Posterior Middle Temporal Gyrus Research Articles

The spatiotemporal dynamics of semantic integration in the human brain

Language depends critically on the integration of lexical information across multiple words to derive semantic concepts. Limitations of spatiotemporal resolution have previously rendered it difficult to isolate processes involved in semantic integration. We utilized intracranial recordings in epilepsy patients (n = 58) who read written word definitions. Descriptions were either referential or non-referential to a common object. Semantically referential sentences enabled high frequency broadband gamma activation (70–150 Hz) of the inferior frontal sulcus (IFS), medial parietal cortex, orbitofrontal cortex (OFC) and medial temporal lobe in the left, language-dominant hemisphere. IFS, OFC and posterior middle temporal gyrus activity was modulated by the semantic coherence of non-referential sentences, exposing semantic effects that were independent of task-based referential status. Components of this network, alongside posterior superior temporal sulcus, were engaged for referential sentences that did not clearly reduce the lexical search space by the final word. These results indicate the existence of complementary cortical mosaics for semantic integration in posterior temporal and inferior frontal cortex.

The visuo-sensorimotor substrate of co-speech gesture processing

Co-speech gestures are integral to human communication and exhibit diverse forms, each serving a distinct communication function. However, existing literature has focused on individual gesture types, leaving a gap in understanding the comparative neural processing of these diverse forms. To address this, our study investigated the neural processing of two types of iconic gestures: those representing attributes or event knowledge of entity concepts, beat gestures enacting rhythmic manual movements without semantic information, and self-adaptors. During functional magnetic resonance imaging, systematic randomization and attentive observation of video stimuli revealed a general neural substrate for co-speech gesture processing primarily in the bilateral middle temporal and inferior parietal cortices, characterizing visuospatial attention, semantic integration of cross-modal information, and multisensory processing of manual and audiovisual inputs. Specific types of gestures and grooming movements elicited distinct neural responses. Greater activity in the right supramarginal and inferior frontal regions was specific to self-adaptors, and is relevant to the spatiomotor and integrative processing of speech and gestures. The semantic and sensorimotor regions were least active for beat gestures. The processing of attribute gestures was most pronounced in the left posterior middle temporal gyrus upon access to knowledge of entity concepts. This fMRI study illuminated the neural underpinnings of gesture-speech integration and highlighted the differential processing pathways for various co-speech gestures.

The neural correlates of sub-lexical semantics and its integration with the lexical meaning in reading Chinese characters

The semantic neural routes in contemporary models of visual word recognition are mainly constructed based on lexical-semantic processing. However, the neural bases of processing semantic cues embodied in sub-lexical units are less clear. The current fMRI study takes the ideographic property of Chinese characters (The semantic radical can provide a semantic cue for the character's meaning) to explore the brain mechanisms of sub-lexical semantic processing and its interaction with lexical-semantic processing in a lexical decision task. The GLM results and further ROI analysis revealed that the lexical-semantic processing relied on the left posterior Middle Temporal Gyrus (pMTG) and Angular Gyrus (AG); the sub-lexical semantic processing relied on the left middle MTG (mMTG) and AG; their integration relied on the left Anterior Temporal Lobe (ATL). It sheds light on investigating the neural circuit of the semantic processing in visual word reading.

Semantic-specific and domain-general mechanisms for integration and update of contextual information.

Recent research has highlighted the importance of domain-general processes and brain regions for language and semantic cognition. Yet, this has been mainly observed in executively demanding tasks, leaving open the question of the contribution of domain-general processes to natural language and semantic cognition. Using fMRI, we investigated whether neural processes reflecting context integration and context update-two key aspects of naturalistic language and semantic processing-are domain-specific versus domain-general. Thus, we compared neural responses during the integration of contextual information across semantic and non-semantic tasks. Whole-brain results revealed both shared (left posterior-dorsal inferior frontal gyrus, left posterior inferior temporal gyrus, and left dorsal angular gyrus/intraparietal sulcus) and distinct (left anterior-ventral inferior frontal gyrus, left anterior ventral angular gyrus, left posterior middle temporal gyrus for semantic control only) regions involved in context integration and update. Furthermore, data-driven functional connectivity analysis clustered domain-specific versus domain-general brain regions into distinct but interacting functional neural networks. These results provide a first characterisation of the neural processes required for context-dependent integration during language processing along the domain-specificity dimension, and at the same time, they bring new insights into the role of left posterior lateral temporal cortex and left angular gyrus for semantic cognition.

Hippocampal functional connectivity mediates the association between cardiorespiratory fitness and cognitive function in healthy young adults.

Higher cardiorespiratory fitness (CRF) induces neuroprotective effects in the hippocampus, a key brain region for memory and learning. We investigated the association between CRF and functional connectivity (FC) of the hippocampus in healthy young adults. We also examined the association between hippocampal FC and neurocognitive function. Lastly, we tested whether hippocampal FC mediates the association between 2-Min Walk Test (2MWT) and neurocognitive function. 913 young adults (28.7 ± 3.7 years) from the Human Connectome Project were included in the analyses. The 2MWT performance result was used as a proxy for cardiovascular endurance. Fluid and crystalized composite neurocognitive scores were used to assess cognition. Resting-state functional MRI data were processed to measure hippocampal FC. Linear regression was used to examine the association between 2MWT, hippocampal FC, and neurocognitive outcomes after controlling for age, sex, years of education, body mass index, systolic blood pressure, and gait speed. Better 2MWT performance was associated with greater FC between the anterior hippocampus and right posterior cingulate and left middle temporal gyrus. No associations between 2MWT and posterior hippocampal FC, whole hippocampal FC, and caudate FC (control region) were observed. Greater anterior hippocampal FC was associated with better crystalized cognition scores. Lastly, greater FC between the anterior hippocampus and right posterior cingulate mediated the association between better 2MWT scores and higher crystalized cognition scores. Anterior hippocampal FC may be one underlying neurophysiological mechanism that promotes the association between 2MWT performance and crystalized composite cognitive function in healthy young adults.

Assessment of Resting-state functional Magnetic Resonance Imaging Connectivity Among Patients with Major Depressive Disorder: A Comparative Study

Background Resting-state functional connectivity analysis has a potential to unearth the putative neuronal underpinnings of various disorders of the brain. Major depressive disorder (MDD) is regarded as a disorder arising from alterations in functional networks of the brain. Purpose There is paucity of literature on resting-state functional magnetic resonance imaging (Rs-fMRI) in MDD, especially from the Indian subcontinent. The purpose of our study was to elucidate the differences in Rs-fMRI connectivity between MDD patients and age and gender matched healthy controls (HC). Methods In this prospective single institute-based study, the patients were recruited consecutively based on Hamilton depression rating scale (HAM-D). Age and gender matched HC were also recruited. Rs-fMRI and anatomical MRI images were acquired for all the subjects (MDD and HC group) and subsequent analysis was done using the CONN toolbox. Results A total of 49 subjects were included in the final analysis (MDD = 28 patients, HC = 21). HAM-D score was noted to be 24.4 ± 4.8 in the MDD group. There was no significant difference between MDD and HC groups as far as age, gender, employment status, and level of education is concerned. Region-of-interest-based analysis of Rs-fMRI data showed a significantly lower connectivity between the left insula and left nucleus accumbens and between left paracingulate gyrus and bilateral posterior middle temporal gyri in MDD group as compared to HC group. Conclusion There is reduced connectivity between certain key regions of the brain in MDD patients, that is, between the left insular cortex and the left nucleus accumbens and between the left paracingulate gyrus and the bilateral posterior middle temporal gyrus. These findings could explain the basis of clinical features of MDD such as anhedonia, rumination of thoughts, reduced visuo-spatial comprehension, reduced language function, and response to external stimuli.

The relationship between APOE genotype, CSF Tau and cognition across the Alzheimer's disease spectrum, moderation and mediation role of insula network connectivity.

To investigate whether insula network connectivity modulates the relationship between apolipoprotein E (APOE) ε4 genotype, cerebrospinal fluid (CSF) biomarkers (Aβ, Tau, and pTau) and cognition across Alzheimer's disease (AD) spectrum. Forty-six cognitive normal (CN), 35 subjective memory complaint (SMC), 41 mild cognitive impairment (MCI), and 32 AD subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI) were obtained. Multivariable linear regression analyses were conducted to investigate the main effects and interaction of the APOE genotype and disease status on the insula functional connectivity (IFC) network. Mediation and moderation analysis were performed to investigate whether IFC strengths regulate the association between APOE genotype, CSF biomarkers and cognition. Additionally, the support vector machine (SVM) model integrating APOE genotype, CSF biomarkers, and neuroimaging biomarkers (insula volumes and altered regional IFCs) was used to classify the AD spectrum. The interactive effect of the APOE genotype and disease on the insula network was found in the left medial superior frontal gyrus (SFGmed.L), right anterior medial prefrontal cortex (aMPFC.R), and bilateral thalamus (THA.B). The functional connectivities (FCs) in the left insula (LIns) connecting with the left posterior middle temporal gyrus (pMTG.L), SFGmed.L, and right lingual gyrus (LING.R) were correlated with cognition. LIns-SFGmed.L and LIns-pMTG.L FCs could moderate the effects of Tau on cognition. Furthermore, LIns-SFGmed.L FC may suppress the association between APOE genotype and cognition. More importantly, the integrated biomarkers from the SVM model yielded strong powers for classifying the AD spectrum. Insula functional connectivity regulated the association between APOE genotype, CSF Tau and cognition and provided stage-dependent biomarkers for early differentiation of the AD spectrum. The present study used a cross-sectional design. Follow-up studies are needed to validate the relationship.

Intraoperative cortical localization of music and language reveals signatures of structural complexity in posterior temporal cortex

Language and music involve the productive combination of basic units into structures. It remains unclear whether brain regions sensitive to linguistic and musical structure are co-localized. We report an intraoperative awake craniotomy in which a left-hemispheric language-dominant professional musician underwent cortical stimulation mapping (CSM) and electrocorticography of music and language perception and production during repetition tasks. Musical sequences were melodic or amelodic, and differed in algorithmic compressibility (Lempel-Ziv complexity). Auditory recordings of sentences differed in syntactic complexity (single vs. multiple phrasal embeddings). CSM of posterior superior temporal gyrus (pSTG) disrupted music perception and production, along with speech production. pSTG and posterior middle temporal gyrus (pMTG) activated for language and music (broadband gamma; 70-150Hz). pMTG activity was modulated by musical complexity, while pSTG activity was modulated by syntactic complexity. This points to shared resources for music and language comprehension, but distinct neural signatures for the processing of domain-specific structural features.

Behavioral and neural underpinnings of empathic characteristics in a Humanitude-care expert.

Humanitude approaches have shown positive effects in elderly care. However, the behavioral and neural underpinnings of empathic characteristics in Humanitude-care experts remain unknown. We investigated the empathic characteristics of a Humanitude-care expert (YG) and those of age-, sex-, and race-matched controls (n = 13). In a behavioral study, we measured subjective valence and arousal ratings and facial electromyography (EMG) of the corrugator supercilii and zygomatic major muscles while participants passively observed dynamic facial expressions associated with anger and happiness and their randomized mosaic patterns. In a functional magnetic resonance imaging (MRI) study, we measured brain activity while participants passively observed the same dynamic facial expressions and mosaics. In a structural MRI study, we acquired structural MRI data and analyzed gray matter volume. Our behavioral data showed that YG experienced higher subjective arousal and showed stronger facial EMG activity congruent with stimulus facial expressions compared with controls. The functional MRI data demonstrated that YG showed stronger activity in the ventral premotor cortex (PMv; covering the precentral gyrus and inferior frontal gyrus) and posterior middle temporal gyrus in the right hemisphere in response to dynamic facial expressions versus dynamic mosaics compared with controls. The structural MRI data revealed higher regional gray matter volume in the right PMv in YG than in controls. These results suggest that Humanitude-care experts have behavioral and neural characteristics associated with empathic social interactions.

TMS reveals a two-stage priming circuit of gesture-speech integration.

Naturalistically, multisensory information of gesture and speech is intrinsically integrated to enable coherent comprehension. Such cross-modal semantic integration is temporally misaligned, with the onset of gesture preceding the relevant speech segment. It has been proposed that gestures prime subsequent speech. However, there are unresolved questions regarding the roles and time courses that the two sources of information play in integration. In two between-subject experiments of healthy college students, we segmented the gesture-speech integration period into 40-ms time windows (TWs) based on two separately division criteria, while interrupting the activity of the integration node of the left posterior middle temporal gyrus (pMTG) and the left inferior frontal gyrus (IFG) with double-pulse transcranial magnetic stimulation (TMS). In Experiment 1, we created fixed time-advances of gesture over speech and divided the TWs from the onset of speech. In Experiment 2, we differentiated the processing stages of gesture and speech and segmented the TWs in reference to the speech lexical identification point (IP), while speech onset occurred at the gesture semantic discrimination point (DP). The results showed a TW-selective interruption of the pMTG and IFG only in Experiment 2, with the pMTG involved in TW1 (-120 ~ -80 ms of speech IP), TW2 (-80 ~ -40 ms), TW6 (80 ~ 120 ms) and TW7 (120 ~ 160 ms) and the IFG involved in TW3 (-40 ~ 0 ms) and TW6. Meanwhile no significant disruption of gesture-speech integration was reported in Experiment 1. We determined that after the representation of gesture has been established, gesture-speech integration occurs such that speech is first primed in a phonological processing stage before gestures are unified with speech to form a coherent meaning. Our findings provide new insights into multisensory speech and co-speech gesture integration by tracking the causal contributions of the two sources of information.

Validity of chronometric TMS for probing the time-course of word production: a modified replication.

In the present study, we used chronometric TMS to probe the time-course of 3 brain regions during a picture naming task. The left inferior frontal gyrus, left posterior middle temporal gyrus, and left posterior superior temporal gyrus were all separately stimulated in 1 of 5 time-windows (225, 300, 375, 450, and 525ms) from picture onset. We found posterior temporal areas to be causally involved in picture naming in earlier time-windows, whereas all 3 regions appear to be involved in the later time-windows. However, chronometric TMS produces nonspecific effects that may impact behavior, and furthermore, the time-course of any given process is a product of both the involved processing stages along with individual variation in the duration of each stage. We therefore extend previous work in the field by accounting for both individual variations in naming latencies and directly testing for nonspecific effects of TMS. Our findings reveal that both factors influence behavioral outcomes at the group level, underlining the importance of accounting for individual variations in naming latencies, especially for late processing stages closer to articulation, and recognizing the presence of nonspecific effects of TMS. The paper advances key considerations and avenues for future work using chronometric TMS to study overt production.

Brain glucose metabolism and gray matter volume in retired professional soccer players: a cross-sectional [18F]FDG-PET/MRI study.

Professional soccer athletes are exposed to repetitive head impacts and are at risk of developing chronic traumatic encephalopathy. To evaluate regional brain glucose metabolism (rBGM) and gray matter (GM) volume in retired soccer players (RSPs). Male RSPs and age and sex-matched controls prospectively enrolled between 2017 and 2019 underwent neurological and neuropsychological evaluations, brain MRI and [18F]FDG-PET in a 3.0-Tesla PET/MRI scanner. Visual analysis was performed by a blinded neuroradiologist and a blinded nuclear physician. Regional brain glucose metabolism and GM volume were assessed using SPM8 software. Groups were compared using appropriate statistical tests available at SPM8 and R. Nineteen RSPs (median [IQR]: 62 [50-64.5] years old) and 20 controls (60 [48-73] years old) were included. Retired soccer players performed worse on mini-mental state examination, digit span, clock drawing, phonemic and semantic verbal fluency tests, and had reduced rBGM in the left temporal pole (pFDR = 0.008) and the anterior left middle temporal gyrus (pFDR = 0.043). Semantic verbal fluency correlated with rBGM in the right hippocampus, left temporal pole, and posterior left middle temporal gyrus (p ≤ 0.042). Gray matter volume reduction was observed in similar anatomic regions but was less extensive and did not survive correction for multiple comparisons (pFDR ≥ 0.085). Individual [18F]FDG-PET visual analysis revealed seven RSPs with overt hypometabolism in the medial and lateral temporal lobes, frontal lobes, and temporoparietal regions. Retired soccer players had a higher prevalence of septum pellucidum abnormalities on MRI. Retired soccer players had reduced rBGM and GM volume in the temporal lobes and septum pellucidum abnormalities, findings possibly related to repetitive head impacts.

MP52-11 MICTURITION-ASSOCIATED BRAIN ACTIVITY IN HEALTHY PATIENTS COMPARED TO STROKE SURVIVORS BEFORE AND AFTER TRANSCUTANEOUS SPINAL CORD STIMULATION

You have accessJournal of UrologyCME1 Apr 2023MP52-11 MICTURITION-ASSOCIATED BRAIN ACTIVITY IN HEALTHY PATIENTS COMPARED TO STROKE SURVIVORS BEFORE AND AFTER TRANSCUTANEOUS SPINAL CORD STIMULATION Sarah Ponce, Veronica Stefania Montero Arcila, Luis Alejandro Morales Ojeda, David Chapman, Rita Jen, Nhi Tuyet Ha, Parag Gad, V. Reggie Edgerton, Evgeniy Kreydin, Kay Jann, and Aidin Abedi Sarah PonceSarah Ponce More articles by this author , Veronica Stefania Montero ArcilaVeronica Stefania Montero Arcila More articles by this author , Luis Alejandro Morales OjedaLuis Alejandro Morales Ojeda More articles by this author , David ChapmanDavid Chapman More articles by this author , Rita JenRita Jen More articles by this author , Nhi Tuyet HaNhi Tuyet Ha More articles by this author , Parag GadParag Gad More articles by this author , V. Reggie EdgertonV. Reggie Edgerton More articles by this author , Evgeniy KreydinEvgeniy Kreydin More articles by this author , Kay JannKay Jann More articles by this author , and Aidin AbediAidin Abedi More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003300.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Compared to healthy individuals, stroke survivors with neurogenic lower urinary tract dysfunction (NLUTD) exhibit decreased cortical activity in response to bladder filling and emptying. The use of transcutaneous spinal cord stimulation (TSCS) has been shown to reduce frequency, urgency and incontinence episodes in these individuals. The objective of this study was to determine whether TSCS also leads to normalization of micturition-related brain activity, as compared to healthy controls. METHODS: Twelve stroke patients with post-stroke NLUTD received 12 weeks of TSCS. Each subject also completed simultaneous urodynamics (UDS) and blood-oxygen-level-dependent (BOLD) fMRI before initiation of TSCS and within 72 hours of completing the final TSCS session. Healthy subjects without LUTS completed an identical fMRI-UDS protocol. BOLD signal during the period of maximum urgency (10 seconds preceding a detrusor contraction) was determined using statistical parametric mapping (SPM) and compared between healthy controls and stroke patients before and after TSCS (p<0.01, cluster size ⋝25 voxels). The SPM models were adjusted for age and sex. RESULTS: Compared to healthy controls, stroke survivors prior to TSCS exhibited diminished activation in the right cerebellum, left putamen, right insula, right anterior cingulate gyrus, right precuneus, bilateral medial frontal gyri, and right superior frontal gyrus compared to healthy controls. Following TSCS, there was no significant difference in BOLD signal in these regions between stroke survivors and healthy controls. However, healthy controls continued to exhibit increased activation in the right precentral (motor cortex) and left postcentral (sensory cortex) gyri, left posterior cingulate and left middle temporal gyrus even after TSCS. CONCLUSIONS: Micturition-related brain activity appears to partially revert to the healthy phenotype in stroke survivors following TSCS. Regions, where differences in BOLD signal between healthy controls and stroke subjects diminish following treatment, are known to be involved in LUT control. As expected, the neurosignature of stroke patients did not revert to the healthy phenotype entirely, as indicated by significant remaining differences in BOLD signal in several brain regions following TSCS. Source of Funding: Urology Care Foundation © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e706 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Sarah Ponce More articles by this author Veronica Stefania Montero Arcila More articles by this author Luis Alejandro Morales Ojeda More articles by this author David Chapman More articles by this author Rita Jen More articles by this author Nhi Tuyet Ha More articles by this author Parag Gad More articles by this author V. Reggie Edgerton More articles by this author Evgeniy Kreydin More articles by this author Kay Jann More articles by this author Aidin Abedi More articles by this author Expand All Advertisement PDF downloadLoading ...

450 A Shared Cortical Language Network for Multimodal Naming

INTRODUCTION: Surgical resections for epilepsy or neoplasms often result in naming deficits. While various brain regions are hypothesized to support separable processes, the language network and its functional mapping to naming remain unclear. However, such knowledge could improve the localization of critical brain regions to preserve language function. METHODS: Data were obtained from epilepsy patients who underwent invasive electrophysiology. Recordings were acquired during three cued-naming tasks using pictures (n = 120), auditory descriptions (n = 82), and orthographic descriptions (n = 68). High-gamma power (65-115Hz) was used to measure activity, and group-level activity was estimated using surface-based mixed-effects multilevel analysis. RESULTS: Analyses showed left-lateralized heteromodal activity in the inferior frontal gyrus (IFG), the middle fusiform gyrus (mFus), and the intraparietal sulcus (IPS) following sensory processing. Activation of mFus peaked 150ms before stimulus offset for auditory (15.2%, p &lt; 10-6) and orthographic (21.4%, p &lt; 10-6) naming and 350ms after picture onset (39.0%, p &lt; 10-6) for visual naming. IPS activation peaked just before stimulus offset for auditory (38.1%, p = 7.7*10-5) and orthographic (27.5%, p = 0.008) naming and 450ms following picture onset (43.0%, p &lt; 10-6) for visual naming. IFG activation peaked just before stimulus offset for auditory (30.1%, p &lt; 10-6) and orthographic (40.1%, p = 10-6) naming and 500ms after picture onset (36.4%, p &lt; 10-6) for visual naming. The left posterior middle temporal gyrus (pMTG) showed heteromodal activity for auditory and orthographic but not visual stimuli with peak activation occurring before convergence of all tasks 250ms before stimulus offset (auditory = 34.1%, p &lt; 10-6;orthographic = 25.5%, p = 0.0035). CONCLUSIONS: These results reveal a heteromodal network of IFG, mFus, and IPS supporting lexical access. Our findings also implicate the role of pMTG in phonological access. Altogether, this work characterizes the roles of key regions within language networks, which could influence surgical approaches to minimize postoperative language deficits.

Predictive Coding and Internal Error Correction in Speech Production.

Speech production involves the careful orchestration of sophisticated systems, yet overt speech errors rarely occur under naturalistic conditions. The present functional magnetic resonance imaging study sought neural evidence for internal error detection and correction by leveraging a tongue twister paradigm that induces the potential for speech errors while excluding any overt errors from analysis. Previous work using the same paradigm in the context of silently articulated and imagined speech production tasks has demonstrated forward predictive signals in auditory cortex during speech and presented suggestive evidence of internal error correction in left posterior middle temporal gyrus (pMTG) on the basis that this area tended toward showing a stronger response when potential speech errors are biased toward nonwords compared to words (Okada et al., 2018). The present study built on this prior work by attempting to replicate the forward prediction and lexicality effects in nearly twice as many participants but introduced novel stimuli designed to further tax internal error correction and detection mechanisms by biasing speech errors toward taboo words. The forward prediction effect was replicated. While no evidence was found for a significant difference in brain response as a function of lexical status of the potential speech error, biasing potential errors toward taboo words elicited significantly greater response in left pMTG than biasing errors toward (neutral) words. Other brain areas showed preferential response for taboo words as well but responded below baseline and were less likely to reflect language processing as indicated by a decoding analysis, implicating left pMTG in internal error correction.

Characterizing the personality and gray matter volume of chimpanzees that exhibit autism-related socio-communicative phenotypes.

Autism spectrum disorder (ASD) is a developmental disorder characterized by stereotypies or repetitive behaviors and impairments in social behavior and socio-communicative skills. One hallmark phenotype of ASD is poor joint attention skills compared to neurotypical controls. In addition, individuals with ASD have lower scores on several of the Big 5 personality dimensions, including Extraversion. Here, we examine these traits in a nonhuman primate model (chimpanzees; Pan troglodytes) to further understand the relationship between personality and joint attention skills, as well as the genetic and neural systems that contribute to these phenotypes. We used archival data including receptive joint attention (RJA) performance, personality based on caretaker ratings, and magnetic resonance images from 189 chimpanzees. We found that, like humans, chimpanzees who performed worse on the RJA task had lower Extraversion scores. We also found that joint attention skills and several personality dimensions, including Extraversion, were significantly heritable. There was also a borderline significant genetic correlation between RJA and Extraversion. A conjunction analysis examining gray matter volume showed that there were five main brain regions associated with both higher levels of Extraversion and social cognition. These regions included the right posterior middle and superior temporal gyrus, bilateral inferior frontal gyrus, left inferior frontal sulcus, and left superior frontal sulcus, all regions within the social brain network. Altogether, these findings provide further evidence that chimpanzees serve as an excellent model for understanding the mechanisms underlying social impairment related to ASD. Future research should further examine the relationship between social cognition, personality, genetics, and neuroanatomy and function in nonhuman primate models.

Tractography-based navigated TMS language mapping protocol.

This study explores the feasibility of implementing a tractography-based navigated transcranial magnetic stimulation (nTMS) language mapping protocol targeting cortical terminations of the arcuate fasciculus (AF). We compared the results and distribution of errors from the new protocol to an established perisylvian nTMS protocol that stimulated without any specific targeting over the entire perisylvian cortex. Sixty right-handed patients with language-eloquent brain tumors were examined in this study with one half of the cohort receiving the tractographybased protocol and the other half receiving the perisylvian protocol. Probabilistic tractography using MRtrix3 was performed for patients in the tractography-based group to identify the AF's cortical endpoints. nTMS mappings were performed and resulting language errors were classified into five psycholinguistic groups. Tractography and nTMS were successfully performed in all patients. The tractogram-based group showed a significantly higher median overall ER than the perisylvian group (3.8% vs. 2.9% p <.05). The median ER without hesitation errors in the tractogram-based group was also significantly higher than the perisylvian group (2.0% vs. 1.4%, p <.05). The ERs by error type showed no significant differences between protocols except in the no response ER, with a higher median ER in the tractogram-based group (0.4% vs. 0%, p <.05). Analysis of ERs based on the Corina cortical parcellation system showed especially high nTMS ERs over the posterior middle temporal gyrus (pMTG) in the perisylvian protocol and high ERs over the middle and ventral postcentral gyrus (vPoG), the opercular inferior frontal gyrus (opIFG) and the ventral precentral gyrus (vPrG) in the tractography-based protocol. By considering the white matter anatomy and performing nTMS on the cortical endpoints of the AF, the efficacy of nTMS in disrupting patients' object naming abilities was increased. The newly introduced method showed proof of concept and resulted in AF-specific ERs and noninvasive cortical language maps, which could be applied to additional fiber bundles related to the language network in future nTMS studies.

Disentangling hand and tool processing: Distal effects of neuromodulation.

Neural processing within a local brain region that responds to more than one object category (e.g., hands and tools) nonetheless have different functional connectivity patterns with other distal brain areas, which suggests that local processing can affect and/or be affected by processing in distal areas, in a category-specific way. Here we wanted to test whether administering either a hand- or tool-related training task in tandem with transcranial direct current stimulation (tDCS) to a region that responds both to hands and tools (posterior middle temporal gyrus; pMTG), modulated local and distal neural processing more for the trained than the untrained category in a subsequent fMRI task. After each combined tDCS/training session, participants viewed images of tools, hands, and animals, in an fMRI scanner. Using multivoxel pattern analysis, we found that tDCS stimulation to pMTG indeed improved the classification accuracy between tools vs. animals, but only when combined with a tool and not a hand training task. Surprisingly, tDCS stimulation to pMTG also improved classification accuracy between hands vs. animals when combined with a tool but not a hand training task. Our findings suggest that overlapping but functionally-specific networks may be engaged separately by using a category-specific training task together with tDCS - a strategy that can be applied more broadly to other cognitive domains using tDCS. By hypothesis, these effects on local processing are a direct result of within-domain connectivity constraints from domain-specific networks that are at play in the processing and organization of object representations.

Different atrophy profiles detected in AD patients who carry APOE4 versus non‐carriers: An ENIGMA‐VBM Multicohort Analysis (N=1,893)

AbstractBackgroundAlzheimer’s disease (AD) is the most common neurodegenerative disorder and apolipoprotein E (APOE) ε4 allele is the greatest common genetic risk factor for late‐onset AD. In one of the largest multi‐cohort VBM analyses to date, we aimed to a) map regional brain cortical volume deficits in people with dementia vs controls (CTL) and b) investigate how atrophy patterns in AD were modulated by carrying the APOE4 genotype.MethodThe ENIGMA voxel based morphometry (VBM; https://sites.google.com/view/enigmavbm) pipeline was used to perform a mega‐analysis and a multi‐cohort meta‐analysis on T1‐weighted brain MRI data from 1,893 subjects (Table 1) across four different cohorts, namely the Alzheimer’s Disease Neuroimaging Initiative (ADNI), phases 1, GO/2, 3, and the Open Access Series of Imaging Studies (OASIS3). 488 participants with AD had APOE genotype data with 172 non‐carriers (ε3/3) and 316 carriers (ε3/4, ε4/4). Protective APOE ε2 carriers were excluded. Within the 488 participants with AD, effects of carrying the APOE4 allele were tested using a VBM analysis adjusting for age, sex, intracranial volumes and differences in cohorts.ResultAs expected, compared to controls (CTL), participants with dementia demonstrated cortical brain volume deficits in medial temporal lobes, notably the bilateral hippocampus, entorhinal cortex, amygdala and fusiform gyrus in Mega‐ &amp; Meta‐analysis (Fig. 1). In those with AD, APOE4 carriers demonstrated relatively higher gray matter volumes in the primary motor cortex, medial frontal gyrus and posterior middle temporal gyrus, compared to non‐carriers (P&lt;0.001, uncorrected; Fig. 2). As expected, APOE ε4 carriers demonstrated lower medial temporal lobe and precuneal gray matter volumes.ConclusionAn expected strong pattern of medial temporal lobe volume reduction was noted in the dementia group compared to CTL. Interestingly, within the dementia group, APOE ε4 carriers showed higher gray matter density in the primary motor cortex, a region not routinely associated with AD nor with amyloid deposition, as shown in a smaller prior study. APOE ε4 carriers showed typical medial temporal and precuneal volume reductions which commonly show amyloid deposition, consistent with the notion that APOE ε4 mediates atrophy mainly via an amyloid dependent mechanism.

Neural Correlates of Naturally Occurring Speech Errors during Picture Naming in Healthy Participants.

Most of our knowledge about the neuroanatomy of speech errors comes from lesion-symptom mapping studies in people with aphasia and laboratory paradigms designed to elicit primarily phonological errors in healthy adults, with comparatively little evidence from naturally occurring speech errors. In this study, we analyzed perfusion fMRI data from 24 healthy participants during a picture naming task, classifying their responses into correct and different speech error types (e.g., semantic, phonological, omission errors). Total speech errors engaged a wide set of left-lateralized frontal, parietal, and temporal regions that were almost identical to those involved during the production of correct responses. We observed significant perfusion signal decreases in the left posterior middle temporal gyrus and inferior parietal lobule (angular gyrus) for semantic errors compared to correct trials matched on various psycholinguistic variables. In addition, the left dorsal caudate nucleus showed a significant perfusion signal decrease for omission (i.e., anomic) errors compared with matched correct trials. Surprisingly, we did not observe any significant perfusion signal changes in brain regions proposed to be associated with monitoring mechanisms during speech production (e.g., ACC, superior temporal gyrus). Overall, our findings provide evidence for distinct neural correlates of semantic and omission error types, with anomic speech errors likely resulting from failures to initiate articulatory-motor processes rather than semantic knowledge impairments as often reported for people with aphasia.