Strategic processing and memory for temporal order in patients with frontal lobe lesions.

This study evaluated whether deficits in memory for temporal order in patients with frontal lobe lesions result from impaired automatic encoding of temporal information or are secondary to deficits in effortful processes, such as the use of organizational strategies and control of interference. Patients with lesions in the dorsolateral prefrontal cortex and control participants were tested on temporal order reconstruction of semantically related and unrelated word lists learned under intentional or incidental conditions. Memory for temporal order in patients with frontal lobe lesions was sensitive to semantic relatedness but not to intention to learn. Tests of item free recall and recognition using similar encoding manipulations indicated that order performance in these patients was dissociable from item memory. Results indicate that automatic processing of temporal information is intact in patients with frontal lobe lesions but that strategic processing of this information is impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal and spatial context memory in patients with focal frontal, temporal lobe, and diencephalic lesions

Patients with focal frontal, temporal lobe, or diencephalic lesions were investigated on measures of temporal (recency) and spatial (position) context memory, after manipulating exposure times to match recognition memory for targets (pictorial stimuli) as closely as possible. Patients with diencephalic lesions from an alcoholic Korsakoff syndrome showed significant impairment on the temporal context (recency) task, as did patients with frontal lesions penetrating the dorsolateral frontal cortex, according to MRI (and PET) evidence. Patients with temporal lobe lesions showed only a moderate (non-significant) impairment on this task, and patients with medial frontal lesions, or large frontal lesions not penetrating the dorsolateral cortical margins, performed as well as healthy controls at this task. On the spatial context memory task, patients with lesions in the temporal lobes showed significant impairment, and patients with right temporal lesions performed significantly worse than patients with left temporal lesions. Patients with diencephalic lesions showed only a modest (non-significant) impairment on this task, and the frontal lobe group performed normally. When a group of patients with temporal lobe lesions resulting from herpes encephalitis were examined separately, an identical pattern of results was obtained, the herpes group being significantly impaired on spatial memory and showing a trend towards impairment for temporal context memory. There were strong correlations between anterograde memory quotients and context memory performance (despite the use of an exposure time titration procedure) and a weak association in the frontal group with one frontal/executive task [corrected] (card-sorting perservations). It is predicted that correlations between temporal context memory and frontal/executive tasks will be greater in samples of patients all of whom have frontal lesions invading the dorsolateral cortical margin.     

Evidence for intact semantic representations in patients with frontal lobe lesions.

Patients with frontal lobe lesions and control participants were assessed on 2 tests of semantic knowledge. In the triadic comparison task, participants were shown all possible triplets of 12 animal names and judged which 2 of each triplet were most alike. In the ordered similarity task, participants rank ordered animals in terms of their similarity to a target animal. For both tasks, semantic structure-- derived from multidimensional scaling techniques-- revealed similar representations in patients with frontal lobe lesions and control participants. Additional pathfinder analyses also produced networks that did not differ between groups. These patients exhibited intact semantic knowledge despite deficits on tests of free recall and verbal fluency that involved the same semantic category and exemplars. Thus, intact representation of semantic knowledge in frontal patients stands in contrast to their marked deficits in strategic retrieval of semantic knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequency judgements of abstract designs by patients with diencephalic, temporal lobe or frontal lobe lesions

Patients with diencephalic, temporal lobe or frontal lobe lesions were compared with healthy controls on a frequency judgement task. The three patient groups were disproportionately impaired at estimating how often a series of abstract designs had been presented relative to controls. Diencephalic and temporal lobe patients did not differ from each other. It is argued that the results may reflect a 'core' memory deficit in the temporal lobe patients. The impairment in the frontal patients may reflect their difficulty in making an organised search in memory for multiple traces of an item, while the deficit shown by the diencephalic patients (particularly those with Korsakoff syndrome) may be due to the combined effects of a generally poor memory and superimposed frontal pathology.     

Protein kinase C from rainbow trout brain: identification and characterization of three isozymes

This study examines the hypothesis that patients with frontal lobe lesions are impaired on tests of letter but not category fluency. This hypothesis was proposed by Moscovitch (1994), based on a series of cognitive studies with young, normal participants. A group of patients with lateral prefrontal lesions and age-matched controls were tested on 2 tests of verbal fluency, the FAS task and a category fluency task that used semantic categories as cues (e.g., animals). Patients with frontal lobe lesions generated fewer items than controls on both letter and category fluency. This effect did not interact with the type of fluency test, suggesting that the frontal lobes are more generally involved in verbal fluency. Moreover, this pattern of findings, along with previous results of impaired free recall and remote retrieval in this patient group, suggests that patients with frontal lobe lesions do not efficiently organize and develop retrieval strategies.     

Letter and category fluency in patients with frontal lobe lesions.

This study examines the hypothesis that patients with frontal lobe lesions are impaired on tests of letter but not category fluency. This hypothesis was proposed by Moscovitch (1994), based on a series of cognitive studies with young, normal participants. A group of patients with lateral prefrontal lesions and age-matched controls were tested on 2 tests of verbal fluency, the FAS task and a category fluency task that used semantic categories as cues (e.g., animals). Patients with frontal lobe lesions generated fewer items than controls on both letter and category fluency. This effect did not interact with the type of fluency test, suggesting that the frontal lobes are more generally involved in verbal fluency. Moreover, this pattern of findings, along with previous results of impaired free recall and remote retrieval in this patient group, suggests that patients with frontal lobe lesions do not efficiently organize and develop retrieval strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Word list learning and prediction of recall after frontal lobe lesions.

The effect of frontal lobe lesions on the accuracy of prediction of recall in a word list learning task was studied. Fifty-nine patients with a focal brain lesion and 21 non-brain-damaged control patients memorized a word list by selective reminding and predicted before each recall trial the number of words they would be able to recall. The patients with left frontal lesions, who were inferior to the patients with right frontal lesions and the control patients in word list recall, overpredicted their recall more than the other brain-damaged patients or the control patients, especially on the 1st trial. The patients with right frontal lesions were less accurate in the prediction of recall than the patients with right posterior lesions or the control patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Difference between transcortical sensory aphasia following the left frontal lesion and transcortical sensory aphasia following the left posterior lesion

We assessed the difference between transcortical sensory aphasia (TCSA) following the left frontal lesions (F-TCSA) and TCSA following the left posterior lesions (P-TCSA). All the patients were right-handed and the 7 patients had the lesions in the only frontal lobe and the 10 patients had the lesions only in the left temporo-parieto-occipital regions. We administered pointing tasks, using 90 line drawings representing single nouns. We presented 6 line drawings a pointing board, and we used two kinds of pointing boards: one showed the line drawings each belonging to different categories (random categorized pointing task), the other showed the line drawings each belonging to only either two different categories (two categorized pointing task) and we presented 15 pointing boards each alternatively. The result was that regarding the patients of P-TCSA showed different number of correct answers between the random categorized pointing task and the two categorized pointing task with statistical significance. Regarding the patients of F-TCSA showed no difference between them. The results indicated that disturbance of P-TCSA on the pointing task was the disturbance of semantic process per se. And the disturbance of F-TCSA on the pointing task was that of not only semantic process but also the whole process including comprehending the presented words, searching the line drawings, comparing the line drawings with the presented word and final selection, which demanded persistent multiple memory process consistent with working memory.     

Extended total aortic arch replacement involving the proximal descending aorta through a median sternotomy

In two experiments, we investigated the interpretation and boundary conditions of the tongue-twister (TT) effect in silent reading. Previously, McCutchen, Bell, France, and Perfetti (1991) observed a TT effect when students made semantic acceptability judgments on sentences, but not when they made lexical decisions on lists of words. Using similar methodology in Experiment 1, along with two changes (using "better" TTs and longer word lists), we observed a TT effect in a lexical decision task. In Experiment 2, a memory span task revealed that students recalled fewer words from TT lists than from control lists. These results suggest that the basic mechanism of the TT effect may be articulatory, rather than working-memory, interference that occurs during lexical access and resurfaces post-lexically, inhibiting efforts to maintain the temporal order of several words.     

Auditory and visual word processing studied with fMRI

Brain activations associated with semantic processing of visual and auditory words were investigated using functional magnetic resonance imaging (fMRI). For each form of word presentation, subjects performed two tasks: one semantic, and one nonsemantic. The semantic task was identical for both auditory and visual presentation: single words were presented and subjects determined whether the word was concrete or abstract. In the nonsemantic task for auditory words, subjects determined whether the word had one syllable or multiple syllables. In the nonsemantic task for visual words, subjects determined whether the word was presented in lower case or upper case. There was considerable overlap in where auditory and visual word semantic processing occurred. Visual and auditory semantic tasks both activated the left inferior frontal (BA 45), bilateral anterior prefrontal (BA 10, 46), and left premotor regions (BA 6) and anterior SMA (BA 6, 8). Left posterior temporal (middle temporal and fusiform gyrus) and predominantly right-sided cerebellar activations were observed during the auditory semantic task but were not above threshold during visual word presentation. The data, when averaged across subjects, did not show obligatory activation of left inferior frontal and temporal language areas during nonsemantic word tasks. Individual subjects showed differences in the activation of the inferior frontal region while performing the same task, even though they showed similar response latency and accuracy.     

Organizational strategies with unilateral or bilateral frontal lobe injury in word learning tasks.

To define the capacity to organize verbal learning after frontal lobe injury, 32 patients with stable frontal lesions were evaluated with list learning tasks. Lesion size and site were determined from CAT or magnetic resonance imaging (MRI) scans. The lists were contructed to assess several potential organizational processes. A mild deficit in recognition performance was observed in patients with left frontal lesions accompanied by residual minor language impairments or in patients with septal lesions. Patients with frontal lesions also had a verbal recall deficit that was related to several factors: poor higher order organization of learning, independent of lesion size or site; a selective secondary memory impairment, associated with a language deficit and size of the lesion in the left frontal region; and excess intralist repetitions in patients with right frontal lesions. Impaired list learning after frontal lesions involves several independent psychological processes. This functional heterogeneity is based on regional anatomical specialization and dissociation of task processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impaired retrieval from remote memory in patients with frontal lobe damage.

Patients with unilateral dorsolateral frontal lobe lesions and matched controls were given 2 tests of remote memory for public information, the Public Events Test and the Famous Faces Test. On both tests, the patients with frontal lobe lesions exhibited impaired recall for remote information. Recognition memory was relatively preserved. Provision of semantic and phonemic cues in the Famous Faces Test did not completely compensate for their recall deficit. These findings suggest that the remote memory impairment exhibited by frontal patients may be related to deficits in strategic search of memory. These deficits in retrieval from remote memory extend the array of memory deficits associated with damage to the frontal lobes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term control of GABA synthesis in brain

Frontal lobe and basal ganglia lesions have been associated with similar cognitive impairments, although their specialized roles in behavior are likely to be different. We examined whether these structures mediate distinctive or overlapping aspects of a complex behavioral process that has been associated with both neural sites, i.e. cognitive flexibility. Patients with focal ischemic lesions to the frontal lobe and basal ganglia were compared on two forms of cognitive flexibility: (1) shifting response set (i.e. reactive flexibility), and (2) producing a diversity of ideas (i.e. spontaneous flexibility). Results indicated that frontal lobe and basal ganglia damage each caused a similar degree of impairment in reactive flexibility, both groups performing at a significantly lower level than posterior cortical lesion and normal comparison groups. However, frontal lobe damage markedly disturbed spontaneous flexibility, while performance after basal ganglia lesion was significantly higher and comparable to posterior cortical lesions. Findings suggest that the frontal lobe and basal ganglia participate differently in the neural substrate of cognitive flexibility. The frontal lobe appears to mediate spontaneous flexibility. The production of diverse ideas may require direct cortical-cortical interactions by the frontal lobe in order to access knowledge systems with novel strategies that transcend the most common semantic linkages. In contrast the corticostriate system appears to mediate reactive flexibility, as the frontal lobe, basal ganglia and their interconnections are required for its operation.     

On the remembrance of times past: The irregular list technique.

Four experiments were designed to examine the processing of time in human memory. These experiments introduce a new way of testing memory for relative temporal duration that uses a list with uneven temporal spacing between items. In this irregular list technique, people are excused from remembering the items themselves and from remembering their relative positions within the list but must judge which of two adjacent interitem intervals had been longer. Although performance was good in this task, it was comparable for vocalized and silent visual presentation. This finding directly contradicts the hypothesis that temporal coding is better in the auditory modality than in the visual modality. The second experiment replicated this result for word lists under conditions in which people were ignorant, until after list presentation, about whether they were to recall the items or to make temporal judgments. The third experiment investigated the effect of filling, with distraction, the interitem intervals in irregularly spaced lists. In the final experiment, we adapted the irregular list technique to examine long-term or semantic memory. We conclude that memory for the genuinely temporal properties of learned experiences can and should be separated from their sequential ordering. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Forms of memory failure in schizophrenia.

Examined effortful and automatic memory task performances in 36 schizophrenic patients and 18 normal controls. Tasks included free recall, recognition, and frequency estimation. Patients demonstrated impairment in recall, in recognition, in semantic encoding, and in frequency estimation. Deficits were observed across tasks despite differences in attentional demands. Results suggest a basic compromise of memory function, which is consistent with recent neuroimaging evidence of structural or physiological abnormalities in frontal and temporal lobe structure in schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal fluency deficits in patients with schizophrenia: Semantic fluency is differentially impaired as compared with phonologic fluency.

Patients with schizophrenia show deficits in phonologic (ability to name words that begin with a specific letter, e.g., F) and semantic (ability to name members of a category, e.g., "animals" fluency.) Whereas the former deficit has been presumed to reflect a dysfunction of the frontal lobe, the latter has been linked to frontal and temporoparietal brain areas. These 2 verbal fluency measures were studied in a sample of 27 schizophrenia patients and 24 normal controls who were matched on age and a putative measure of premorbid intellectual ability. A 2-min production task of switching between letters and between categories measured demand for flexibility. On switching and nonswitching tasks controls produced more words during semantic versus phonologic fluency. Conversely, schizophrenia patients produced more words for letters than for categories, suggesting dysfunction of the frontal and temporoparietal areas of the brain. Furthermore, the greater impairment of semantic fluency may be related to a breakdown of semantic information processing beyond "executive" search and retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Semantic fluency in Alzheimer's, Parkinson's, and Huntington's disease: Dissociation of storage and retrieval failures.

Patients with Alzheimer's disease (AD), Huntington's disease (HD), and Parkinson's disease (PD), and normal controls were compared on 2 versions of a semantic fluency task: a standard, uncued version and a version in which Ss were cued with subordinate categories. All patients were impaired relative to controls on the standard version. On the cued version, PD and HD patients improved significantly, but AD patients did not. AD patients' fluency, but not PD or HD patients', correlated significantly with confrontation naming ability. Impairment exhibited by PD and HD patients on standard semantic fluency tasks may be due to a retrieval deficit, whereas that of AD patients may be due to degradation of semantic memory stores. In addition, the pattern of performance exhibited by a nonaphasic patient with bilateral frontal lobe lesions suggests that the retrieval functions involved may depend on integrity of the prefrontal cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Longitudinal analysis of phonemic clustering and switching during word-list generation in Huntington's disease.

Two characteristics of word-list generation performance are forming clusters (i.e., contiguous words from the same subcategory) and switching among them. Patients with frontal lobe pathology show reduced switching on letter-cued word generation tasks, and clustering has been associated with temporal lobe functioning. Letter-cued word generation was examined in 72 patients with Huntington"s disease (HD) and 41 healthy participants of equivalent age and education. As predicted, the patients showed reduced switching but normal clustering. In addition, switching but not clustering correlated inversely with disease severity, as measured by both movement and mental status scales. Furthermore, 5-year longitudinal analysis revealed a monotonic decrease in switching over time, whereas clustering performance remained stable. Control participants performed uniformly over time on both measures. These results are consistent with a progressive reduction in cognitive flexibility attributed to disruption of frontal circuits secondary to neostriatal pathology in HD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Altered serial position learning after frontal lobe lesion

The serial position function is a powerful and highly reliable feature of human learning, with well-described primacy and recency effects. We tested the hypothesis that frontal lobe lesions in patients would disrupt the serial position function since such patients are known to have disturbed temporal ordering, learning in the presence of interference, encoding and organizational approaches to learning. Performance was compared in patients with focal, acquired lesions of frontal and non-frontal cortices, using a standardized paradigm of verbal list learning. Results indicated a similar pattern of performance on first trial learning for the two groups. However, across learning trials, frontal lesion subjects failed to maintain significant primacy and recency effects. Non-frontal lesion subjects consistently showed the expected U-shaped serial position curve across all trials. Subjective organization in learning was particularly deficient in the dorsolateral frontal lesion subjects. We propose that serial position effects are qualitatively different after frontal lobe lesion, being transitory and prone to alteration by the cumulative effects of disturbed temporal-spatial processing across learning trials.     

A Meta-Analytic Review of Verbal Fluency Deficits in Huntington's Disease.

A meta-analysis of 30 studies with 1,511 participants was conducted to estimate and compare the magnitude of deficits on tests of phonemic and semantic fluency for patients with Huntington's disease (HD) relative to healthy control participants. As has been found for patients with focal frontal cortical lesions (but not for patients with focal temporal cortical lesions), symptomatic HD patients were comparably impaired on tests of phonemic and semantic fluency (rs=.71 and .73, respectively). However, in contrast to patients with focal frontal lobe injuries, fluency deficits did not qualify as differential deficits relative to verbal intelligence or psychomotor speed. Therefore, for patients with HD, deficits on tests of phonemic and semantic fluency do not appear to reflect executive dysfunction but a more generalized cognitive impairment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)