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Asbtract Humans spend a lifetime learning, storing and refining a repertoire of motor memories. For example, through experience, we become proficient at manipulating a large range of objects with distinct dynamical properties. However, it is unknown what principle underlies how our continuous stream of sensorimotor experience is segmented into separate memories and how we adapt and use this growing repertoire. Here we develop a theory of motor learning based on the key principle that memory creation, updating and expression are all controlled by a single computation--contextual inference. Our theory reveals that adaptation can arise both by creating and updating memories (proper learning) and by changing how existing memories are differentially expressed (apparent learning). This insight enables us to account for key features of motor learning that had no unified explanation: spontaneous recovery.sup.1, savings.sup.2, anterograde interference.sup.3, how environmental consistency affects learning rate.sup.4,5 and the distinction between explicit and implicit learning.sup.6. Critically, our theory also predicts new phenomena--evoked recovery and context-dependent single-trial learning--which we confirm experimentally. These results suggest that contextual inference, rather than classical single-context mechanisms.sup.1,4,7-9, is the key principle underlying how a diverse set of experiences is reflected in our motor behaviour. A theory of motor learning based on the principle of contextual inference reveals that adaptation can arise by both creating and updating memories and changing how existing memories are differentially expressed, and predicts evoked recovery and context-dependent single-trial learning., Author(s): James B. Heald [sup.1] [sup.2] [sup.3] , Máté Lengyel [sup.2] [sup.4] , Daniel M. Wolpert [sup.1] [sup.2] [sup.3] Author Affiliations: (1) Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia [...]

The present study examined the relationship between multisensory integration and the temporal binding window (TBW) for multisensory processing in adults with Autism spectrum disorder (ASD). The ASD group was less likely than the typically developing group to perceive an illusory flash induced by multisensory integration during a sound-induced flash illusion (SIFI) task. Although both groups showed comparable TBWs during the multisensory temporal order judgment task, correlation analyses and Bayes factors provided moderate evidence that the reduced SIFI susceptibility was associated with the narrow TBW in the ASD group. These results suggest that the individuals with ASD exhibited atypical multisensory integration and that individual differences in the efficacy of this process might be affected by the temporal processing of multisensory information., Author(s): Sayaka Kawakami [sup.1] , Shota Uono [sup.2] , Sadao Otsuka [sup.3] [sup.4] , Sayaka Yoshimura [sup.2] [sup.4] , Shuo Zhao [sup.1] [sup.4] [sup.5] , Motomi Toichi [sup.1] [sup.4] Author [...]

Individuals with autism spectrum disorders (ASD) exhibit alterations in sensory processing, including changes in the integration of information across the different sensory modalities. In the current study, we used the sound-induced flash illusion to assess multisensory integration in children with ASD and typically-developing (TD) controls. Thirty-one children with ASD and 31 age and IQ matched TD children (average age = 12 years) were presented with simple visual (i.e., flash) and auditory (i.e., beep) stimuli of varying number. In illusory conditions, a single flash was presented with 2-4 beeps. In TD children, these conditions generally result in the perception of multiple flashes, implying a perceptual fusion across vision and audition. In the present study, children with ASD were significantly less likely to perceive the illusion relative to TD controls, suggesting that multisensory integration and cross-modal binding may be weaker in some children with ASD. These results are discussed in the context of previous findings for multisensory integration in ASD and future directions for research. Keywords Autism spectrum disorders * Sensory processing * Audiovisual * Multisensory integration * Audition Vision, Introduction Autism spectrum disorders (ASD) are characterized by atypical social communication and by the presence of restricted interests and/or repetitive behaviors (APA and APA DSM-5 Task Force 2013; APA 2000). [...]

This study explores the effects of visual condition and target size during four reach-to-grasp tasks between autistic children and healthy controls. Twenty children with autism and 20 healthy controls participated in the study. Qualisys motion capture system and kinematic measures were used to record movement. Autistic group showed significantly longer movement time, larger normalized jerk score, more movement unit than controls, especially in non-visual feedback and small target blocks. Autistic group also showed significantly larger maximal grip aperture and normalized maximal grip aperture in visual feedback condition than controls. Autistic children demonstrate motor coordination problems and also depend on more visual cuing in high accuracy tasks. Autistic children develop other compensatory skills while performing tasks. Keywords Autism * Kinematics * Reach to grasp * Visual feedback * Target size, Introduction Autism is a developmental disorder which is diagnosed on three main features: deficits in social interaction, deficits in communication, and stereotyped or restricted behavior. Numerous studies have shown the [...]

Background: The aim of the present study was to map the pathophysiology of resting state functional connectivity accompanying structural and functional abnormalities in children with bipolar disorder. Methods: Children with bipolar disorder and demographically matched healthy controls underwent resting-state functional magnetic resonance imaging. A model-free independent component analysis was performed to identify intrinsically interconnected networks. Results: We included 34 children with bipolar disorder and 40 controls in our analysis. Three distinct resting state networks corresponding to affective, executive and sensorimotor functions emerged as being significantly different between the pediatric bipolar disorder (PBD) and control groups. All 3 networks showed hyperconnectivity in the PBD relative to the control group. Specifically, the connectivity of the dorsal anterior cingulate cortex (ACC) differentiated the PBD from the control group in both the affective and the executive networks. Exploratory analysis suggests that greater connectivity of the right amygdala within the affective network is associated with better executive function in children with bipolar disorder, but not in controls. Limitations: Unique clinical characteristics of the study sample allowed us to evaluate the pathophysiology of resting state connectivity at an early state of PBD, which led to the lack of generalizability in terms of comorbid disorders existing in a typical PBD population. Conclusion: Abnormally engaged resting state affective, executive and sensorimotor networks observed in children with bipolar disorder may reflect a biological context in which abnormal task-based brain activity can occur. Dual engagement of the dorsal ACC in affective and executive networks supports the neuroanatomical interface of these networks, and the amygdala's engagement in moderating executive function illustrates the intricate interplay of these neural operations at rest., Introduction Pediatric bipolar disorder (PBD) is a cyclical illness with episodes of mania and depression complicated by neurocognitive dysfunction. (1-3) Mania is characterized by symptoms such as grandiosity, decreased need [...]

Background: Prepulse inhibition (PPI) of the startle reflex is modulated by a complex neural network. Prepulse inhibition impairments are found at all stages of schizophrenia. Previous magnetic resonance imaging (MRI) studies suggest that brain correlates of PPI differ between patients with schizophrenia and healthy controls; however, these studies included only patients with chronic illness and medicated patients. Our aim was to examine the structural brain correlates of PPI in antipsychotic-naive patients with first- episode schizophrenia. Methods: We performed acoustic PPI assessment and structural MRI (1.5 and 3 T) in men with first-episode schizophrenia and age-matched controls. Voxel-based morphometry was used to investigate the association between PPI and grey matter volumes. Results: We included 27 patients and 38 controls in the study. Patients had lower PPI than controls. The brain areas in which PPI and grey matter volume correlated did not differ between the groups. Independent of group, PPI was significantly and positively associated with regional grey matter volume in the right superior parietal cortex. Prepulse inhibition and grey matter volume associations were also observed in the left rostral dorsal premotor cortex, the right presupplementary motor area and the anterior medial superior frontal gyrus bilaterally. Follow-up analyses suggested that the rostral dorsal premotor cortex and presupplementary motor area correlations were driven predominantly by the controls. Limitations: We used 2 different MRI scanners, which might have limited our ability to find subcortical associations since interscanner consistency is low for subcortical regions. Conclusion: The superior parietal cortex seems to be involved in the regulation of PPI in controls and antipsychotic-naive men with first-episode schizophrenia. Our observation that PPI deficits in schizophrenia may be related to the rostral dorsal premotor cortex and presupplementary motor area, brain areas involved in maintaining relevant sensory information and voluntary inhibition, warrants further study., Introduction Disturbances in attention and information processing are thought to play a pivotal role in the symptomatology of schizophrenia. (1) Patients with schizophrenia are generally unable to focus their attention [...]

The mechanisms linking sensation and action during learning are poorly understood. Layer 2/3 neurons in the motor cortex might participate in sensorimotor integration and learning; they receive input from sensory cortex and excite deep layer neurons, which control movement. Here we imaged activity in the same set of layer 2/3 neurons in the motor cortex over weeks, while mice learned to detect objects with their whiskers and report detection with licking. Spatially intermingled neurons represented sensory (touch) and motor behaviours (whisker movements and licking). With learning, the population-level representation of task-related licking strengthened. In trained mice, population-level representations were redundant and stable, despite dynamism of single-neuron representations. The activity of a subpopulation of neurons was consistent with touch driving licking behaviour. Our results suggest that ensembles of motor cortex neurons couple sensory input to multiple, related motor programs during learning., Author(s): D. Huber [1, 3, 4]; D. A. Gutnisky [1, 4]; S. Peron [1]; D. H. O'Connor [1]; J. S. Wiegert [2]; L. Tian [1]; T. G. Oertner [2]; L. [...]

Classical studies of mammalian movement control define a prominent role for the primary motor cortex. Investigating the mouse whisker system, we found an additional and equally direct pathway for cortical motor control driven by the primary somatosensory cortex. Whereas activity in primary motor cortex directly evokes exploratory whisker protraction, primary somatosensory cortex directly drives whisker retraction, providing a rapid negative feedback signal for sensorimotor integration. Motor control by sensory cortex suggests the need to reevaluate the functional organization of cortical maps. 10.1126/science.1195797

A framework for action planning, called ideomotor theory, suggests that actions are represented by their perceivable effects. Thus, any activation of the effect image, either endogenously or exogenously, will trigger the corresponding action. We review contemporary studies relating to ideomotor theory in which researchers have investigated various manipulations of action effects and how those effects acquire discriminative control over the actions. Evidence indicates that the knowledge about the relation between response and effect is still a critical component even when other factors, such as stimulus--response or response--response relations, are controlled. When consistent tone effects are provided after responses are made, performance in serial-reaction tasks is better than when the effects are random. Methodology in which acquisition and test stages are used with choice-reaction tasks shows that an action is automatically associated with its effect bilaterally and that anticipation of the effect facilitates action. Ideomotor phenomena include stimulus-response compatibility, in which the perceptual feature of the stimulus activates its corresponding action code when the stimulus itself resembles the effect codes. For this reason, other stimulus-driven action facilitation such as ideomotor action and imitation are treated as ideomotor phenomena and are reviewed. Ideomotor theory also implies that ongoing action affects perception of concurrent events, a topic which we review briefly. Issues concerning ideomotor theory are identified and evaluated. We categorize the range of ideomotor explanations into several groups by whether intermediate steps are assumed to complete sensorimotor transformation or not and by whether a general theoretical framework or a more restricted one is provided by the account. Keywords: ideomotor theory, motor control, action planning, common coding, response-effect association DOI: 10.1037/a0020541

Schutz and Lipscomb (2007) reported an audiovisual illusion in which the length of the gesture used to produce a sound altered the perception of that sound's duration. This contradicts the widely accepted claim that the auditory system generally dominates temporal tasks because of its superior temporal acuity. Here, in the first of 4 experiments, we show that impact gestures influence duration ratings of percussive but not sustained sounds. In the 2nd, we show that the illusion is present even if the percussive sound occurs up to 700 ms after the visible impact, but disappears if the percussive sound precedes the visible impact. In the 3rd experiment, we show that only the motion after the visible impact influences perceived tone duration. The 4th experiment (replacing the impact gestures with the written text long and short) suggests that the phenomenon is not due to response bias. Given that visual influence in this paradigm is dependent on the presence of an ecologically plausible audiovisual relationship, we conclude that cross-modal causality plays a key role in governing the integration of sensory information. Keywords: sensory integration, causality, auditory, visual, optimal integration DOI: 10.1037/a0016455

In older adults, maintaining balance and processing information typically interfere with each other, suggesting that executive functions may be engaged for both. We investigated associations between measures of inhibitory processes and standing postural control in healthy young and older adults. Perceptual and motor inhibition was measured using a protocol adapted from Nassauer and Halperin (2003, Dissociation of perceptual and motor inhibition processes through the use of novel computerized conflict tasks. Journal of the International Neuropsychological Society, 9, 25-30). These measures were then correlated to postural sway during standing conditions that required resolving various levels of sensory conflict, for example, world-fixed versus sway-referenced floor and visual scene. In the older adults, perceptual inhibition was positively correlated with sway amplitude on a sway-referenced floor and with a fixed visual scene (r = .68, p < .001). Motor inhibition was not correlated with sway on either group. Perceptual inhibition may be a component of the sensory integration process important for maintaining balance in older adults. Key Words: Attention--Balance--Inhibition--Sensory.

Objective. Our objective was to identify the spatial distribution of local atrophy within mobility-related brain regions in relationship with quantitative gait characteristics. Methods. Gray matter volume was obtained from 220 older adults (78.0 years old, 63% women, 77% white) for brain regions of five domains: motor (motor, sensorimotor and supplementary areas, basal ganglia, cerebellum), visuospatial attention (interior and superior posterior parietal lobules), cognitive processing speed/executive control function (dorsolateral prefrontal cortex), memory (hippocampus), and motor imagery (parahippocampus, posterior cingulated cortex) domains. Spatial (step width, step length) and temporal (double support time) gait characteristics were measured using the GaitMat II instrumented walking surface. Multivariable linear regression models were adjusted for demographics, total brain volume, and peripheral (body mass index, ankle arm index, arthritis, vibratory sensation) and central (markers of diffuse brain structural abnormalities and of brain function) risk factors for gait impairment. Results. Shorter steps and longer double support times were associated with smaller sensorimotor regions and also with smaller frontoparietal regions within the motor, visuospatial, and cognitive processing speed domains. The associations between wider step and smaller pallidum and inferior parietal lobule were less robust. None of the gait measures were associated with the cerebellum or with regions of the memory or motor imagery domains. Conclusions. Spatial and temporal characteristics of gait are associated with distinct brain networks in older adults. Addressing focal neuronal losses in these networks may represent an important strategy to prevent mobility disability. Key Words: Brain networks--Gait analysis.

ABSTRACT. The evolution of joint dynamics and muscle patterning in the shoulder and elbow was studied for cyclical line drawing tasks at different frequencies, amplitudes, and orientations in the horizontal [...]

ABSTRACT. Haptic guidance can improve the immediate performance of a motor task by enforcing a desired pattern of kinematics, but several studies have found that it impairs motor learning. In [...]

ABSTRACT. Motor programming at the self-select paradigm was adopted in 2 experiments to examine the processing demands of independent processes. One process (INT) is responsible for organizing the internal features [...]

ABSTRACT. The authors investigated the coordination of periodic right-hand tapping with single stimulus-evoked discrete left-hand taps to check for task interactions and a possible relationship between phase resetting (see tapping [...]

Understanding how the genome empowers the nervous system to express behaviors remains a critical challenge in behavioral genetics. The startle response is an attractive behavioral model for studies on the relationship between genes, brain, and behavior, as the ability to respond rapidly to harmful changes in the environment is a universal survival trait. Drosophila melanogaster provides a powerful system in which genetic studies on individuals with controlled genetic backgrounds and reared under controlled environmental conditions can be combined with neuroanatomical studies to analyze behaviors. In a screen of 720 lines of D. melanogaster, carrying single P[GT1] transposon insertions, we found 267 lines that showed significant changes in startle-induced locomotor behavior. Excision of the transposon reversed this effect in five lines out of six tested. We infer that most of the 267 lines show mutant effects on startle-induced locomotion that are caused by the transposon insertions. We selected a subset of 15 insertions in the same genetic background in autosomal genes with strong mutant effects and crossed them to generate all 105 possible nonreciprocal double heterozygotes. These hybrids revealed an extensive network of epistatic interactions on the behavioral trait. In addition, we observed changes in neuroanatomy that were caused by these 15 mutations, individually and in their double heterozygotes. We find that behavioral and neuroanatomical phenotypes are determined by a common set of genes that are organized as partially overlapping genetic networks. behavioral genetics | epistasis| sensorimotor integration | startle behavior | P-element insertional mutagenesis

Does manipulating the time available to image executing a sensorimotor skill impact subsequent skill execution outcomes in a similar manner as manipulating execution time itself?. Novice and skilled golfers performed a series of imaged golf putts followed by a series of actual golf putts under instructions that emphasized either speeded or nonspeeded imaging/putting execution. Novices putted less accurately (i.e., higher putting error score) following either putting or imagery instructions in which speed was stressed. Skilled golfers showed the opposite pattern. Although more time available to execute a skill enhances novice performance, this extra time harms the proceduralized skill of experts. Manipulating either actual execution time or imagined execution time produces this differential impact on novice and skilled performance outcomes. These results are discussed in terms of the functional equivalence between imagery and action and expertise differences in the attentional control structures governing complex sensorimotor skill execution. Keywords: Expertise; Attention; Imagery; Embodied cognition; Speed-accuracy trade-off.

Everyone has the feeling that perception is usually accurate--we apprehend the layout of the world without significant error, and therefore we can interact with it effectively. Several fines of experimentation, however, show that perceived layout is seldom accurate enough to account for the success of visually guided behaviour. A visual world that has more texture on one side, for example, induces a shift of the body's straight ahead to that side and a mislocalization of a small target to the opposite side. Motor interaction with the target remains accurate, however, as measured by a jab with the finger. Slopes of hills are overestimated, even while matching the slopes of the same hills with the forearm is more accurate. The discrepancy shrinks as the estimated range is reduced, until the two estimates are hardly discrepant for a segment of a slope within arm's reach. From an evolutionary standpoint, the function of perception is not to provide an accurate physical layout of the world, but to inform the planning of future behaviour. Illusions--inaccuracies in perception--are perceived as such only when they can be verified by objective means, such as measuring the slope of a hill, the range of a landmark, or the location of a target. Normally such illusions are not checked and are accepted as reality without contradiction. Keywords: Roelofs effect; Vision; Perception; Illusions; Slope illusion.

ABSTRACT. On a winding open road, a driver consistently looks to the inside of each bend before turning the steering wheel. When researchers disrupt this coordination by instructing drivers not [...]

This article examined the effects of body-object interaction (BOI) on semantic processing. BOI measures perceptions of the ease with which a human body can physically interact with a word's referent. In Experiment 1, BOI effects were examined in 2 semantic categorization tasks (SCT) in which participants decided if words are easily imageable. Responses were faster and more accurate for high BOI words (e.g., mask) than for low BOI words (e.g., ship). In Experiment 2, BOI effects were examined in a semantic lexical decision task (SLDT), which taps both semantic feedback and semantic processing. The BOI effect was larger in the SLDT than in the SCT, suggesting that BOI facilitates both semantic feedback and semantic processing. The findings are consistent with the embodied cognition perspective (e.g., Barsalou's, 1999, Perceptual Symbols Theory), which proposes that sensorimotor interactions with the environment are incorporated in semantic knowledge. Keywords: Embodied cognition; Sensorimotor knowledge; Semantic Categorization; Semantic processing; Semantic feedback

A necessary consequence of the nature of neural transmission systems is that as change in the physical state of a time-varying event takes place, delays produce error between the instantaneous registered state and the external state. Another source of delay is the transmission of internal motor commands to muscles and the inertia of the musculoskeletal system. How does the central nervous system compensate for these pervasive delays? Although it has been argued that delay compensation occurs late in the motor planning stages, even the earliest visual processes, such as phototransduction, contribute significantly to delays. I argue that compensation is not an exclusive property of the motor system, but rather, is a pervasive feature of the central nervous system (CNS) organization. Although the motor planning system may contain a highly flexible compensation mechanism, accounting not just for delays but also variability in delays (e.g., those resulting from variations in luminance contrast, internal body temperature, muscle fatigue, etc.), visual mechanisms also contribute to compensation. Previous suggestions of this notion of 'visual prediction' led to a lively debate producing re-examination of previous arguments, new analyses, and review of the experiments presented here. Understanding visual prediction will inform our theories of sensory processes and visual perception, and will impact our notion of visual awareness. Keywords: biased competition; compensation; coordinate transformation; feedforward control; flash-lag; internal models; lateral interactions; neural representation; reference frames; time delays; visual awareness

ABSTRACT. The authors examined the relative success of varying sensory stimulation modalities that they presented via a mobile reinforcement procedure for promoting left-knee extensions in 3-month-old infants. They separated 53 [...]

In 5 experiments, the authors examined the perceptual and cognitive processes used to track the locations of objects during locomotion. Participants learned locations of 9 objects on the outer part of a turntable from a single viewpoint while standing in the middle of the turntable. They subsequently pointed to objects while facing the learning heading and a new heading, using imagined headings that corresponded to their current actual body heading and the other actual heading. Participants in 4 experiments were asked to imagine that the objects moved with them as they turned and were shown or only told that the objects would move with them; in Experiment 5, participants were shown that objects could move with them but were asked to ignore this as they turned. Results showed that participants tracked object locations as though the objects moved with them when shown but not when told about the consequences of their locomotion. Once activated, this processing mode could not be suppressed by instructions. Results indicated that people process object locations in a body- or an environment-stabilized manner during locomotion, depending on the perceptual consequences of locomotion. Keywords: spatial updating, body-stabilized spatial processing, environment-stabilized spatial processing

Individual variability in Zahlen-Verbindungs-test performance was identified in stages of the sensorimotor processing system using measures from female participants. Results showed a relation between speed of motor processing and intelligence.

While audiovisual integration is well known in speech perception, faces and speech are also informative with respect to speaker recognition. To date, audiovisual integration in the recognition of familiar people has never been demonstrated. Here we show systematic benefits and costs for the recognition of familiar voices when these are combined with time-synchronized articulating faces, of corresponding or noncorresponding speaker identity, respectively. While these effects were strong for familiar voices, they were smaller or nonsignificant for unfamiliar voices, suggesting that the effects depend on the previous creation of a multimodal representation of a person's identity. Moreover, the effects were reduced or eliminated when voices were combined with the same faces presented as static pictures, demonstrating that the effects do not simply reflect the use of facial identity as a 'cue' for voice recognition. This is the first direct evidence for audiovisual integration in person recognition.

We motivate and present a definition of an embodied, grounded individual sensorimotor interaction history, which captures the time-extended behavior characteristics of humans and many animals. We present an architecture that […]

Both animal and human studies suggest that action goals are defined in external coordinates regardless of their sensory modality. The present study used an auditory-manual task to test whether the default use of such an external reference frame is innately determined or instead acquired during development because of the increasing dominance of vision over manual control. In Experiment I, congenitally blind, late blind, and age-matched sighted adults had to press a left or right response key depending on the bandwidth of pink noise bursts presented from either the left or right loudspeaker. Although the spatial location of the sounds was entirely task-irrelevant, all groups responded more efficiently with uncrossed hands when the sound was presented from the same side as the responding hand ('Simon effect'). This effect reversed with crossed hands only in the congenitally blind: They responded faster with the hand that was located contralateral to the sound source, in Experiment II, the instruction to the participants was changed: They now had to respond with the hand located next to the sound source. In contrast to Experiment I ('Simon-task'), this task required an explicit matching of the sound's location with the position of the responding hand. In Experiment II, the congenitally blind participants showed a significantly larger crossing deficit than both the sighted and late blind adults. This pattern of results implies that developmental vision induces the default use of an external coordinate frame for multisensory action control; this facilitates not only visual but also auditory-manual control. action control | blindness | multisensory | spatial compatibility effects

We hypothesize that one role of sensorimotor feedback for rhythmic movements in biological organisms is to synchronize the frequency of movements to the mechanical resonance of the body. Our hypothesis is based on recent studies that have shown the advantage of moving at mechanical resonance and how such synchronization may be possible in biology. We test our hypothesis by developing a physical system that consists of a silicon-neuron central pattern generator (CPG), which controls the motion of a beam, and position sensors that provide feedback information to the CPG. The silicon neurons that we use are integrated circuits that generate neural signals based on the Hodgkin-Huxley dynamics. We use this physical system to develop a model of the interaction between the sensory feedback and the complex dynamics of the neurons to create the closed-loop system behavior. This model is then used to describe the conditions under which our hypothesis is valid and the general effects of sensorimotor feedback on the rhythmic movements of this system. Index Terms--Central pattern generators, rhythmic movements, sensorimotor feedback, silicon neurons.

Recent models of the conceptual system hold that concepts are grounded in simulations of actual experiences with instances of those concepts in sensory-motor systems (e.g., Barsalou, 1999, 2003; Solomon & Barsalou, 2001). Studies supportive of such a view have shown that verifying a property of a concept in one modality, and then switching to verify a property of a different concept in a different modality generates temporal processing costs similar to the cost of switching modalities in perception. In addition to non-emotional concepts, the present experiment investigated switching costs in verifying properties of positive and negative (emotional) concepts. Properties of emotional concepts were taken from vision, audition, and the affective system. Parallel to switching costs in neutral concepts, the study showed that for positive and negative concepts, verifying properties from different modalities produced processing costs such that reaction times were longer and error rates were higher. Importantly, this effect was observed when switching from the affective system to sensory modalities, and vice-versa. These results support the embodied cognition view of emotion in humans. Keywords: Embodied cognition; Affects; Simulation; Concepts; Knowledge; Emotion

The rate and pattern of rectal distension affect rectal distensibility, perception, and anal relaxation in health. Because rectal urgency is a prominent symptom in fecal incontinence (FI), we assessed rectal distensibility, contractions, perception, and anal pressures during rectal distention in 21 healthy, asymptomatic women (age 61 [+ or -] 2 yr, mean [+ or -] SE) and 51 women with FI (60 [+ or -] 2 yr). Rectal staircases (0-32 mmHg, 4-mm steps) and ramp distensions [0-200 ml at 25, 50, and 100 ml/min with a phase of sustained distension (SD), lasting 1 min, between inflation and deflation]. The rectum was stiffer during rapid than slow ramp distention. This effect was more prominent at a lower volume (50 ml) and was also more pronounced in older subjects and in FI. A rectal contractile response was observed not only during inflation but also during SD and during deflation. During inflation, this contractile response was rate dependent in controls but not in FI. During staircase but not ramp distentions, the threshold for the desire to defecate was lower in FI. During ramp distentions, the duration of perception was significantly longer in FI. The rate of distention did not affect rectal perception (i.e., sensory thresholds or duration of perception) during ramp distentions. Baseline anal pressures and the magnitude of anal relaxation during rectal distention were also reduced in FI. In addition to reduced rectal capacity and compliance, women with FI had an exaggerated rate-dependent reduction in rectal distensibility, lower sensory thresholds, and more prolonged perception, indicative of rectoanal dysfunctions. hypersensitivity; compliance; perception; rate; sensation; contractions

Iron deficiency in human infancy reportedly leads to developmental delays and changes in neurobiology that may be irreversible. Using a rodent model, the present study examined whether dietary iron deficiency late in pregnancy and during lactation alters sensorimotor development and brain monoaminergic systems. Rats were assigned to 1 of 4 dietary treatments during gestation and lactation: 1) iron sufficient control; 2) prenatal iron deficiency beginning on gestational d 15 (G15); 3) postnatal iron deficiency beginning on postnatal d 4 (P4); 4) iron deficiency beginning on G15 followed by an iron sufficient diet on P4. Developmental milestones, open field behavior, brain iron and proteins, monoamines, and their transporters were evaluated between P6 and P21. Only G15 iron deficient rats had greater dopaminergic activity than controls as indicated by increased tyrosine hydroxylase levels, phosphorylated tyrosine hydroxylase levels, and cellular dopamine in prefrontal cortex and striatum at P15. These rats also showed delayed eye opening, ear development, and reduced locomotor activity. Iron repletion at P4 returned most measures to control levels by the time of weaning. Postnatal iron deficiency reduced striatal and ventral midbrain iron as well as cellular dopamine levels in prefrontal cortex and striatum at P21. Developmental delays in ear development and achievement in bar holding and surface righting also resulted from postnatal iron deficiency. These results indicate that iron deficiency begun at G15 affects early dopamine neurobiology, the development of specific developmental milestones, and behavior in preweaned rats.

One generally has the impression that one feels one's hand at the same location as one sees it. However, because our brain deals with possibly conflicting visual and proprioceptive information about hand position by combining it into an optimal estimate of the hand's location, mutual calibration is not necessary to achieve such a coherent percept. Does sensory integration nevertheless entail sensory calibration? We asked subjects to move their hand between visual targets. Blocks of trials without any visual feedback about their hand's position were alternated with blocks with veridical visual feedback. Whenever vision was removed, individual subjects' hands slowly drifted toward the same position to which they had drifted on previous blocks without visual feedback. The time course of the observed drift depended in a predictable manner (assuming optimal sensory combination) on the variable errors in the blocks with and without visual feedback. We conclude that the optimal use of unaligned sensory information, rather than changes within either of the senses or an accumulation of execution errors, is the cause of the frequently observed movement drift. The conclusion that seeing one's hand does not lead to an alignment between vision and proprioception has important consequences for the interpretation of previous work on visuomotor adaptation. adaptation | motor control | vision | proprioception | drift

Human swallowing involves the integration of sensorimotor information with complexities such as taste; however, the interaction between the taste of food and its effects on swallowing control remains unknown. We assessed the effects of pleasant (sweet) and aversive (bitter) tastes on human cortical swallowing motor pathway excitability. Healthy adult male volunteers underwent a transcranial magnetic stimulation (TMS) mapping study (n = 9, mean age: 34 yr) to assess corticobulbar excitability before and up to 60 min after 10-min liquid infusions either 1) as swallowing tasks or 2) delivered directly into the stomach. Infusions were composed of sterile water (neutral), 10% glucose (sweet), and 0.5 mM quinine hydrochloride (bitter). The order of delivery was randomized, and each infusion was given on separate days. Pharyngeal motor-evoked potentials (PMEPs) were recorded from an intraluminal catheter as a measure of corticobulbar excitability and compared using repeated-measures and one-way ANOVA. After the swallowing task (water, glucose, or quinine), repeated-measures ANOVA revealed a significant time interaction across tastants (P [less than or equal to] 0.01). One-way ANOVA for each taste showed changes in PMEP amplitudes for both quinine (P [less than or equal to] 0.001) and glucose (P [less than or equal to] 0.009) solutions but not for water (P = 0.1). Subsequent t-tests showed that glucose and quinine reduced PMEPs by 47% (SD 34) and 37% (SD 54), respectively, at 30 min (P [less than or equal to] 0.03). No changes were observed after the infusion of any solution directly into the stomach (P = 0.51). In conclusion, cortical swallowing pathways are similarly modulated by both sweet and bitter tasting stimuli. Changes likely reflect a close interaction between taste and swallowing activity mediated in the central nervous system. transcranial magnetic stimulation; gustatory; deglutition; sensation; healthy volunteer

Studies on the behavior of the vestibulo-ocular reflex (VOR) reveal that the monocular reflex gain is adjusted according to target position relative to each eye. In this paper, we present a nonlinear approach in modeling the viewing-context dependency of the slow-phase angular VOR. We show that including appropriate nonlinearities in the responses of premotor neurons in the brainstem is sufficient to account for the online modulation of the VOR with target position. This approach allows very complex behaviors in response to sensory patterns without resorting to currently assumed cortical computations. A local premotor topology with nonlinear properties has repercussions in the study of all ocular reflexes, since it implies context dependent dynamics in all behavioral responses (pursuit, optokinetic, VOR, saccades, etc.) that share this network. Local nonlinearities in spinal circuits could similarly influence the context dependence of other motor systems (such as stretch reflex modulation during rhythmic walking). Index Terms--Eye movement, neural topology, reflex modulation, sensory-motor mapping, vestibulo-ocular reflex.

ABSTRACT. The current study was based on the hypothesis that chronic developmental stuttering in adults involves a deficiency in oral kinesthesia. The authors used a target-accuracy task to compare oral [...]