Left Temporal Lobe Research Articles

Raising Clinical Suspicion for Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS): Recurrent Seizures, Stroke-like Episodes, and Cortical Atrophy in Young Patients (P3-1.007)

<h3>Objective:</h3> Phenotypic variability and lack of familiarity with criteria can make diagnosis of MELAS challenging. Clinicians should be cognizant and consider early MR spectroscopy with genetic screening. <h3>Background:</h3> MELAS is a rare, progressive mitochondrial disorder that can be missed if clinical suspicion is low. <h3>Design/Methods:</h3> A thorough chart review was conducted. <h3>Results:</h3> <h3>Case 1:</h3> A 33-year-old female presented with recurrent right-sided visual scotomas. MRI showed focal DWI changes to the occipital lobe. Continuous video-EEG showed subclinical occipital lobe seizures. The patient had a recurrent episode of right-sided vision changes, speech difficulty and poor comprehension. MRI showed cortical atrophy and DWI abnormalities without ADC mismatch in the left occipital and left posterior temporal lobes. Stroke and infectious workup was unrevealing. Another episode of numbness, hearing loss, and word-finding difficulty prompted MR spectroscopy, screening lactate level, and genetic analysis. The diagnosis of MELAS was established based on the patient’s recurrent seizures, cortical visual loss, acute lesions on MRI, high plasma lactate, and a confirmed, possibly pathogenic mutation in MT-TL1. She suffered from neurological deterioration and passed away 6 months later. <h3>Case 2:</h3> Patient is a 26-year-old male with a long history of migraines with visual disturbances. MRI showed edema in the left occipital lobe. Subsequently, he presented with an intractable headache associated with left-sided peripheral vision loss and left leg weakness. MRI was notable for hyperintense flair signal in the right occipital lobe and marked atrophy. EEG showed frequent seizures and workup for stroke and encephalitis was unrevealing. Lactate levels were elevated and genetic screening was notable for MT-TL1 mutation. <h3>Conclusions:</h3> Patients younger than 40 with stroke-like symptoms, brain atrophy disproportionate to age, and negative infectious and vascular workup should be evaluated for MELAS. MR Spectroscopy, lactate levels, and genetic testing are important non-invasive screening measures. <b>Disclosure:</b> Mr. Tallavajhala has nothing to disclose. Dr. Bochenek has stock in JNJ, Abbott, Moderna, Pfizer. Ms. Dwivedi has nothing to disclose. Ms. Caffio-Learner has nothing to disclose. Miss Suliman has nothing to disclose. Dr. Bashir has nothing to disclose. Dr. Kurukumbi has nothing to disclose.

Neurosyphilis Presenting as Limbic Encephalitis: a Case Report (P10-10.007)

<h3>Objective:</h3> To present an interesting case of neurosyphilis mimicking limbic encephalitis. <h3>Background:</h3> Neurosyphilis can occur at any stage of infection and it classically presents as meningitis, cranial neuropathies, vasculitis, tabes dorsalis, or neuropsychiatric manifestations, however rarely temporal lobe abnormalities resembling limbic encephalitis have been reported. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> 51-year-old male with no past medical history presents initially with 3 weeks of altered mental status, confusion and memory loss. Prior to admission to the hospital, he presented with a generalized tonic-clonic seizure. His MRI showed T2 hyperintensities in the left hippocampus, amygdala, and mesial temporal lobe with associated diffusion restriction. Cerebrospinal fluid (CSF) studies showed 58 white blood cells/mm3 (73% lymphocytes), a protein concentration of 165 mg/dL and a glucose concentration of 35 mg/dL. HIV serology, serum cryptococcal Antigen, HSV and VZV PCR on CSF and neuronal autoantibodies on serum were negative. EEG showed left lateralized periodic discharges. The patient was initially treated with empiric anti-infective therapy including acyclovir, ceftriaxone, and ampicillin. Subsequently, serum syphilis screen was positive with reflex Rapid Plasma Reagin (RPR) titer at 1:64. CSF Venereal Disease Research Laboratory (VDRL) was positive at 1:64. In light of these results, the patient was transitioned to intravenous aqueous penicillin G 24 million units daily through continuous infusion. His mental status markedly improved after a few days of treatment. Repeat EEG showed only mild encephalopathy. He was discharged on levetiracetam and high dose IV penicillin G to complete a 14-day course. <h3>Conclusions:</h3> Syphilis is commonly known as a great imitator; it is a treatable condition so it should not be missed. We need to be more cognizant of this diagnosis when evaluating patients with temporal lobe involvement on MRI, lymphocytic pleocytosis and hypoglycorrhachia. Although HSV and autoimmune diseases are the most common causes of limbic encephalitis, as presented in our case, syphilis testing should be considered. <b>Disclosure:</b> Dr. Hu has nothing to disclose. Dr. El Helou has nothing to disclose. Nayrobi Pena Cotui has nothing to disclose. Dr. Balobaid has nothing to disclose. Dr. Montalvo Perero has nothing to disclose.

Signs of Electro-cortical Disconnection revealed by Hd-EEG in Acute Stroke Patients: a Case Study. (P10-1.010)

<h3>Objective:</h3> To assess electro-cortical disconnection induced by stroke lesions in two patients with Hd-EEG study. <h3>Background:</h3> There are overwhelming evidences that stroke lesions induce local and remote effects beyond the site of the primary anatomical damage. These networks effects have been studied mainly via neuroimaging techniques. However, little is known about the electrocortical disconnection caused by acute stroke. Moreover, the spatial resolution has been limited by the adoption of standard EEG. <h3>Design/Methods:</h3> 128 channels Hd-EEG was recorded in two acute stroke patients (Patient 1 and Patient 2) in awake state. Patient 1 presented with aphasia and neglect in ischemic stroke involving left insula, temporal and parietal lobe. Patient 2 had mild left side paresis with evidence of extensive hypoperfusion and small multiple ischemic infarcts in right ICA occlusion. Raw data were pre-processed in MATLAB using AMICA in EEGLAB. Power spectra analysis was performed on delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz) and beta (12–25 Hz) frequencies at whole-brain level and within each hemisphere. Values were then compared between the two hemispheres (lesioned vs not lesioned) using a t-test analysis (p&lt;0.05). <h3>Results:</h3> Patient 1 had not only higher delta and theta power over temporo-parietal and posterior frontal regions but also absence of alpha power over posterior occipital regions. In addition to high delta and theta activity over a broad region including frontal and temporoparietal areas in the hypo-perfused hemisphere, Hd-EEG in Patient 2 showed abnormal delta activity over contralateral frontal regions. <h3>Conclusions:</h3> Our findings point to the presence of electro-cortical disconnection that extends the focal lesion borders. Both patients had either delta activity or loss of alpha power in regions distant from the location of the primary local damage/hypoperfusion that was characterized by slowing. Hd-EEG may reveal network disruption in acute stroke patients in a novel and complementary way compared to neuroimaging. <b>Disclosure:</b> Dr. Monai has nothing to disclose. Miss Sevak has nothing to disclose. The institution of Dr. GJINI has received research support from NIH. The institution of Dr. Struck has received research support from Ceribell. Dr. Boly has nothing to disclose.

Initial Clinical Experience with Thin-Film Polyimide Subdural Electrodes for Seizure Monitoring (P2-1.005)

<h3>Objective:</h3> NA <h3>Background:</h3> Subdural grid-and-strips are used routinely in pre-surgical evaluations for people with drug-resistant epilepsy (DRE). Thin-film polyimide electrodes (NeuroOne Evo, 0.08mm) which have been approved for clinical use, are thinner and better conform to brain convolutions than current market grids. <h3>Design/Methods:</h3> We present two patients with DRE who underwent intracranial EEG (iEEG) monitoring with thin-film polyimide subdural electrode grid- and-strip electrodes as well as traditional EEG for pre-surgical evaluation. Patient 1 had a prior left mesial temporal lobe ablation with seizure recurrence. They underwent left temporal craniotomy with implantation of two subdural grids, three strips and additional depth electrodes. IEEG demonstrated two habitual seizures arising from anterior temporal subdural strips. Functional mapping identified the basal-temporal and Wernicke’s speech areas. Left anterior temporal lobectomy was performed and he remains seizure free 9 months post-resection. Patient 2 underwent bilateral stereoEEG electrode placement with coverage in the frontal/temporal/insular regions and subdural strip electrodes. IEEG demonstrated seizure onset from the left hippocampus and right hippocampal spikes. Given bilateral findings, they underwent Responsive Neurostimulation System implantation. <h3>Results:</h3> The two patients underwent subdural electrode placements without complications. IEEG recordings were comparable between NeuroOne Evo and traditional electrodes in terms of integrity, artifactual content and signal recording characteristics. The thinner profile of the Evo grid tail facilitated dura closure and reduced mass effect compared to traditional grids. By trimming material from the tip of the subdural strip, the electrode was placed through a burr hole without difficulty. Recording from these grids contributed to presurgical evaluation and led to surgical interventions. <h3>Conclusions:</h3> Our initial experience suggests that thin-film electrodes are a viable option for subdural iEEG that could safely minimize intracranial mass effect/brain shift and improve surgical ease of use. <b>Disclosure:</b> Dr. Reina has nothing to disclose. Dr. Song has received personal compensation in the range of $0-$499 for serving as a Consultant for Clearpoint Neuro. The institution of Dr. Song has received research support from NIH. Dr. Culler has nothing to disclose. Dr. Aronson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Medtronic.

A Rare Familial Case of MELAS in a 66-Year-Old Female and Her 33-Year-Old Son (P12-5.005)

<h3>Objective:</h3> Mitochondrial encephalopathy, lactic acidosis, and stroke like episodes (MELAS) is a mitochondrial disorder presenting most commonly between 2 to 40 years of age, with 75% of cases before age 20. Rare cases have been reported past age 60. We report on a case of a family presenting with late onset MELAS in the same year. <h3>Background:</h3> A 66-year-old female with a past medical history of sensorineural hearing loss, type 2 diabetes, hypertension and hyperlipidemia presented with word finding difficulty and right sided neglect. MRI demonstrated a DWI lesion in the left temporal lobe consistent with infarct. Vessel imaging, echocardiogram, and cardiac monitor were unremarkable, and she was discharged on clopidogrel. She returned 11 days later with worsening aphasia and MRI revealed extension of her stroke into the left occipital lobe and right cerebellum. It was then discovered her previously healthy 33-year-old son had been diagnosed with MELAS three months prior. The son had presented with subtle speech difficulties and was found to have a right temporal DWI and T2 hyperintense lesion on MRI. CSF and serum studies were unremarkable for infectious and autoimmune causes. He was discharged following improvement of symptoms but returned the following day after having generalized seizure. MRI revealed expansion of the lesion into the right parietal lobe. MR Spectroscopy showed an elevated lactate peak leading to a presumptive diagnosis of MELAS. He was started on L-Arginine and CoQ10. In both cases, genetic testing revealed a pathogenic MT-TL1 m.3243A&gt;G variant consistent with MELAS (9.7% heteroplasmy in mother and 31% heteroplasmy in son). <h3>Design/Methods:</h3> NA <h3>Results:</h3> NA <h3>Conclusions:</h3> This case demonstrates low heteroplasmy can lead to a later presentation of MELAS requiring MELAS to be on the differential even in people older than 60. <b>Disclosure:</b> Dr. Iordanova has nothing to disclose. Dr. Wong has nothing to disclose. Dr. Cheng has nothing to disclose.

Can PSMA-Targeting PET/CT Be a Valuable Instrument to Assess the Presence of Brain Metastases in Lung Cancer Patients?: A Case Report.

A 78-year-old man with synchronous diagnosis of prostate cancer and lung adenocarcinoma was referred to our institute for prostate cancer staging with [18F]F-prostate-specific membrane antigen (PSMA) 1007 PET/CT. In addition to the previously known lesion of the right lung, PSMA-targeted PET/CT highlighted 2 areas of abnormal uptake in the brain, in the left frontal and temporal lobes. A subsequent MRI confirmed the lesions observed on PET/CT. Because PSMA-targeting radiopharmaceuticals do not accumulate in healthy brain parenchyma, and recent literature reported promising performances of PSMA-targeted PET/CT in gliomas and metastases from tumors other than prostate cancer, this employment of PSMA radioligands needs to be further explored.

The involvement of the semantic neural network in rule identification of mathematical processing

The role of the visuospatial network in mathematical processing has been established, but the involvement of the semantic network in mathematical processing is still poorly understood. The current study utilized a number series completion paradigm with the event-related potential (ERP) technique to examine whether the semantic network supports mathematical processing and to find the corresponding spatiotemporal neural marker. In total, 32 right-handed undergraduate students were recruited and asked to complete the number series completion as well as the arithmetical computation task in which numbers were presented in sequence. The event-related potential and multi-voxel pattern analysis showed that the rule identification process involves more semantic processing when compared with the arithmetical computation processes, and it elicited higher amplitudes for the late negative component (LNC) in left frontal and temporal lobes. These results demonstrated that the semantic network supports the rule identification in mathematical processing, with the LNC acting as the neural marker.

The central role of the left inferior longitudinal fasciculus in the face-name retrieval network.

Unsuccessful retrieval of proper names (PNs) is commonly observed in patients suffering from neurological conditions such as stroke or epilepsy. While a large body of works has suggested that PN retrieval relies on a cortical network centered on the left anterior temporal lobe (ATL), much less is known about the white matter connections underpinning this process. Sparse studies provided evidence for a possible role of the uncinate fasciculus, but the inferior longitudinal fasciculus (ILF) might also contribute, since it mainly projects into the ATL, interconnects it with the posterior lexical interface and is engaged in common name (CN) retrieval. To ascertain this hypothesis, we assessed 58 patients having undergone a neurosurgery for a left low-grade glioma by means of a famous face naming (FFN) task. The behavioural data were processed following a multilevel lesion approach, including location-based analyses, voxel-based lesion-symptom mapping (VLSM) and disconnection-symptom mapping. Different statistical models were generated to control for sociodemographic data, familiarity, biographical knowledge and control cognitive performances (i.e., semantic and episodic memory and CN retrieval). Overall, VLSM analyses indicated that damage to the mid-to-anterior part of the ventro-basal temporal cortex was especially associated with PN retrieval deficits. As expected, tract-oriented analyses showed that the left ILF was the most strongly associated pathway. Our results provide evidence for the pivotal role of the ILF in the PN retrieval network. This novel finding paves the way for a better understanding of the pathophysiological bases underlying PN retrieval difficulties in the various neurological conditions marked by white matter abnormalities.

Brain Areas Critical for Picture Naming: A Systematic Review and Meta-Analysis of Lesion-Symptom Mapping Studies.

Lesion-symptom mapping (LSM) studies have revealed brain areas critical for naming, typically finding significant associations between damage to left temporal, inferior parietal, and inferior fontal regions and impoverished naming performance. However, specific subregions found in the available literature vary. Hence, the aim of this study was to perform a systematic review and meta-analysis of published lesion-based findings, obtained from studies with unique cohorts investigating brain areas critical for accuracy in naming in stroke patients at least 1 month post-onset. An anatomic likelihood estimation (ALE) meta-analysis of these LSM studies was performed. Ten papers entered the ALE meta-analysis, with similar lesion coverage over left temporal and left inferior frontal areas. This small number is a major limitation of the present study. Clusters were found in left anterior temporal lobe, posterior temporal lobe extending into inferior parietal areas, in line with the arcuate fasciculus, and in pre- and postcentral gyri and middle frontal gyrus. No clusters were found in left inferior frontal gyrus. These results were further substantiated by examining five naming studies that investigated performance beyond global accuracy, corroborating the ALE meta-analysis results. The present review and meta-analysis highlight the involvement of left temporal and inferior parietal cortices in naming, and of mid to posterior portions of the temporal lobe in particular in conceptual-lexical retrieval for speaking.

Remote assessment of cognition and quality of life following radiotherapy for glioma: deep-learning-based predictive models and MRI correlates.

Glioma irradiation often unavoidably damages the brain volume and affects cognition. This study aims to evaluate the relationship of remote cognitive assessments in determining cognitive impairment of irradiated glioma patients in relation to the quality of life and MRI changes. Thirty patients (16-76 aged) with two imaging (pre- and post-RT) and completed cognitive assessments were recruited. Cerebellum, right and left temporal lobes, corpus callosum, amygdala and spinal cord were delineated and their dosimetry parameters were collected. Cognitive assessments were given post-RT via telephone (Telephone Interview Cognitive Status (TICS), Telephone Montreal Cognitive Assessment (T-MoCA), Telephone Mini Addenbrooke's Cognitive Examination (Tele-MACE)). Regression models and deep neural network (DNN) were used to evaluate the relationship between brain volume, cognition and treatment dose in patients. Cognitive assessments were highly inter-correlated (r > 0.9) and impairment was shown between pre- and post-RT findings. Brain volume atrophy was shown post-RT, and cognitive impairments were correlated with radiotherapy-associated volume atrophy and dose-dependent in the left temporal lobe, corpus callosum, cerebellum and amygdala. DNN showed a good area under the curve for cognitive prediction; TICS (0.952), T-MoCA (0.909) and Tele-MACE (0.822). Cognition can be evaluated remotely in which radiotherapy-related brain injury is dose-dependent and volume-dependent. Prediction models can assist in the early identification of patients at risk for neurocognitive decline following RT for glioma, thus facilitating potential treatment interventions.

Word production and comprehension in frontotemporal degeneration: A neurocognitive computational Pickian account

Over a century ago, Arnold Pick reported deterioration of word production and comprehension in frontotemporal degeneration, now a common finding. Individuals with semantic dementia (SD) and behavioral variant frontotemporal dementia (bvFTD) present with word retrieval difficulty, while their comprehension is less affected. Computational models have illuminated naming and comprehension in poststroke and progressive aphasias, including SD, but there are no simulations for bvFTD. Here, the WEAVER++/ARC model, previously applied to poststroke and progressive aphasias, is extended to bvFTD. Simulations tested the hypothesis of a loss of activation capacity in semantic memory in SD and bvFTD, caused by network atrophy (Pick, 1908a). The outcomes revealed that capacity loss explains 97% of the variance in naming and comprehension of 100 individual patients. Moreover, capacity loss correlates with individual ratings of atrophy in the left anterior temporal lobe. These results support a unified account of word production and comprehension in SD and bvFTD.

Cortical thinning in male obstructive sleep apnoea patients with excessive daytime sleepiness.

Obstructive sleep apnoea is associated with excessive daytime sleepiness due to sleep fragmentation and hypoxemia, both of which can lead to abnormal brain morphology. However, the pattern of brain structural changes associated with excessive daytime sleepiness is still unclear. This study aims to investigate the effects of excessive daytime sleepiness on cortical thickness in patients with obstructive sleep apnoea. 61 male patients with newly diagnosed obstructive sleep apnoea were included in the present study. Polysomnography and structural MRI were performed for each participant. Subjective daytime sleepiness was assessed using the Epworth Sleepiness Scale score. Surface-based morphometric analysis was performed using Statistical Parametric Mapping 12 and Computational Anatomy 12 toolboxes to extract cortical thickness. Using the median Epworth Sleepiness Scale score, patients were divided into the non-sleepiness group and the sleepiness group. The cortical thickness was markedly thinner in the sleepiness group in the left temporal, frontal, and parietal lobe and bilateral pre- and postcentral gyri (pFWE < 0.05). There was a significant negative correlation between the cortical thickness and the Epworth Sleepiness Scale score. After adjusting for age, body mass index, and obstructive sleep apnoea severity, the Epworth Sleepiness Scale score remained an independent factor affecting the cortical thickness of the left middle temporal lobe, transverse temporal and temporal pole. Subjective daytime sleepiness is associated with decreased cortical thickness, and the Epworth Sleepiness Scale score may be of utility as a clinical marker of brain injury in patients with obstructive sleep apnoea.

Semantic cognition in healthy ageing: Neural signatures of representation and control mechanisms in naming typical and atypical objects

Effective use of conceptual knowledge engages semantic representation and control processes to access information in a goal-driven manner. Neuropsychological findings of patients presenting either degraded knowledge (e.g., semantic dementia) or disrupted control (e.g., semantic aphasia) converge with neuroimaging evidence from young adults, and delineate the neural segregation of representation and control mechanisms. However, there is still scarce research on the neurofunctional underpinnings of such mechanisms in healthy ageing. To address this, we conducted an fMRI study, wherein young and older adults performed a covert naming task of typical and atypical objects. Three main age-related differences were found. As shown by age group and typicality interactions, older adults exhibited overactivation during naming of atypical (e.g., avocado) relative to typical concepts in brain regions associated to semantic representation, including anterior and medial portions of left temporal lobe (respectively, ATL and MTG). This provides evidence for the reorganization of neural activity in these brain regions contingent to the enrichment of semantic repositories in older ages. The medial orbitofrontal gyrus was also overactivated, indicating that the processing of atypical concepts (relative to typical items) taxes additional control resources in the elderly. Increased activation in the inferior frontal gyrus (IFG) was observed in naming typical items (relative to atypical ones), but only for young adults. This suggests that naming typical items (e.g., strawberry) taxes more on control processes in younger ages, presumably due to the semantic competition set by other items that share multiple features with the target (e.g., raspberry, blackberry, cherry). Together, these results reveal the dynamic nature of semantic control interplaying with conceptual representations as people grow older, by indicating that distinct neural bases uphold semantic performance from young to older ages. These findings may be explained by neural compensation mechanisms coming into play to support neurocognitive changes in healthy ageing.

Altered neuromagnetic activity in default mode network in childhood absence epilepsy.

The electrophysiological characterization of resting state oscillatory functional connectivity within the default mode network (DMN) during interictal periods in childhood absence epilepsy (CAE) remains unclear. Using magnetoencephalographic (MEG) recordings, this study investigated how the connectivity within the DMN was altered in CAE. Using a cross-sectional design, we analyzed MEG data from 33 children newly diagnosed with CAE and 26 controls matched for age and sex. The spectral power and functional connectivity of the DMN were estimated using minimum norm estimation combined with the Welch technique and corrected amplitude envelope correlation. Default mode network showed stronger activation in the delta band during the ictal period, however, the relative spectral power in other bands was significantly lower than that in the interictal period (p corrected < 0.05 for DMN regions, except bilateral medial frontal cortex, left medial temporal lobe, left posterior cingulate cortex in the theta band, and the bilateral precuneus in the alpha band). It should be noted that the significant power peak in the alpha band was lost compared with the interictal data. Compared with controls, the interictal relative spectral power of DMN regions (except bilateral precuneus) in CAE patients was significantly increased in the delta band (p corrected < 0.01), whereas the values of all DMN regions in the beta-gamma 2 band were significantly decreased (p corrected < 0.01). In the higher frequency band (alpha-gamma1), especially in the beta and gamma1 band, the ictal node strength of DMN regions except the left precuneus was significantly higher than that in the interictal periods (p corrected < 0.01), and the node strength of the right inferior parietal lobe increased most significantly in the beta band (Ictal: 3.8712 vs. Interictal: 0.7503, p corrected < 0.01). Compared with the controls, the interictal node strength of DMN increased in all frequency bands, especially the right medial frontal cortex in the beta band (Controls: 0.1510 vs. Interictal: 3.527, p corrected < 0.01). Comparing relative node strength between groups, the right precuneus in CAE children decreased significantly (β: Controls: 0.1009 vs. Interictal: 0.0475; γ 1: Controls:0.1149 vs. Interictal:0.0587, p corrected < 0.01) such that it was no longer the central hub. These findings indicated DMN abnormalities in CAE patients, even in interictal periods without interictal epileptic discharges. Abnormal functional connectivity in CAE may reflect abnormal anatomo-functional architectural integration in DMN, as a result of cognitive mental impairment and unconsciousness during absence seizure. Future studies are needed to examine if the altered functional connectivity can be used as a biomarker for treatment responses, cognitive dysfunction, and prognosis in CAE patients.

Are AI language models such as ChatGPT ready to improve the care of individuals with epilepsy?

Are AI language models such as ChatGPT ready to improve the care of individuals with epilepsy?

Typicality in the brain during semantic and episodic memory decisions

Concept typicality is a key semantic dimension supporting the categorical organization of items based on their features, such that typical items share more features with other members of their category than atypical items, which are more distinctive. Typicality effects manifest in better accuracy and faster response times during categorization tasks, but higher performance for atypical items in episodic memory tasks, due to their distinctiveness. At a neural level, typicality has been linked to the anterior temporal lobe (ATL) and the inferior frontal gyrus (IFG) in semantic decision tasks, but patterns of brain activity during episodic memory tasks remain to be understood. We investigated the neural correlates of typicality in semantic and episodic memory to determine the brain regions associated with semantic typicality and uncover effects arising when items are reinstated during retrieval. In an fMRI study, 26 healthy young subjects first performed a category verification task on words representing typical and atypical concepts (encoding), and then completed a recognition memory task (retrieval). In line with previous literature, we observed higher accuracy and faster response times for typical items in the category verification task, while atypical items were better recognized in the episodic memory task. During category verification, univariate analyses revealed a greater involvement of the angular gyrus for typical items and the inferior frontal gyrus for atypical items. During the correct recognition of old items, regions belonging to the core recollection network were activated. We then compared the similarity of the representations from encoding to retrieval (ERS) using Representation Similarity Analyses. Results showed that typical items were reinstated more than atypical ones in several regions including the left precuneus and left anterior temporal lobe (ATL). This suggests that the correct retrieval of typical items requires finer-grained processing, evidenced by greater item-specific reinstatement, which is needed to resolve their confusability with other members of the category due to their higher feature similarity. Our findings confirm the centrality of the ATL in the processing of typicality while extending it to memory retrieval.

Studyof the microstructure of brain white matter in medial temporal lobe epilepsy based on diffusion tensor imaging.

To compare the white matter (WM) asymmetry in left and right medial temporal lobe epilepsy (mTLE) with and without hippocampal sclerosis (HS+, HS-) and assess the correlation of preoperative asymmetry and the dynamics of WM fibers with surgical outcomes. Preoperative MRI scans were collected from 58 mTLE patients (40 HS+, 18 HS-); 15 (11 HS+, 4 HS-) then underwent postoperative MRI scans. DTI parameters, including the fractional anisotropy (FA), mean diffusion coefficient (MD), axial diffusion coefficient (AD), and radial diffusion coefficient (RD), were extracted from 20 paired WM tracts by PANDA based on the JHU WM tractography atlas. The bilateral cerebral parameters and the pre- to postoperative changes in the DTI parameters of specific fiber tracts were compared. The asymmetry indexes (AIs) of paired fibers were also analyzed. There were fewer asymmetrical WM fibers in HS- patients than in HS+ patients. The pattern of WM asymmetry differed between left and right mTLE patients. Differences in the FA AI of the inferior fronto-occipital fasciculus and inferior longitudinal fasciculus (ILF) were found in left HS+ patients with different surgical outcomes. All mTLE patients exhibited decreases in FA and increases in MD and RD in specific ipsilateral WM fibers. In International League Against Epilepsy (ILAE) grade 1 patients, the MD values in the ipsilateral CGH increased over time, whereas the RD values in the ipsilateral ILF and the AD values in the ipsilateral ILF and UNC decreased. In ILAE grade 2-5 patients, the FA values in the ipsilateral cingulate gyrus part of the cingulum (CGC) increased over time. The WM tract asymmetry was more extensive in HS+ patients than in HS- patients. The preoperative WM fiber AIs in left HS+ patients may be useful for surgical prognosis. Additionally, pre- to postoperative changes in WM fibers may help predict surgical outcomes.

Chronic aphasias after left-hemisphere resective surgery

Surgical resection of brain tumours is associated with an increased risk of aphasia. However, relatively little is known about outcomes in the chronic phase (i.e., >6 months). Using voxel-based lesion symptom mapping (VLSM) in 46 patients, we investigated whether chronic language impairments are related to the location of surgical resection, residual tumour characteristics (e.g., peri-resection treatment effects, progressive infiltration, oedema) or both. Approximately 72% of patients scored below the cut-off for aphasia. Action naming and spoken sentence comprehension deficits were associated with lesions in the left anterior temporal and inferior parietal lobes, respectively. Voxel-wise analyses revealed significant associations between ventral language pathways and action naming deficits. Reading impairments were also associated with increasing disconnection of cerebellar pathways. The results indicate chronic post-surgical aphasias reflect a combination of resected tissue and tumour infiltration of language-related white matter tracts, implicating progressive disconnection as the critical mechanism of impairment.

Intraparenchymal and Subarachnoid Hemorrhage in Stereotactic Electroencephalography Caused by Indirect Adjacent Arterial Injury: Illustrative Case

The complication rate of stereotactic electroencephalography (SEEG) is generally low, but various types of postoperative hemorrhage have been reported. We presented an unusual hemorrhagic complication after SEEG placement. A 20-year-old man presented with suspected frontal lobe epilepsy. We implanted 11 SEEG electrodes in the bilateral frontal lobes and the left insula. Computed tomography after implantation showed intraparenchymal hemorrhage in the left temporal lobe and insula and subarachnoid hemorrhage in the left Sylvian cistern. Later, the point of vessel injury was revealed from the identification of a pseudoaneurysm, but this location was not along the planned or actual electrode trajectory. The cause of hemorrhage was suggested to be indirect injury from stretching of the arachnoid trabeculae by the puncture needle.

Structural correlates of language processing in primary progressive aphasia.

Understanding the relationships between brain structure and language behaviour in primary progressive aphasia provides crucial information about these diseases' pathomechanisms. However, previous investigations have been limited from providing a statistically reliable view of broad language abilities by sample size, variant focus and task focus. In this study, the authors aimed to determine the relationship between brain structure and language behaviour in primary progressive aphasia, to determine the degree to which task-associated regions were atrophied across disease variants and to determine the degree to which task-related atrophy overlaps across disease variants. Participants were 118 primary progressive aphasia patients and 61 healthy, age-matched controls tested from 2011 to 2018 in the German Consortium for Frontotemporal Lobar Degeneration cohort. Diagnosis of primary progressive aphasia required progressive deterioration of mainly speech and language for ≥ 2 years, and variant was diagnosed by the criteria of Gorno-Tempini et al. (Classification of primary progressive aphasia and its variants. Neurology. 2011;76(11):1006-1014). Twenty-one participants not fulfilling a specific subtype were classified as mixed-variant and excluded. Language tasks of interest included the Boston naming test, a German adaptation of the Repeat and Point task, phonemic and category fluency tasks and the reading/writing subtest of the Aachen Aphasia Test. Brain structure was measured by cortical thickness. We observed networks of language task-associated temporal, frontal and parietal cortex. Overlapping task-associated atrophy was observed in the left lateral, ventral and medial temporal lobes, middle and superior frontal gyri, supramarginal gyrus and insula. Some regions, primarily in the perisylvian region, were associated with language behaviour despite showing no significant atrophy. The results crucially extend less powerful studies associating brain and language measures in primary progressive aphasia. Cross-variant atrophy in task-associated regions suggests partially shared underlying deficits, whereas unique atrophy reinforces variant-specific deficits. Language task-related regions that are not obviously atrophied suggest regions of future network disruption and encourage understanding of task deficits beyond clearly atrophied cortex. These results may pave the way for new treatment approaches.