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Background and ObjectivesThere is growing evidence that bilingualism can induce neuroplasticity and modulate neural efficiency, resulting in greater resistance to neurologic disease. However, whether bilingualism is beneficial to neural health in the presence of epilepsy is unknown. We tested whether bilingual individuals with temporal lobe epilepsy (TLE) have improved whole-brain structural white matter network organization.MethodsHealthy controls and individuals with TLE recruited from 2 specialized epilepsy centers completed diffusion-weighted MRI and neuropsychological testing as part of an observational cohort study. Whole-brain connectomes were generated via diffusion tractography and analyzed using graph theory. Global analyses compared network integration (path length) and specialization (transitivity) in TLE vs controls and in a 2 (left vs right TLE) × 2 (bilingual vs monolingual) model. Local analyses compared mean local efficiency of predefined frontal-executive and language (i.e., perisylvian) subnetworks. Exploratory correlations examined associations between network organization and neuropsychological performance.ResultsA total of 29 bilingual and 88 monolingual individuals with TLE matched on several demographic and clinical variables and 81 age-matched healthy controls were included. Globally, a significant interaction between language status and side of seizure onset revealed higher network organization in bilinguals compared with monolinguals but only in left TLE (LTLE). Locally, bilinguals with LTLE showed higher efficiency in frontal-executive but not in perisylvian networks compared with LTLE monolinguals. Improved whole-brain network organization was associated with better executive function performance in bilingual but not monolingual LTLE.DiscussionHigher white matter network organization in bilingual individuals with LTLE suggests a neuromodulatory effect of bilingualism on whole-brain connectivity in epilepsy, providing evidence for neural reserve. This may reflect attenuation of or compensation for epilepsy-related dysfunction of the left hemisphere, potentially driven by increased efficiency of frontal-executive networks that mediate dual-language control. This highlights a potential role of bilingualism as a protective factor in epilepsy, motivating further research across neurologic disorders to define mechanisms and develop interventions.

OBJECTIVE Risk for memory decline is a common concern for individuals with temporal lobe epilepsy (TLE) undergoing surgery. Global and local network abnormalities are well documented in TLE. However, it is less known whether network abnormalities predict postsurgical memory decline. The authors examined the role of preoperative global and local white matter network organization and risk of postoperative memory decline in TLE. METHODS One hundred one individuals with TLE (n = 51 with left TLE and 50 with right TLE) underwent preoperative T1-weighted MRI, diffusion MRI, and neuropsychological memory testing in a prospective longitudinal study. Fifty-six age- and sex-matched controls completed the same protocol. Forty-four patients (22 with left TLE and 22 with right TLE) subsequently underwent temporal lobe surgery and postoperative memory testing. Preoperative structural connectomes were generated via diffusion tractography and analyzed using measures of global and local (i.e., medial temporal lobe [MTL]) network organization. Global metrics measured network integration and specialization. The local metric was calculated as an asymmetry of the mean local efficiency between the ipsilateral and contralateral MTLs (i.e., MTL network asymmetry). RESULTS Higher preoperative global network integration and specialization were associated with higher preoperative verbal memory function in patients with left TLE. Higher preoperative global network integration and specialization, as well as greater leftward MTL network asymmetry, predicted greater postoperative verbal memory decline for patients with left TLE. No significant effects were observed in right TLE. Accounting for preoperative memory score and hippocampal volume asymmetry, MTL network asymmetry uniquely explained 25%–33% of the variance in verbal memory decline for left TLE and outperformed hippocampal volume asymmetry and global network metrics. MTL network asymmetry alone produced good diagnostic classification of memory decline in left TLE (i.e., an area under the receiver operating characteristic curve of 0.80–0.84 and correct classification of 65%–76% of cases with cross-validation). CONCLUSIONS These preliminary data suggest that global white matter network disruption contributes to verbal memory impairment preoperatively and predicts postsurgical verbal memory outcomes in left TLE. However, a leftward asymmetry of MTL white matter network organization may confer the highest risk for verbal memory decline. Although this requires replication in a larger sample, the authors demonstrate the importance of characterizing preoperative local white matter network properties within the to-be-operated hemisphere and the reserve capacity of the contralateral MTL network, which may eventually be useful in presurgical planning.

PurposeBrain radiotherapy can impair fine motor skills (FMS). FMS are essential for activities of daily living, enabling hand-eye coordination for manipulative movements. We developed normal tissue complication probability (NTCP) models for decline in FMS after fractionated brain RT.MethodsOn a prospective trial, 44 primary brain tumor patients received fractioned RT, underwent high-resolution volumetric MRI and diffusion tensor imaging, and comprehensive FMS assessments (Delis-Kaplan Executive Function System Trail Making Test Motor Speed [DKEFS-MS], and Grooved Pegboard Dominant/Non-Dominant Hands [PDH/PNDH]) at baseline and 6 months post-RT. Regions of interest subserving motor function (including cortex, superficial white matter, thalamus, basal ganglia, and white matter tracts) were autosegmented using validated methods and manually verified. Dosimetric and clinical variables were included in multivariate NTCP models, using automated bootstrapped logistic regression, least absolute shrinkage and selection operator (LASSO) logistic regression, and random forests with nested cross-validation.ResultsHalf of patients showed decline on PNDH, 17 of 42 (40.4%) on PDH, and 11 of 44 (25%) on DKEFS-TM. Automated bootstrapped logistic regression selected a one-term model including maximum dose to dominant postcentral white matter. LASSO selected this term and steroid use. The top five variables in random forest were all dosimetric: mean and maximum dose to dominant corticospinal tract; maximum dose to dominant thalamus; mean dose to dominant caudate; maximum dose to dominant postcentral white matter. This technique performed best with AUC 0.69 (95% CI 0.68 – 0.70) on nested cross-validation.ConclusionWe present the first NTCP models for FMS impairment after brain RT. Dose to several supratentorial motor-associated ROIs correlated with decline in dominant hand fine motor dexterity in primary brain tumor patients, outperforming clinical variables. These data can guide prospective fine motor-sparing strategies for brain RT.

Background and ObjectivesRisk for memory decline is a substantial concern in patients with temporal lobe epilepsy (TLE) undergoing anterior temporal lobectomy (ATL). Although prior studies have identified associations between memory and integrity of white matter (WM) networks within the medial temporal lobe (MTL) preoperatively, we contribute a study examining whether microstructural asymmetry of deep and superficial WM networks within the MTL predicts postoperative memory decline.MethodsPatients with drug-resistant TLE were recruited from 2 epilepsy centers in a prospective longitudinal study. All patients completed preoperative T1 and diffusion-weighted MRI (DWI) as well as preoperative and postoperative neuropsychological testing. Preoperative fractional anisotropy (FA) of the WM directly beneath the neocortex (i.e., superficial WM [SWM]) and of deep WM tracts associated with memory were calculated. Asymmetry was calculated for hippocampal volume and FA of each WM tract or region and examined in linear and logistic regressions with preoperative to postoperative memory change as the primary outcome.ResultsData were analyzed from 42 patients with TLE (19 left TLE [LTLE], 23 right TLE [RTLE]) who underwent ATL. Leftward FA asymmetry of the entorhinal SWM was associated with decline on prose and associative recall in LTLE, whereas leftward FA asymmetry of the uncinate fasciculus (UNC) was associated with decline on prose recall only. After controlling for preoperative memory score and hippocampal volume, leftward FA asymmetry of the entorhinal SWM uniquely contributed to decline in both prose and associative recall (β = −0.46; SE 0.14 and β = −0.68; SE 0.22, respectively) and leftward FA asymmetry of the UNC uniquely contributed to decline in prose recall (β = −0.31; SE 0.14). A model combining asymmetry of hippocampal volume and entorhinal FA correctly classified memory outcomes in 79% of patients with LTLE for prose (area under the curve [AUC] 0.89; sensitivity 82%; specificity 75%) and 81% of patients for associative (AUC 0.79; sensitivity 83%; specificity 80%) recall. Entorhinal SWM asymmetry was the strongest predictor in both models.DiscussionPreoperative asymmetry of deep WM and SWM integrity within the MTL is a strong predictor of postoperative memory decline in TLE, suggesting that surgical decision-making may benefit from considering each patient's WM network adequacy and reserve in addition to hippocampal integrity.Classification of EvidenceThis study provides Class II evidence that preoperative asymmetry of deep WM and SWM integrity within the MTL is a predictor of postoperative memory decline.

Inhibitory control is thought to play a key role in how bilinguals switch languages and may decline in aging. We tested these hypotheses by examining age group differences in the reversed language dominance effect-a signature of inhibition of the dominant language that leads bilinguals to name pictures more slowly in the dominant than the nondominant language in mixed-language testing blocks. Twenty-five older and 48 younger Spanish-English bilinguals completed a cued language-switching task. To test if inhibition is applied at the whole-language or lexical level, we first presented one set of pictures repeatedly, then introduced a second list halfway through the experiment. Younger bilinguals exhibited significantly greater reversed language dominance effects than older bilinguals (who exhibited nonsignificant language dominance effects). In younger bilinguals, dominance reversal transferred to, and was even larger in, the second list (compared to the first). The latter result may suggest that inhibition is partially offset by repetition in ways that are not yet fully understood. More generally, these results support the hypotheses that aging impairs inhibitory control of the dominant language, which young bilinguals rely on to switch languages. Additionally, inhibition is applied primarily at the whole-language level, and speculatively, this form of language control may be analogous to nonlinguistic proactive control. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Investigators in neuroscience have turned to Big Data to address replication and reliability issues by increasing sample sizes, statistical power, and representativeness of data. These efforts unveil new questions about integrating data arising from distinct sources and instruments. We focus on the most frequently assessed cognitive domain - memory testing - and demonstrate a process for reliable data harmonization across three common measures. We aggregated global raw data from 53 studies totaling N = 10,505 individuals. A mega-analysis was conducted using empirical bayes harmonization to remove site effects, followed by linear models adjusting for common covariates. A continuous item response theory (IRT) model estimated each individual’s latent verbal learning ability while accounting for item difficulties. Harmonization significantly reduced inter-site variance while preserving covariate effects, and our conversion tool is freely available online. This demonstrates that large-scale data sharing and harmonization initiatives can address reproducibility and integration challenges across the behavioral sciences.TeaserWe present a global effort to devise harmonization procedures necessary to meaningfully leverage big data.

OBJECTIVE: Risk for memory decline is a common concern for individuals with temporal lobe epilepsy (TLE) undergoing surgery. Global and local network abnormalities are well-documented in TLE. However, it is less known whether network abnormalities predict post-surgical memory decline. We examined the role of pre-operative global and local white matter network organization in risk for post-operative memory decline in TLE. METHODS: One-hundred one individuals with TLE (51 left; L-TLE) and 56 controls underwent T1-weighted, diffusion-MRI and neuropsychological memory testing in a prospective longitudinal study. Forty-four patients subsequently underwent temporal lobe surgery and post-operative memory testing. Structural connectomes were generated via tractography and analyzed using measures of global (integration and specialization) and local (medial temporal lobe [MTL] specialization) network organization. RESULTS: Pre-operatively, higher global network integration and specialization were associated with higher verbal memory function in L-TLE. Higher pre-operative global network integration and specialization, as well as more leftward local specialization, predicted greater post-surgical verbal memory decline for L-TLE. Accounting for pre-operative memory score and hippocampal volume asymmetry, local network specialization additionally explained 25-33% of the variance in outcomes for L-TLE and outperformed hippocampal asymmetry. Local network specialization alone produced good diagnostic accuracy (AUC=.80-.84) in L-TLE. SIGNIFICANCE: Global white matter network disruption contributes to verbal memory impairment pre-operatively and predicts post-surgical memory outcomes in L-TLE. However, leftward asymmetry of MTL network organization confers the highest risk for memory decline. This demonstrates the importance of characterizing local network properties within the to-be-operated hemisphere and the reserve capacity of the contralateral MTL network.

The present study investigated cognitive mechanisms underlying the ability to stop "autocorrect" errors elicited by unexpected words in a read-aloud task, and the utility of autocorrection for predicting Alzheimer's disease (AD) biomarkers.Cognitively normal participants (totalParticipants produced more autocorrect errors in paragraphs with dominant than with nondominant targets, and with function than with content targets. Cognitively normal participants with high CSF Tau/Aβ42 (i.e., an AD-like biomarker profile) produced more autocorrect total errors than those below the Tau/Aβ42 threshold, an effect also significant with dominant-function targets alone (e.g., sayingDifficulty stopping autocorrect errors is associated with biomarkers indicating preclinical AD, and reveals promise as a diagnostic tool. Greater vulnerability of function over content words to autocorrection in individuals with AD-like biomarkers implicates monitoring and attention (rather than semantic processing) in the earliest of cognitive changes associated with AD risk. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

PURPOSE We investigated associations between imaging biomarkers of cerebellar injury and neurocognitive function among primary brain tumor patients receiving partial brain radiotherapy (RT). METHODS On a prospective trial, 65 patients underwent volumetric brain MRI, diffusion tensor imaging, and memory, executive function, language, attention, and processing speed (PS) assessment pre-, 3, 6, and 12 months post-RT. Delis-Kaplan Executive Function System Trail Making [DKEFS-TM] Visual Scanning and Number and Letter Sequencing and Wechsler-Adult Intelligence Scale-IV [WAIS] Coding subtests evaluated PS. Cerebellar regions of interest (ROIs) were autosegmented, including cortex and white matter (WM). Supratentorial cortical and WM structures subserving the above cognitive domains were also autosegmented. Supratentorial PS-associated ROIs included the posterior, mid-posterior, central, mid-anterior, and anterior corpus callosum along with the bilateral intrahemispheric WM. Volume (cm3) was measured in all ROIs at each timepoint. Diffusion biomarkers (fractional anisotropy [FA] and mean diffusivity [MD]) were measured in all WM structures at each timepoint. Linear mixed-effects models assessed cerebellar biomarkers as predictors of neurocognitive scores. If found to be associated, cerebellar biomarkers were subsequently evaluated as predictors of cognitive scores controlling for domain-specific supratentorial ROI biomarkers. RESULTS Left (p=0.04) and right (p< 0.001) cerebellar WM volume declined over time. Cerebellar biomarkers were not associated with memory, executive function, or language. Left cerebellar cortex atrophy correlated with worse DKEFS-TM Number (p=0.01) and Letter (p=0.01) Sequencing scores. Right cerebellar cortex atrophy correlated with worse DKEFS-TM Visual Scanning (p=0.02) and Number (p=0.03) and Letter (p=0.02) Sequencing scores. Greater right cerebellar WM MD correlated with worse DKFS-TM Visual Scanning performance (p=0.03). These associations remained significant after controlling for corpus callosum and intrahemispheric WM injury biomarkers. CONCLUSION Biomarkers of cerebellar injury correlated with worse post-RT PS, independent of corpus callosum and intrahemispheric WM damage. Cerebellar dose avoidance may preserve PS.

ObjectiveEmerging research highlights the importance of basal-temporal cortex, centered on the fusiform gyrus, to both pre-surgical naming ability and post-surgical naming outcomes in temporal lobe epilepsy (TLE). In this study, we investigate whether integrity of the white matter network that interconnects this basal region to the distributed language network affects naming ability and risk for post-surgical naming decline.MethodsPatients with drug-resistant TLE were recruited from two epilepsy centers in a prospective longitudinal study. The pre-surgical dataset included 50 healthy controls, 47 left TLE (L-TLE), and 41 right TLE (R-TLE) patients. All participants completed pre-surgical T1- and diffusion-weighted MRI (dMRI), as well as neuropsychological tests of auditory and visual naming. Nineteen L-TLE and 18 R-TLE patients underwent anterior temporal lobectomy (ATL) and also completed post-surgical neuropsychological testing. Pre-surgical fractional anisotropy (FA) of the white matter directly beneath the fusiform neocortex (i.e., superficial white matter; SWM) and of deep white matter tracts with connections to the basal-temporal cortex [inferior longitudinal fasciculus (ILF) and inferior frontal occipital fasciculus (IFOF)] was calculated. Clinical variables, hippocampal volume, and FA of each white matter tract or region were examined in linear regressions with naming scores, or change in naming scores, as the primary outcomes.ResultsPre-surgically, higher FA in the bilateral ILF, bilateral IFOF, and left fusiform SWM was associated with better visual and auditory naming scores (all ps&nbsp

Objective:The present study investigated the ability of the Multilingual Naming Test (MINT), a picture naming test recently added to the National Alzheimer’s Coordinating Center’s (NACC) Uniform Data Set neuropsychological test battery, to detect naming impairment (i.e., dysnomia) across stages of Alzheimer’s disease (AD).Method:Data from the initial administration of the MINT were obtained on NACC participants who were cognitively normal (N= 3,981) or diagnosed with mild cognitive impairment (N= 852) or dementia (N= 1,148) with presumed etiology of AD. Dementia severity was rated using the Clinical Dementia Rating (CDR) scale.Results:Cross-sectional multiple regression analyses revealed significant effects of diagnostic group, sex, education, age, and race on naming scores. Planned comparisons collapsing across age and education groups revealed significant group differences in naming scores across levels of dementia severity. ROC curve analyses showed good diagnostic accuracy of MINT scores for distinguishing cognitively normal controls from AD dementia, but not from MCI. Within the cognitively normal group, there was a robust interaction between age and education such that naming scores exhibited the most precipitous drop across age groups for the least educated participants. Additionally, education effects were stronger in African-Americans than in Whites (a race-by-education interaction), and race effects were stronger in older than in younger age groups (a race-by-age interaction).Conclusions:The MINT successfully detects naming deficits at different levels of cognitive impairment in patients with MCI or AD dementia, but comparison to age, sex, race, and education-corrected norms to determine impairment is essential.

Individuals with left temporal lobe epilepsy (TLE) have a higher rate of atypical (i.e., bilateral or right hemisphere) language lateralization compared to healthy controls. In addition, bilinguals have been observed to have a less left-lateralized pattern of language representation. We examined the combined influence of bilingual language experience and side of seizure focus on language lateralization profiles in TLE to determine whether bilingualism promotes re-organization of language networks. Seventy-two monolingual speakers of English (21 left TLE; LTLE, 22 right TLE; RTLE, 29 age-matched healthy controls; HC) and 24 English-dominant bilinguals (6 LTLE, 7 RTLE, 11 HC) completed a lexical-semantic functional MRI task and standardized measures of language in English. Language lateralization was determined using laterality indices based on activations in left vs right homologous perisylvian regions-of-interest (ROIs). In a fronto-temporal ROI, LTLE showed the expected pattern of weaker left language lateralization relative to HC, and monolinguals showed a trend of weaker left language lateralization relative to bilinguals. Importantly, these effects were qualified by a significant group by language status interaction, revealing that bilinguals with LTLE had greater rightward language lateralization relative to monolingual LTLE, with a large effect size particularly in the lateral temporal region. Rightward language lateralization was associated with better language scores in bilingual LTLE. These preliminary findings suggest a combined effect of bilingual language experience and a left hemisphere neurologic insult, which may together increase the likelihood of language re-organization to the right hemisphere. Our data underscore the need to consider bilingualism as an important factor contributing to language laterality in patients with TLE. Bilingualism may be neuroprotective pre-surgically and may mitigate post-surgical language decline following left anterior temporal lobectomy, which will be important to test in larger samples.

Epilepsy is a common neurological disorder associated with alterations in cortical and subcortical brain networks. Despite a historical focus on gray matter regions involved in seizure generation and propagation, the role of white matter (WM) network disruption in epilepsy and its comorbidities has sparked recent attention. In this review, we describe patterns of WM alterations observed in focal and generalized epilepsy syndromes and highlight studies linking WM disruption to cognitive and psychiatric comorbidities, drug resistance, and poor surgical outcomes. Both tract-based and connectome-based approaches implicate the importance of extratemporal and temporo-limbic WM disconnection across a range of comorbidities, and an evolving literature reveals the utility of WM patterns for predicting outcomes following epilepsy surgery. We encourage new research employing advanced analytic techniques (e.g., machine learning) that will further shape our understanding of epilepsy as a network disorder and guide individualized treatment decisions. We also address the need for research that examines how neuromodulation and other treatments (e.g., laser ablation) affect WM networks, as well as research that leverages larger and more diverse samples, longitudinal designs, and improved magnetic resonance imaging acquisitions. These steps will be critical to ensuring generalizability of current research and determining the extent to which neuroplasticity within WM networks can influence patient outcomes.

The current study investigated how Alzheimer’s disease (AD) affects production of speech errors in reading-aloud. Twelve Spanish-English bilinguals with AD and 19 matched controls read-aloud 8 paragraphs in four conditions (a) English-only, (b) Spanish-only, (c) English-mixed (mostly English with 6 Spanish words), and (d) Spanish-mixed (mostly Spanish with 6 English words). Reading elicited language intrusions (e.g., saying la instead of the), and several types of within-language errors (e.g., saying their instead of the). Patients produced more intrusions (and self-corrected less often) than controls, particularly when reading non-dominant language paragraphs with switches into the dominant language. Patients also produced more within-language errors than controls, but differences between groups for these were not consistently larger with dominant versus non-dominant language targets. These results illustrate the potential utility of speech errors for diagnosis of AD, suggest a variety of linguistic and executive control impairments in AD, and reveal multiple cognitive mechanisms needed to mix languages fluently. The observed pattern of deficits, and unique sensitivity of intrusions to AD in bilinguals, suggests intact ability to select a default language with contextual support, to rapidly translate and switch languages in production of connected speech, but impaired ability to monitor language membership while regulating inhibitory control.

Objective The current study investigated how Alzheimer's disease (AD) affects production of speech errors in reading-aloud of mixed-language passages with language switches on cognates (e.g., family/familia), noncognates (e.g., people/gente), and function words (the/la). Method Twelve Spanish-English bilinguals with AD and 22 controls read-aloud 8 paragraphs in 4 conditions: (a) English-default content switches, (b) English-default function switches, (c) Spanish-default content switches, and (d) Spanish-default function switches. Results Reading elicited language intrusions (e.g., saying la instead of the), and several types of within-language errors (e.g., saying their instead of the). Reversed language-dominance effects were intact in AD; both patients and controls produced many intrusions on dominant language targets, and relatively fewer intrusions on nondominant language targets. The opposite held for within-language errors, which were more common with nondominant than dominant targets. Patients produced the most intrusion errors with cognate switch words (which best distinguished patients from controls in ROC curves of all speech error types), while controls had equal difficulty switching on cognate and function word targets. Conclusions Reversed language-dominance effects appear to illustrate automatic inhibitory control over the dominant language, but could instead reflect limited resources available for monitoring when completing a task in the nondominant language. The greater sensitivity of intrusion errors with cognate than with function word targets for distinguishing patients from controls implies that language control may be aided by relatively intact knowledge of grammatical constraints over code-switching in bilinguals with AD. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

When switching languages, bilinguals recruit a language control network that overlaps with brain regions known to support general cognitive control, but it is unclear whether these same regions are recruited in passive comprehension of language switches. Using fMRI with a blocked design, 24 Spanish-English bilinguals silently read 36 paragraphs in which the default language was Spanish or English, and that had either (1) no switches, (2) function word switches or (3) content word switches. Relative to no switches, function switches activated the right IFG, bilateral MFG, and left IPL/SMG. In contrast, switching on content words produced limited neural switching costs observed only in the left IFG. Switching into the dominant language was more costly in the right SMG than switching into the nondominant language, and neural switching costs were correlated with switching costs in the dominant language in cued picture-naming. Seemingly passive reading comprehension involves brain regions known to support cognitive control in active switching during production, possibly reflecting the operation of a modality-general switch mechanism.

The current study examined the cognitive mechanisms underlying task and language switching by comparing them with each other, and with flanker task performance, at multiple points of the response time distribution. Ninety-eight Spanish-English bilinguals completed cued language and color-shape switching tasks, and 2 versions of a nonlinguistic flanker task. Bilinguals responded more quickly and exhibited smaller mixing costs in the language task, but surprisingly exhibited larger switching costs than in the color-shape task. This language-task disadvantage was especially apparent in slower reaction times (RTs), because switching costs increased significantly through the slowest end of the RT distribution only in the language task (but not in the color-shape task). Although the flanker task resembled the language task to a greater extent than the color-shape task in some measures (e.g., flanker effects were largest in the slowest RT bins, like language switching costs), in other measures the 2 switching tasks resembled each other and the flanker task stood out as different (i.e., trial sequence effects and correlations between tasks in various cost measures). These results reveal that different measures of switching costs even in tasks with very similar designs, vary in the extent to which they measure switching ability, both between tasks, and even between different trials within the same task. Distributional analysis of RTs across tasks suggests that slow responses, particularly when switching between non-naturally competing responses, might not measure switching ability at all, and raises the possibility that smaller switching costs can even reflect reduced ability to juggle tasks in some cases. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Tip-of-the-tongue (TOT) states often entail a phenomenological sense that retrieval is blocked, but incomplete activation is more commonly assumed as the underlying mechanism. Bilinguals have more TOTs than monolinguals, and commonly report that one language feels less accessible after immersion in another although evidence for this is minimal. Kreiner and Degani (2015) reported Russian-Hebrew bilinguals had more TOTs for Hebrew words after watching a movie in Russian, and surprisingly, native Hebrew speakers who did not know Russian also had more TOTs. Aiming to replicate this work, 72 Spanish-English bilinguals and 72 monolinguals completed a similar protocol in Experiment 1. Bilinguals and monolinguals exhibited significant and similarly sized interference effects after watching a Spanish movie. In Experiment 2, monolinguals completed five conditions: (a) Russian movie, (b) Spanish with English subtitles movie, (c) American Sign Language movie, (d) Spanish movie without audio and instructions to copy movements, and (e) a non-linguistic control (playing Tetris). All but the last two conditions elicited interference (increased TOTs and reduced correct retrievals). We suggest that even a brief pseudo-immersion experience can interfere with lexical-retrieval in the dominant language possibly via whole-language inhibition, supporting notions of blocked retrieval, albeit not at the level of individual lexical representations as previously proposed.

In the last decade, the debate about the causal role of the motor system in speech perception has been reignited by demonstrations that motor processes are engaged during the processing of speech sounds. However, the exact role of the motor system in auditory speech processing remains elusive. Here we evaluate which aspects of auditory speech processing are affected, and which are not, in a stroke patient with dysfunction of the speech motor system. The patient’s spontaneous speech was marked by frequent phonological/articulatory errors, and those errors were caused, at least in part, by motor-level impairments with speech production. We found that the patient showed a normal phonemic categorical boundary when discriminating two nonwords that differ by a minimal pair (e.g., ADA-AGA). However, using the same stimuli, the patient was unable to identify or label the nonword stimuli (using a button-press response). A control task showed that he could identify speech sounds by speaker gender, ruling out a general labeling impairment. These data suggest that the identification (i.e. labeling) of nonword speech sounds may involve the speech motor system, but that the perception of speech sounds (i.e., discrimination) does not require the motor system. This means that motor processes are not causally involved in perception of the speech signal, and suggest that the motor system may be used when other cues (e.g., meaning, context) are not available.

Bilingual language switching may increase general switching efficiency, but the evidence on this question is mixed. We hypothesized that group differences in switching might be stronger at a long cue-target interval (CTI), which may better tap general switching abilities (Yehene & Meiran, 2007). Eighty Spanish-English bilinguals and 80 monolinguals completed a color-shape switching task, and an analogous language-switching task, varying CTI (short vs. long) in both tasks. With longer preparation time (long CTI), bilinguals exhibited significantly smaller task-switching costs than monolinguals, but only in the first half of trials. Group differences diminished with practice, though practice benefitted RTs on short CTI trials more than long, and bilinguals committed fewer errors with practice especially at short CTI. Groups did not differ in mixing costs; however, across CTIs and tasks, bilinguals and monolinguals alike, exhibited robust correlations between mixing costs, but not between switching costs. These results confirm an association between bilingualism and switching efficiency that may be magnified with manipulations that target general switching ability (or could reflect better ability to take advantage of preparation time). However, practice effects observed within experimental paradigms, and between task correlations in costs, may reflect cognitive mechanisms specific to laboratory tasks much more than associations with general switching ability and executive control mechanisms-for which more reliable and valid measures can hopefully be developed in future work. (PsycINFO Database Record

Structural adaptations in brain regions involved in domain-general cognitive control are associated with life-long bilingualism and may contribute to the executive function advantage of bilinguals over monolinguals. To the degree that these adaptations support bilingualism, their disruption by Alzheimer's disease (AD) may compromise the ability to maintain proficiency in two languages, particularly in the less proficient, or nondominant, language that has greater control demands. The present study assessed this possibility in Spanish-English bilinguals with AD (n = 21) and cognitively normal controls (n = 30) by examining the brain correlates of dominant versus nondominant language performance on the Multilingual Naming Test (MINT), adjusting for age and education. There were no significant structural correlates of naming performance for either language in controls. In patients with AD, dominant language MINT performance was associated with cortical thickness of the entorhinal cortex and middle temporal gyrus, consistent with previous findings of temporal atrophy and related decline of naming abilities in AD. Nondominant language MINT performance, in contrast, was correlated with thickness of the left caudal anterior cingulate cortex (ACC), a central cognitive control region involved in error monitoring and task switching. The relationship between naming in the nondominant language and ACC in patients with AD but not in controls may reflect increased reliance on the ACC for nondominant language use in the face of atrophy of other control network components. The results are consistent with the possibility that the increased burden nondominant language use places on cognitive control systems compromised in AD may account for faster nondominant than dominant language decline in AD.

Motor theories of perception posit that motor information is necessary for successful recognition of actions. Perhaps the most well known of this class of proposals is the motor theory of speech perception, which argues that speech recognition is fundamentally a process of identifying the articulatory gestures (i.e. motor representations) that were used to produce the speech signal. Here we review neuropsychological evidence from patients with damage to the motor system, in the context of motor theories of perception applied to both manual actions and speech. Motor theories of perception predict that patients with motor impairments will have impairments for action recognition. Contrary to that prediction, the available neuropsychological evidence indicates that recognition can be spared despite profound impairments to production. These data falsify strong forms of the motor theory of perception, and frame new questions about the dynamical interactions that govern how information is exchanged between input and output systems.

Color is important in our daily interactions with objects, and plays a role in both low- and high-level visual processing. Previous neuropsychological studies have shown that color perception and object-color knowledge can doubly dissociate, and that both can dissociate from processing of object form. We present a case study of an individual who displayed an impairment for knowledge of the typical colors of objects, with preserved color perception and color naming. Our case also presented with a pattern of, if anything, worse performance for naming living items compared to non-living things. The findings of the experimental investigation are evaluated in light of two theories of conceptual organization in the brain: the Sensory/Functional Theory and the Domain-Specific Hypothesis. The dissociations observed in this case compel a model in which sensory/motor modality and semantic domain jointly constrain the organization of object knowledge.