Article

Parkinson's disease has been found to impair comprehension of complex sentences.
Here we follow up on earlier findings that sentences describing two successive
events in the form of "Before B, A" are understood worse by Parkinson patients
than sentences in the form of "After A, B". Before-initial sentences express
events in an order inconsistent with their actual order of occurrence and
therefore require additional computations during comprehension. In a behavioral
study we tested whether 28 German Parkinson patients reading 'before'- and
'after'-initial sentences correctly understood the sequence of events. A second
functional magnetic resonance imaging study investigated 16 different patients
who read sentences while in the scanner. The behavioral study revealed that
'before' sentences were misunderstood with regard to the temporal sequence of
events in 53% (controls 6.5%). The imaging study demonstrated a functional
network of the caudate nucleus, middle frontal gyrus, medial superior frontal
gyrus, parietal lobule and inferior temporal gyrus. This network was dynamically
modulated for 'before' compared to 'after' sentences in healthy controls but not
in Parkinson patients.
The current results suggest that the additional
computations required for 'before' sentences are supported by a network with the
caudate nucleus as a central element. This network was compromised in Parkinson
patients. We propose that dysfunction of the caudate nucleus networks underlies
Parkinson patients' difficulty in dealing with complex sentence structures.
CI - Copyright (c) 2012 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS