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Impaired facial affect recognition and emotional changes in subjects with transmodal cortical lesions
No full textThe present study attempts to identify cortical lesion sites associated with deficits in the decoding of emotional facial expressions and with changes of emotional states. A consecutive sample of 68 subjects with lesions caused by microsurgical tumor resection or by intracerebral hemorrhage were compared with 16 clinical and 15 healthy control subjects. A set of neuropsychological test measures - two experimental tasks requiring the sorting and rating of emotional facial expressions, and an adjective checklist as a measure of mood state - were administered. An analysis according to the functional properties of the areas with lesions revealed that subjects with combined lesions of heteromodal and limbic/paralimbic cortices of the right hemisphere showed the strongest deficits in the decoding of emotional facial expressions. In contrast, subjects with lesions of limbic/paralimbic cortices alone, or subjects with lesions of unimodal or primary motor or sensory cortices displayed only minor deficits. Subjects with combined lesions of heteromodal and limbic/paralimbic cortices of the left hemisphere showed the most negative mood states. Our results suggest that heteromodal and limbic/paralimbic, i.e. transmodal cortices may he viewed as 'bottleneck' structures for the decoding of emotional facial expressions and for the modulation of mood states. Lesions of transmodal cortices deprive limbic structures of one of their main sources of input and are therefore likely to produce deficits in various forms of complex human emotional-cognitive behaviors and emotional states
Posterior parahippocampal gyrus lesions in the human impair egocentric learning in a virtual environment
No full textFunctional imaging studies have shown that the posterior parahippocampal gyrus (PHG) is involved in allocentric (world-centered) object and scene recognition. However, the putative role of the posterior PHG in egocentric (body-centered) spatial memory has received only limited systematic investigation. Thirty-one subjects with pharmacoresistant medial temporal lobe epilepsy (TLE) and temporal lobe removal were compared with 19 matched healthy control subjects on a virtual reality task affording the navigation in a virtual maze (egocentric memory). Lesions of the hippocampus and PHG of TLE subjects were determined by three-dimensional magnetic resonance imaging volumetric assessment. The results indicate that TLE subjects with right-sided posterior PHG lesions were impaired on virtual maze acquisition when compared with controls and TLE subjects with anterior PHG lesions. Larger posterior PHG lesions were significantly related to stronger impairments in virtual maze performance. Our results point to a role of the right-sided posterior PHG for the representation and storage of egocentric information. Moreover, access to both allocentric and egocentric streams of spatial information may enable the posterior PHG to construct a global and comprehensive representation of spatial environments
Abnormal size of the amygdala predicts impaired emotional memory in major depressive disorder
No full textBackground: Amygdala and hippocampus show significant structural abnormalities in major depressive disorder (MDD). Individuals with MDD have difficulties in emotional memory. A relationship between emotional memory deficits and structural abnormalities of amygdala and hippocampus in MDD has been proposed but not shown, yet. Methods: The current study assessed memory for emotional faces in 21 young women with recent-onset MDD and 23 matched control subjects. All subjects underwent structural magnetic resonance imaging (3D-MRI) and a clinical and neuropsychological assessment. Results: Depressive subjects had significantly enlarged amygdala size and significantly reduced hippocampal size compared with controls. Depressive subjects were significantly impaired in leaming emotional facial expressions, with deficits being most pronounced for fearful, surprised and disgusted faces. Depressive subjects with amygdala volumes 1 SD or more above the mean of control subjects showed the strongest impairments. Correlation analyses revealed that larger left amygdala volumes were significantly related to worse memory performance and to higher anxiety scores of depressive subjects. Smaller left hippocampal volumes of depressive subjects were related to higher anxiety scores as well. Limitations: All MDD subjects were taking antidepressant medication at the time of the study. Longitudinal studies are needed to clarify whether the behavioral and/or volumetric abnormalities of MDD subjects can be attributed to medication or MDD or both. Conclusions: It might be speculated that amygdala enlargement in young MDD subjects is correlated with amygdalar overactivation and resolves with antidepressant treatment, as was shown for amygdalar over-activation. (c) 2006 Elsevier B.V. All rights reserved
Cerebellar lesions in the PICA but not SCA territory impair cognition
No full textThe authors sought to clarify whether lesions in different parts of the cerebellum result in differential cognitive and affective impairment. Six subjects with cerebellar lesions due to posterior inferior cerebellar artery ( PICA) infarction, five subjects with lesions in the SCA vascular territory, and 11 matched controls were administered a battery of standard neuropsychological tests. PICA lesions but not SCA lesions resulted in cognitive and affective deficits pointing to a dominant role of posterior cerebellar regions in cognitive and affective processing
Implicit and explicit memory after focal thalamic lesions
No full textBackground: Lesions of the thalamus interfere with cognitive functions mainly in the area of declarative learning and memory. Little is known about the role the thalamus plays in implicit learning. Objective: To study explicit and implicit learning and memory in subjects with thalamic lesions and to analyze the influence of lesion characteristics on cognitive performance. Methods: The authors studied the performance of 15 subjects with focal thalamic infarction or hemorrhage on a comprehensive neuropsychological test battery focusing on tests of explicit memory and learning of a nondeclarative motor skill. Subjects with thalamic lesions were compared to 15 healthy matched control subjects and to a clinical control group of 22 subjects who had sustained basal ganglia lesions. Results: Subjects with thalamic lesions showed well-preserved intellectual and executive functions but demonstrated deficits on measures of attention and psychomotor speed, explicit memory, and implicit visuomotor sequence learning. Lesion size in the thalamus was clearly related to subjects' long-term explicit memory performance. However, few of the neuropsychological deficits found seemed specific to the long-term neuropsychological outcome of focal thalamic infarctions. Subjects with lesions in the basal ganglia demonstrated similar deficits. Conclusions: Focal subcortical lesions in the thalamus and the basal ganglia lead to a similar profile of neuropsychological deficits. Lesions in the thalamus not only affect declarative memory but also interfere with nondeclarative motor skill learning
Allocentric memory impaired and egocentric memory intact as assessed by virtual reality in recent-onset schizophrenia
No full textPresent evidence suggests that schizophrenia is associated with explicit memory deficits, whereas implicit memory seems to be largely preserved. Virtual reality studies on declarative allocentric memory in schizophrenia are rare, and studies on implicit egocentric memory in schizophrenia are lacking. However, virtual realities have a major advantage for the assessment of spatial navigation and memory formation, as computer-simulated first-person environments can simulate navigation in a large-scale space. Twenty-five subjects with recent-onset schizophrenia were compared with 25 healthy matched control subjects on two virtual reality tasks affording the navigation and learning of a virtual park (allocentric memory) and a virtual maze (egocentric memory). Compared with control subjects, schizophrenia subjects were significantly impaired in learning the virtual park. However, schizophrenia subjects were as able as control subjects to learn the virtual maze. Stronger disorganized symptoms of schizophrenia subjects were significantly related to more errors on the virtual maze. It is concluded that egocentric spatial learning adds to the many other implicit cognitive skills being largely preserved in schizophrenia. Possibly, the more global neural network supporting egocentric spatial learning is less affected than the declarative hippocampal memory system in early stages of schizophrenia and may offer opportunities for compensation in the presence of focal deficits
Implicit and explicit memory after focal thalamic lesions
No full textBackground: Lesions of the thalamus interfere with cognitive functions mainly in the area of declarative learning and memory. Little is known about the role the thalamus plays in implicit learning. Objective: To study explicit and implicit learning and memory in subjects with thalamic lesions and to analyze the influence of lesion characteristics on cognitive performance. Methods: The authors studied the performance of 15 subjects with focal thalamic infarction or hemorrhage on a comprehensive neuropsychological test battery focusing on tests of explicit memory and learning of a nondeclarative motor skill. Subjects with thalamic lesions were compared to 15 healthy matched control subjects and to a clinical control group of 22 subjects who had sustained basal ganglia lesions. Results: Subjects with thalamic lesions showed well-preserved intellectual and executive functions but demonstrated deficits on measures of attention and psychomotor speed, explicit memory, and implicit visuomotor sequence learning. Lesion size in the thalamus was clearly related to subjects' long-term explicit memory performance. However, few of the neuropsychological deficits found seemed specific to the long-term neuropsychological outcome of focal thalamic infarctions. Subjects with lesions in the basal ganglia demonstrated similar deficits. Conclusions: Focal subcortical lesions in the thalamus and the basal ganglia lead to a similar profile of neuropsychological deficits. Lesions in the thalamus not only affect declarative memory but also interfere with nondeclarative motor skill learning
Impaired associative memory in temporal lobe epilepsy subjects after lesions of hippocampus, parahippocampal gyrus, and amygdala
No full textThere has been growing interest in the differential role of medial temporal lobe structures in learning and memory. The goal of the present study was to clarify how lesions of hippocampus, parahippocampal gyrus, and amygdala interfere with associative learning and memory. Thirty subjects with pharmacoresistant medial temporal lobe epilepsy (TLE) and temporal lobe removal were compared with 30 matched healthy control subjects. A set of neuropsychological test measures and an associative learning task requiring the learning and recall of objects and faces were administered. The lesions of hippocampus, parahippocampal gyrus, amygdala, and fusiform gyrus of TLE subjects were determined by three-dimensional magnetic resonance imaging (3-D MRI) volumetric assessment. The results indicate that TLE subjects with combined large hippocampal lesions, large parahippocampal gyrus (i.e., perirhinal/entorhinal) lesions, and large amygdala lesions learned and recalled the associative task significantly worse than control subjects or subjects with small lesions of the hippocampus, parahippocampal gyrus, and amygdala. Regression analysis revealed that larger lesions of the parahippocampal gyrus (i.e., perirhinal/entorhinal cortices) were significantly related to increasing deficits on the task, and that hippocampal and amygdala lesion size did not significantly improve the prediction. Our results suggest that perirhinal and entorhinal cortices may contribute predominantly to the associative learning and recall of objects and faces. (C) 2004 Wiley-Liss, Inc
Cerebellar lesions in the PICA but not SCA territory impair cognition
No full textThe authors sought to clarify whether lesions in different parts of the cerebellum result in differential cognitive and affective impairment. Six subjects with cerebellar lesions due to posterior inferior cerebellar artery ( PICA) infarction, five subjects with lesions in the SCA vascular territory, and 11 matched controls were administered a battery of standard neuropsychological tests. PICA lesions but not SCA lesions resulted in cognitive and affective deficits pointing to a dominant role of posterior cerebellar regions in cognitive and affective processing
Reduced amygdala and hippocampus size in trauma-exposed women with borderline personality disorder and without posttraumatic stress disorder.
No full textBackground Individuals with posttraumatic stress disorder (PTSD) display reduced hippocampus size and impaired cognition. However, studies on individuals with borderline personality disorder (BPD) are rare, and studies on trauma-exposed patients with BPD but without PTSD are lacking. Methods Twenty-four trauma-exposed women with BPD (10 with PTSD and 14 without) and 25 healthy controls underwent 3-dimensional structural magnetic resonance imaging of the amygdala and hippocampus and a clinical and neuropsychological investigation. Results Compared with controls, patients with BPD and PTSD displayed significantly reduced amygdala (34%) and hippocampus (12%) size and significantly impaired cognition. Trauma-exposed patients with BPD but without PTSD also showed significantly reduced amygdala (22%) and hippocampus (11%) size but normal cognition. Amygdala and hippocampus size did not differ significantly between patients with and without PTSD. Limitations The sample sizes of trauma-exposed groups are relatively small. A larger sample size may have revealed statistically significant differences in amygdala size between those with and without PTSD. Conclusion Our results demonstrate strong amygdala size reduction in trauma-exposed patients with BPD with or without PTSD, much exceeding that reported for trauma-exposed individuals without BPD. Our data suggest that BPD is associated with small amygdala size. Furthermore, evidence is increasing that amygdala and hippocampus size reduction is not only due to PTSD, but also to traumatic exposure
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