1,721,146 research outputs found
Pathological switiching between languages following frontal lesions in a bilingual patient
No full textCerebral lesions may alter the capability of bilingual subjects to separate their languages and use each language in appropriate contexts. Patients who show pathological mixing intermingle different languages within a single utterance. By contrast, patients affected by pathological switching alternate their languages across different utterances (a self contained segment of speech that stands on its own and conveys its own independent meaning). Cases of pathological mixing have been reported after lesions to the left temporoparietal lobe. By contrast, information on the neural loci involved in pathological switching is scarce. In this paper a description is given for the first time of a patient with a lesion to the left anterior cingulate and to the frontal lobe-also marginally involving the right anterior cingulate area-who presented with pathological switching between languages in the absence of any other linguistic impairment. Thus, unlike pathological mixing that typically occurs in bilingual aphasia, pathological switching may be independent of language mechanisms
Pathological switching between languages following frontal lesion in a bilingual patient
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CT and MRI findings after stereotactic resection of brain lesions
No full textOBJECTIVE: To describe postoperative CT and MRI findings and their time course in uncomplicated cases after stereotactic volumetric resections of brain lesions. MATERIALS AND METHODS: One-hundred twenty-eight imaging studies (CT, 86; MRI, 42), performed 6 h to 2 years after 52 stereotactic operations, were retrospectively reviewed and analyzed in relation to time of surgery in cases without complications. RESULTS: The extent of resection bed did not change during the first week after operation; reduction of size then began and continued up to 3-6 months. Mass effect and edema showed no changed during the first 4 days, then later regressed gradually. Pneumocephalus was found in 58% of cases in the first 3 weeks, but never later. Benign, surgically-induced enhancement appeared at the margins of encephalotomy and retractor at the end of the first postoperative week, became more prominent during the following weeks, and lasted up to 3-5 months. In the majority of cases enhancement prevented recognition of the residual tumor. Dural enhancement was observed at the craniotomy site very early after the operation and persisted up to 1 year. Meningeal enhancement over convexities was found in 44% of MRI studies. CONCLUSION: Extent of the resection bed, mass effect, edema, and pneumocephalus show, in uncomplicated cases, a regular regression during the postoperative period. The time course of enhancement is complex and can be a source of diagnostic misinterpretation
Causal Role of the Sensorimotor Cortex in Action Simulation: Neuropsychological Evidence
No full textInterest in sensorimotor cortex involvement in higher cognitive functions has recently been revived, although whether the cortex actually contributes to the simulation of body part movements has not yet been established. Neurosurgical patients with selective lesions to the hand sensorimotor representation offer a unique opportunity to demonstrate that the sensorimotor cortex plays a causal role in hand action simulations. Patients with damage to hand representation showed a selective deficit in simulating hand movements compared with object movements (Experiment 1). This deficit extended to objects when the patients imagined moving them with their own hands while maintaining the ability to visualize them rotating in space (Experiment 2). The data provide conclusive evidence for a causal role of the sensorimotor cortex in the continuous update of sensorimotor representations while individuals mentally simulate motor acts
Real-time neuropsychological testing during endovascular occlusion of a fusiform aneurysm in the left middle cerebral artery
Full text linkReal-time neuropsychological testing (RTNT) was used to test whether permanent endovascular occlusion of the insular branch of the left middle cerebral artery (MCA) helped avoid cognitive and neurological complications following the procedure. This patient suffered from a fusiform aneurysm along the insular branch of the MCA in the territory supplied in the left inferior frontal gyrus, around Broca's area. Pre-intervention neuropsychological testing was normal. During temporary occlusion lasting 25 min, the patient continuously performed at ceiling on the RTNT neuropsychological and language tasks. Thus, permanent occlusion followed. In addition, fMRI was used to investigate changes induced by the procedure. In the language domain, rearrangements in activation in Broca's area and in the left insula were detected by silent and overt production tasks. In the motor domain, decreased activation in the sensorimotor cortex during right-hand movement control was reported along with decreased right-hand sensibility. Post-intervention neuropsychological testing was normal. Results showed that RTNT can be used reliably during temporary occlusion in the specific case of a quite small branch of the MCA to provide continuous feedback on the patient's cognitive and language status and is predictive of post-intervention functioning. In addition, the study enabled us to detect changes in functional organization triggered by temporary occlusion of a branch of the left middle cerebral artery
What do we know about pre- and postoperative plasticity in patients with glioma? A review of neuroimaging and intraoperative mapping studies
Full text linkBrain plasticity potential is a central theme in neuro-oncology and is currently receiving increased attention. Advances in treatment have prolonged life expectancy in neuro-oncological patients and the long-term preservation of their quality of life is, therefore, a new challenge. To this end, a better understanding of brain plasticity mechanisms is vital as it can help prevent permanent deficits following neurosurgery. Indeed, reorganization processes can be fundamental to prevent or recover neurological and cognitive deficits by reallocating brain functions outside the lesioned areas. According to more recent studies in the literature, brain reorganization taking place following neurosurgery is associated with good neurofunctioning at follow-up. Interestingly, in the last few years, the number of reports on plasticity has notably increased. Aim of the current review was to provide a comprehensive overview of pre- and postoperative neuroplasticity patterns. Within this framework, we aimed to shed light on some tricky issues, including i) involvement of the contralateral healthy hemisphere, ii) role and potential changes of white matter and connectivity patterns, and iii) reorganization in low- versus high-grade gliomas. We finally discussed the practical implications of these aspects and role of additional potentially relevant factors to be explored. Final purpose was to provide a guideline helpful in promoting increase in the extent of tumor resection while preserving the patients' neurological and cognitive functioning
Generation and recognition of abstract rules in different frontal lobe subgroups
No full textThe Left Lateral cortex is known to have a role in inductive reasoning tasks. A more specific hypothesis on its role is that it is crucial in the generation of new abstract rules, rather than in the selection and implementation of a specific rule among a set of previously learned ones. Two new tests - the Generation of Hypotheses test and the Recognition of the Rule test - were administered to 46 patients with focal damage to the frontal cortex. Patients were divided in three frontal subgroups: Left Lateral, Right Lateral and Medial. On the basis of the new hypothesis, it was predicted that (i) the Left Lateral subgroup would fail in the Generation of Hypotheses test but would show spared performance on the Recognition of the Rule test and that (ii) the other frontal subgroups would perform normally on both tests. The findings on the Left Lateral and Right Lateral frontal subgroup were consistent with the predictions. This suggests that the Left Lateral frontal cortex is critical specifically for the generation of hypotheses in inductive reasoning. The Medial frontal subgroup, in contrast with our expectations, was impaired on Generation test; two hypotheses have been raised to explain this finding. (c) 2005 Elsevier Ltd. All rights reserved
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