BACKGROUND AND OBJECTIVES:Direct electrocortical stimulation (DES) is the gold standard for mapping eloquent cortex, yet existing functional atlases are limited by sampling biases and density-based methods that obscure a region's true functional probability. Consequently, interpatient variability and the functional contributions of nontraditional language areas, such as the middle frontal gyrus, remain poorly characterized, particularly in epilepsy populations where functional reorganization is common. We therefore developed a probabilistic functional atlas of extraoperative DES and applied data-driven methods to characterize the functional organization of language, motor, and sensory cortex. METHODS:This was a retrospective observational study of patients undergoing intracranial monitoring for drug-resistant epilepsy (2008-2023). Electrical stimulation was delivered to intracranial electrodes during language tasks, and language, motor, and sensory findings were recorded. Positive and negative stimulation sites were analyzed in standard patient space and using the Human Connectome Project parcellation atlas. A multilevel statistical framework, including probability mapping, bootstrapped region-of-interest analyses, and kernel density estimation, defined structure-function relationships. Generalized linear mixed-effects models assessed the influence of clinical variables on language disruption. RESULTS:We analyzed 2,124 trials from 125 patients (mean age 30 years; 47% female). Instead of eloquent functions clustering into discrete canonical regions, they were distributed throughout the cortex along probabilistic continua. Language disruption demonstrated high interpatient variability with the middle frontal gyrus emerging as a high probability area for naming and speech arrest. Motor responses were not confined to the precentral gyrus but frequently extended into parietal association cortex. Clinically, early seizure onset (p = 0.006) and the presence of a temporal lobe lesion (p = 0.003) independently predicted a lower probability of language disruption in the temporal lobe. DISCUSSION:This extraoperative DES atlas provides a comprehensive benchmark for understanding functional cortical organization in epilepsy. We add evidence to the growing literature that language and motor systems are more distributed and variable than classically described. Substantial interpatient variability underscores the necessity of individualized mapping to guide safe neurosurgical planning. Limitations include the retrospective design and sampling bias inherent to electrode placement.

OBJECTIVE:People with focal epilepsy experience one or more seizures prior to diagnosis. The Human Epilepsy Project (HEP) was a prospective study enrolling people with newly diagnosed focal epilepsy. It collected information including cognitive testing at the time of enrollment. This was completed utilizing a computerized test battery called the Cogstate Brief Battery (CBB). A prior analysis found that enrollment CBB test scores were below that of age matched controls and that performance on testing was not independently associated with the longer-term development of treatment resistance over the course of the HEP study. The present study assesses the impact of pretreatment seizures on cognition at time of diagnosis, considering time-to-treatment initiation in relation to seizure onset, pre-treatment seizure frequency, and pretreatment seizure classification. METHODS:Participants with newly diagnosed focal epilepsy and no other major medical comorbidities or intellectual disability (estimated IQ > 70) were enrolled between June 29, 2012, and September 1, 2019. A subset of the 448 enrolled participants (N = 183) were over 18 years old, had complete HEP enrollment data that included pre-treatment seizure histories, and complete enrollment CBB testing for analysis in this study. Performance on enrollment CBB testing was modeled using multiple linear regression with pre-treatment seizure characteristics including seizure type and duration between seizure onset and treatment initiation, controlling for other key baseline participant characteristics. RESULTS:There were no independent associations between cognitive measures on the CBB at the time of enrollment and pre-treatment seizures after correcting for potentially confounding variables. Z-scores for the attention composite on CBB (an average of Identification and Detection tests) were not associated with a global pre-treatment seizure score that quantified time with seizures (days) and seizure count by seizure type (motor, non-motor, bilateral tonic clonic) (p = 0.29). Similarly, z-scores for the memory composite (an average of the One Card Learning test and One Back tests) were not associated with the pre-treatment seizure score (p = 0.1). No additional independent associations were found to be significant between z-scores for attention or memory composites and other potential explanatory variables. SIGNIFICANCE:This study highlights an important finding for people who develop focal epilepsy and otherwise are in good health: pre-treatment time-limited seizures do not have an independent impact on cognition early on, as measured by a brief validated cognitive screening test. This suggests that that cognition at the time of epilepsy diagnosis may be more strongly related to underlying etiology, chronic disease, and comorbidities.

Objective: Seizures can impact cognition both acutely and chronically. However, among those without significant comorbidities and broadly average cognition at epilepsy onset, the relationship between cognitive function at the time of diagnosis and long-term seizure control has been relatively unexplored. This analysis investigated associations between participant characteristics including specific aspects of cognitive performance at the time of focal epilepsy diagnosis and antiseizure medication (ASM) treatment resistance. Methods: This was a secondary analysis of Human Epilepsy Project (HEP) data, which enrolled people with newly diagnosed focal epilepsy and broadly average cognition (estimated IQ >= 70) from June 29, 2012, to September 1, 2019. Participants analyzed in this study were between 18 and 60 years old, and scored within an acceptable range (i.e., Standard Score of >= 80) on measures estimating premorbid cognitive ability were offered the Cogstate Brief Battery (CBB). Participant characteristics were analyzed, including the presence of any anxiety disorders or depression, and summary CBB scores. HEP participants who were classified by the study as treatment resistant if they had experienced failure to achieve seizure freedom after two adequate trials of ASMs. Treatment resistance was modeled using multiple logistic regression to assess for independent associations between attention and working memory after correcting for the presence of the other potentially explanatory variables. Results: 200 HEP participants had comprehensive enrollment records including CBB results and complete seizure outcome data for analysis in this study. After correcting for potentially confounding variables, there were no independent associations between cognitive measures on the CBB at the time of enrollment and subsequent development of ASM treatment resistance. Specifically, z-scores for reaction time on the CBB (an average of the CBB Identification and Detection tests) were not associated with treatment resistance (p = 0.51) and z-scores for memory performance (an average of the CBB One Card Learning test and One Back tests) were not associated with treatment resistance (p = 0.24). There were no significant independent associations between age or the presence of depression or anxiety disorders at the time of CBB testing and treatment resistance. However, there was an independent association between employment status and treatment resistance, with those who were employed or students (>18 years old) at the time of enrollment and CBB testing having 0.35 times lower odds of treatment resistance (95 %CI 0.15-0.81, p symbolscript 0.01). Significance: The findings from this study suggest that in otherwise healthy people with new onset focal epilepsy who have broadly average intelligence, attention and working memory as measured by the CBB at the time of diagnosis is not associated with treatment resistance. Although performance on cognitive testing at epilepsy onset may not be predictive of risk of treatment resistance in this population, other individual characteristics such as employment status at the time of diagnosis may be indirect markers of long-term seizure outcomes and require further investigation.

ObjectiveA previous investigation of people with newly diagnosed focal epilepsy participating in the Human Epilepsy Project 1 (HEP1) revealed an association between learning difficulties and structural brain differences, suggesting an underlying relationship prior to seizure onset. To investigate physicians’ practices of documentation learning difficulties during clinical encounters, we conducted a review of initial epileptologist encounter notes from HEP1 participants who self-reported early life learning difficulties separately as part of study enrollment.MethodsHEP1 enrolled 67 North American participants between June 2012 and November 2017 who self-reported one or more difficulties with learning (i.e., having repeated grade, receiving learning support/remediation, and/or formal diagnosis of a learning disability) prior to epilepsy diagnosis as part of the study enrollment. The epileptologist’s initial encounter note was then reviewed in detail for each of these participants. Documentation of learning issues and specific diagnoses of learning disabilities was compared to participant characteristics. Regression analysis was used to test for any independent associations between participant characteristics and physician documentation of learning difficulties.ResultsThere were significant independent relationships between age, sex, and physician documentation of learning difficulties. On average, participants ages 22 and younger were 12.12 times more likely to have their learning difficulties documented compared to those 23 years and older (95 % CI: 2.226 to 66.02, p = 0.004). Additionally, male participants had 7.2 times greater odds of having their learning difficulty documented compared to female participants (95 % CI: 1.538 to 33.717, p = 0.012). There were no significant independent associations between race, language, employment, or geographical region.SignificanceThese findings highlight disparities in physician documentation for people with newly diagnosed focal epilepsy and a history of learning difficulties. In the HEP1 cohort, physicians were more likely to document learning difficulties in males and in younger individuals. Systematic practice standards are important for reducing healthcare disparities across populations, improving clinical care to individuals, as well as enabling more accurate retrospective study of clinical phenomenon.

Objective The Human Epilepsy Project (HEP) is a large multinational cohort study of people with newly diagnosed and treated focal epilepsy. HEP utilized the Cogstate Brief Battery (CBB) as a self-directed online assessment to examine cognitive outcomes in study participants. The CBB has previously been validated in healthy individuals and people with various brain disorders, but its use in adults participating in HEP has not been assessed. In this study, we describe how the CBB was used in the HEP cohort and assess factors associated with test completion among study participants. Methods Enrollment data for HEP included 408 participants with comprehensive enrollment records, of whom 249 completed CBB assessments. HEP enrolled cognitively normal-range participants between the ages of 12 and 60 from June 29, 2012, to November 7, 2017, with newly diagnosed focal epilepsy and within 4 months of initial treatment. Baseline participant characteristics were analyzed, including demographics, pre-treatment seizure histories, MRI abnormalities, and the presence of any learning difficulties while in school, including formal learning disability diagnoses, repeated grades, and remediation. HEP participant characteristics for those who completed CBB testing were compared to those who did not using multiple logistic regression. Results The analysis of HEP participants who completed CBB testing showed that, after controlling for other factors, male participants were more likely to engage in testing (OR 2.14, 95 % CI 1.29 to 3.5, p < 0.01), Black subjects were less likely (OR 0.45, 95 % CI 0.22 to 0.9, p = 0.02), primary English speakers were more likely (OR 3.1, 95 % CI 1.21 to 7.96, p = 0.02), and those with a history of learning challenges were less likely (OR 0.69, 95 % CI 0.49 to 0.97, p = 0.03). There were no significant associations between completing CBB testing and age, employment (employed or student vs not), education (higher education vs not), diagnostic delay, pre-diagnostic seizure burden, or initial seizure semiology (motor vs non-motor). Significance The findings from this study highlight factors associated with the application of remote and unsupervised assessments of cognition in a prospective cohort of adults with focal epilepsy. These factors can be considered when interpreting performance on the CBB in HEP, as well as assisting the design of future studies that use similar approaches.

OBJECTIVE:Visual assessment of magnetic resonance imaging (MRI) from the Human Epilepsy Project 1 (HEP1) found 18% of participants had atrophic brain changes relative to age without known etiology. Here, we identify the underlying factors related to brain volume differences in people with focal epilepsy enrolled in HEP1. METHODS:Enrollment data for participants with complete records and brain MRIs were analyzed, including 391 participants aged 12-60 years. HEP1 excluded developmental or cognitive delay with intelligence quotient <70, and participants reported any formal learning disability diagnoses, repeated grades, and remediation. Prediagnostic seizures were quantified by semiology, frequency, and duration. T1-weighted brain MRIs were analyzed using Sequence Adaptive Multimodal Segmentation (FreeSurfer v7.2), from which a brain tissue volume to intracranial volume ratio was derived and compared to clinically relevant participant characteristics. RESULTS:Brain tissue volume changes observable on visual analyses were quantified, and a brain tissue volume to intracranial volume ratio was derived to compare with clinically relevant variables. Learning difficulties were associated with decreased brain tissue volume to intracranial volume, with a ratio reduction of .005 for each learning difficulty reported (95% confidence interval [CI] = -.007 to -.002, p = .0003). Each 10-year increase in age at MRI was associated with a ratio reduction of .006 (95% CI = -.007 to -.005, p < .0001). For male participants, the ratio was .011 less than for female participants (95% CI = -.014 to -.007, p < .0001). There were no effects from seizures, employment, education, seizure semiology, or temporal lobe electroencephalographic abnormalities. SIGNIFICANCE:This study shows lower brain tissue volume to intracranial volume in people with newly treated focal epilepsy and learning difficulties, suggesting developmental factors are an important marker of brain pathology related to neuroanatomical changes in focal epilepsy. Like the general population, there were also independent associations between brain volume, age, and sex in the study population.

Objective Neuropsychologists labor over scoring the Rey Complex Figure Test (RCFT), a measure of visuospatial functioning and nonverbal memory. Compelling arguments suggest that pathognomonic signs of the RCFT are observable to the "naked eye." Standard scoring systems are insensitive to lateralizing temporal lobe epilepsy (TLE) and alternative "qualitative" scoring systems are ineffective and time-consuming. Method: We examined accuracy of TLE lateralization using subjective classifications and standard scoring. Participants were 84 TLE patients (53 female; mean age(=)36yrs) and 46 controls (27 female; mean age = 27.5). The former were classified as right (n = 41) or left (n = 43) TLE by neurologists using EEG and MRI studies. RCFT were scored using standard scoring with cut-offs of z <= -2 classified as impaired and were rated as "characteristic" of RTLE (Ugly) or LTLE (Not Ugly) performance by neuropsychologists. Accuracy of seizure lateralization for both methods was examined. Results: Neuropsychologists' ratings accuracy were at or below chance. Standard scoring criteria showed chance or slightly better lateralization prediction. Standard scoring predicted RTLE laterality more accurately than subjective ratings for copy trials; standard scoring was no better at lateralizing RTLE with delays. Subjective ratings were better at distinguishing TLE patients from controls. Conclusion: Findings highlight concerns regarding the usefulness of the RCFT in TLE lateralization, regardless of scoring approach.

OBJECTIVELittle is known about psychiatric symptoms among patients with migraine and newly diagnosed focal epilepsy. The investigators compared symptoms of depression, anxiety, and suicidality among people with newly diagnosed focal epilepsy with migraine versus without migraine.METHODSThe Human Epilepsy Project is a prospective multicenter study of patients with newly diagnosed focal epilepsy. Depression (measured with the Center for Epidemiologic Studies Depression Scale), anxiety (measured with the 7-item Generalized Anxiety Disorder scale), and suicidality scores (measured with the Columbia-Suicide Severity Rating Scale [C-SSRS]) were compared between participants with versus without migraine. Data analysis was performed with the Kolmogorov-Smirnov test for normality assessment, the Mann-Whitney U test, chi-square test, and linear regression.RESULTSOf 349 patients with new-onset focal epilepsy, 74 (21.2%) had migraine. There were no differences between the patients without migraine versus those with migraine in terms of age, race, and level of education. There were more women in the group with migraine than in the group without migraine (75.7% vs. 55.6%, p=0.0018). The patients with epilepsy and comorbid migraine had more depressive symptoms than the patients with epilepsy without migraine (35.2% vs. 22.7%, p=0.031). Patients with epilepsy with comorbid migraine had more anxiety symptoms than patients with epilepsy without migraine, but this relation was mediated by age in logistic regression, with younger age being associated with anxiety. Comorbid migraine was not associated with C-SSRS ideation or behavior.CONCLUSIONSAmong a sample of patients with newly diagnosed focal epilepsy, 21.2% had migraine. Migraine comorbidity was associated with higher incidence of depressive symptoms. Future studies should be performed to better assess these relationships and possible treatment implications.

ABSTRACTBackgroundLittle is known regarding long-term outcomes of patients hospitalized with COVID-19.MethodsWe conducted a prospective study of 6-month outcomes of hospitalized COVID-19 patients. Patients with new neurological complications during hospitalization who survived were propensity score-matched to COVID-19 survivors without neurological complications hospitalized during the same period. The primary 6-month outcome was multivariable ordinal analysis of the modified Rankin Scale(mRS) comparing patients with or without neurological complications. Secondary outcomes included: activities of daily living (ADLs;Barthel Index), telephone Montreal Cognitive Assessment and Neuro-QoL batteries for anxiety, depression, fatigue and sleep.ResultsOf 606 COVID-19 patients with neurological complications, 395 survived hospitalization and were matched to 395 controls; N=196 neurological patients and N=186 controls completed follow-up. Overall, 346/382 (91%) patients had at least one abnormal outcome: 56% had limited ADLs, 50% impaired cognition, 47% could not return to work and 62% scored worse than average on ≥1 Neuro-QoL scale (worse anxiety 46%, sleep 38%, fatigue 36%, and depression 25%). In multivariable analysis, patients with neurological complications had worse 6-month mRS (median 4 vs. 3 among controls, adjusted OR 2.03, 95%CI 1.22-3.40, P=0.01), worse ADLs (aOR 0.38, 95%CI 0.29-0.74, P=0.01) and were less likely to return to work than controls (41% versus 64%, P=0.04). Cognitive and Neuro-QOL metrics were similar between groups.ConclusionsAbnormalities in functional outcomes, ADLs, anxiety, depression and sleep occurred in over 90% of patients 6-months after hospitalization for COVID-19. In multivariable analysis, patients with neurological complications during index hospitalization had significantly worse 6-month functional outcomes than those without.

Magnetic resonance imaging (MRI)-negative temporal lobe epilepsy (TLE) may be a distinct syndrome from TLE with mesial temporal sclerosis (TLE-MTS). Imaging and neuropsychological features of TLE-MTS are well-known; yet, these features are only beginning to be described in MRI-negative TLE. This study examined whether a quantitative measure of cortical gray and white matter blurring (GWB) was elevated in the temporal lobes ipsilateral to the seizure onset zone of individuals with MRI-negative TLE relative to TLE-MTS and healthy controls (HCs) and whether GWB elevations were associated with neuropsychological comorbidity. Gray-white matter blurring from 34 cortical regions and hippocampal volumes were quantified and compared across 28 people with MRI-negative TLE, 15 people with TLE-MTS, and 51 HCs. Declarative memory was assessed with standard neuropsychological tests and the intracarotid amobarbital procedure (IAP). In the group with MRI-negative TLE (left and right onsets combined), hippocampal volumes were within normal range but GWB was elevated, relative to HCs, across several mesial and lateral temporal lobe regions ipsilateral to the seizure onset zone. Gray-white matter blurring did not differ between the groups with TLE-MTS and HC or between the groups with TLE-MTS and MRI-negative TLE. The group with MRI-negative TLE could not be distinguished from the group with TLE-MTS on any of the standard neuropsychological tests; however, ipsilateral hippocampal volumes and IAP memory scores were lower in the group with TLE-MTS than in the group with MRI-negative TLE. The group with left MRI-negative TLE had lower general cognitive abilities and verbal fluency relative to the HC group, which adds to the characterization of neuropsychological comorbidities in left MRI-negative TLE. In addition, ipsilateral IAP memory performance was reduced relative to contralateral memory performance in MRI-negative TLE, indicating some degree of ipsilateral memory dysfunction. There was no relationship between hippocampal volume and IAP memory scores in MRI-negative TLE; however, decreased ipsilateral IAP memory scores were correlated with elevated GWB in the ipsilateral superior temporal sulcus of people with left MRI-negative TLE. In sum, GWB elevations in the ipsilateral temporal lobe of people with MRI-negative TLE suggest that GWB may serve as a marker for reduced structural integrity in regions in or near the seizure onset zone. Although mesial temporal abnormalities might be the major driver of memory dysfunction in TLE-MTS, a loss of structural integrity in lateral temporal lobe regions may contribute to IAP memory dysfunction in MRI-negative TLE.

BACKGROUND:Migraine and epilepsy are comorbid conditions. While it is well known that epilepsy can have an impact on cognitive abilities, there is conflicting evidence in the literature on the relationship between migraine and cognitive function. The aim of this study was to assess whether migraine comorbidity in patients with newly diagnosed focal epilepsy is associated with cognitive dysfunction. METHODS:This is a post hoc analysis of data prospectively collected for the Human Epilepsy Project (HEP). There were 349 participants screened for migraine with the 13 questions used in the American Migraine Prevalence and Prevention (AMPP) study. Participants were also screened for depression using the Neurological Disorder Depression Inventory for Epilepsy (NDDI-E) and the Center for Epidemiologic Studies Depression Scale (CES-D) and for anxiety using the Generalized Anxiety Disorder-7 (GAD-7) scale. Cognitive performance was assessed with the Cogstate Brief Battery and Aldenkamp-Baker Neuropsychological Assessment Schedule (ABNAS). RESULTS:About a fifth (21.2%) of patients with a new diagnosis of focal epilepsy screened positive for migraine. There were more women and less participants employed full time among the participants with comorbid migraine. They reported slightly more depressive and anxious symptoms than the participants without migraine. Migraine comorbidity was associated with ABNAS memory score (median: 2, range: 0-12, Mann Whitney U p-value: 0.015). However, migraine comorbidity was not associated with Cogstate scores nor ABNAS total scores or other ABNAS domain scores. In linear regressions, depression and anxiety scores were associated with the ABNAS memory score. CONCLUSION:In this study, there was no association between migraine comorbidity and objective cognitive scores in patients with newly diagnosed focal epilepsy. The relationship between migraine comorbidity and subjective memory deficits seemed to be mediated by the higher prevalence of depression and anxiety symptoms in patients with epilepsy with comorbid migraine.

"Winners of the Third Annual TCN/AACN Student Project Competition." The Clinical Neuropsychologist, 32(4), pp. 739–740

Critical decisions regarding resection boundaries for epilepsy surgery are often based on results of electrical stimulation mapping (ESM). Despite the potentially serious implications for postoperative functioning, age‐referenced data that might facilitate the procedure are lacking. Age might be particularly relevant, as pediatric ESM studies have shown a paucity of language sites in young children followed by a rapid increase at approximately 8‐10 years. Beyond adolescence, it has generally been assumed that the language system remains stable, and therefore, potential age‐related changes across the adult age span have not been examined. However, increasing age during adulthood is associated with both positive and negative language‐related changes, such as a broadening vocabulary and increased word finding difficulty. Because most patients who undergo ESM are adults, we aimed to determine the potential impact of age on the incidence of ESM‐identified naming sites across the adult age span in patients with refractory epilepsy.

a New York University School of Medicine, Department of Neurology, Epilepsy Division, New York, NY 10016, United States of America b St. George's University School of Medicine, Department of Physiology, Neuroscience, and Behavioral Sciences, West Indies, Grenada c University of Calgary, Alberta Children's Hospital, Calgary, Alberta, Canada d The Rockefeller University, Laboratory of Neural Systems, New York, NY 10065, United States of America e New York University School of Medicine, Department of Radiology, New York, NY 10016, United States of America f University of California San Diego, Multimodal Imaging Laboratory, San Diego, CA 92093, United States of America

Epilepsy is a prevalent condition characterized by variations in its clinical presentation, etiology, and amenability to treatment. Through history, neuropsychologists have played a significant role in performing research studies on changes in language, memory, and executive functioning in patients with epilepsy, including those undergoing surgical treatment for medically refractory seizures. These studies provided a foundation for establishing neuropsychologists as critical members of interdisciplinary clinical teams specializing in evaluation and treatment of epilepsy. This article describes a number of elements of specialized neuropsychological practice that have evolved over the years within a tertiary care epilepsy center. Through diagnostic interview and objective testing, the neuropsychologist is able to provide a more complete and objective understanding of a patient's cognitive and behavioral functioning than what is obtained by other clinicians through brief office visits. While assessment of cognition, mood, and behavior is the most commonly provided service to patients with epilepsy from all age groups, there are many instances when neuropsychologists in surgical settings are called to perform more specialized procedures, including the intracarotid amytal (Wada) procedure, electrocortical stimulation mapping of language eloquent brain regions, and functional brain imaging procedures. While working as a neuropsychologist on an interdisciplinary epilepsy care team requires specialized knowledge and clinical training, it is extremely satisfying due to the diversity of the patient population and the particular challenges resulting from the often unique manner that cognition and behavior can be affected in patients with epilepsy across the lifespan.

The differential contribution of medial-temporal lobe regions to verbal declarative memory is debated within the neuroscience, neuropsychology, and cognitive psychology communities. We evaluate whether the extent of surgical resection within medial-temporal regions predicts longitudinal verbal learning and memory outcomes. This single-center retrospective observational study involved patients with refractory temporal lobe epilepsy undergoing unilateral anterior temporal lobe resection from 2007 to 2015. Thirty-two participants with Engel Class 1 and 2 outcomes were included (14 left, 18 right) and followed for a mean of 2.3 years after surgery (±1.5 years). Participants had baseline and postsurgical neuropsychological testing and high-resolution T1-weighted MRI scans. Postsurgical lesions were manually traced and coregistered to presurgical scans to precisely quantify resection extent of medial-temporal regions. Verbal learning and memory change scores were regressed on hippocampal, entorhinal, and parahippocampal resection volume after accounting for baseline performance. Overall, there were no significant differences in learning and memory change between patients who received left and right anterior temporal lobe resection. After controlling for baseline performance, the extent of left parahippocampal resection accounted for 27% (p = .021) of the variance in verbal short delay free recall. The extent of left entorhinal resection accounted for 37% (p = .004) of the variance in verbal short delay free recall. Our findings highlight the critical role that the left parahippocampal and entorhinal regions play in recall for verbal material.

To preserve postoperative language, electrical stimulation mapping is often conducted prior to surgery involving the language-dominant hemisphere. Object naming is the task most widely used to identify language cortex, and sites where stimulation elicits naming difficulty are typically spared from resection. In clinical practice, sites classified as positive undergo no further testing regarding the underlying cause of naming failure. Word production is a complex function involving multiple mechanisms that culminate in the identification of the target word. Two main mechanisms, i.e., semantic and phonological, underlie the retrieval of stored information regarding word meaning and word sounds, and naming can be hampered by disrupting either of these. These two mechanisms are likely mediated by different brain areas, and therefore, stimulation-identified naming sites might not be functionally equivalent. We investigated whether further testing at stimulation-identified naming sites would reveal an anatomical dissociation between these two mechanisms. In 16 patients with refractory temporal lobe epilepsy (TLE) with implanted subdural electrodes, we tested whether, despite inability to produce an item name, patients could reliably access semantic or phonological information regarding objects during cortical stimulation. We found that stimulation at naming sites in superior temporal cortex tended to impair phonological processing yet spared access to semantic information. By contrast, stimulation of inferior temporal naming sites revealed a greater proportion of sites where semantic access was impaired and a dissociation between sites where stimulation spared or disrupted semantic or phonological processing. These functional–anatomical dissociations reveal the more specific contribution to naming provided by these cortical areas and shed light on the often profound, interictal word-finding deficit observed in temporal lobe epilepsy. Additionally, these techniques potentially lay the groundwork for future studies to determine whether particular naming sites that fall within the margins of the desired clinical resection might be resected without significant risk of decline.