1,721,009 research outputs found
Acute effects of surgery on emotion and personality of brain tumor patients: Surgery impact, histological aspects, and recovery
Full text linkBackground. Cognitive effects of brain surgery for the removal of intracranial tumors are still under investigation. For many basic sensory/motor or language-based functions, focal, albeit transient, cognitive deficits have been reported low-grade gliomas (LGGs); however, the effects of surgery on higher-level cognitive functions are still largely unknown. It has recently been shown that, following brain tumors, damage to different brain regions causes a variety of deficits at different levels in the perception and interpretation of emotions and intentions. However, the effects of different tumor histologies and, more importantly, the effects of surgery on these functions have not been examined. Methods. The performance of 66 patients affected by high-grade glioma (HGG), LGG, and meningioma on 4 tasks tapping different levels of perception and interpretations of emotion and intentions was assessed before, immediately after, and (for LGG patients) 4 months following surgery. Results. Results showed that HGG patients were generally already impaired in the more perceptual tasks before surgery and did not show surgery effects. Conversely, LGG patients, who were unimpaired before surgery, showed a significant deficit in perceptual tasks immediately after surgery that was recovered within few months. Meningioma patients were substantially unimpaired in all tasks. Conclusions. These results show that surgery can be relatively safe for LGG patients with regard to the higher-level, more complex cognitive functions and can provide further useful information to the neurosurgeon and improve communication with both the patient and the relatives about possible changes that can occur immediately after surgery
When mild pure alexia may not be reducible to hemianopic alexia
No full textIndividuals with pure alexia often have visual field defects such as right homonymous hemianopia. Relatively few attempts have been made to develop criteria to differentiate pure alexia from hemianopic alexia. In this Commentary we provide concrete suggestions to distinguish the two disorders. We also report on additional assessments with two previously reported cases for whom the diagnosis of pure alexia was called into question and an alternative proposal was offered that the reading deficits were instead due to hemianopia. We show that the results of clinical and neuropsychological tests do not support the account that the reading impairment was caused by the visual field defect. In particular, for both cases, the right homonymous hemianopia was not complete, and a split-field reading task demonstrated an inability also to read words presented in the intact left visual field. In conclusion, pure alexics may indeed show fairly modest word-length effects; however, the presence of right homonymous hemianopia and a non-extreme gradient of reading speed alone are not sufficient grounds to put in doubt the diagnosis. We propose that a fuller clinical and neuropsychological examination taking into account the possible confounding effects of the visual field defects will help to distinguish pure alexia from hemianopic alexia
Left basal ganglia case of dynamic aphasia or impairment of extra-language cognitive processes?
No full text
Cortical bases of elementary deductive reasoning: Inference, memory, and metadeduction
No full textElementary deduction is the ability of unreflectively drawing conclusions from explicit or implicit premises, on the basis of their logical forms. This ability is involved in many aspects of human cognition and interactions. To date, limited evidence exists on its cortical bases. We propose a model of elementary deduction in which logical inferences, memory, and meta-logical control are separable subcomponents. We explore deficits in patients with left, medial and right frontal lesions, by both studying patients' deductive abilities and providing measures of their meta-logical sensitivity for proof difficulty. We show that lesions to left lateral and medial frontal cortex impair abilities at solving elementary deductive problems, but not so lesions to right frontal cortex. Furthermore, we show that memory deficits differentially affect patients according to the locus of the lesion. Left lateral patients with working memory deficits had defective deductive abilities, but not so left lateral patients with spared working memory. In contrast, in medial patients both deductive and meta-deductive abilities were affected regardless of the presence of memory deficits. Overall, the results are compatible with a componential view of elementary deduction, and call for the elaboration of more fine-grained models of deductive abilities. (c) 2009 Elsevier Ltd. All rights reserved
Cognitive reserve proxies do not differentially account for cognitive performance in patients with focal frontal and non-frontal lesions
Full text linkObjective: Cognitive reserve (CR) suggests that premorbid efficacy, aptitude and flexibility of cognitive processing can aid the brain’s ability to cope with change or damage. Our previous work has shown that age and literacy attainment predict the cognitive performance of frontal patients on frontal-executive tests. However, it remains unknown whether CR also predicts the cognitive performance of non-frontal patients.Method: We investigated the independent effect of a CR proxy, NART IQ, as well as age and lesion group (frontal versus non-frontal) on measures of executive function, intelligence, processing speed and naming in 166 patients with focal, unilateral frontal lesions, 91 patients with focal, unilateral non-frontal lesions and 136 healthy controls.Results: Fitting multiple linear regression models for each cognitive measure revealed that NART IQ predicted executive, intelligence and naming performance. Age also significantly predicted performance on the executive and processing speed tests. Finally, belonging to the frontal group predicted executive and naming performance while membership of the non-frontal group predicted intelligence.Conclusions: These findings suggest that age, lesion group and literacy attainment play independent roles in predicting cognitive performance following stroke or brain tumour. However, the relationship between CR and focal brain damage does not differ in the context of frontal and non-frontal lesions. <br/
Supervisory and Routine Processes in Noun and Verb Generation in Nondemented Patients with Parkinson’s Disease
No full text
Mechanisms of rule acquisition and rule following in inductive reasoning
Full text linkDespite the recent interest in the neuroanatomy of inductive reasoning processes, the regional specificity within prefrontal cortex (PFC) for the different mechanisms involved in induction tasks remains to be determined. In this study, we used fMRI to investigate the contribution of PFC regions to rule acquisition (rule search and rule discovery) and rule following. Twenty-six healthy young adult participants were presented with a series of images of cards, each consisting of a set of circles numbered in sequence with one colored blue. Participants had to predict the position of the blue circle on the next card. The rules that had to be acquired pertained to the relationship among succeeding stimuli. Responses given by subjects were categorized in a series of phases either tapping rule acquisition (responses given up to and including rule discovery) or rule following (correct responses after rule acquisition). Mid-dorsolateral PFC (mid-DLPFC) was active during rule search and remained active until successful rule acquisition. By contrast, rule following was associated with activation in temporal, motor, and medial/anterior prefrontal cortex. Moreover, frontopolar cortex (FPC) was active throughout the rule acquisition and rule following phases before a rule became familiar. We attributed activation in mid-DLPFC to hypothesis generation and in FPC to integration of multiple separate inferences. The present study provides evidence that brain activation during inductive reasoning involves a complex network of frontal processes and that different subregions respond during rule acquisition and rule following phases.</jats:p
- …
