Functional deficit in the medial prefrontal cortex during a language comprehension task in patients with schizophrenia.
OBJECTIVE
We and others have observed that patients with schizophrenia commonly presented a reduced left recruitment in language semantic brain regions. However, most studies include patients with leftward and rightward lateralizations for language. We investigated whether a cohort comprised purely of patients with typical lateralization (leftward) presented a reduced left recruitment in semantic regions during a language comprehension task. The goal was to reduce the inter-subject variability and thus improve the resolution for studying functional abnormalities in the language network.


METHODS
Twenty-three patients with schizophrenia (DSM-IV) were matched with healthy subjects in age, sex, level of education and handedness. All patients exhibited leftward lateralization for language. Functional MRI was performed as subjects listened to a story comprising characters and social interactions. Functional MRI signal variations were analyzed individually and compared among groups.


RESULTS
Although no differences were observed in the recruitment of the semantic language network, patients with schizophrenia presented significantly lower signal variations compared to controls in the medial part of the left superior frontal gyrus (MF1) (x=-6, y=58, z=20; Z(score)=5.6; p<0.001 uncorrected). This region corresponded to the Theory of Mind (ToM) network. Only 5 of the 23 patients (21.7%) and 21 of the 23 (91.3%) control subjects demonstrated a positive signal variation in this area.


CONCLUSIONS
A left functional deficit was observed in a core region of the ToM network in patients with schizophrenia and typical lateralizations for language. This functional defect could represent a neural basis for impaired social interaction and communication in patients with schizophrenia.
Dollfus
Sonia
S
Groupe d'Imagerie Neurofonctionnelle, UMR 6194 CNRS/CEA/Université de Caen, Université Paris 5, Centre Cyceron, Bl H. Becquerel, Caen, 14000, France. dollfus-s@chu.caen.fr
Razafimandimby
Annick
A
Maiza
Olivier
O
Lebain
Pierrick
P
Brazo
Perrine
P
Beaucousin
Virginie
V
Lecardeur
Laurent
L
Delamillieure
Pascal
P
Mazoyer
Bernard
B
Tzourio-Mazoyer
Nathalie
N
D000328:Adult; D015331:Cohort Studies; D032882:Comprehension / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D017352:Echo-Planar Imaging; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology; D010100:Oxygen / Q000097:blood*; D018187:Personal Construct Theory; D017397:Prefrontal Cortex / Q000503:physiopathology*; D011999:Recruitment, Neurophysiological / Q000502:physiology; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D012660:Semantics; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000503:physiopathology
D010100:Oxygen