Contributions of volumetrics of the hippocampus and thalamus to verbal memory in temporal lobe epilepsy patients

Recent theories have posited that the hippocampus and thalamus serve distinct, yet related, roles in episodic memory. Whereas the hippocampus has been implicated in long-term memory encoding and storage, the thalamus, as a whole, has been implicated in the selection of items for subsequent encoding and the use of retrieval strategies. However, dissociating the memory impairment that occurs following thalamic injury as distinguished from that following hippocampal injury has proven difficult. This study examined relationships between MRI volumetric measures of the hippocampus and thalamus and their contributions to prose and rote verbal memory functioning in 18 patients with intractable temporal lobe epilepsy (TLE). Results revealed that bilateral hippocampal and thalamic volume independently predicted delayed prose verbal memory functioning. However, bilateral hippocampal, but not thalamic, volume predicted delayed rote verbal memory functioning. Follow-up analyses indicated that bilateral thalamic volume independently predicted immediate prose, but not immediate rote, verbal recall, whereas bilateral hippocampal volume was not associated with any of these immediate memory measures. These findings underscore the cognitive significance of thalamic atrophy in chronic TLE, demonstrating that hippocampal and thalamic volume make quantitatively, and perhaps qualitatively, distinct contributions to episodic memory functioning in TLE patients. They are also consistent with theories proposing that the hippocampus supports long-term memory encoding and storage, whereas the thalamus is implicated in the executive aspects of episodic memory.     

Different types of working memory binding in epilepsy patients with unilateral anterior temporal lobectomy

The medial temporal lobe is an important structure for long-term memory formation, but its role in working memory is less clear. Recent studies have shown hippocampal involvement during working memory tasks requiring binding of information. It is yet unclear whether this is limited to tasks containing spatial features. The present study contrasted three binding conditions and one single-item condition in patients with unilateral anterior temporal lobectomy.A group of 43 patients with temporal lobectomy (23 left; 20 right) and 20 matched controls were examined with a working memory task assessing spatial relational binding (object–location), non-spatial relational binding (object–object), conjunctive binding (object–colour) and working memory for single items. We varied the delay period (3 or 6 s), as there is evidence showing that delay length may modulate working memory performance.The results indicate that performance was worse for patients than for controls in both relational binding conditions, whereas patients were unimpaired in conjunctive binding. Single-item memory was found to be marginally impaired, due to a deficit on long-delay trials only.In conclusion, working memory binding deficits are found in patients with unilateral anterior temporal lobectomy. The role of the medial temporal lobe in working memory is not limited to tasks containing spatial features. Rather, it seems to be involved in relational binding, but not in conjunctive binding. The medial temporal lobe gets involved when working memory capacity does not suffice, for example when relations have to be maintained or when the delay period is long.     

Dichotic listening with forced attention in patients with temporal lobe epilepsy: significance of left hemisphere cognitive dysfunction

Fifty right-handed patients with focal temporal lobe epilepsy were administered a dichotic listening test with consonant-vowel syllables under non-forced, forced right and forced left attention conditions, and a neuropsychological test battery. Dichotic listening performance was compared in subgroups with and without left hemisphere cognitive dysfunction, measured by the test battery, and in subgroups with left and right temporal epileptic focus. Left hemisphere cognitive dysfunction led to more correct responses to left ear stimuli in all three attention conditions, and fewer correct responses to right ear stimuli in the non-forced attention condition. This was probably caused by basic left hemisphere perceptual dysfunction. Dichotic listening was less affected by a left-sided epileptic focus than by left hemisphere cognitive dysfunction. General cognitive functioning influenced dichotic listening performance stronger in forced than in non-forced attention conditions. Larger cerebral networks were probably involved in the forced attention conditions due to the emphasis on conscious effort.     

Progress in Executive-Function Research: From Tasks to Functions to Regions to Networks

ABSTRACT— It has long been observed that damage to the frontal cortex affects a person's ability to control thought, behavior, and emotion while sometimes leaving fundamental processes such as vision, hearing, and long-term memory intact. Such observations have led theoreticians to suppose that a set of executive control functions exists, at the top of the hierarchy of mental processes. To study these executive functions and their relation to the frontal cortex and its subregions, researchers have long employed several now-classic cognitive tests in patients with brain damage. Yet until recently it has proved difficult to reliably localize the putative executive functions to discrete regions. This article illustrates how recent progress in executive-functions research has been driven by the coupling of sophisticated neuroscience techniques with advances in experimental psychology. Taking examples from recent studies, it shows how experimental tasks may be decomposed into cognitive components that can be localized to discrete—but structurally connected—brain regions. What emerges is a new ontology for executive function in terms of which cognitive components exist and of how, and when, they are recruited during task performance.     

额叶在启动效应中的作用机制：对额叶损伤病人颜色命名和词命名任务的分析

以额叶损伤病人为被试,探讨在知觉型联想启动和知觉启动中,额叶的作用及其内在机制。实验任务包括颜色命名和词命名任务,以及相应的再认任务。结果表明,额叶损伤病人在颜色命名和词命名任务中,对旧词和重组颜色词的命名时间都没有明显差别,联想启动和颜色启动效应受损,但轻度记忆损伤病人与正常对照组之间的再认成绩相似。相关分析发现联想启动和颜色启动与额叶的多项功能有中度相关。这表明,额叶参与了知觉型联想启动效应和知觉启动,并且与其抑制和注意等执行功能有关。     

Prospective memory,working memory,planning, and attention in schizophrenia and bipolar disorder: A comparative study

There is a need to study prospective memory (PM) and its relationship with aspects of frontal lobe functioning in schizophrenia and bipolar disorder. The study aims to investigate event‐based (EB) and time‐based (TB) PM functioning in the two groups, and its association with working memory, planning, and attention. A word categorisation task was developed to assess PM functioning among 90 participants (schizophrenia, bipolar disorder, and a control group). Frontal lobe functioning was assessed using Tower of London, N‐Back test, and triads test. Mean comparisons revealed significantly higher impairment in TB PM in comparison to EB PM in both the clinical groups. Significant relationship between PM and frontal lobe impairment was found. Relationship between PM and frontal lobe deficits in the clinical groups emphasises the need to include its assessment at an early stage and to develop PM rehabilitation strategies to improve the quality of living.     

Factors affecting medial temporal lobe engagement for past and future episodic events: an ALE meta-analysis of neuroimaging studies

Remembering the past and envisioning the future are at the core of one's sense of identity. Neuroimaging studies investigating the neural substrates underlying past and future episodic events have been growing in number. However, the experimental paradigms used to select and elicit episodic events vary greatly, leading to disparate results, especially with respect to the laterality and antero-posterior localization of hippocampal and adjacent medial temporal activations (i.e., parahippocampal, entorhinal and perirhinal cortices, amygdala). Although a central concern in today's literature, the issue of hippocampal and medial temporal lobe laterality and antero-posterior segregation in past and future episodic events has not yet been addressed extensively. Using the activation likelihood estimation (ALE) procedure (Turkeltaub, Eden, Jones, & Zeffiro, 2002), we performed a meta-analysis of hippocampal and adjacent medial temporal coordinates extracted from neuroimaging studies examining past remembering and future envisioning. We questioned whether methodological choices could influence the laterality of activations, namely (1) the type of cue used (generic vs. specific), (2) the type of task performed (recognition vs. recall/imagine), (3) the nature of the information retrieved (episodic vs. "strictly" episodic events) and (4) the age of participants. We consider "strictly" episodic events as events which are not only spatio-temporally unique and personal like episodic events, but are also associated with contextual and phenomenological details. These four factors were compared two-by-two, generating eight whole-brain statistical maps. Results indicate that (1) specific cues tend to activate more the right anterior hippocampus compared to the use of generic cues, (2) recall/imagine tasks tend to recruit more the left posterior parahippocampal gyrus compared to recognition tasks, (3) (re/pre)experiencing strictly episodic events tends to activate more the bilateral posterior hippocampus compared to episodic events and (4) older subjects tend to activate more the right anterior hippocampus compared to younger subjects. Importantly, our results stress that strictly episodic events triggered by specific cues elicit greater left posterior hippocampal activation than episodic events triggered by specific cues. These findings suggest that such basic methodological choices have an impact on the conclusions reached regarding past and future (re/pre)experiencing and their neural substrates.     

Memory for between‐list and within‐list information in amnesic patients with temporal lobe and diencephalic lesions

Patients with medial temporal lobe damage and diencephalic damage were compared on two tests of verbal temporal order memory: between‐list discrimination and within‐list discrimination. Both patient groups were impaired relative to a group of healthy control participants. In addition, despite comparable levels of item recognition, the diencephalic group was impaired relative to the medial temporal lobe group on both within‐list and between‐list discrimination. Temporal order memory for between‐list information showed a significant correlation with a composite measure of recognition memory, and the results are discussed in terms of the patients' reliance on familiarity and distance‐based processes to make temporal order judgments.     

The roles of the temporal lobe in creative insight: an integrated review

Recent studies have revealed that the temporal lobe, a cortical region thought to be in charge of episodic and semantic memory, is involved in creative insight. This work examines the contributions of discrete temporal regions to insight. Activity in the medial temporal regions is indicative of novelty recognition and detection, which is necessary for the formation of novel associations and the “Aha!” experience. The fusiform gyrus mainly affects the formation of gestalt-like representation and perspective taking. The anterior and posterior middle temporal gyri (MTG) are individually associated with extensive semantic processing and inhibiting salient or routine word associations, which are necessary to form non-salient, novel and remote associations. The anterior and posterior superior temporal gyri (STG) are individually responsible for integrating/binding and accessing various types of available conceptual representations. Based on the current knowledge, an integrated model of the temporal lobe's role in insight and some future directions are proposed.     

认知功能的性别差异

我们了概述认知功能的性别差异, 尤其是情节记忆功能的性别差异。已有的研究结果表明女性在言语生成、情节记忆、面孔识别任务中比男性存在明显的优势, 而男性的优势则表现在视空间任务中, 如视空间情节记忆任务。本文批判性地讨论了一个流行的假设: 类固醇激素影响认知功能的性别差异, 得出的结论是内源性睾丸激素或雌二醇均未显著影响认知功能的性别差异。     

The role of white matter hyperintensities and medial temporal lobe atrophy in age-related executive dysfunctioning

Various studies support an association between white matter hyperintensities (WMH) and deficits in executive function in nondemented ageing. Studies examining executive functions and WMH have generally adopted executive function as a phrase including various functions such as flexibility, inhibition, and working memory. However, these functions include distinctive cognitive processes and not all may be affected as a result of WMH. Furthermore, atrophy of the medial temporal lobe (MTA) is frequently observed in ageing. Nevertheless, in previous studies of nondemented ageing MTA was not considered when examining a relationship between white matter and executive function. The goal of the present study was to examine how WMH and MTA relate to a variety of executive functions, including flexibility, fluency, inhibition, planning, set shifting, and working memory. Strong correlations were observed between WMH and MTA and most of the executive functions. However, only MTA was related to flexibility and set shifting performance. Regression analysis furthermore showed that MTA was the strongest predictor of working memory, after which no further significant association with WMH was noted. Alternatively, both MTA and periventricular hyperintensities independently predicted inhibition performance. These findings emphasize the importance of MTA when examining age-related decline in executive functioning.     

Contributions of Neuroscience to Our Understanding of Cognitive Development

ABSTRACT— One major contribution of neuroscience to understanding cognitive development has been in demonstrating that biology is not destiny—that is, demonstrating the remarkable role of experience in shaping the mind, brain, and body. Only rarely has neuroscience provided wholly new insights into cognitive development, but often it has provided evidence of mechanisms by which observations of developmental psychologists could be explained. Behavioral findings have often remained controversial until an underlying biological mechanism for them was offered. Neuroscience has demonstrated promise for detecting cognitive problems before they are behaviorally observable—and, hence, promise for early intervention. In this article, we discuss examples drawn from imitation and mirror neurons, phenylketonuria (PKU) and prefrontal dopamine, maternal touch and stress reactivity, and nongenetic (behavioral) intergenerational transmission of biological characteristics.     

Cognitive reserve and cognitive function in healthy older people: a meta-analysis

The associations between proxy measures of cognitive reserve (CR) and cognition vary across studies and cognitive domains. This meta-analysis aimed to assess the relationship between CR and cognition in multiple domains (memory, executive function, visuospatial ability, and language). CR was considered in terms of three key proxy measures – educational level, occupational status, and engagement in cognitively stimulating activities – individually and in combination. One-hundred and thirty-five studies representing 128,328 participants were included. Of these, 109 used a measure of education, 19 used a measure of occupation, 31 used a measure of participation in cognitively stimulating activities, and 6 used a combination of these. All three proxy measures had a modest positive association with cognition; occupational status and cognitive activities showed the most variation across cognitive domains. This supports the view that the commonly used proxy measures of CR share an underlying process but that each additionally provides a unique contribution to CR.     

Purpose in life and cognitive functioning in adulthood

With an increasingly aging population, more work is needed to identify factors which may promote the maintenance of normal cognitive functioning. The current study tested the concurrent association between sense of purpose in life and the cognitive variables of episodic memory, executive functioning, and composite cognitive functioning in adults (N = 3489, M_age = 56.3 years, SD = 12.27, Range = 32–84 years) from the Midlife in the United States study (MIDUS). Correlational analyses suggested that purpose in life was associated with higher scores for memory, executive functioning, and overall cognition. Bootstrapping tests of moderation found no evidence for a moderating effect of age on purpose and the cognitive variables. Future studies should attempt to explain the mechanisms behind this relationship and explore the potential for interventions to promote healthy cognitive and purposeful aging.     

Memory deficits in young schizophrenics with normal general intellectual function

The aim of the present study was to examine different dimensions of memory functioning in young schizophrenics with normal general intellectual abilities. Thirty-three patients with schizophrenia and 33 healthy controls were included in the study. The results suggest that immediate short-term memory is intact, though there emerged a working memory deficit in the schizophrenia group. Deficient encoding of verbal material was observed in some, but not in other, testing conditions. There also seemed to be a retrieval deficit for verbal material in schizophrenia, though no storage deficit was indicated. Impaired memory for non-verbal material was also revealed. These results occurred in a context of intact executive functioning as measured by the Wisconsin Card Sorting Test. The results indicate that temporal and frontal structures, as well as their interconnections, may be compromised in schizophrenia.     

边界促进空间导航的认知神经机制

边界是指在人的视野中占据较大比例,且具有立体拓展平面的障碍物,对于人类和动物的空间导航行为具有极大的促进作用。认知发展研究发现儿童早期(1岁半～2岁)通过加工边界的空间几何结构实现物体定位,并且随着年龄的发展逐渐学会利用边界的高度信息(3.1岁～4.7岁)、长度信息(4～5岁)、视觉阻碍性信息(5岁)等完成空间导航。基于这些认知过程,神经影像学研究主要以成人为研究被试,发现大脑中的内侧颞叶和顶叶脑区在边界加工中有着不同功能作用。具体而言,边界的空间几何结构及构成要素(高度、长度和角度)体位置的学习和提取则由海马负责。但是,仍存在一些研究问题值得未来深入S探c讨i。e第n一c,e拓展深化边界促进与后顶叶之间的功能交互。第三,密切关注大脑对场地边界与场地中心编码的心理或神经表征的区别和联系。第四,重点考察阿尔兹海默症有关基因易感人群在基于边界导航的行为受损情况。最后,延伸探讨边界在长时记忆、时间知觉、视觉空间、社交网络等领域的影响机制。     

Development of the Cognitive Dysfunction Questionnaire (CDQ) in a population based sample

The study reports on the development of a questionnaire for assessment of adult cognitive dysfunction (CDQ). Participants in a population-based sample (65±15 years, N=370) responded to a 90-item pilot version covering multiple aspects of memory/cognition. Based on exploratory principal components analyses and correlations with criterion measures of cognitive functioning (MMSE, Block Design, semantic/episodic memory), 20 items loading on 6 components were selected for the final version of the questionnaire. Cronbach's α for the total score was 0.90. There was evidence of construct validity as judged by correlations between CDQ scores, objective cognitive measures, and a subjective memory measure (PRMQ). Discriminant validity was demonstrated by a low and non-significant correlation with depressive symptoms. Further evidence of construct validity was provided by correlations with age and educational attainment. In conclusion, the CDQ is promising as a self-rating screening tool for cognitive dysfunction, and will be the subject of further development and validation.     

‘Language of the past’ – Exploring past tense disruption during autobiographical narration in neurodegenerative disorders

Compromised retrieval of autobiographical memory (ABM) is well established in neurodegenerative disorders. The recounting of autobiographical events is inextricably linked to linguistic knowledge, yet no study to date has investigated whether tense use during autobiographical narration is disrupted in dementia syndromes. This study investigated the incidence of correct past tense use during ABM narration in patients with Alzheimer's disease (AD, n = 10) and semantic dementia (SD, n = 10) in comparison with healthy older Controls (n = 10). Autobiographical narratives were analysed for episodic content (internal/external) and classified according to tense use (past/present). Across both patient groups, use of the past tense was significantly compromised relative to Controls, with increased levels of off‐target present tense verbs observed. Voxel‐based morphometry analyses based on structural MRI revealed differential associations between past tense use and regions of grey matter intensity in the brain. Bilateral temporal cortices were implicated in the SD group, whereas frontal, lateral, and medial temporal regions including the right hippocampus emerged in AD. This preliminary study provides the first demonstration of the disruption of specific linguistic constructs during autobiographical narration in AD and SD. Future studies are warranted to clarify at what point in the disease trajectory such deficits in tense use emerge, and whether these deficits are a product or contributing factor in memory disruption in these syndromes.     

Language localization in cases of left temporal lobe arachnoid cyst: evidence against interhemispheric reorganization

We investigated whether left-hemisphere arachnoid cysts lead to reorganization of the language function using PET. A group analysis demonstrated that patients showed no more right-hemisphere activation than a matched control group. Several patients had clear language localizations in the left hemisphere during language comprehension; none of the patients showed right-hemisphere activation. We conclude that left-hemisphere tissue must suffer considerable compromise before reorganization of language into the right hemisphere becomes necessary. Language activations within the left hemisphere are clearly displaced. This is consistent with mere physical displacement in some patients rather than reorganization within the left hemisphere; in others intrahemispheric reorganization cannot be excluded.