Effects of lesions invading the postcentral gyrus on somatosensory thresholds on the face

Patients with unilateral removals from either the parietal, frontal or temporal lobe and normal control subjects were examined on three tests of tactile sensibility. The patients with surgical excisions from the parietal lobe were subdivided into two groups: those whose lesions invaded the face area in the primary sensory cortex and those whose lesions spared this area. A significant percentage of patients with lesions that invaded the face area had mild to severe sensory deficits on the side of the face contralateral to the lesion. A much smaller number of patients had deficits on the ipsilateral side. Lesions to the face area in the primary sensory cortex were, however, associated with a lower incidence of severe and persistent sensory deficits when compared to previous results on the effects of lesions to the hand area on the sensory capacity of the hand. These results suggest that there is some preservation of sensory function after damage to the face area in the primary sensory cortex, presumably due to the bilateral representation of the face.     

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)     

Component mechanisms underlying the processing of hierarchically organized patterns: Inferences from patients with unilateral cortical lesions.

Subjects identified target letters that occurred randomly at the local or global level in a divided attention task. The visual angle of the stimuli was varied. Neurologically intact controls showed a reaction time advantage for local targets which increased as visual angle increased. Patients with lesions centered in the posterior superior temporal gyrus (STG) showed a larger local advantage than controls if the lesion was on the right and a global advantage if the lesion was on the left. STG patients were no more influenced by visual angle than were controls. Control subjects also showed the usual interference of global distractors on responding to local targets. STG patients showed little evidence of interference. Control patients with lesions centered in the rostral inferior parietal lobe performed normally. The findings suggest that several component mechanisms are involved in the processing of hierarchical levels of structure, each linked to specific anatomical regions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Input and central processing expressed in ERP and heart rate changes to rare target and rare nontarget stimuli

Whether late positive components of event-related potentials (ERPs) parallel changes in heart rate (HR) indicative of attention/orienting to rare stimuli has been debated. In the present study, a three-stimulus design was used, with rare target, rare nontarget, and frequent standard stimuli delivered under identical conditions except that instructions to subjects described the targets to which subjects should respond but did not describe the nontargets. In Experiment 1, stimuli varied among modalities; in Experiment 2, auditory stimuli were employed. Both ERPs and HR were consistent with automatic processing preceding two stages of controlled processing. Rare stimuli evoked larger parietal P300 and initial HR deceleration than standards. Presumably because of load-reducing effects of long interstimulus intervals, targets and nontargets were not distinguished before a late slow wave and a late phase of HR acceleration. Neither rare stimulus elicited a recognizable frontal P3a.     

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.     

An assessment of oxidative damage to proteins, lipids, and DNA in brain from patients with Alzheimer's disease

Oxidative stress may contribute to neuronal loss in Alzheimer's disease (AD). The present study compares the levels of oxidative damage to proteins, lipids, and DNA bases from seven different brain areas of AD and matched control tissues by using a range of techniques. No differences in levels of lipid peroxidation were found in any of the brain regions by using two different assay systems. Overall, there was a trend for protein carbonyl levels to be increased in AD in frontal, occipital, parietal, and temporal lobe, middle temporal gyrus, and hippocampus, but a significant difference was found only in the parietal lobe. Gas chromatography-mass spectrometry was used to measure products of damage to all four DNA bases. Increased levels of some (8-hydroxyadenine, 8-hydroxyguanine, thymine glycol, Fapy-guanine, 5-hydroxyuracil, and Fapy-adenine), but not all, oxidized DNA bases were observed in parietal, temporal, occipital, and frontal lobe, superior temporal gyrus, and hippocampus. The baseline level of oxidative DNA damage in the temporal lobe was higher than in other brain regions in both control and AD brain. The finding of increased oxidative damage to protein and DNA strengthens the possibility that oxidative damage may play a role in the pathogenesis of AD in at least some key brain regions.     

Analysis of Parkinson's disease and related syndromes using 123I-IMP-SPECT with the ARG method

We studied regional cerebral blood flow (rCBF) in 8 patients with non-demented Parkinson's disease (PD). 1 patient with progressive supranuclear palsy (PSP), 1 patient with multiple system atrophy (MSA), and 7 normal control subjects using single photon emission computed tomography (SPECT) with the IMP-ARG method. Regions of interest were studied in the cerebral cortex (upper frontal, lower frontal, temporal, occipital, parietal), thalamus, basal ganglia, and cerebellum. In patients with PD, rCBF was normal in 4/8, and decreased in occipital lobe in 4/8. In patient with PSP, rCBF was decreased in the upper and lower frontal lobes, and in the cerebellum. In patient with MSA, rCBF was diminished in the cerebellum. The results of our study were almost compatible with the conventional rCBF study by positron emission tomography (PET), however, the decrease of rCBF in occipital lobe had rarely been reported, suggesting that might be related to visuospatial dysfunction in Parkinson's disease.     

Effects of divided attention on temporal processing in patients with lesions of the cerebellum or frontal lobe.

Prefrontal cortex and cerebellum have both been implicated in temporal processing tasks although the exact contribution of each system remains unclear. To investigate this issue, control participants and patients with either prefrontal or cerebellar lesions were tested on temporal and nontemporal perceptual tasks under 2 levels of attentional load. Each trial involved a comparison between a standard tone and a subsequent comparison tone that varied in frequency, duration, or both. When participants had to make concurrent judgments on both dimensions, patients with frontal lobe lesions were significantly impaired on both tasks whereas the variability of cerebellar patients increased in the duration task only. This dissociation suggests that deficits on temporal processing tasks observed in frontal patients can be related to the attention demands of such tasks; cerebellar patients have a more specific problem related to timing. (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.     

Regional cerebral blood flow in pediatric moyamoya disease: age-dependent decline in specific regions

Thirteen pediatric patients (ages 4-13 years) who underwent surgical treatment were examined regarding their rCBF in the preoperative periods. The postoperative rCBF was measured 39 times in these 13 patients. Thirteen healthy normal subjects (ages from 6 to 21 years) were also examined. The rCBF in the operculum and in the frontal, parietal, and occipital lobes was measured with 133Xe inhalation method and single photon emission computed tomography. In the parietal and occipital lobes, the preoperative rCBF had a negative and significant correlation with their ages, but not in the operculum or frontal lobe. However, subsequent to the surgical treatment, the rCBF increased significantly in the patients 5 years old or less, and then post-operative rCBF values had significant negative correlations with age in each region.     

The role of chloramphenicol in the treatment of bloodstream infection due to vancomycin-resistant Enterococcus

OBJECTIVE: The objective of this study was to contrast overt verbal versus covert autonomic responses to facial stimuli in a patient with false recognition following frontal lobe damage. BACKGROUND: False recognition has been linked to frontal lobe dysfunction. However, previous studies have relied exclusively on overt measures of memory and have not examined whether or not patients with false recognition continue to demonstrate preserved covert discrimination of familiar and unfamiliar items. METHODS: We recorded skin conductance responses (SCRs) in a patient with frontal lobe damage and in normal control subjects while they performed a familiarity decision task using famous and unfamiliar faces as stimuli. RESULTS: Patient J.S. produced significantly more overt false recognition errors and misidentifications in response to unfamiliar faces than control subjects. However, similar to the control subjects, he showed accurate covert autonomic discrimination of truly familiar faces from unfamiliar ones. Furthermore, SCRs to falsely recognized unfamiliar faces were not significantly different from SCRs generated to unfamiliar faces that J.S. correctly rejected. CONCLUSIONS: Our findings provide further neuropsychological evidence that overt and covert forms of face recognition memory are dissociable. In addition, the failure to detect an autonomic correlate for the false recognition errors and misidentifications in J.S. suggests that these memory distortions were not related to the spurious activation of stored memory representations for specific familiar faces. Instead, these incorrect responses may have been driven by the sense of familiarity evoked by novel faces that had a general resemblance to faces encountered previously. We propose that false recognition in J.S. resulted from the breakdown of strategic frontal memory retrieval, monitoring, and decision functions critical for attributing the experience of familiarity to its appropriate source.     

Cognitive frontal lobe dysfunction in obsessive-compulsive disorder

BACKGROUND: There is evidence that dysfunction within associative frontostriatal circuits represents a feature of obsessive-compulsive disorder (OCD). Previous neuropsychologic studies have yielded diverging results, which may in part be explained by differences in the selection of subjects and methods. The present study focused on the question of cognitive frontal lobe performance in OCD. METHODS: Twenty-nine unmedicated OCD patients were compared to a double-size control group of normal subjects matched individually for age, sex, and intelligence. A series of 12 neuropsychologic tests was applied, most of which are thought to be sensitive to different aspects of cognitive frontal lobe function. RESULTS: OCD patients were unimpaired at tests of abstraction, problem solving, set-shifting, response inhibition, active memory search, and choice reaction speed. Deficits of approximately one standard deviation were observed at timed tests of verbal and nonverbal fluency, attentional processing, and weight sorting. CONCLUSIONS: OCD patients exhibited selective deficits in tasks involving controlled attentional processing and self-guided, spontaneous behavior. We discuss a link between this neuropsychologic profile and dysfunctioning within the anterior cingulate, but not the dorsolateral prefrontal circuit.     

Overestimation and unreliability in "feeling-of-doing" judgements about temporal ordering performance: impaired self-awareness following frontal lobe damage

"Feeling-of-doing" accuracy in a temporal ordering task in 33 patients with frontal lobe lesions and a matched control group was investigated. The temporal ordering task used word lists that had high, medium, or no semantic interrelatedness. Patients with frontal lobe lesions showed an impairment in temporal ordering across all three word lists. Both groups performed better on the lists with higher semantic interrelatedness. Patients with frontal lobe lesions overestimated their ability to order words accurately. On the less semantically interrelated lists, metamemory judgment in patients with frontal lesions did not correlate with their performance. These results indicate that both temporal order judgment and metacognitive decisions about temporal order judgment are subserved by the prefrontal cortex and further clarifies the role of the frontal lobes in behavioral monitoring.     

Distribution of the Rhesus haplotype frequencies in the Düsseldorf administrative center (North Rhine-Westphalia)

Patients with medically intractable epilepsy and either hippocampal sclerosis or frontal lobe lesions were compared with healthy controls, to investigate a possible neuroanatomical correlate of a component of working memory: the central executive. Patients were tested on a short-term memory task which comprised visuo-spatial and verbal components, in single and concurrent trials. Differences were found between the patient groups for dual-task capacity, despite being equated on single-task trials. Patients with frontal lobe damage were the most affected by the demands of attention division. The results of this study do not support the thesis of a hippocampal role in the working memory component examined, but point to a frontal lobe focus for this janusian cognitive function. An unexpected finding of an increment in performance over the trials of visuo-spatial assessment, in patients with hippocampal sclerosis, is presented.     

Cognitive impairment following frontal lobe damage and its relevance to human amnesia.

Whether frontal lobe pathology can account for some of the cognitive impairment oberved in amnesic patients with Korsakoff's syndrome was investigated. Various cognitive and memory tests were given to patients with circumscribed frontal lobe lesions, patients with Korsakoff's syndrome, non-Korsakoff amnesic patients, and control Ss. Patients with frontal lobe lesions were not amnesic. Nevertheless, they exhibited 2 deficits that were also exhibited by patients with Korsakoff's syndrome but not by other amnesic patients: (a) impairment on the Wisconsin Card Sorting Test and (b) impairment on the Initiation and Perseveration subscale of the Dementia Rating Scale. Thus, frontal lobe pathology can explain some of the cognitive deficits observed in patients with Korsakoff's syndrome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A neuropsychological examination of the underlying deficit in attention deficit hyperactivity disorder: Frontal lobe versus right parietal lobe theories.

A neuropsychological approach was used to examine the frontal lobe and right parietal lobe theories of attention deficit hyperactivity disorder (ADHD). Considerable attempts were made to select as pure a group of ADHD boys as possible. The performance of 10-14-year-old ADHD boys (n?=?22), both on and off stimulant medication, was compared with the performance of non-ADHD control boys (n?=?22) on tasks purported to assess frontal lobe functioning (Stopping Task, Antisaccade Task, Tower of Hanoi) and right parietal lobe functioning (Visual-Spatial Cuing Task, Turning Task, Spatial Relations). Three important findings emerged: (a) unmedicated ADHD boys exhibited performance deficits on tasks in both frontal and parietal domains compared with control boys, (b) unmedicated ADHD boys appeared to be more severely impaired on the frontal tasks than on the parietal tasks, and (c) medicated ADHD boys performed better in both task domains compared with unmedicated ADHD boys. Several alternative interpretations of the results are discussed. (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)     

An evaluation of the marmoset Callithrix jacchus (sagüi) as an experimental model for the dyslipoproteinemia of human Schistosomiasis mansoni

BACKGROUND: There have been only a few brain computed tomography imaging studies, with mostly negative findings, in subjects with borderline personality disorder (BPD). This is the first MRI study which evaluated the structural abnormalities of the brain in subjects with the sole diagnosis of BPD. METHODS: Twenty-five subjects with BPD were compared with age-, gender-matched healthy comparison subjects (n=25) on volumes of the frontal lobes, the temporal lobes, the lateral ventricles, and the cerebral hemispheres in brain magnetic resonance imaging. RESULTS: Subjects with BPD had a significantly smaller frontal lobe compared to comparison subjects (multivariate regression analysis, t=2.225, df=46, P=0.031). There were no significant differences in volumes of the temporal lobes, the lateral ventricles, and the cerebral hemispheres between subjects with and without BPD. LIMITATIONS: Strict inclusion and exclusion criteria employed in the present study may make it difficult to generalize our findings. The gray matter and white matter of the brain were not measured separately. Differences in head tilt during image acquisition were not corrected. CONCLUSIONS: The current study reports a smaller frontal lobe volume on brain MRI in subjects with BPD compared with healthy comparison subjects. This finding may serve as a potentially useful biological variable that may allow for subtyping BPD.     

Emotional Response in Patients With Frontal Brain Damage: Effects of Affective Valence and Information Content.

The authors investigated the role of the frontal lobes in the emotional response in 19 patients with brain damage and 23 control subjects. They studied the modulation of the startle blink reflex by affective pictures, and other autonomic responses. Patients showed a dissociation between the startle reflex and the affective valence ratings of the pictures, as a result of a low inhibition of the startle reflex by pleasant pictures. Pictures elicited lower skin conductance responses (SCRs) in patients than in controls, whereas the groups did not differ in the SCRs prompted by less significant acoustic stimuli. The findings point to the frontal lobe as a structure involved in the emotional response and in the physiological emotional arousal related to the complexity of the stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control of Fixation and Saccades in Humans With Chronic Lesions of Oculomotor Cortex.

To elucidate the dynamic interactions of cortical and subcortical oculomotor systems, the authors investigated reflexive and strategic control over fixation and saccades in patients with chronic unilateral lesions that involved either frontal or parietal cortex. They measured the effects of indicating the location of the forthcoming target and removing the fixation stimulus on the latencies of eye movements toward a peripheral visual target in 12 patients with frontal eye field (FEF) lesions, 9 patients with lesions restricted to parietal cortex, and 12 neurologically healthy controls. They found that chronic damage to FEF cortex disrupts cortico-collicular interactions, resulting in hypoactivity in the contralesional superior colliculus and a loss of strategic control over the intrinsic collicular circuits that regulate fixation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)