A model for visual naming based on spatiotemporal dynamics of ECoG high-gamma modulation

Neuropsychological outcomes after resection of cortical sites with visual naming associated electrocorticographic high-gamma modulation

This prospective study compared the topography of high-gamma modulation (HGM) during a story-listening task requiring negligible patient cooperation, with the conventional electrical stimulation mapping (ESM) using a picture-naming task, for presurgical language localization in pediatric drug-resistant epilepsy. Patients undergoing extraoperative monitoring with subdural electrodes were included. Electrocorticographic signals were recorded during quiet baseline and a story-listening task. The likelihood of 70- to 150-Hz power modulation during the listening task relative to the baseline was estimated for each electrode and plotted on a cortical surface model. Sensitivity, specificity, accuracy, and diagnostic odds ratio (DOR) were estimated compared to ESM, using a meta-analytic framework. Nineteen patients (10 with left hemisphere electrodes) aged 4-19 years were analyzed. HGM during story listening was observed in bilateral posterior superior temporal, angular, supramarginal, and inferior frontal gyri, along with anatomically defined language association areas. Compared to either cognitive or both cognitive and orofacial sensorimotor interference with naming during ESM, left hemisphere HGM showed high specificity (0.82-0.84), good accuracy (0.66-0.70), and DOR of 2.23 and 3.24, respectively. HGM was a better classifier of ESM language sites in the left temporoparietal cortex compared to the frontal lobe. Incorporating visual naming with the story-listening task substantially improved the accuracy (0.80) and DOR (13.61) of HGM mapping, while the high specificity (0.85) was retained. In the right hemisphere, no ESM sites for aphasia were seen, and the results of HGM and ESM comparisons were not significant. HGM associated with story listening is a specific determinant of left hemisphere ESM language sites. It can be used for presurgical language mapping in children who cannot cooperate with conventional language tasks requiring active engagement. Incorporation of additional language tasks, if feasible, can further improve the diagnostic accuracy of language localization with HGM.

BackgroundGestational disruptions are linked to the risk of schizophrenia; but in most cases, there is a lack of a clear history or observable anomaly indicating that the disruptions are likely to be subtle (Murray et al., 2017). The time-locked development of cortical sulci in a human embryo is highly sensitive to developmental disruptions (Chi et al., 1977). We can retrospectively infer the likely timing of embryonic/fetal disruption in schizophrenia by studying the structure of major cortical sulci that represent lobar development in adults with schizophrenia.MethodsAnatomical T1 MRI scans from a publicly available dataset (COBRE) of 68 patients with schizophrenia and 72 controls were used to evaluate the sulcal depth. 5 major primary sulci that are invariable, representing lobar development (calcarine sulcus, superior temporal sulcus, superior frontal sulcus, interparietal sulcus and inferior frontal sulcus) with formation representing distinct developmental periods (16, 23, 25, 26 and 28 weeks respectively (Chi et al., 1977)) were chosen. Sulcal depth was measured using Morphologist interface of BrainVISA 4.5 (http://brainvisa.info/). Following the construction of 3-dimensional models of cortical folds, various sulci were automatically classified using a probabilistic algorithm with maximum depth computed for each identified sulcus. The 5 sulci were consistently labeled automatically across all subjects. The identified sulci were visually inspected to ensure that the boundaries are in accordance with Ono’s Atlas of Cerebral Sulci (Ono et al., 1990).ResultsA repeated measure ANOVA with 5 sulci and 2 hemispheres as within-subject factors and gender, age and intracranial volume as covariates revealed a significant between-subjects effect for diagnosis (F[1,134]=14.8, p=0.0002). Gender (F[1,134]=7.4, p=0.007) and age (F[1,134]=4.5, p=0.035) also had significant effect in the model. Parameter estimates revealed a significant effect of diagnosis (Controls>Patients) for left superior temporal (t=3.2, p=0.002), right superior temporal (t=2.8, p=0.006), right inferior frontal (t=2.7, p=0.007) and left calcarine (t=2.2, p=0.03) sulci. 5 non-collinear factors representing the 5 bilateral sulci were obtained using varimax rotation, and related to overall MATRICS standardized composite score in patients using multiple regression. The depth of the superior frontal sulcus was the only predictor of the variation in the cognitive score (F[1,54]=8.7, p=0.005).DiscussionThe above findings suggest that the gestational cortical disruption underlying schizophrenia is likely to predate, if not, coincide with the appearance of calcarine sulcus (i.e. 16 weeks, early second trimester) and affects frontal, temporal and occipital lobes. Nevertheless, the burden of cognitive deficits may relate specifically to aberrant superior frontal development occurring in late second trimester.

Intraoperative mapping of eloquent cortex during left (speech dominant) anterior temporal lobectomy has shown a significant proportion of patients to have sites on the anterior superior temporal gyrus at which visual confrontation naming can be disrupted by electrical stimulation. The purpose of this investigation was to conduct a randomized clinical trial to determine whether sparing versus resection of the superior temporal gyrus affected visual confrontation naming outcome after standard left anterior temporal lobectomy. Also examined was the degree to which inherent patient characteristics were associated with language outcome regardless of surgical technique. Thirty patients with intractable left temporal lobe epilepsy undergoing standard anterior temporal lobectomy were randomized in regard to whether the superior temporal gyrus was resected or spared. Patients were tested preoperatively and 6-8 months postoperatively by using two conventional tests of visual confrontation naming ability. No significant differences were found between the groups in either confrontation naming or surgical outcome. Postoperative decline in nominal speech was most closely associated with later age at onset of epilepsy/absence of hippocampal sclerosis. It appears that specific types of localization-related temporal lobe epilepsy are more closely associated with the risk of adverse language outcome after anterior temporal lobectomy than with the surgical variations investigated in this study.

New skills may be learned from the outcomes of their own internally generated actions (experiential learning) or from the observation of the consequences of externally generated actions (observational learning). Observational learning requires the coordination of cognitive functions and the processing of social information. Due to the “social” abilities underlying observational learning, the study of this process in individuals with limited social abilities such as those affected by Autism Spectrum Disorders (ASD) is worthy of being investigated. We asked a group of 16 low-functioning young children with ASD and group of 16 sex- and mental age-matched typically developing (TD) children to build a house with a set of bricks after a video-demonstration showing an actor who built the house (observational task – OBS task) and then to build by trial and error another house (experiential task – EXP task). For ASD group, performances in learning tasks were correlated with measures of cortical thickness of specific Regions of Interest (ROI) and volume of deep gray matter structures known to be related with such kinds of learning. According to our a priori hypothesis, for OBS task we selected the following ROI: frontal lobe (pars opercularis, pars triangularis, and premotor area), parietal lobe (inferior parietal gyrus), temporal lobe (superior temporal gyrus), cerebellar hemispheres. For EXP task, we selected the following ROI: precentral frontal gyrus and superior frontal gyrus, cerebellar hemispheres, basal ganglia, thalamus. Although performances of ASD and TD children improved in both OBS and EXP tasks, children with ASD obtained lower scores of goal achievement than TD children in both learning tasks. Only in ASD group, goal achievement scores positively correlated with hyperimitations indicating that children with ASD tended to have a “copy-all” approach that facilitated the goal achievement. Moreover, the marked hyperimitative tendencies of children with ASD were positively associated with the thickness of left pars opercularis, left premotor area, and right superior temporal gyrus, areas belonging to mirror neuron system, and with the volume of both cerebellar hemispheres. These findings suggest that in children with ASD the hyperimitation can represent a learning strategy that might be related to the mirror neuron system.

Background: Hereditary Transthyretin Amyloidosis (ATTRv) is a systemic disease that primarily affects the peripheral and autonomic nervous systems. Recently, the Central Nervous System has been investigated. Besides cognitive dysfunction, amyloid deposition was identified in the brain, cerebellum, leptomeningeal and subarachnoid meningeal vessels, and the brainstem. In vivo brain MRI studies showed diverse results, such as leptomeningeal involvement, microbleedings, cortical atrophy, and, in some cases, no abnormalities were observed. To date, studies have not investigated cortical and subcortical areas using software for automatic brain segmentation. Objective: We aimed to investigate the brain volume, and cortical thickness in patients with ATTRv amyloidosis. Methods: 3DT1-weighted images (T1) of brain MRI of twenty ATTRv patients (mean age=41.7±9.2) and 23 sex/age-matched healthy individuals (41.7±9.3) were analyzed. Cortical measures of volume and thickness were obtained for both groups through FreeSurfer software (“crecon-all” script). SPSS software was used for the statistical analyses. Results: Compared to controls, ATTRv patients displayed smaller volumes of cerebellum. No difference between the groups was found in the hypothalamus volume. The study indicated a thinner cortical thickness in ATTRv amyloidosis in the following regions: banks of the superior temporal sulcus, fusiform gyrus, inferior, superior, and middle temporal gyri, orbitofrontal cortex, pars opercularis, pars orbitalis, lateral orbitofrontal cortex, precentral gyrus, inferior parietal cortex, supramarginal and postcentral gyri, occipital lateral cortex, pericalcarine cortex, cuneus, and insula. Disease duration was negatively correlated with cortical thickness of insula, pars opercularis and inferior and superior temporal gyri. No correlation was found between disease duration and the cerebellum volume. Conclusion: The study showed a thinner cortical thickness in specific brain regions in ATTRv amyloidosis. The reasons for this finding and its relationship with amyloid deposition are not fully understood. Further research involving a larger number of patients is necessary to confirm these findings and identify their clinical manifestations.

Horizontal portion of arcuate fasciculus fibers track to pars opercularis, not pars triangularis, in right and left hemispheres: A DTI study

<bold>Objective</bold>To explore the cortical control mechanisms of auditory comprehension and verbal expression deficits in post-stroke aphasia (PSA) patients based on a naturalistic paradigm that closely mimics real-world scenarios. <bold>Methods</bold> A total of 26 PSA patients (PSA group) treated in the Second Rehabilitation Hospital of Shanghai from March 2024 and February 2025 were enrolled, along with 21 gender-, age-, and education-matched healthy controls (control group). All participants completed an auditory comprehension-verbal expression task under functional near-infrared spectroscopy (fNIRS) monitoring. A block-task paradigm was designed based on a natural question-answer language model, consisting three phases, including listening to questions embedded in short narratives, thinking, and responding, with the entire paradigm repeated six times. fNIRS monitoring encompassed bilateral temporal, parietal, and prefrontal lobes. The Western Aphasia Battery (WAB) and the Boston Diagnostic Aphasia Examination (BDAE) were used to evaluate language function. The fNIRS system was used to assess cortical activation levels in various channels and brain regions, including the superior temporal gyrus (STG), middle temporal gyrus (MTG), supramarginal gyrus (SMG), fusiform gyrus (FG), angular gyrus (AG), somatosensory association cortex (SAC), primary somatosensory cortex (PSC), primary motor cortex (PMC), pre-motor and supplementary motor cortex (PMSC), pars triangularis of Broca's area (PT), pars opercularis (PO), dorsolateral prefrontal cortex (DLPFC), and frontal eye fields (FEF), during auditory comprehension and verbal expression tasks. To analyze the correlations between WAB auditory comprehension/verbal expression scores, WAB-AQ scores, BDAE scores, and cortical activation levels in the PSA group during auditory comprehension and verbal expression tasks.<bold>Results</bold>In the auditory comprehension task, the control group showed significant bilateral brain activation, with higher activation levels in the right hemisphere than the left, including the superior temporal gyrus (STG) (P=0.041), middle temporal gyrus (MTG) (P=0.002), and supramarginal gyrus (SMG) (P=0.028). In contrast, the PSA group primarily relied on the right-hemisphere homologue of Wernicke's area, including the STG (P=0.030) and MTG (P=0.024), with significantly reduced activation in the left hemisphere (P&lt;0.05). During the verbal expression task, the control group showed pronounced activation in the left Broca's area and related regions, including the PT (P=0.036), PO (P=0.001), and PMC (P=0.002), with symmetrical activation in the right hemisphere. The PSA group demonstrated compensatory activation in the right hemisphere, including the PT (P=0.035), PO (P=0.002), and PMC (P=0.017), while activation in the left hemisphere(particularly Broca's area) decreased significantly(P&lt;0.05). WAB auditory comprehension scores in patients with PSA correlated with the degree of activation in the bilateral DLPFC (r=-0.401, P=0.047), PMSC (r =-0.417, P=0.038), and PMC (r=-0.414, P=0.040). WAB spontaneous speech scores correlated with activation in the left DLPFC (r =-0.423, P=0.035), PMC (r =-0.400, P = 0.048), and PSC (r =-0.481, P = 0.015), as well as with activation in the right STG (r=-0.404, P = 0.045). <bold>Conclusion</bold> The degree of cortical activation during auditory comprehension and verbal expression tasks in PSA patients is significantly correlated with language function impairment scores, emphasizing the crucial role of the right hemisphere in PSA recovery.

P10. ‘Clustered sparse’ fMRI using simultaneous multislice excitation in language mapping

BackgroundFunctional MRI (fMRI) studies conducted on young adults reveal a predominantly left-lateralized cortical language network during semantic and phonological processing (SP and PP, respectively). Both linguistic dimensions have been advanced as potential cognitive markers of pathological aging. However, the neural mechanisms underlying SP and PP among healthy older adults remain poorly understood.AimThis study aimed to investigate the dynamics of language lateralization among native Spanish-speaking older adults in relation to their behavioral performance in specific semantic and phonological tasks.MethodologyTwenty-eight healthy, right-handed older Chilean adults (mean age: 67.7, SD±: 7.44, range: 60–87) took part in an fMRI session during which they performed semantic and phonological tasks. They were also evaluated for overall language performance using the Spanish version of ScreeLing and verbal fluency tasks. A fixed-effect analysis was performed to explore group-level differences. Standard regression analyses were also used to assess the association between brain activation and language performance.ResultsBoth SP and PP elicited bilateral activation in the pars triangularis and opercularis of the inferior frontal gyrus (IFG) and the superior temporal gyrus. Activation was also observed in the left inferior parietal gyrus. Semantic fluency performance was significantly associated with activation in the right angular gyrus and the pars opercularis of the IFG. In contrast, phonological fluency was associated with bilateral activation in the IFG pars orbitalis.ConclusionAmong healthy older adults, SP and PP recruit bilateral language-related brain regions, potentially reflecting compensatory mechanisms associated with normal aging. Notably, the IFG pars orbitalis may play a distinct role in supporting phonological fluency, despite not being a region traditionally linked to PP. Further research is needed to clarify the contribution of this region to phonological performance among aging adults.

Chapter 10 - White-matter pathways for speech and language processing

Neural underpinnings for model-oriented therapy of aphasic word production

The ability to recognize abstract features of voice during auditory perception is an intricate feat of human audition. For the listener, this occurs in near-automatic fashion to seamlessly extract complex cues from a highly variable auditory signal. Voice perception depends on specialized regions of auditory cortex, including superior temporal gyrus (STG) and superior temporal sulcus (STS). However, the nature of voice encoding at the cortical level remains poorly understood. We leverage intracerebral recordings across human auditory cortex during presentation of voice and nonvoice acoustic stimuli to examine voice encoding at the cortical level in 8 patient-participants undergoing epilepsy surgery evaluation. We show that voice selectivity increases along the auditory hierarchy from supratemporal plane (STP) to the STG and STS. Results show accurate decoding of vocalizations from human auditory cortical activity even in the complete absence of linguistic content. These findings show an early, less-selective temporal window of neural activity in the STG and STS followed by a sustained, strongly voice-selective window. Encoding models demonstrate divergence in the encoding of acoustic features along the auditory hierarchy, wherein STG/STS responses are best explained by voice category and acoustics, as opposed to acoustic features of voice stimuli alone. This is in contrast to neural activity recorded from STP, in which responses were accounted for by acoustic features. These findings support a model of voice perception that engages categorical encoding mechanisms within STG and STS to facilitate feature extraction.

Ictal bruxism is a rare motor manifestation in temporal lobe epilepsy with unclear network underpinnings. We report the first case demonstrating SEEG-guided network characterization of ictal bruxism in a 55-year-old man with drug-resistant temporal lobe epilepsy who continued to experience stereotyped seizures with rhythmic teeth grinding after a failed anterior temporal lobectomy. SEEG recorded one spontaneous and two stimulation-induced seizures sampling from the superior temporal gyrus, anterior ventral insula (aVInsula), and nine additional regions of interest. Recordings identified seizures originating from the superior temporal gyrus with early propagation to the anterior insulo-opercular regions at bruxism onset. Direct cortical stimulation of both superior temporal gyrus and aVInsula reproduced seizures and bruxism, confirming causal network associations. Time-frequency and coherence analyses demonstrated significant increases in beta and gamma band synchrony between the superior temporal gyrus /AVINSULA and opercular regions, particularly the pars opercularis and frontoparietal operculum, aligning with bruxism onset across all three seizures. Notably, bruxism occurred in the absence of ipsilateral mesial temporal structures, setting it apart from other oro-alimentary automatisms, such as lip smacking, that exhibit theta-predominant coherence within mesial temporal networks. This case highlights ictal bruxism as a network-level phenomenon in temporal lobe epilepsy that warrants classification distinct from typical oro-alimentary automatisms to optimize seizure localization and surgical outcomes.

Resting-state functional MRI (rs-fMRI) is a noninvasive tool for studying brain function, with growing applications in clinical oncology, such as preoperative planning and brain reorganization mapping. Direct electrical stimulation (DES) during awake surgery remains the gold standard for causally identifying functional brain regions. Although previous studies have mapped the speech articulation network (SAN) from rs-fMRI using DES-positive points, the inclusion of DES-negative points remains unexplored. This study integrates both positive and negative DES data to create a more comprehensive SAN atlas and refine its functional borders using presurgical functional connectivity from glioma patients. We analyzed 25 glioma patients (16 high-grade, 9 low-grade) who underwent awake surgery with DES mapping for speech articulation. Seventy-four DES points (32 positive, 42 negative) were identified in gray matter. Presurgical rs-fMRI data were used for seed-based connectivity analysis, with DES-positive and DES-negative points analyzed separately. Group SAN-positive and SAN-negative networks were assessed for overlap across each other and with regions from an anatomical atlas. DES-negative and DES-positive points were used to estimate the sensitivity and specificity of the group SAN-positive network at different thresholds for group frequency. The DES-positive SAN was bilaterally located in the rolandic operculum, inferior frontal gyrus, and superior temporal gyrus, consistent with previous studies. DES-negative points revealed distinct connectivity patterns, with only partial overlap, helping to delineate the SAN's functional borders, particularly in the central sulcus (posterior and anterior) and inferior frontal gyrus (pars triangularis and opercularis). Anticorrelated networks from DES-positive points further differentiated the roles of positive and negative sites within the SAN. A 41% threshold in the SAN-positive gives approximately 80% specificity and sensitivity. DES-positive points define the SAN robustly. DES-negative points served to establish a threshold for the group SAN atlas and a more detailed definition of the functional SAN borders.