Frontal lobe dysfunction and memory impairment in patients with chronic progressive multiple sclerosis

Deficits in semantic encoding have been described in patients with frontal lobe disease who also show memory impairments. As a group, patients with multiple sclerosis (MS) exhibit memory impairment, fail to make effective use of semantic encoding to aid memory, and perform poorly on verbal fluency and concept formation tests which are sensitive to frontal lobe damage. In the present study the semantic encoding capacity of MS patients was measured using a modification of Wicken's release from proactive interference (PI) paradigm. Individual patients varied considerably in the severity of their impairments on verbal fluency, verbal recognition memory and on Wisconsin Card Sorting Task, but even patients who evidenced both memory impairment and signs of frontal lobe dysfunction showed normal release from PI after a categorical shift. Memory disturbances in MS are unlikely to result from an incapacity for semantic encoding, which seems preserved in MS, but may arise instead from deficits in processing information rapidly.     

Short-term longitudinal change in cognitive performance in later life.

Changes in mean performance on memory, information processing, and intellectual ability tasks over a 3-year period were examined. The sample consisted of 328 community-dwelling men and women (from an original sample of 484 individuals) aged 55-86 years. Ss completed tasks yielding measures of verbal processing time, working memory, implicit memory, vocabulary, verbal fluency, world knowledge, reading comprehension, word recall, and text recall. The results showed significant average decline on working memory, verbal fluency, and world knowledge. There were also interactions for 2 processing time measures and working memory, showing greater decline in the earlier-born cohort group than in the later-born cohort group. A step-down analysis revealed that covarying declines in other variables, including processing time, did not eliminate significant declines in working memory, verbal fluency, and world knowledge.     

Preserved topographical memory following right temporal lobectomy

In an attempt to study remote memory for visuospatial information, geographical knowledge was examined in patient J.N., who had received a radical right temporal lobectomy to remove a large glioblastoma. In postoperative tests J.N. displayed severe deficits in anterograde memory for visuospatial and verbal material, visuoperceptual functions, constructions, attention, and response initiation. Despite her global cognitive deficiencies she performed normally on the WAIS Information Scale and the Fargo Map Test, a measure of geographical knowledge. In contrast, patients known to have severe amnesia exhibited impairments on tests of geographical knowledge that required precise localization of features such as cities. Assuming that J.N.'s performance is typical of patients with extensive damage to the right temporal lobe, the findings suggest that the integrity of the right temporal lobe is not essential for the retrieval of premorbidly established visuospatial memories.     

Memory strategies with brain damage

The ability of anterograde amnesics with and without a history of alcoholism and patients with frontal lobe damage to think about memory, memorizing, and remembering was assessed. Alcoholic Korsakoffs' and frontal lobe patients' knowledge and use of memory strategies was deficient when compared with controls whereas nonalcoholic amnesics' was not. The use of the categorization mnemonic was assessed in a verbal learning experiment. Frontal lobe patients failed to spontaneously categorize a categorizable word list when trying to memorize it. Nevertheless, when forced to categorize the list, they benefited from the imposed structure. Nonalcoholic amnesics spontaneously categorized the list and benefited from the resulting organization.     

Ethanol reduces rCFB activation of left dorsolateral prefrontal cortex during a verbal fluency task

In a previous study in normal subjects (Wendt et al., 1994), using a reversing checkerboard as activation stimulus, we found that the coupling between local neuronal activity and regional cerebral blood flow was preserved following ethanol, and that a right-sided occipital activation response seen during sobriety became symmetrical during inebriation. In the present study we investigated if ethanol has a detrimental effect also on the activation of the left dorsolateral prefrontal cortex found in normals during verbal fluency. Measurements of regional cerebral blood flow in 20 healthy, young, male, right-handed volunteers during rest and verbal fluency were made during sobriety and inebriation (0.06% blood alcohol concentration) with a 1-week interval. We found a decrease in word production during inebriation. The normal activation within the frontotemporal part of the left dorsolateral prefrontal cortext was preserved during inebriation. The activation of this region seems thus to be robust to the effects of ethanol. During inebriation no activation response to the word fluency test was found in the anterior prefrontal part of the dorsolateral prefrontal cortex. This region is important for working, temporal, and short-term memory functions, processes that are affected by ethanol. Hemispheric functioning and specialization seem to be adversely affected by ethanol, regardless of which hemisphere is most involved while sober.     

Neuropsychological Functioning Associated with High-Altitude Exposure

This article focuses on neuropsychological functioning at moderate, high, and extreme altitude. This article summarizes the available literature on respiratory, circulatory, and brain determinants on adaptation to hypoxia that are hypothesized to be responsible for neuropsychological impairment due to altitude. Effects on sleep are also described. At central level, periventricular focal damages (leuko-araiosis) and cortical atrophy have been observed. Frontal lobe and middle temporal lobe alterations are also presumed. A review is provided regarding the effects on psychomotor performance, perception, learning, memory, language, cognitive flexibility, and metamemory. Increase of reaction time and latency of P300 are observed. Reduced thresholds of tact, smell, pain, and taste, together with somesthetic illusions and visual hallucinations have been reported. Impairment in codification and short-term memory are especially noticeable above 6,000 m. Alterations in accuracy and motor speed are identified at lower altitudes. Deficits in verbal fluency, language production, cognitive fluency, and metamemory are also detected. The moderating effects of personality variables over the above-mentioned processes are discussed. Finally, methodological flaws found in the literature are detailed and some applied proposals are suggested.     

Qualitative evaluation of divergent thinking in patients with schizophrenia

Patients with schizophrenia show deficits across a broad spectrum of neurocognitive domains. In particular, deficits in verbal fluency are common. Verbal fluency tests are neuropsychological tests that assess frontal lobe function or executive function but also assess divergent thinking. However, few studies have considered the impairment of verbal fluency from the viewpoint of divergent thinking. To consider the structure of divergent thinking, not only verbal assessments but also non-verbal assessments are indispensable. We administered several fluency tests, the idea fluency test, the design fluency test, and word (letter and category) fluency tests to 26 patients with schizophrenia and 26 healthy control subjects to evaluate divergent thinking in both groups and assessed their responses qualitatively. An acceptable minimal level of intelligence was maintained in the patient group. Although attention and executive functioning were relatively preserved in the subjects with schizophrenia, they demonstrated significant deficits in divergent thinking and had particular difficulty in producing ideas and designs requiring concept flexibility, a conversion of viewpoint, originality, or novelty. Research on deficits in divergent thinking in patients with schizophrenia may contribute to the development of cognitive and behavioral rehabilitation programs.     

Investigating the lower level demands of writing: handwriting movements interfere with immediate verbal serial recall

The research identifies if handwriting captures attention for significant periods, resulting in a decline in working memory performance. Additionally, the experiments isolate whether the movements produced during handwriting contribute to that interference. To do this, verbal serial recall was compared between three different tasks???a listening task; a listening?+?handwriting task (i.e., motor and verbal demands); and a listening?+?handwriting-like drawing task (i.e., motor demands), in two experiments. Results showed that verbal serial recall was worse in the handwriting and drawing conditions compared to the listening condition. The handwriting and drawing conditions did not differ. In a third experiment, handwriting fluency was compared between a recall and no-recall task. This showed that handwriting fluency remains stable despite the addition of a verbal working memory task. In conclusion, the handwriting movements capture attention for significant periods, with little deterioration in recall due to the verbal component of handwriting.     

Working Memory and Spoken Language Comprehension in Young Children

This study has two theoretical dimensions: (a) to explore which components of Baddeley's (1986) working memory model are associated with children's spoken language comprehension, and (b) to compare the extent to which measures of the components of this fractionated model and an index of a unitary model (listening span) are able to predict individual differences in spoken language comprehension. Correlational analyses revealed that within a group of 66 4– and 5-year-old children both listening span and phonological memory, but not visuospatial memory, were associated with vocabulary knowledge and spoken language comprehension. However, of the proposed measures of central executive function—dual task coordination, sustained attention, verbal fluency—only the latter was related to children's ability to understand spoken language. Hierarchical regression analyses indicated that variance in vocabulary knowledge was best explained by phonological memory skills, whereas individual differences in spoken language comprehension exhibited unique and independent associations with verbal fluency.     

Manipulation of frontal brain asymmetry by cognitive tasks

The purpose of the present study was to evaluate whether verbal fluency tasks may specifically induce relatively greater left than right hemispheric activation in the dorsolateral prefrontal cortex. The effectiveness of the manipulation was evaluated by EEG, which was recorded during performance of the verbal fluency task and during two control conditions, i.e., a baseline condition without cognitive demands, and a mental arithmetic task, respectively. The results demonstrate that the desired effect can only be achieved in individuals with good performance on the verbal fluency task. Good and poor performers do not only differ in lateral asymmetry, but also in the most affected region within the prefrontal cortex. Whereas good performers show relatively increased activation in the cortical region and hemisphere putatively most specialized for this kind of task (i.e., the left dorsolateral frontal cortex), poor performers show a marked shift of frontopolar asymmetry to the right.     

额叶参与对新异联系的启动效应——来自脑损伤病人的证据

对新异联系的启动效应是内隐记忆的一种形式,又称联想启动。采用知觉辨认任务,探讨额叶损伤与联想启动的关系。25例额叶损伤病人及18例匹配的正常被试参与实验。结果表明,额叶受损病人辨认旧词对与重组词对的正确率没有明显差别;而且,轻度记忆损伤的额叶病人再认成绩正常,但联想启动值低于对照组,内隐记忆和外显数、坚持性反应数和语词流畅性等有中度相关。这些结果提示,额叶不仅与情节记忆、工作记忆等外显记忆有关,也参与了以非相关词对为材料的联想启动。     

A System for Relational Reasoning in Human Prefrontal Cortex

The integration of multiple relations between mental representations is critical for higher level cognition. For both deductive- and inductive-reasoning tasks, patients with prefrontal damage exhibited a selective and catastrophic deficit in the integration of relations, whereas patients with anterior temporal lobe damage, matched for overall IQ but with intact prefrontal cortex, exhibited normal relational integration. In contrast, prefrontal patients performed more accurately than temporal patients on tests of both episodic memory and semantic knowledge. These double dissociations suggest that integration of relations is a specific source of cognitive complexity for which intact prefrontal cortex is essential. The integration of relations may be the fundamental common factor linking the diverse abilities that depend on prefrontal function, such as planning, problem solving, and fluid intelligence.     

Semantic and Phonemic Verbal Fluency in Blinds

A person who has suffered the total loss of a sensory system has, indirectly, suffered a brain lesion. Semantic and phonologic verbal fluency are used for evaluation of executive function and language. The aim of this study is evaluation and comparison of phonemic and semantic verbal fluency in acquired blinds. We compare 137 blinds and 124 sighted people in verbal fluency task. The tasks were phonemic and semantic verbal fluency test that subjects should be generate as many word as possible in a limited amount of time for a given letter (Phonemic fluency) or a given category (Semantic fluency). Independent T Test was used to comparing blind with sighted. Findings show significant difference between two groups so that that sighted subjects have higher performance in semantic verbal fluency task (p = 0.000). Comparing sighted and blind subjects in phonemic verbal fluency task shows performance in sighted subjects (p = 0.000). Based on this study blinds have lower performance in semantic and phonemic verbal fluency task as a executive function of frontal lobe.     

Assessing executive abilities following acute stroke with the trail making test and digit span

The Trail Making Test and Digit Span are neuropsychological tests widely used to assess executive abilities following stroke. The Trails B and Digits Backward conditions of these tests are thought to be more sensitive to executive impairment related to frontal lobe dysfunction than the Trails A and Digits Forward conditions. Trails B and Digits Backward are also thought to be more sensitive to brain damage in general. Data from the Stroke and Lesion Registry maintained by the Washington University Cognitive Rehabilitation Research Group were analyzed to compare the effects of frontal versus nonfrontal strokes and to assess the effects of stroke severity. Results showed that the performance of patients with frontal and nonfrontal strokes was comparable in each condition of both the Trail Making Test and Digit Span, providing no support for the widely held belief that Trails B and Digits Backward are more sensitive to frontal lobe damage. Further, Trails A was as strongly correlated with stroke severity as Trails B, whereas Digits Backward was more strongly correlated with stroke severity than Digits Forward. Overall, the Trail Making Test and Digit Span are sensitive to brain damage but do not differentiate between patients with frontal versus nonfrontal stroke.     

Decision-making competence in younger and older adults: which cognitive abilities contribute to the application of decision rules?

Older adults perform worse than younger adults when applying decision rules to choose between options that vary along multiple attributes. Although previous studies have shown that general fluid cognitive abilities contribute to the accurate application of decision rules, relatively little is known about which specific cognitive abilities play the most important role. We examined the independent roles of working memory, verbal fluency, semantic knowledge, and components of executive functioning. We found that age-related decline in applying decision rules was statistically mediated by age-related decline in working memory and verbal fluency. Our results have implications for theories of aging and decision-making.     

Relations between source amnesia and frontal lobe functioning in older adults

A study is reported in which the relations among normal aging, source amnesia, and frontal lobe functioning were explored. Twenty-four older adults (aged 60-84 years) were tested on their ability to remember where they had acquired new factual information; they were also given the Wisconsin Card Sorting Test (WCST), a test of verbal fluency, and other psychometric tests. The degree of source amnesia in this normal sample correlated with age, verbal fluency, and some measures from the WCST. Source amnesia was not related to Performance IQ, however, or to a measure of fact recall. The implications for the relations among aging, memory, and frontal lobe functions are discussed.     

Age differences in implicit memory: fragmented object identification and category exemplar generation.

In a cross-sectional study of 164 participants aged 21 to 91, the authors examined age differences on two implicit tests, fragmented object identification (FOI) and category exemplar generation (CEG), and on tests of explicit memory, attention, and verbal fluency. FOI results revealed impaired perceptual skill learning in those over 60 and a decrease in perceptual priming across young, middle-aged, and older groups. CEG priming was impaired in those over 80. Regression analysis revealed explicit contamination of priming on both the FOI and CEG tests. Across the three implicit measures, age accounted for 4 to 13% of the variance when explicit memory was controlled. Semantic fluency predicted CEG priming, suggesting possible frontal lobe involvement on the test. Altogether, results indicate that age has a small but reliable influence on implicit memory.     

Verbal fluency in children with ADHD: Strategy using and temporal properties

Verbal fluency tasks are commonly used in cognitive and developmental neuropsychology in assessing executive functions, language skills as well as divergent thinking. Twenty-two typically developing children and 22 children with ADHD between the ages of 8 and12 years were examined using verbal fluency tasks, prepotent response inhibition, and working memory tests. The clinical group showed impaired inhibitory and spatial working memory processes. We used different qualitative analyses of verbal fluency tasks to explore the lexical and executive strategies (word clustering and switching), and the temporal properties of the responses. Children with ADHD had a leeway in applying relevant lexical or executive strategies related to difficulties in strategy using. The reduced efficiency of children with ADHD in semantic fluency task is based on suboptimal shifting between word clusters and is related to the lack of ability of producing new clusters of items. The group difference appeared at the level of accessing and/or activating common words; however, the executive process of searching the lexicon extensively is intact.     

Knowing the meaning, getting the point, bridging the gap, and carrying the message: aspects of discourse following closed head injury in childhood and adolescence

Pragmatic communication or discourse was studied in 33 children and adolescents following closed head injury. Three-quarters of the sample was impaired on at least one of four discourse tests (knowing the alternate meanings of ambiguous words in context; getting the point of figurative or metaphoric expressions; bridging the inferential gaps between events in stereotyped social situations; and producing speech acts that express the apparent intentions of others). Resolution of ambiguity was correlated with word fluency and verbal domain knowledge, but not with object naming; understanding of metaphor was correlated with verbal domain knowledge, but not with literal sentence comprehension or with the formation of analogies; making inferences was correlated with working memory capacity but not with social knowledge; and producing speech acts was not correlated either with sentence construction or with social knowledge. These associations and dissociations reveal some of the correlates of impaired discourse processing after closed head injury in childhood and adolescence, as well as bearing on theoretical questions concerning the nature of normally developing discourse processes.