Spain. Plots were installed following regeneration fellings, and regeneration was monitored annually between 2001 and 2015. We used contingency tables and principal component analysis (PCA) to evaluate the main factors affecting the spatial distribution of the regeneration. PCA was also used to assess the temporal variation as a function of climatic variables. Finally, we checked for the existence of interspecific and intraspecific synchrony through Tau-Kendall synchrony analysis. We found that natural regeneration of P. pinea was more successful than that of P. pinaster over the whole of the studied period. Contingency tables showed that P. pinaster regeneration was associated with conspecific adult trees, while the relationship between P. pinea regeneration and adult trees varied depending on the regeneration development stage, i.e., seedling or saplings. Furthermore, we found that natural regeneration in both species could be enhanced through the presence of mixtures of adult trees. The spatial variability, analyzed through PCA, showed similar responses in both species, although temporal variability associated with climate variables differed between P. pinea and P. pinaster. Finally, we found different synchrony patterns affecting natural regeneration, depending on the species and the regeneration stages. In this context, temporal patterns seem to be species specific during the sapling stage of regeneration. These findings allow the observed regeneration patterns in Mediterranean pinewoods to be generalized at forest management scale. [ABSTRACT FROM AUTHOR]

Highlights • Heart rate indices of infant attention varied as a function of multimodal synchrony. • Speaking faces enhanced behavioral and heart rate indices of infant attention. • Effects of synchrony and speaking faces were additive, suggesting independence. Abstract Attention is a state of readiness or alertness, associated with behavioral and psychophysiological responses, that facilitates learning and memory. Multisensory and dynamic events have been shown to elicit more attention and produce greater sustained attention in infants than auditory or visual events alone. Such redundant and often temporally synchronous information guides selectivity and facilitates perception, learning, and memory of properties of events specified by redundancy. In addition, events involving faces or other social stimuli provide an extraordinary amount of redundant information that attracts and sustains attention. In the current study, 4- and 8-month-old infants were shown 2-min multimodal videos featuring social or nonsocial stimuli to determine the relative roles of synchrony and stimulus category in inducing attention. Behavioral measures included average looking time and peak look duration, and convergent measurement of heart rate (HR) allowed for the calculation of HR-defined phases of attention: Orienting (OR), sustained attention (SA), and attention termination (AT). The synchronous condition produced an earlier onset of SA (less time in OR) and a deeper state of SA than the asynchronous condition. Social stimuli attracted and held attention (longer duration of peak looks and lower HR than nonsocial stimuli). Effects of synchrony and the social nature of stimuli were additive, suggesting independence of their influence on attention. These findings are the first to demonstrate different HR-defined phases of attention as a function of intersensory redundancy, suggesting greater salience and deeper processing of naturalistic synchronous audiovisual events compared with asynchronous ones. [ABSTRACT FROM AUTHOR]

Certain deficits of episodic memory among young adults are the delayed consequences of an earlier mild or moderate Traumatic Brain Injury (mTBI). We examined alterations in hippocampal Local Field Oscillations (LFOs) of equivalently-impaired juvenile rodents to identify reliable functional markers of single-incidence mTBI. Two persistent, behavior-dependent, electrophysiological markers of injury were identified in the absence of external physiological symptoms by the analysis of wirelessly-transmitted hippocampal LFOs (3–80 Hz) during repeat measures of the Novel Object Recognition (NOR) paradigm. Using a new method for detecting functional network activity at a single recording site, we correlated instantaneous increases in theta frequency and gamma magnitude with injury during periods of functional network organization and dissolution, presented here as Theta Epochs (TEs) and Theta Non-Epochs (TNEs), respectively. We estimated the efficacy of networks across pairs of such sites using new metrics such as the Coherence of Theta Phase (PCOH) and Inter-Epoch Intervals (IEIs) and demonstrated that behavioral deficits observed during the NOR testing stage correspond to electrophysiological deficits recorded during the preceding NOR familiarization stage. Increased theta frequency during TNEs and increased smoothness of PCOH during TEs were found to be robust markers of injury during memory-reliant behaviors. [ABSTRACT FROM AUTHOR]

Pale field-rats have long disappeared from Australia's arid and semiarid zones, other than for some Pilbara islands and a single mainland population of indeterminate status and extent identified at Shark Bay in 1968. Hence, it was noteworthy when a field-rat was first caught at Heirisson Prong in 1994, 40 km north-east of the previous location at Shark Bay. Further individuals were caught regularly from late 1995. The population peaked in July-October 2000 (with captures of ~190 individuals per month) and had collapsed by July 2001 (with only the occasional animal caught thereafter). None were caught beyond 2006, despite regular trapping to 2013. This irruption and collapse was beyond the established range of the species and was in atypical habitat. Widespread trapping after the collapse suggested that the population inhabited few localised 'source' areas and a broad area of 'sink' habitat, with the latter occupied only after extraordinarily high rainfall events leading to higher grass cover. A return to dry years and the consequent loss of cover (aided by an abundant rabbit population) and strong growth in predator numbers (feral cats and small birds of prey) in response to the high number of field-rats appears to have facilitated the collapse. [ABSTRACT FROM AUTHOR]

The present discourse links the electrical and chemical properties of the brain with neurotransmitters and movement behaviors to further elucidate strategies to diagnose and treat brain disease. Neuromolecular imaging (NMI), based on electrochemical principles, is used to detect serotonin in nerve terminals (dorsal and ventral striata) and somatodendrites (ventral tegmentum) of reward/motor mesocorticolimbic and nigrostriatal brain circuits. Neuronal release of serotonin is detected at the same time and in the same animal, freely moving and unrestrained, while open-field behaviors are monitored via infrared photobeams. The purpose is to emphasize the unique ability of NMI and the BRODERICK PROBE® biosensors to empirically image a pattern of temporal synchrony, previously reported, for example, in Aplysia using central pattern generators (CPGs), serotonin and cerebral peptide-2. Temporal synchrony is reviewed within the context of the literature on central pattern generators, neurotransmitters and movement disorders. Specifically, temporal synchrony data are derived from studies on psychostimulant behavior with and without cocaine while at the same time and continuously, serotonin release in motor neurons within basal ganglia, is detected. The results show that temporal synchrony between the neurotransmitter, serotonin and natural movement occurs when the brain is NOT injured via, e.g., trauma, addictive drugs or psychiatric illness. In striking contrast, in the case of serotonin and cocaine-induced psychostimulant behavior, a different form of synchrony and also asynchrony can occur. Thus, the known dysfunctional movement behavior produced by cocaine may well be related to the loss of temporal synchrony, the loss of the ability to match serotonin in brain with motor activity. The empirical study of temporal synchrony patterns in humans and animals may be more relevant to the dynamics of motor circuits and movement behaviors than are studies of static parameters currently relied upon within the realms of science and medicine. There are myriad applications for the use of NMI to discover clinically relevant diagnoses and treatments for brain disease involving the motor system.

• Variability in amplitude of resting-state networks (RSNs) was assessed across 37,842 subjects. • Network amplitudes are closely linked to functional connectivity between RSNs. • Temporal synchrony between brain regions is a key factor determining RSN amplitudes. • Sex effects on temporal synchrony differ between sensory and cognitive RSNs. • Genetic variants associated with RSN amplitudes overlap with those associated with synchrony. Resting-state fMRI studies have shown that multiple functional networks, which consist of distributed brain regions that share synchronised spontaneous activity, co-exist in the brain. As these resting-state networks (RSNs) have been thought to reflect the brain's intrinsic functional organization, intersubject variability in the networks' spontaneous fluctuations may be associated with individuals' clinical, physiological, cognitive, and genetic traits. Here, we investigated resting-state fMRI data along with extensive clinical, lifestyle, and genetic data collected from 37,842 UK Biobank participants, with the object of elucidating intersubject variability in the fluctuation amplitudes of RSNs. Functional properties of the RSN amplitudes were first examined by analyzing correlations with the well-established between-network functional connectivity. It was found that a network amplitude is highly correlated with the mean strength of the functional connectivity that the network has with the other networks. Intersubject clustering analysis showed the amplitudes are most strongly correlated with age, cardiovascular factors, body composition, blood cell counts, lung function, and sex, with some differences in the correlation strengths between sensory and cognitive RSNs. Genome-wide association studies (GWASs) of RSN amplitudes identified several significant genetic variants reported in previous GWASs for their implications in sleep duration. We provide insight into key factors determining RSN amplitudes and demonstrate that intersubject variability of the amplitudes primarily originates from differences in temporal synchrony between functionally linked brain regions, rather than differences in the magnitude of raw voxelwise BOLD signal changes. This finding additionally revealed intriguing differences between sensory and cognitive RSNs with respect to sex effects on temporal synchrony and provided evidence suggesting that synchronous coactivations of functionally linked brain regions, and magnitudes of BOLD signal changes, may be related to different genetic mechanisms. These results underscore that intersubject variability of the amplitudes in health and disease need to be interpreted largely as a measure of the sum of within-network temporal synchrony and amplitudes of BOLD signals, with a dominant contribution from the former. [ABSTRACT FROM AUTHOR]

Observable lip movements of the speaker influence perception of auditory speech. A classical example of this influence is reported by listeners who perceive an illusory (cross-modal) speech sound (McGurk-effect) when presented with incongruent audio-visual (AV) speech stimuli. Recent neuroimaging studies of AV speech perception accentuate the role of frontal, parietal, and the integrative brain sites in the vicinity of the superior temporal sulcus (STS) for multisensory speech perception. However, if and how does the network across the whole brain participates during multisensory perception processing remains an open question. We posit that a large-scale functional connectivity among the neural population situated in distributed brain sites may provide valuable insights involved in processing and fusing of AV speech. Varying the psychophysical parameters in tandem with electroencephalogram (EEG) recordings, we exploited the trial-by-trial perceptual variability of incongruent audio-visual (AV) speech stimuli to identify the characteristics of the large-scale cortical network that facilitates multisensory perception during synchronous and asynchronous AV speech. We evaluated the spectral landscape of EEG signals during multisensory speech perception at varying AV lags. Functional connectivity dynamics for all sensor pairs was computed using the time-frequency global coherence, the vector sum of pairwise coherence changes over time. During synchronous AV speech, we observed enhanced global gamma-band coherence and decreased alpha and beta-band coherence underlying cross-modal (illusory) perception compared to unisensory perception around a temporal window of 300-600 ms following onset of stimuli. During asynchronous speech stimuli, a global broadband coherence was observed during cross-modal perception at earlier times along with pre-stimulus decreases of lower frequency power, e.g., alpha rhythms for positive AV lags and theta rhythms for negative AV lags. Thus, our study indicates that the temporal integration underlying multisensory speech perception requires to be understood in the framework of large-scale functional brain network mechanisms in addition to the established cortical loci of multisensory speech perception. [ABSTRACT FROM AUTHOR]

Gamma oscillations in cortex have been extensively studied with relation to behavior in both humans and animal models; however, their computational role in the processing of behaviorally relevant signals is still not clear. One oft-overlooked characteristic of gamma oscillations is their spatial distribution over the cortical space and the computational consequences of such an organization. Here, we advance the proposal that the spatial organization of gamma oscillations is of major importance for their function. The interaction of specific spatial distributions of oscillations with the functional topography of cortex enables select amplification of neuronal signals, which supports perceptual and cognitive processing.

This psychophysics study used musicians as a model to investigate whether musical expertise shapes the temporal integration window for audiovisual speech, sinewave speech or music. Musicians and non-musicians judged the audiovisual synchrony of speech, sinewave analogues of speech, and music stimuli at 13 audiovisual stimulus onset asynchronies (±360, ±300 ±240, ±180, ±120, ±60, and 0 ms). Further, we manipulated the duration of the stimuli by presenting sentences/melodies or syllables/tones. Critically, musicians relative to non-musicians exhibited significantly narrower temporal integration windows for both music and sinewave speech. Further, the temporal integration window for music decreased with the amount of music practice, but not with age of acquisition. In other words, the more musicians practiced piano in the past three years, the more sensitive they became to the temporal misalignment of visual and auditory signals. Collectively, our findings demonstrate that music practicing fine-tunes the audiovisual temporal integration window to various extents depending on the stimulus class. While the effect of piano practicing was most pronounced for music, it also generalized to other stimulus classes such as sinewave speech and to a marginally significant degree to natural speech.

Sexual signals play an important role in mate attraction. In this study, we explore male vocal behavior and female mate attraction in long-tailed manakins, tropical lekking birds where males perform cooperative displays to attract females, and males provide only gametes to choosy females. We monitored female visitation at 37 sites using two techniques: video recordings and automated radiotelemetry. Simultaneously, we used digital recorders to sample male vocal behavior, quantifying vocal output as well as frequency matching and temporal synchrony in male--male duets. We compared male vocal performance to the rate at which females visited male display sites. Video data revealed that both male vocal output and the temporal synchrony of male--male duets were positively related to female visitation, matching our expectations. Telemetry data, in contrast, revealed no such relationship. Our results suggest that telemetry data may yield biased estimates of patterns of female choice, because the tracked females may not adequately represent the pool of potential female visitors to leks. We also demonstrate that male vocal behavior and female visitation vary, in concert, with time of day, peaking in the early morning, with a pronounced drop in the mid-day heat. We compare these results with those of another study, of the same species, in a montane environment with cooler daytime temperatures. [ABSTRACT FROM AUTHOR]

Gamma oscillations in cortex have been extensively studied with relation to behavior in both humans and animal models; however, their computational role in the processing of behaviorally relevant signals is still not clear. One oft-overlooked characteristic of gamma oscillations is their spatial distribution over the cortical space and the computational consequences of such an organization. Here, we advance the proposal that the spatial organization of gamma oscillations is of major importance for their function. The interaction of specific spatial distributions of oscillations with the functional topography of cortex enables select amplification of neuronal signals, which supports perceptual and cognitive processing. [ABSTRACT FROM AUTHOR]

This psychophysics study used musicians as a model to investigate whether musical expertise shapes the temporal integration window for audiovisual speech, sinewave speech, or music. Musicians and non-musicians judged the audiovisual synchrony of speech, sinewave analogs of speech, and music stimuli at 13 audiovisual stimulus onset asynchronies (±360, ±300 ±240, ±180, ±120, ±60, and 0 ms). Further, we manipulated the duration of the stimuli by presenting sentences/melodies or syllables/tones. Critically, musicians relative to non-musicians exhibited significantly narrower temporal integration windows for both music and sinewave speech. Further, the temporal integration window for music decreased with the amount of music practice, but not with age of acquisition. In other words, the more musicians practiced piano in the past 3 years, the more sensitive they became to the temporal misalignment of visual and auditory signals. Collectively, our findings demonstrate that music practicing fine-tunes the audiovisual temporal integration window to various extents depending on the stimulus class. While the effect of piano practicing was most pronounced for music, it also generalized to other stimulus classes such as sinewave speech and to a marginally significant degree to natural speech. [ABSTRACT FROM AUTHOR]

The present discourse links the electrical and chemical properties of the brain with neurotransmitters and movement behaviors to further elucidate strategies to diagnose and treat brain disease. Neuromolecular imaging (NMI), based on electrochemical principles, is used to detect serotonin in nerve terminals (dorsal and ventral striata) and somatodendrites (ventral tegmentum) of reward/motor mesocorticolimbic and nigrostriatal brain circuits. Neuronal release of serotonin is detected at the same time and in the same animal, freely moving and unrestrained, while open-field behaviors are monitored via infrared photobeams. The purpose is to emphasize the unique ability of NMI and the BRODERICK PROBE® biosensors to empirically image a pattern of temporal synchrony, previously reported, for example, in Aplysia using central pattern generators (CPGs), serotonin and cerebral peptide-2. Temporal synchrony is reviewed within the context of the literature on central pattern generators, neurotransmitters and movement disorders. Specifically, temporal synchrony data are derived from studies on psychostimulant behavior with and without cocaine while at the same time and continuously, serotonin release in motor neurons within basal ganglia, is detected. The results show that temporal synchrony between the neurotransmitter, serotonin and natural movement occurs when the brain is NOT injured via, e.g., trauma, addictive drugs or psychiatric illness. In striking contrast, in the case of serotonin and cocaine-induced psychostimulant behavior, a different form of synchrony and also asynchrony can occur. Thus, the known dysfunctional movement behavior produced by cocaine may well be related to the loss of temporal synchrony, the loss of the ability to match serotonin in brain with motor activity. The empirical study of temporal synchrony patterns in humans and animals may be more relevant to the dynamics of motor circuits and movement behaviors than are studies of static parameters currently relied upon within the realms of science and medicine. There are myriad applications for the use of NMI to discover clinically relevant diagnoses and treatments for brain disease involving the motor system. [ABSTRACT FROM AUTHOR]

Background: The auditory brainstem response (ABR) is usually abnormal in individuals with auditory neuropathy spectrum disorder (ANSD). However, in some such individuals the ABR is preserved at low repetition rates. This study attempts to understand the speech perception abilities of ANSD individuals who have preserved temporal synchronicity. Material and methods: There were 149 individuals with ANSD in the study. They were classified into two groups based on preserved or absent ABR. Speech identification scores (SISs) in these individuals in quiet and in the presence of noise were compared. Results: At low repetition rates some 12.5% of subjects had preserved ABR with low amplitude wave V. Of these, 81% had an SIS of more than 50% in quiet. However, in patients with absent ABR, only 27% of individuals had an SIS of more than 50%. For subjects who had preserved ABR the mean SIS was 73.1% in quiet and 36.5% in noise compared to 35.9% in quiet and 20.2% in noise for individuals who had absent ABR. Conclusions: One in eight of the patients with ANSD had preserved ABR. Speech understanding was also better in quiet and in the presence of noise in individuals with preserved ABR. We conclude that speech reception abilities depend upon neural synchronicity at the level of the auditory nerve. [ABSTRACT FROM AUTHOR]

Capturing the functionality of active dendritic processing into abstract mathematical models will help us to understand the role of complex biophysical neurons in neuronal computation and to build future useful neuromorphic analog Very Large Scale Integrated (aVLSI) neuronal devices. Previous work based on an aVLSI multi-compartmental neuron model demonstrates that the compartmental response in the presence of either of two widely studied classes of active mechanisms, is a nonlinear sigmoidal function of the degree of either input temporal synchrony OR input clustering level. Using the same silicon model, this work expounds the interaction between both active mechanisms in a compartment receiving input patterns of varying temporal AND spatial clustering structure and demonstrates that this compartmental response can be captured by a combined sigmoid and radial-basis function over both input dimensions. This paper further shows that the response to input spatio-temporal patterns in a one-dimensional multi-compartmental dendrite, can be described by a radial-basis like function of the degree of temporal synchrony between the inter-compartmental inputs. [ABSTRACT FROM PUBLISHER]

Despite humans' ability to communicate about concepts relating to different senses, word learning research tends to largely focus on labeling visual objects. Although sensory modality is known to influence memory and learning, its specific role for word learning remains largely unclear. We investigated associative word learning in adults, that is the association of an object with its label, by means of event-related brain potentials (ERPs). We evaluated how learning is affected by object modality (auditory vs visual) and temporal synchrony of object-label presentations (sequential vs simultaneous). Across 4 experiments, adults were, in training phases, presented either visual objects (real-world images) or auditory objects (environmental sounds) in temporal synchrony with or followed by novel pseudowords (2 × 2 design). Objects and pseudowords were paired either in a consistent or an inconsistent manner. In subsequent testing phases, the consistent pairs were presented in matching or violated pairings. Here, behavioral and ERP responses should reveal whether consistent object-pseudoword pairs had been successfully associated with one another during training. The visual-object experiments yielded behavioral learning effects and an increased N400 amplitude for violated versus matched pairings indicating short-term retention of object-word associations, in both the simultaneous and sequential presentation conditions. For the auditory-object experiments, only the simultaneous, but not the sequential presentation, revealed similar results. Across all experiments, we found behavioral and ERP correlates of associative word learning to be affected by both sensory modality and partly, by temporal synchrony of object-label combinations. Based on our findings, we argue for independent advantages of temporal synchrony and visual modality in associative word learning., Competing Interests: Declaration of competing interest The authors have no conflicts of interests to declare., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Multimodal signals (acoustic+visual) are known to be used by many anuran amphibians during courtship displays. The relative degree to which each signal component influences female mate choice, however, remains poorly understood. In this study we used a robotic frog with an inflating vocal sac and acoustic playbacks to document responses of female túngara frogs to unimodal signal components (acoustic and visual). We then tested female responses to a synchronous multimodal signal. Finally, we tested the influence of spatial and temporal variation between signal components for female attraction. Females failed to approach the isolated visual cue of the robotic frog and they showed a significant preference for the call over the spatially separate robotic frog. When presented with a call that was temporally synchronous with the vocal sac inflation of the robotic frog, females did not show a significant preference for this over the call alone; when presented with a call that was temporally asynchronous with vocal sac inflation of the robotic frog, females discriminated strongly against the asynchronous multimodal signal in favor of the call alone. Our data suggest that although the visual cue is neither necessary nor sufficient for attraction, it can strongly modulate mate choice if females perceive a temporal disjunction relative to the primary acoustic signal. [ABSTRACT FROM AUTHOR]

To see whether there is a difference in temporal resolution of synchrony perception between audio–visual (AV), visuo–tactile (VT), and audio–tactile (AT) combinations, we compared synchrony–asynchrony discrimination thresholds of human participants. Visual and auditory stimuli were, respectively, a luminance-modulated Gaussian blob and an amplitude-modulated white noise. Tactile stimuli were mechanical vibrations presented to the index finger. All the stimuli were temporally modulated by either single pulses or repetitive-pulse trains. The results show that the temporal resolution of synchrony perception was similar for AV and VT (e.g., ~4 Hz for repetitive-pulse stimuli), but significantly higher for AT (~10 Hz). Apart from having a higher temporal resolution, however, AT synchrony perception was similar to AV synchrony perception in that participants could select matching features through attention, and a change in the matching-feature attribute had little effect on temporal resolution. The AT superiority in temporal resolution was indicated not only by synchrony–asynchrony discrimination but also by simultaneity judgments. Temporal order judgments were less affected by modality combination than the other two tasks. [ABSTRACT FROM AUTHOR]

Abstract: Computationally, audio-visual temporal synchrony detection is analogous to visual motion detection in the sense that both solve the correspondence problem. We examined whether audio-visual synchrony detection is mediated by a mechanism similar to low-level motion sensors, by one similar to a higher-level feature matching process, or by both types of mechanisms as in the case of visual motion detection. We found that audio-visual synchrony–asynchrony discrimination for temporally dense random pulse trains was difficult, whereas motion detection is known to be easy for spatially dense random dot patterns (random dot kinematograms) due to the operation of low-level motion sensors. Subsequent experiments further indicated that the temporal limiting factor of audio-visual synchrony discrimination is the temporal density of salient features not the temporal frequency of the stimulus, nor the physical density of the stimulus. These results suggest that audio-visual synchrony perception is based solely on a salient feature matching mechanism similar to that proposed for high-level visual motion detection. [Copyright &y& Elsevier]

Abstract: The temporal correlation hypothesis proposes using distributed synchrony for the binding of different stimulus features. However, synchronized spikes must travel over cortical circuits that have varying-length pathways, leading to mismatched arrival times. This raises the question of how initial stimulus-dependent synchrony might be preserved at a destination binding site. Earlier, we proposed constraints on tolerance and segregation parameters for a phase-coding approach, within cortical circuits, to address this question [C. Günay, A.S. Maida, Temporal binding as an inducer for connectionist recruitment learning over delayed lines, Neural Networks 16 (5–6) (2003) 593–600]. The purpose of the present paper is twofold. First, we conduct simulation studies that explore the effectiveness of the proposed constraints. Second, we place the studies in a broader context of synchrony-driven recruitment learning [L. Shastri, V. Ajjanagadde, From simple associations to systematic reasoning: a connectionist representation of rules, variables, and dynamic bindings using temporal synchrony, Behav. Brain Sci. 16 (3) (1993) 417–451; L.G. Valiant, Circuits of the Mind, Oxford University Press, Oxford, 1994] which brings together von der Malsburg''s temporal binding [C. von der Malsburg, The correlation theory of brain function, in: E. Domany, J.L. van Hemmen, K. Schulten (Ed.), Models of Neural Networks, vol. 2, Physics of Neural Networks, Chapter 2, Springer, New York, 1994, pp. 95–120, (Originally appeared as a Technical Report at the Max-Planck Institute for Biophysical Chemistry, Gottingen, 1981)] and Feldman''s recruitment learning [J.A. Feldman, Dynamic connections in neural networks, Biol. Cybern. 46 (1982) 27–39]. A network based on Valiant''s neuroidal architecture is used to implement synchrony-driven recruitment learning. Complementing similar approaches, we use a continuous-time learning procedure allowing computation with spiking neurons. The viability of the proposed binding scheme is investigated by conducting simulation studies which examine binding errors. In the simulation, binding errors cause the formation of illusory conjunctions among features belonging to separate objects. Our results indicate that when tolerance and segregation parameters obey our proposed constraints, the sets of correct bindings are dominant over sets of spurious bindings in reasonable operating conditions. We also improve the stability of the recruitment method in deep hierarchies for use in limited size structures suitable for computer simulations. [Copyright &y& Elsevier]

The literature on the role of gestures in children with language delay (LD) is partial and controversial. The present study explores gestural production and modality of expression in children with LD and semantic and temporal relationships between gestures and words in gesture + word combinations. Thirty-three children participated (mean age, 26 months), who were recruited through a screening programme for LD. Cognitive skills, lexical abilities, and the use of spontaneous gestures in a naming task were evaluated when the children were 32 months old. When the children were 78 months old, their parents were interviewed to collect information about an eventual diagnosis of developmental language disorder (DLD). According to these data, the children fell into three groups: children with typical development ( n = 13), children with LD who did not show DLD (transient LD; n = 9), and children with LD who showed DLD ( n = 11). No significant differences emerged between the three groups for cognitive and lexical skills (comprehension and production), for number of gestures spontaneously produced, and for the sematic relationships between gestures and words. Differences emerged in the modality of expression, where children with transient LD produced more unimodal gestural utterances than typical-development children, and in the temporal relationships between gestures and words, where the children who would show DLD provided more frequent representational gestures before the spoken answer than typical-development children. We suggest a different function for gestures in children with T-LD, who used representational gestures to replace the spoken word they were not yet able to produce, and in children with LD-DLD, who used representational gestures to access spoken words.

We are capable of drawing a variety of inferences effortlessly, spontaneously, and with remarkable efficiency—as though these inferences are a reflex response of our cognitive apparatus. This remarkable human ability poses a challenge for cognitive science and computational neuroscience: How can a network of slow neuron-like elements represent a large body of systematic knowledge and perform a wide range of inferences with such speed? The connectionist model SHRUTI attempts to address this challenge by demonstrating how a neurally plausible network can encode a large body of semantic and episodic facts, systematic rules, and knowledge about entities and types, and yet perform a wide range of explanatory and predictive inferences within a few hundred milliseconds. Relational structures (frames, schemas) are represented in SHRUTI by clusters of cells, and inference in SHRUTI corresponds to a transient propagation of rhythmic activity over such cell-clusters wherein dynamic bindings are represented by the synchronous firing of appropriate cells. SHRUTI encodes mappings across relational structures using high-efficacy links that enable the propagation of rhythmic activity, and it encodes items in long-term memory as coincidence and coincidence-error detector circuits that become active in response to the occurrence (or non-occurrence) of appropriate coincidences in the on going flux of rhythmic activity. Finally, “understanding” in SHRUTI corresponds to reverberant and coherent activity along closed loops of neural circuitry. Over the past several years, SHRUTI has undergone several enhancements that have augmented its expressiveness and inferential power. This paper describes some of these extensions that enable SHRUTI to (i) deal with negation and inconsistent beliefs, (ii) encode evidential rules and facts, (iii) perform inferences requiring the dynamic instantiation of entities, and (iv) seek coherent explanations of observations. [ABSTRACT FROM AUTHOR]

The perception of a moving object can lead to the expectation of its sound, yet little is known about how visual expectations influence auditory processing. We examined how visual perception of an object moving continuously across the visual field influences early auditory processing of a sound that occurred congruently or incongruently with the object's motion. In Experiment 1, electroencephalogram (EEG) activity was recorded from adults who passively viewed a ball that appeared either on the left or right boundary of a display and continuously traversed along the horizontal midline to make contact and elicit a bounce sound off the opposite boundary. Our main analysis focused on the auditory-evoked event-related potential. For audio-visual (AV) trials, a sound accompanied the visual input when the ball contacted the opposite boundary (AV-synchronous), or the sound occurred before contact (AV-asynchronous). We also included audio-only and visual-only trials. AV-synchronous sounds elicited an earlier and attenuated auditory response relative to AV-asynchronous or audio-only events. In Experiment 2, we examined the roles of expectancy and multisensory integration in influencing this response. In addition to the audio-only, AV-synchronous, and AV-asynchronous conditions, participants were shown a ball that became occluded prior to reaching the boundary of the display, but elicited an expected sound at the point of occluded collision. The auditory response during the AV-occluded condition resembled that of the AV-synchronous condition, suggesting that expectations induced by a moving object can influence early auditory processing. Broadly, the results suggest that dynamic visual stimuli can help generate expectations about the timing of sounds, which then facilitates the processing of auditory information that matches these expectations., Competing Interests: Declaration of competing interest None., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

It is well established that gesture facilitates learning, but understanding the best way to harness gesture and how gesture helps learners are still open questions. Here, we consider one of the properties that may make gesture a powerful teaching tool: its temporal alignment with spoken language. Previous work shows that the simultaneity of speech and gesture matters when children receive instruction from a teacher (Congdon et al., 2017). In Study 1, we ask whether simultaneity also matters when children themselves are the ones who produce speech and gesture strategies. Third-graders (N = 75) were taught to produce one strategy in speech and one strategy in gesture for correctly solving mathematical equivalence problems; they were told to produce these strategies either simultaneously (S + G) or sequentially (S➔G; G➔S) during a training session. Learning was assessed immediately after training, at a 24-h follow-up, and at a 4-week follow-up. Children showed evidence of learning and retention across all three conditions. Study 2 was conducted to explore whether it was the special relationship between speech and gesture that helped children learn. Third-graders (N = 87) were taught an action strategy instead of a gesture strategy; all other aspects of the design were the same. Children again learned across all three conditions. But only children who produced simultaneous speech and action retained what they had learned at the follow-up sessions. Results have implications for why gesture is beneficial to learners and, taken in relation to previous literature, reveal differences in the mechanisms by which doing versus seeing gesture facilitates learning. [ABSTRACT FROM AUTHOR]