Document Detail

Top-down and bottom-up processes in the extrastriate cortex of cirrhotic patients: an ERP study.
MedLine Citation:
PMID:  16793339     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: This study aims to evaluate the efficiency of top-down and bottom-up processes in the extrastriate cortex of cirrhotic patients without overt hepatic encephalopathy (HE). METHODS: Reaction times (RTs), accuracy and event-related potentials (ERPs) were recorded during the execution of a visual Simon task in 17 cirrhotic patients and 10 healthy controls. Amplitude and latency of the P1 and N1 (indexes of bottom-up processes) and of the N2pc (index of top-down processes) were measured. RESULTS: Patients were slower than controls, and patients with minimal HE (MHE) were slower than patients without MHE. The distribution analysis of RTs showed that the Simon effect decays with slower RTs in all the groups and that the shape of the distribution was different in MHE patients. No differences were found between cirrhotic patients and controls for P1 and N1 amplitude and latency. In contrast, N2pc latency was delayed in cirrhotic patients compared to controls independently of MHE. CONCLUSIONS: In the extrastriate cortex of cirrhotic patients without HE, top-down processes are altered whereas bottom-up processes are preserved. SIGNIFICANCE: The analysis of exogenous and endogenous visual components of ERPs provides a model to study the functional dissociation between top-down and bottom-up processes inside the extrastriate cortex.
Sami Schiff; Daniela Mapelli; Antonino Vallesi; Raffaele Orsato; Angelo Gatta; Carlo Umiltà; Piero Amodio
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-06-21
Journal Detail:
Title:  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology     Volume:  117     ISSN:  1388-2457     ISO Abbreviation:  Clin Neurophysiol     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-07-31     Completed Date:  2006-09-26     Revised Date:  2008-09-10    
Medline Journal Info:
Nlm Unique ID:  100883319     Medline TA:  Clin Neurophysiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  1728-36     Citation Subset:  IM    
Department of Clinical and Experimental Medicine, University of Padua, Via Giustiniani, 2, 35128, Padova, Italy.
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MeSH Terms
Brain / physiopathology*
Evoked Potentials / physiology*
Hepatic Encephalopathy / etiology,  physiopathology*
Liver Cirrhosis / complications,  physiopathology*
Middle Aged
Photic Stimulation
Reaction Time

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