Il ruolo del corpo calloso nella comunicazione interemisferica è documentato nell'uomo. Alterazioni della comunicazione interemisferica sono state evidenziate nei disturbi psichiatrici, soprattutto nella schizofrenia (Mohr et al., 2000). lo scopo dello studio è valutare la connettività interemisferica in un campione di soggetti con schizofrenia comparati a controlli sani mediante la risonanza magnetica funzionale. i risultati ottenuti dimostrano la presenza nei pazienti di diffuse iperattivazioni e ipoattivazioni localizzate, verosimilmente riconducibili a una condizione di overworking diffuso cerebrale durante l'esecuzione della task.

Background: The role of the CC in sustaining inter-hemispheric connectivity is well documented in humans both for simple and more cognitively demanding tasks. Alterations in inter-hemispheric communication have been shown in schizophrenia subjects (Mohr et al., 2000) with few studies investigating interhemispheric information exchange using behavioural tasks. In contrast some studies found no differences between schizophrenia patients and normal controls, but also excessively slow responses involving the left hemisphere were present in schizophrenics (Shelton & Knight, 1984; Florio and colleagues, 2002; Bellani et al., 2010). Moreover, there is some evidence of abnormally long interhemispheric transfer time (IHTT) in schizophrenia showed by evoked related potential studies (Barnett et al., 2005; Barnett and Kirk 2005; Endrass et al., 2002). Objectives: In the present study, we aimed to study interhemispheric connectivity in a sample of schizophrenia patients and healthy controls using functional Magnetic Resonance Imaging (fMRI) and a visuomotor task named Poffenberger’s task . Methods: A sample of 21 healthy controls and 21 schizophrenia patients underwent a simple visual manual reaction-time (RT) task (Poffenberger’s paradigm) during a fMRI session. This paradigm was employed to measure interhemispheric transfer (IT) by subtracting mean reaction times (RT) for the uncrossed hemifield-hand conditions, that is, those conditions not requiring an IT, from the crossed hemifield-hand conditions, that is, those conditions requiring an IT to relay visual information from the hemisphere of entry to the hemisphere subserving the response. The obtained difference is widely believed to reflect callosal conduction time. fMRI data were acquired using a 3 Tesla Siemens scanner. We performed separate One Sample t-test CUD for patients and controls. Results: The blood oxygenation level-dependent (BOLD) response was present in the genu of corpus callosum in males and females separately and in the whole group (p<0.01 uncorrected). In the patient group, there is a diffuse hyperactivation in the brain (p<0.01). Hyper-activations and hypo-activations were found in the schizophrenic patients in comparison to the healthy controls depending on the area of the brain and on the task. The blood oxygenation level-dependent (BOLD) response was higher in the pre-central gyrus (frontal motor cortex), middle frontal gyrus, inferior frontal gyrus, post central gyrus (parietal sensory cortex), and in the putamen for the crossed-uncrossed difference condition. With p<0.01 (uncorrected) activations were wider and also included corpus callosum. Interestingly when females and males are analysed separately, significant hyperactivations persisted only in female SCZ patients excepted for putamen and precentral gyrus that were no more significant. Conclusions: Our results confirmed previous published studies in humans that tested the implication of corpus callosum in visuo-motor task. In particular our results confirmed the structure-function relationship that involves brain interhemispheric processes in a sample healthy subjects and referred to a specific activation restricted in the genu of corpus callosum. The genu is thought to be associated with the prefrontal cortex to the premotor interhemispheric transfer. We investigated the role of the CC in regulating functional communication between the hemispheres in schizophrenia patients compared to healthy controls and hyper-activations and hypo-activations were found. These results may reflect a brain diffuse overwork related to the demanding task that is not present in healthy subjects.

BRAIN COMMUNICATION IN SCHIZOPHRENIA: INSIGHT FROM THE PREVENT STUDY

BELLANI, Marcella
2012

Abstract

Il ruolo del corpo calloso nella comunicazione interemisferica è documentato nell'uomo. Alterazioni della comunicazione interemisferica sono state evidenziate nei disturbi psichiatrici, soprattutto nella schizofrenia (Mohr et al., 2000). lo scopo dello studio è valutare la connettività interemisferica in un campione di soggetti con schizofrenia comparati a controlli sani mediante la risonanza magnetica funzionale. i risultati ottenuti dimostrano la presenza nei pazienti di diffuse iperattivazioni e ipoattivazioni localizzate, verosimilmente riconducibili a una condizione di overworking diffuso cerebrale durante l'esecuzione della task.
BRAIN COMMUNICATION; SCHIZOPHRENIA
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11562/398735
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