头颅MRI海马像异常与难治性内侧颞叶癫(癎)患者近期记忆损害

目的 探讨难治性内侧颞叶癫(癎)(MTLE)患者影像学异常及发作间期放电(IEDs)优势侧对近期记忆损害的影响.方法 纳入2006年9月至2007年4月我院癫(癎)中心门诊就诊的难治性MTLE患者50例,根据MRI海马像检查将其分为左侧MRI(+)组、右侧MRI(+)组、MRI(-)组及双侧MRI(+)组.综合多次IEDs结果进行评定,若一侧独立IEDs≥75%,则判为IEDs优势侧.采用临床记忆量表(CMS)对患者进行记忆评定.结果 年龄、性别、职业、文化程度、是否来自农村、病程、发作情况、药物治疗各因素在4组间的分布相匹配.各组记忆商(MQ)及分量表的年龄量表分比CMS正常均数差(P＜0.05).右侧MR[(+)组无意义图形再认得分(9.42±7.46)相对于左侧MRI(+)组(16.26±4.43)和MRI(-)组(18.26±5.49)低(F=4.281,P＜0.05).MRI(-)者中左侧IEDs、右侧IEDs、双侧IEDs 3组间MQ及各分量表的年龄量表分值均无统计学意义.结论 右侧MRI(+)MTLE患者在空间图形记忆方面的损害更加显著,无意义图形再认对于非语言记忆的评价有较高的特异性.     

头部MRI阴性的颞叶内侧癫痫患者认知功能障碍研究

目的评估头部MRI阴性颞叶内侧癫痫(MTLE)患者认知功能受损特点。方法回顾性分析27名头部MRI阴性的MTLE患者资料,其中左侧MTLE 14例(左侧MTLE组),右侧MTLE 13例(右侧MTLE组)。癫痫患者与性别、年龄和受教育程度严格匹配的14名健康对照者(对照组)均接受蒙特利尔认知评估量表(Mo CA)和失礼识别任务的测评。结果在Mo CA得分方面,两组MTLE患者的Mo CA总分及各分项测试得分均低于对照组(P 0. 05);右侧MTLE组复制立方体得分低于左侧MTLE组和对照组(P 0. 05);右侧MTLE组的画钟试验得分低于左侧MTLE组(P 0. 05);左侧MTLE组句子复述、语言流畅性测试得分低于右侧MTLE组(P 0. 05)。在失礼识别任务得分方面,两组MTLE患者得分均低于对照组(P 0. 05);左侧MTLE组比右侧MTLE组更低(P 0. 05)。结论头部MRI阴性MTLE患者的一般认知功能及高级社会认知功能均受损。     

Impaired associative memory in temporal lobe epilepsy subjects after lesions of hippocampus, parahippocampal gyrus, and amygdala

There has been growing interest in the differential role of medial temporal lobe structures in learning and memory. The goal of the present study was to clarify how lesions of hippocampus, parahippocampal gyrus, and amygdala interfere with associative learning and memory. Thirty subjects with pharmacoresistant medial temporal lobe epilepsy (TLE) and temporal lobe removal were compared with 30 matched healthy control subjects. A set of neuropsychological test measures and an associative learning task requiring the learning and recall of objects and faces were administered. The lesions of hippocampus, parahippocampal gyrus, amygdala, and fusiform gyrus of TLE subjects were determined by three-dimensional magnetic resonance imaging (3-D MRI) volumetric assessment. The results indicate that TLE subjects with combined large hippocampal lesions, large parahippocampal gyrus (i.e., perirhinal/entorhinal) lesions, and large amygdala lesions learned and recalled the associative task significantly worse than control subjects or subjects with small lesions of the hippocampus, parahippocampal gyrus, and amygdala. Regression analysis revealed that larger lesions of the parahippocampal gyrus (i.e., perirhinal/entorhinal cortices) were significantly related to increasing deficits on the task, and that hippocampal and amygdala lesion size did not significantly improve the prediction. Our results suggest that perirhinal and entorhinal cortices may contribute predominantly to the associative learning and recall of objects and faces.     

Verbal semantic memory in temporal lobe epilepsy

OBJECTIVES: Temporal lobe epilepsy (TLE) may determine memory difficulties not explained by episodic memory impairment. The present study was aimed to verify the presence of specific semantic memory dysfunctions in TLE and to explore their relations to epilepsy variables. SUBJECTS AND METHODS: Forty-seven patients with lateralized temporal (n = 26) or extra-temporal lobe epilepsy (n = 21) and 23 healthy subjects were compared. Picture Naming and Pointing to a Picture were used to explore expressive and receptive vocabulary and the Semantic Questionnaire evaluated semantic judgment of verbally presented items. The Selective Reminding Procedure for word list learning and Story Recall were used to assess episodic memory. Spontaneous speech and the Token Test controlled for language disturbances, and Raven's Coloured Progressive Matrices were used to evaluate abstract reasoning ability. RESULTS: Multivariate analysis of variance of test scores showed significant impairment of semantic memory in patients with left TLE compared to healthy controls, whereas episodic memory was impaired in left temporal and extra-temporal epilepsy (as measured by word learning) and all epilepsy groups (as measured by Story Recall). In the TLE groups, naming abilities were more compromised than single-word comprehension and semantic judgment - which were not significantly affected. No deficits in language abilities or in abstract reasoning were found in any patient group. Factor analysis of memory tests scores in the patients produced two factors, one semantic and the other episodic. Regression analysis revealed that the semantic factor was related to abstract reasoning, left hemisphere lateralization of seizures, and age of seizure onset; while the episodic factor was related to age. CONCLUSIONS: Left TLE may determine significant verbal semantic memory compromise, maybe due to impaired access to the semantic-lexical storage. In non-aphasic epilepsy patients, comparison of performance on semantic and episodic memory tests may be useful for assessing the nature of memory failures, and may complement clinical and neurophysiological means for defining the epileptic center.     

立体定向海马杏仁核复合体毁损术治疗MRI阴性与MRI阳性颞叶癫(癎)疗效的差异

目的 观察深部脑电记录电极引导立体定向手术治疗顽固性癫(癎)的手术疗效,并对照术前MRI阳性患者与MRI阴性患者手术疗效差别.方法 对267例顽固性癫(癎)患者采用深部脑电记录电极引导立体定向脑内核团毁损术,并对其中127例进行回访,对回访结果行Engel分级评定,根据患者MRI表现是否阳性将获访患者分为两组,计算两组患者(癎)性发作消失率、显效率、有效率及无效率,并对其间差异分别作统计学分析.结果 随访2 ～70个月,Engel分级Ⅰ级41例,Ⅱ级7例,Ⅲ级22例,Ⅳ级57例,总体(癎)性发作消失率32％.MRI阴性患者组(癎)性发作消失率50％.MRI阳性组(癎)性发作消失率16％.经比较,两组患者(癎)性发作消失率的差别有统计学意义(x2=16.33,P＜ 0.005).结论 头颅MRI示阴性者手术疗效较头颅MRI有阳性发现者手术疗效明显要好,推荐MRI阴性的药物难治性癫(癎)患者首选立体定向毁损.     

Medial temporal lobe atrophy and memory deficits in elderly stroke patients

Medial temporal lobe atrophy (MTA) and its role in memory deficits have been studied extensively in patients with various dementias and non-degenerative neurologic diseases. In stroke patients MTA is a significant risk factor for dementia. However, its role in memory decline in non-demented stroke patients is not yet known. Our aim was to evaluate the relationship between MTA and cognitive functions in a large cohort of elderly patients, who underwent a comprehensive neuropsychologic examination and magnetic resonance imaging 3 months after an ischemic stroke. The study sample (n = 260) was divided into three groups according to the severity of MTA. After adjusting for age, volume of infarcts and cortical atrophy, we found that patients with moderate to severe MTA performed significantly worse in tests of learning, story recall, visual reproduction, block design and mental speed. In contrast, the groups did not differ in tests of digit span, flexibility, verbal fluency and conceptualization. Our conclusion is that in aged stroke patients, MTA is associated with poor performance in specific cognitive domains. The most vulnerable domains are memory and visuospatial functions, whereas verbal and executive functions seem to be unrelated to MTA.     

Do I know you? Face perception and memory in patients with selective amygdalo-hippocampectomy.

In 1968, Milner (Neuropsychologia 6 (1968) 191) demonstrated a face-memory impairment in patients with right, but not left, temporal-lobe excisions. Because all the removals included lateral and inferior temporal neocortex together with amygdala, parahippocampal gyrus and varying amounts of hippocampus, a combined-lesion effect could not be ruled out. We therefore examined the contribution of right temporal structures to recognition of previously unfamiliar faces by repeating Milner's original study, testing patients who had undergone selective amygdalo-hippocampectomy (AH), in addition to those with anterior temporal-lobectomy (TL). The paradigm involved selecting 12 previously studied faces from an array of 25 photographs. The Mooney Closure Faces Test was also administered. Subjects included 29 AH patients (14 left (LAH) and 15 right (RAH)) and 59 TL patients (30 L and 29 R) who were categorized further based on extensive (18 LTH and 21 RTH) or minimal (12 LTh and 8 RTh) hippocampal encroachment. Twenty age- and education-matched normal control subjects (NC) were also tested. For the face-memory task, one-way ANOVA revealed a strong group effect (P<0.001), and post-hoc tests confirmed that both the RTH and RAH groups recognized fewer faces than the NC and LAH groups; the RAH group also differed from the LTh, LTH and RTh groups. No group differences were found for the closure test. Our findings suggest that right medial temporal-lobe structures are critically involved in the retention, but probably not in the perception, of new faces.     

Remote memory in temporal lobe epilepsy

PURPOSE: The present study aims at characterizing remote memory in patients with temporal lobe epilepsy (TLE); it also considers the impact of its most important variables (lateralization of the lesion, duration of epilepsy, age at onset, and seizure frequency) on remote memory. METHODS: We examined the performance of 38 patients with unilateral TLE (19 right TLE and 19 left TLE) and 35 healthy subjects on six remote memory tasks. Memory for personal events was assessed by using the Autobiographical Memory Interview and the Modified Crovitz Test. Memory for public events was evaluated by means of photographs of famous faces and famous scenes, questions about famous events, and the Dead/Alive Test. RESULTS: Both right-TLE and left-TLE groups had impaired memory for autobiographic episodes and public events relative to normal subjects. In contrast, personal semantic memory was preserved. In addition, an effect of laterality was recorded, with right-TLE patients obtaining significantly better scores than left-TLE patients on every test. Duration of epilepsy, age at onset, and seizure frequency did not influence performance on remote memory measures. CONCLUSIONS: The comprehensive neuropsychological study of 38 TLE patients showed that this neurologic condition affects remote memory systems differently. We discuss the different factors that could account for this pattern of performance on the bases of both functional brain organization and memory theories.     

Quality of life and memory performance in patients with temporal lobe epilepsy

OBJECTIVE: To explore the contribution of memory performance to quality of life (QOL) in patients with left or right temporal lobe epilepsy (TLE). SUBJECTS AND METHODS: Sixty-five patients with left or right TLE compiled the QOL in Epilepsy-89 Inventory (QOLIE-89), the State-Trait Anxiety Inventory (STAI) and the Hopelessness Scale (BDI) for self-evaluation of QOL and mood. Memory was assessed by tests of verbal and non-verbal memory and the Questionnaire of Memory Efficiency (QME). A neuropsychological battery was also administered to assess general intelligence, attention, visual perception, language, set shifting, word fluency and conceptual-motor tracking. RESULTS: On factor analysis, the neuropsychological battery and mood scales consisted of six factors (Memory, Mental Speed, Mood, Praxis, Sorting and Perception), while the QOLIE-89 consisted of five factors (Psychosocial Satisfaction, Epilepsy-Related Effects, Role, Physical Performance, Cognition). On regression analysis, overall QOLIE-89 score was predicted by the factor Mood and QME score. The QOLIE-89 factor Cognition was predicted by QME score and the Memory, Mental Speed, Perception and Praxis factors of the neuropsychological battery. CONCLUSION: In TLE patients self-reported memory, as assessed by QME, is an important predictor of QOL, and also correlates with performance on memory tests. This suggests that memory improvement by specific training may help to improve QOL in these patients.     

Extrahippocampal gray matter atrophy and memory impairment in patients with medial temporal lobe epilepsy

Memory impairment observed in patients with medial temporal lobe epilepsy (MTLE) is classically attributed to hippocampal atrophy. The contribution of extrahippocampal structures in shaping memory impairment in patients with MTLE is not yet completely understood, even though atrophy in MTLE extends beyond the hippocampus. We aimed to evaluate the neuropsychological profile of patients with MTLE focusing on memory, and to investigate whether gray matter concentration (GMC) distribution within and outside the medial portion of the temporal lobes would be associated with their neuropsychological performance. We performed a voxel based morphometry study of 36 consecutive patients with MTLE and unilateral hippocampal atrophy. We observed a significant simple regression between general and verbal memory performance based on Wechsler Memory Scale-Revised and the GMC of medial temporal and extratemporal structures in patients with left MTLE. We also performed a "regions of interest analysis" of the medial temporal lobe, and we observed that the GMC of the hippocampus, entorhinal, and perirhinal cortices were consistently associated with general and verbal memory performance in patients with MTLE. We also observed that the GMC of the cingulate and orbito-frontal cortex are independently associated with verbal and general memory performances. Our results suggest that general and verbal memory impairments in patients with left MTLE are associated with atrophy of the hippocampus, the entorhinal, and the perirhinal cortex. We also suggest that atrophy and dysfunction of limbic and frontal structures such as the cingulate and the orbito-frontal cortex contribute to memory impairment in MTLE.     

A dissociation between implicit and explicit verbal memory in left temporal lobe epilepsy

PURPOSE: Temporal lobe epilepsy patients are well known to present deficits on explicit verbal memory procedures (e.g., recall, recognition). The integrity of implicit memory procedures in these patients is not established. Previous studies in this area used implicit memory measures contaminated by the effects of explicit memory. METHODS: We examined the integrity of verbal implicit and explicit memory in left temporal lobe epilepsy (LTLE) patients and hypothesized that a clear dissociation in performance would be found with a relative preservation of implicit memory. TLE patients (n = 15) and age- and education-matched healthy normal patients (n = 15) were shown a 40-word study list, followed by a test phase requiring completion of word stems based on the study words or new/unseen words. Experimental conditions involved instructions to provide either the old (study) words or novel/nonlist words when completing the stem. Measures of automaticity and recollection provided uncontaminated indices of implicit and explicit memory, respectively. RESULTS: The data showed a significant difference (p < 0.001) between the patients (Recollection, 0.12; SD, 0.18) and controls (0.50, SD, 0.15) on the measure of explicit memory. In contrast, the patients (Automaticity, 0.51; SD, 0.11) and controls (0.45, SD, 0.18) performed similarly on the implicit memory measure, with patient scores clearly at normative levels based on other Process Dissociation Procedure data. CONCLUSIONS: The data demonstrate the integrity of implicit memory in LTLE patients. Finding a dissociation between the two forms of verbal memory in LTLE patients provides evidence that they rely on different neuroanatomic systems.     

Seizure semiology and electroencephalography in young children with lesional temporal lobe epilepsy

PurposeThis study aimed to discuss the clinical features of seizure semiology and electroencephalography (EEG) in young children with lesional temporal lobe epilepsy (TLE).MethodChildren with lesional TLE received presurgical evaluation for intractable epilepsy. They were followed up for more than one year after temporal lobectomy. We reviewed the medical history and video-EEG monitoring of children with TLE to analyze the semiology of seizures and EEG findings and compared the semiology of seizures and EEG findings of childhood TLE and adult TLE.ResultsA total of 84 seizures were analyzed in 11 children (aged 23–108 months). The age of seizure onset was from 1 month to 26 months (a mean of 17.6 months). All of the patients exhibited prominent motor manifestations including epileptic spasm, tonic seizure, and unilateral clonic seizure. Seven children manifested behavioral arrest similar to an automotor seizure in adult TLE but with a shorter duration and higher frequency. The automatisms were typically orofacial, whereas manual automatisms were rarely observed. The EEG recordings revealed that diffuse discharge patterns were more common in younger children, whereas focal or unilateral patterns were more typical in older children. All of the patients were seizure-free after temporal lobectomy with more than one-year follow-up. All of the children had a mental development delay or regression; however, there was improvement after surgery, especially in those with surgery performed early.ConclusionIn contrast to TLE in adults, young children with lesional TLE probably represent a distinct nosological and probably less homogeneous syndrome. Although they had generalized clinical and electrographic features, resective epilepsy surgery should be considered as early as possible to obtain seizure control and improvement in mental development.     

Differential contributions of the anterior temporal and medial temporal lobe to the retrieval of memory for person identity information

Although previous studies have suggested the importance of the bilateral anterior temporal (ATL) and medial temporal lobes (MTL) in the retrieval of person identity information, there is little evidence concerning how these regions differentially contribute to the process. Here we investigated this question using functional magnetic resonance imaging (fMRI). Before scanning, subjects learned associations among faces (F), names (N), and job titles (as a form of person-related semantics, S). During retrieval with fMRI, subjects were presented with previously learned and new S stimuli, and judged whether the stimuli were old or new. Successful retrieval (H) trials were divided into three conditions: retrieval of S and associated F and N (HSFN); retrieval of S and associated F (HSF); and retrieval of S only (HS). The left ATL was significantly activated in HSFN, compared to HSF or HS, whereas the right ATL and MTL were significantly activated in HSFN and HSF relative to HS. In addition, activity in bilateral ATL was significantly correlated with reaction time for HSFN, whereas we found no significant correlation between activity in the right MTL and reaction time in any condition. The present findings suggest that the left ATL may mediate associations between names and person-related semantic information, whereas the right ATL mediates the association between faces and person-related semantic information in memory for person identity information. In addition, activation of the right MTL region implies that this area may contribute to a more general relational processing of associative components, including memory for person identity information.     

海马有病损的颞叶内侧癫(癎)手术15例临床分析

目的 探讨海马有病损的颞叶内侧癫(癎)的手术价值.方法 回顾性分析经手术治疗的15例伴有海马病损颞叶内侧癫(癎)患者.均经详细了解发作症状学、附加蝶骨电极的长程视频脑电图及颅脑磁共振等检查;经正规而详尽的术前评估,行前颞叶切除术,术后随访至少半年以上.结果 术后依据Engel分级,显效(Ⅰ级和Ⅱ级)占80.0％ (12/15)、好转(Ⅲ级)占20.0％(3/15)、无效(Ⅳ级)为0.0％.结论 颞叶内侧癫(癎)手术效果确切,是基层医院开展癫(癎)手术的理想选择.     

Lateralizing value of memory tests in drug-resistant temporal lobe epilepsy

Our aim was to test the lateralizing value of a neuropsychological battery including several memory tests on a large sample of consecutive patients with drug-resistant temporal lobe epilepsy (TLE) evaluated for epilepsy surgery. We studied 73 right-handed patients (56% males, mean age 35.3 +/- 11.2 years, 49% left TLE) aged 16 years or older with normal IQ who underwent a preoperative neuropsychological assessment including several memory tests and were seizure-free after at least 1 year of follow-up. Forty-seven had TLE due to hippocampal sclerosis, whilst 26 had TLE secondary to tumors or other lesions. Receiver Operating Characteristic (ROC) analysis and discriminant function analysis were used to evaluate the lateralization value of selected tests and of the battery as a whole, respectively. In patients with TLE secondary to tumors or other lesions, no test showed significant lateralizing value. In patients with TLE due to hippocampal sclerosis, the immediate (P < 0.01) and delayed (P < 0.001) Rey Auditory Verbal Learning Test (RAVLT) displayed substantial discriminatory ability. The battery as a whole correctly classified 82% of patients with respect to side of epileptogenesis. Our findings suggest that a non-invasive, relatively short and unexpensive neuropsychological battery based on memory tests may profitably complement other well-established diagnostic procedures such as video-EEG or magnetic resonance imaging (MRI), at least in patients with drug-resistant TLE due to hippocampal sclerosis.     

Long-term epilepsy surgery outcomes in patients with MRI-negative temporal lobe epilepsy

Purpose: The outcome of surgery in patients with temporal lobe epilepsy (TLE) and normal high‐resolution magnetic resonance imaging (MRI) has been significantly worse than in patients with unilateral hippocampal damage upon MRI. The purpose of this study was to determine the long‐term outcomes of consecutive true MRI‐negative TLE patients who all underwent standardized preoperative evaluation with intracranial electroencephalography (EEG) electrodes. Methods: In this study we present all adult MRI‐negative TLE surgery candidates evaluated between January 1990 and December 2006 at Kuopio Epilepsy Center in Kuopio University Hospital, which provides a national center for epilepsy surgery in Finland. During this period altogether 146 TLE surgery candidates were evaluated with intracranial electrodes, of whom 64 patients with normal high‐resolution MRI were included in this study. Results: Among the 38 patients who finally underwent surgery, at the latest follow‐up (mean 5.8 years), 15 (40%) were free of disabling seizures (Engel class I) and 6 (16%) were seizure‐free (Engel class IA). Twenty‐one (55%) of 38 patients had poor outcomes (Engel class III–IV). Outcomes did not change compared to 12‐month follow‐up. Histopathologic examination failed to reveal any focal pathology in 68% of our MR‐negative cases. Only patients with noncongruent positron emission tomography (PET) results had worse outcomes (p = 0.044). Discussion: Our results suggest that epilepsy surgery outcomes in MRI‐negative TLE patients are comparable with extratemporal epilepsy surgery in general. Seizure outcomes in the long‐term also remain stable. Modern imaging techniques could further improve the postsurgical seizure‐free rate. However, these patients usually require chronic intracranial EEG evaluation to define epileptogenic areas.     

The perceptual richness of complex memory episodes is compromised by medial temporal lobe damage

Perceptual richness, a defining feature of episodic memory, emerges from the reliving of multimodal sensory experiences. Although the importance of the medial temporal lobe (MTL) to episodic memory retrieval is well documented, the features that determine its engagement are not well characterized. The current study assessed the relationship between MTL function and episodic memory's perceptual richness. We designed a laboratory memory task meant to capture the complexity of memory for life episodes, while manipulating memory's perceptual content. Participants encoded laboratory episodes with rich (film clips) and impoverished (written narratives) perceptual content that were matched for other characteristics such as personal significance, emotionality and story content. At retrieval, participants were probed to describe the stories' perceptual features and storyline. Participants also recalled autobiographical memories (AMs) in a comparison condition. We compared the performance of patients with unilateral medial temporal lobe epilepsy (mTLE) and healthy controls to assess how damage to the MTL affects retrieval in these conditions. We observed an overall decrease in detail count in the mTLE group, along with a disproportionate deficit in perceptual details that was most acute in the AM and the perceptually enriched film clip conditions. Our results suggest that the impaired sense of reliving the past that accompanies MTL insult is mediated by a paucity of perceptual episodic memory details. We also introduce a new protocol that successfully mimics naturalistic memories while benefiting from the experimental control provided by using laboratory stimuli. © 2014 Wiley Periodicals, Inc.     

颞叶癫痫对前瞻性记忆的影响

目的 探讨颞叶癫痫对基于事件的前瞻性记忆(event-based prospective memory,EBPM)和基于时间的前瞻性记忆(time-based prospective memory,TBPM)的影响,验证颞叶参与前瞻性记忆的神经机制假说.方法 采用McDaniel等建立的前瞻性记忆神经心理学试验方法,测试62例颞叶癫痫患者(33例服用抗癫痫药物和29例未服用药物,颞叶癫痫组)和年龄、教育程度相匹配的30名健康者(健康对照组)的EBPM和TBPM.结果 颞叶癫痫组简易精神状态检查(MMSE)、数字广度测试(DS)、词汇流畅性测试(VFT)的成绩均低于健康对照组,且MMSE、VFT两组间差异有统计学意义.与健康对照组[ EBPM测试(6.83±1.34)分,TBPM测试(5.00±1.70)分]相比,颢叶癫痫组的EBPM测试[(3.95±2.77)分]和TBPM测试[(3.08±2.42)分]的成绩差异均有统计学意义(t=6.72、4.39,均P＜0.01),且TBPM测试得分均低于EBPM.其中服药和未服药两组间EBPM测试成绩[(3.82±2 70)、(4.10±2.90)分]差异无统计学意义(t=-0.40,P ＞0.05),两组间TBPM测试成绩[(2.55±2.20)、(3.69±2.55)分]差异亦无统计学意义(t=-1.90,P＞0.05).结论 颞叶癫痫患者存在前瞻性记忆损害,提示颞叶参与前瞻性记忆的神经机制过程;与EBPM相比,TBPM损害更明显,提示TBPM需要更多的自我发动过程.     

Recognition memory for faces and scenes in amnesia: dissociable roles of medial temporal lobe structures

The relative contributions of the hippocampus and the perirhinal cortex to recognition memory are currently the subject of intense debate. Whereas some authors propose that both structures play a similar role in recognition memory, others suggest that the hippocampus might mediate recollective and/or associative aspects of recognition memory, whereas the perirhinal cortex may mediate item memory. Here we investigate an alternative functional demarcation between these structures, following reports of stimulus-specific perceptual deficits in amnesics with medial temporal lobe (MTL) lesions. Using a novel recognition memory test for faces and scenes, participants with broad damage to MTL structures, which included the hippocampus and the perirhinal cortex, were impaired on both face and scene memory. By contrast, participants with damage limited to the hippocampus showed deficits only in memory for scenes. These findings imply that although both the hippocampus and surrounding cortex contribute to recognition memory, their respective roles can be distinguished according to the type of material to be remembered. This interaction between lesion site and stimulus category may explain some of the inconsistencies present in the literature.