Reflective and reflexive action control in patients with frontal brain lesions

Two types of action control derived from the model of action phases (H. Heckhausen & P. M. Gollwitzer, 1987) were analyzed in patients with frontal lesions, patients with nonfrontal lesions, and university students. In Study 1, reflective action control in terms of goal selection was assessed, and impaired deliberation was found in patients with frontal lesions. Study 2 assessed reflexive action control in terms of automatic action initiation as a result of forming implementation intentions (P. M. Gollwitzer, 1999). All participants sped up their responses to critical stimuli by forming implementation intentions. Moreover, lesion patients with weak performances on the Tower of Hanoi (TOH) task did worse than patients with strong TOH performances in Study 1 but better than control participants in Study 2. Findings are interpreted as a functional dissociation between conscious reflective action control and automatic reflexive action control.     

Phonological and semantic fluencies are mediated by different regions of the prefrontal cortex

Verbal phonological and semantic fluencies were investigated in 24 patients with unilateral prefrontal lesions and 10 normal control subjects. Lesions were limited to small areas within either the dorsolateral (Brodmann's area 46/9) or ventromedial (posterior part of the gyrus rectus) cortices. In a phonological fluency task, patients with lesions to the left dorsolateral region were impaired. In semantic fluency, not only the left dorsolateral group but also the two right frontal damaged groups performed worse than the control group. In agreement with previous studies, our results show that the phonological fluency is mediated by the left dorsolateral prefrontal cortex. In contrast to this, performance on the semantic fluency task depends on a wider portion of the prefrontal cortex involving the left and right dorsolateral and the right ventromedial areas.     

Executive dysfunction and gray matter atrophy in amnestic mild cognitive impairment

Recent studies have shown that impairment in executive function (EF) is common in patients with amnestic mild cognitive impairment (aMCI). However, the neuroanatomic basis of executive impairment in patients with aMCI remains unclear. In this study, multiple regression voxel-based morphometry analyses were used to examine the relationship between regional gray matter volumes and EF performance in 50 patients with aMCI and 48 healthy age-matched controls. The core EF components (response inhibition, working memory and task switching, based on the EF model of Miyake et al) were accessed with computerized tasks. Atrophic brain areas related to decreases in the three EF components in patients with aMCI were located in the frontal and temporal cortices. Within the frontal cortex, the brain region related to response inhibition was identified in the right inferior frontal gyrus. Brain regions related to working memory were located in the left anterior cingulate gyrus, left premotor cortex, and right inferior frontal gyrus, and brain regions related to task shifting were distributed in the bilateral frontal cortex. Atrophy in the right inferior frontal gyrus was most closely associated with a decrease in all three EF components in patients with aMCI. Our data, from the perspective of brain morphology, contribute to a better understanding of the role of these brain areas in the neural network of EF.     

Allocentric versus egocentric spatial memory after unilateral temporal lobectomy in humans

Thirty patients who had undergone either a right or left unilateral temporal lobectomy (14 RTL; 16 LTL) and 16 control participants were tested on a computerized human analogue of the Morris Water Maze. The procedure was designed to compare allocentric and egocentric spatial memory. In the allocentric condition, participants searched for a target location on the screen, guided by object cues. Between trials, participants had to walk around the screen, which disrupted egocentric memory representation. In the egocentric condition, participants remained in the same position, but the object cues were shifted between searches to prevent them from using allocentric memory. Only the RTL group was impaired on the allocentric condition, and neither the LTL nor RTL group was impaired on additional tests of spatial working memory or spatial manipulation. The results support the notion that the right anterior temporal lobe stores long-term allocentric spatial memories.     

Traditional and computerized assessment procedures applied to the evaluation of memory change after temporal lobectomy.

After establishing that 40 temporal lobectomy patients (20 right, 20 left) demonstrated the same pattern of memory compromise as has been reported in prior studies, we examined the sensitivity of computerized tests of everyday memory skills to the cognitive change associated with temporal resection. Multiple cognitive deficits occur after left, but not after right, temporal lobectomies. Memory impairment after surgery is not limited to traditionally structured memory tests but is also evident on tasks designed to simulate activities of daily life.     

Sleep enhances memory consolidation in children

Sleep is an active state that plays an important role in the consolidation of memory. It has been found to enhance explicit memories in both adults and children. However, in contrast to adults, children do not always show a sleep‐related improvement in implicit learning. The majority of research on sleep‐dependent memory consolidation focuses on adults; hence, the current study examined sleep‐related effects on two tasks in children. Thirty‐three typically developing children aged 6–12 years took part in the study. Actigraphy was used to monitor sleep. Sleep‐dependent memory consolidation was assessed using a novel non‐word learning task and the Tower of Hanoi cognitive puzzle, which involves discovering an underlying rule to aid completion. Children were trained on the two tasks and retested following approximately equal retention intervals of both wake and sleep. After sleep, children showed significant improvements in performance of 14% on the non‐word learning task and 25% on the Tower of Hanoi task, but no significant change in score following the wake retention interval. Improved performance on the Tower of Hanoi may have been due to children consolidating explicit aspects of the task, for example rule‐learning or memory of previous sequences; thus, we propose that sleep is necessary for consolidation of explicit memory in children. Sleep quality and duration were not related to children's task performance. If such experimental sleep‐related learning enhancement is generalizable to everyday life, then it is clear that sleep plays a vital role in children's educational attainment.     

Figural fluency: differential impairment in patients with left versus right frontal lobe lesions.

Based on an experimental study, Jones-Gotman and Milner demonstrated that patients with right frontal lobe lesions were impaired on design fluency. We sought a clinical adaptation and developed a psychometrically sound technique for design fluency. The present study explores the validity of the Ruff Figural Fluency Test (RFFT) in discriminating patients with either right frontal or nonright frontal lobe lesions. In the first of two studies, six subjects with circumscribed focal lesions were given the RFFT and the Jones-Gotman and Milner figural fluency task. In the second study, we identified a larger sample of 30 patients with focal lesions in the right frontal, left frontal, right posterior, or left posterior cortex. The results from both studies support the validity of the RFFT as a measure which is sensitive to right anterior dysfunction.     

Distribution of cerebral atrophy assessed by magnetic resonance imaging reflects patterns of neuropsychological deficits in Alzheimer's dementia

Neuropsychological deficits were investigated with respect to regional distribution of cerebral atrophy as assessed by volumetric magnetic resonance imaging (MRI) in 50 patients with Alzheimer's dementia (AD; NINCDS-ADRDA criteria) and 20 healthy volunteers. When compared between groups, test performance of all investigated neuropsychological domains including declarative memory, language, praxia, psychomotor speed, as well as attention and concentration was significantly impaired. These deficits were differentially correlated with regional atrophic changes. In particular, volumes of the right amygdala-hippocampus complex correlated with declarative memory performance, whereas volumes of the left temporo-parietal regions correlated with performance in naming and praxia. Furthermore, left frontal lobe atrophy was associated with verbal fluency. Our data confirm the central role that medial temporal atrophy plays for declarative memory deficits in AD and indicate that additional changes in the parietal, temporal and frontal lobes are responsible for further neuropsychological deficits characteristic of this disorder.     

Combined deficits of saccades and visuo-spatial orientation after cortical lesions

Functionally, saccadic eye movements are closely linked to visuo-spatial orientation. Anatomically, the network of cortical areas controlling saccades also seems to be involved in spatial attention and orientation. Consequently, lesions should cause deficits in both categories. We investigated this in 34 patients with focal unilateral lesions of the posterior parietal cortex (PPC), the frontal eye fields (FEF), the supplementary motor area (SMA), or the dorsolateral prefrontal cortex (PFC). Saccadic eye movements were recorded using infrared reflection oculography. Visual hemineglect or other visuo-spatial disorders were investigated by a series of standardized paper-pencil tests. Further, the internal spatial coordinates (subjective visual vertical and subjective straight ahead) were assessed psychophysically. Depending on the site of the lesion, different patterns of deficits were identified: lesions of the PPC impaired reflexive exploration of visual space in terms of delayed and hypometric visually triggered saccades into the contralesional hemifield, related to the severity of visual hemineglect. Further, PPC lesions specifically affected basic functions of the perceptual analysis of space, such as the internal spatial coordinates and spatial constancy across saccades. The latter was tested by applying visual double-step stimuli, where saccade-related extraretinal information had to be taken into account for achieving spatial accuracy. Frontal lesions left these functions intact. FEF lesions, however, impaired systematic intentional exploration of space, thus causing an exploratory-motor type of visual hemineglect. Prefrontal (PFC) lesions impaired the working memory for saccade-related spatial information, and SMA lesions affected temporal properties such as the timing of saccadic sequences, but did not cause specific visuo-spatial deficits. In conclusion, patients with frontal or parietal cortical lesions often exhibit combined saccadic and visuo-spatial disorders, most of which are topically specific.     

Left temporal lobe brain damage pattern on the Wechsler Adult Intelligence Scale

This study supports an association of left temporal brain damage with the unusual WAIS subtest pattern of more impaired Information and Vocabulary than Similarities scores. Temporal lesions may impair well-learned verbal memory more than reasoning skills. Thirty-six patients with localized left hemisphere brain damage in the frontal, parietal or occipital, and temporal lobe were compared using an index in which Information and Vocabulary were contrasted to Similiarities. Index scores were adjusted for age. Seventy-five percent of the temporal patients had negative index scores, and 75% of the frontal patients had positive index scores. Temporal patients tended to score more negatively on the index than did frontal patients, p less than .05.     

Modulation of the neuronal circuitry subserving working memory in healthy human subjects by repetitive transcranial magnetic stimulation

We studied the effect of repetitive transcranial magnetic stimulation (rTMS) on changes in regional cerebral blood flow (rCBF) as revealed by positron emission tomography (PET) while subjects performed a 2-back verbal working memory (WM) task. rTMS to the right or left dorsolateral prefrontal cortex (DLPFC), but not to the midline frontal cortex, significantly worsened performance in the WM task while inducing significant reductions in rCBF at the stimulation site and in distant brain regions. These results for the first time demonstrate the ability of rTMS to produce temporary functional lesions in elements of a neuronal network thus changing its distributed activations and resulting in behavioral consequences.     

Performance of the Towers of Hanoi task and cortical electroencephalographic power changes associated with infancy, adolescence, and early adulthood

The executive functions, which depend on the adequate maturation and functioning of the prefrontal cortex and its connection to posterior zones, follow a process of development as age increases. This work studied changes in the absolute power (AP) of EEG activity recorded in the prefrontal and parietal areas during the performance of the Tower of Hanoi task in children, adolescents, and young adults. Three groups of healthy male subjects such as G1, 11–13; G2, 18–20; and G3, 26–30, years of age were recorded at the F3, F4, P3, and P4 derivations under two conditions: basal and performance of the Towers of Hanoi task. The majority of subjects in G1 failed to complete the task in the allotted time (7 min), while those in G2 and G3 were able to resolve the task quickly and efficiently. During the Towers of Hanoi task, G1 showed an increase of AP in the delta band only in the frontal areas, with a decrease in the alpha1 and alpha2 sub-bands only at the parietal derivations, while G2 and G3 were characterized by an increase of AP in the delta band and a decreased AP in the alpha1 and alpha2 sub-bands in all derivations. These data demonstrate that during the performance of the Towers of Hanoi task, the prefrontal and parietal areas show a characteristic EEG pattern in relation to age. It is probable that the AP patterns obtained in G2 and G3 are associated with the functional changes at cortical levels that adolescents and early adults require to achieve an adequate and fast performance of the Towers of Hanoi task.     

左颞叶和颅底占位性病变在韦氏智力量表中的损害模式

目的 :探讨左颞叶和颅底占位性病变在韦氏智力量表分测验中的损害模式。方法 :对 96例脑部占位性病变患者采用韦氏智力量表 (WAIS -RC)中的常识、词汇和相似性分测验进行测试。同时采用一个常识、词汇与相似性相对照的参数来对不同部位的患者进行比较。结果 :左颞叶和颅底占位性病变患者在常识和词汇分测验上比相似性分测验成绩差 ,5 8.8%的左颞叶患者和 72 .7%的颅底部患者参数〔(常识 +词汇 ) /2 -相似性〕为负数 ,而左额叶组、左顶叶 /左枕叶组及右半球组患者参数值则正数比率高 ,比率分别为 6 3.6 %、5 7.9%及 5 9.3%。与左额叶组、左顶叶 /左枕叶组和右半球组相比 ,左颞叶组和颅底组参数值更多为负数 ,差异有显著性 ,P <0 .0 5。结论 :本研究显示左颞叶及颅底部损害与常识和词汇分测验比相似性测验受损更明显相联系 ,支持左颞叶和颅底部损害可能更易损害记忆功能 ,尤其是语义记忆功能。     

Memory for visuospatial location following selective hippocampal sclerosis: the use of different coordinate systems

This study addressed the role of the medial temporal lobe regions and, more specifically, the contribution of the human hippocampus in memory for body-centered (egocentric) and environment-centered (allocentric) spatial location. Twenty-one patients with unilateral atrophy of the hippocampus secondary to long-standing epilepsy (left, n = 7; right, n = 14) and 15 normal control participants underwent 3 tasks measuring recall of egocentric or allocentric spatial location. Patients with left hippocampal sclerosis were consistently impaired in the allocentric conditions of all 3 tasks but not in the egocentric conditions. Patients with right hippocampal sclerosis were impaired to a lesser extent and in only 2 of the 3 tasks. It was concluded that hippocampal structures are crucial for allocentric, but not egocentric, spatial memory.     

Spatiotemporal memory and rate of forgetting in acute schizophrenics

Some schizophrenics show anomalies in the frontal and temporal lobes. It is uncertain whether the cognitive deficits shown by Type I schizophrenics are caused directly by such anomalies, or by a deficit in the exertion of attentional effort. In this study, 16 acute schizophrenics, who broadly fitted the Type I characterization and their controls were given a battery of cognitive tests. The patients were impaired on effort-demanding tasks such as the Wisconsin Card Sorting Test, a verbal fluency test and the WAIS, which are susceptible in varying degrees to frontal, temporal and parietal lobe lesions. Patients were not disproportionately impaired, however, on a test of temporal memory and another of spatial memory, an impairment pattern that selectively reflects frontal and medial temporal lobe lesions respectively, nor were they impaired on a rate of forgetting task sensitive to medial temporal lobe lesions. These tasks were chosen not only because performance on them is selectively sensitive to frontotemporal lobe lesions, but also because it seems to depend on exerting minimum amounts of attentional effort. It is tentatively concluded that the cognitive deficits shown by Type I schizophrenics are caused by a problem in exerting attentional effort of unknown origin.     

正常成人认知功能与年龄、性别、受教育程度的关系

目的 :探讨认知功能与年龄、性别、受教育程度的关系。方法 :对 12 0名正常受试者采用全套韦氏成人智力测验 (WAIS -RC)、逻辑记忆测验 (即刻、延迟 )、视觉再生 (即刻、延迟 )、Stroop测验 (C、C -W)、词汇流畅测验、连线测验A、连线测验B、汉诺塔测验 (TOH)、威斯康辛卡片分类测验—改良版 (M -WCST)等神经心理学测验进行测评。结果 :男性在某些语言功能、视觉空间能力上优于女性 ;年龄是影响右侧大脑半球认知功能的重要因素 ;受教育年限主要影响语言的抽象、概括能力。结论 :性别、年龄、受教育年限是影响认知功能的重要因素     

Memory selectivity and unilateral cerebral dysfunction

The relative speed of recall of pleasant and unpleasant experiences was investigated in patients with unilateral temporal lobe epilepsy and after unilateral temporal lobectomy. Indications have been obtained that right, but not left, temporal lobe dysfunction may impair hedonic aspects of memory selectivity.     

The role of inferior parietal and inferior frontal cortex in working memory

Verbal working memory involves two major components: a phonological store that holds auditory-verbal information very briefly and an articulatory rehearsal process that allows that information to be refreshed and thus held longer in short-term memory (A. Baddeley, 1996, 2000; A. Baddeley & G. Hitch, 1974). In the current study, the authors tested two groups of patients who were chosen on the basis of their relatively focal lesions in the inferior parietal (IP) cortex or inferior frontal (IF) cortex. Patients were tested on a series of tasks that have been previously shown to tap phonological storage (span, auditory rhyming, and repetition) and articulatory rehearsal (visual rhyming and a 2-back task). As predicted, IP patients were disproportionately impaired on the span, rhyming, and repetition tasks and thus demonstrated a phonological storage deficit. IF patients, however, did not show impairment on these storage tasks but did exhibit impairment on the visual rhyming task, which requires articulatory rehearsal. These findings lend further support to the working memory model and provide evidence of the roles of IP and IF cortex in separable working memory processes.     

Event-related potential correlates of impaired visuospatial working memory in schizophrenia

Previous studies have reported that patients with schizophrenia demonstrate impaired performance during working memory (WM) tasks. The current study aimed to determine whether WM impairments in schizophrenia are accompanied by reduced slow wave (SW) activity during on-line maintenance of mnemonic information. Event-related potentials were obtained from patients with schizophrenia and well controls as they performed a visuospatial delayed response task. On 50% of trials, a distractor stimulus was introduced during the delay. Compared with controls, patients with schizophrenia produced less SW memory negativity, particularly over the right hemisphere, together with reduced frontal enhancement of SW memory negativity in response to distraction. The results indicate that patients with schizophrenia generate less maintenance phase neuronal activity during WM performance, especially under conditions of distraction.     

Human amnesia and animal models of amnesia: performance of amnesic patients on tests designed for the monkey

The performance of amnesic patients was assessed on five tasks, which have figured prominently in the development of animal models of human amnesia in the monkey. The amnesic patients were impaired on four of these tasks (delayed nonmatching to sample, object-reward association, 8-pair concurrent discrimination learning, and an object discrimination task), in correspondence with previous findings for monkeys with bilateral medial temporal or diencephalic lesions. Moreover, performance of the amnesic patients correlated with the ability to verbalize the principle underlying the tasks and with the ability to describe and recognize the stimulus materials. These tasks therefore seem to be sensitive to the memory functions that are affected in human amnesia, and they can provide valid measures of memory impairment in studies with monkeys. For the fifth task (24-hour concurrent discrimination learning), the findings for the amnesic patients did not correspond to previous findings for operated monkeys. Whereas monkeys with medial temporal lesions reportedly learn this task at a normal rate, the amnesic patients were markedly impaired. Monkeys may learn this task differently than humans.