Abnormal object recall and anterior cingulate overactivation correlate with formal thought disorder in schizophrenia.
BACKGROUND
The neural basis of formal thought disorder (FTD) is unknown. An influential theory is that FTD results from impaired semantic memory processing. We explored the neural correlates of semantic memory retrieval in schizophrenia using an imaging task assessing semantic object recall.


METHODS
Sixteen healthy control subjects and sixteen schizophrenia patients whose FTD symptoms were measured with the Thought Disorder Index completed a verbal object-recall task during functional magnetic resonance imaging. Participants viewed two words describing object features that either evoked (object recall) or did not evoke a semantic concept.


RESULTS
Schizophrenia patients tended to overrecall objects for feature pairs that did not describe the same object. Functionally, rostral anterior cingulate cortex (ACC) activation in patients positively correlated with FTD severity during both correct recalled and overrecalled trials. Compared with control subjects, during object recalling, patients overactivated bilateral ACC, temporooccipital junctions, temporal poles and parahippocampi, right inferior frontal gyrus, and dorsolateral prefrontal cortex, but underactivated inferior parietal lobules.


CONCLUSIONS
Our results support impaired semantic memory retrieval as underlying FTD pathophysiology. Schizophrenia patients showed abnormal activations of brain areas involved in semantic memory, verbal working memory, and initiation and suppression of conflicting responses, which were associated with semantic overrecall and FTD.
Assaf
Michal
M
Olin Neuropsychiatry Research Center, Institute of Living, Hartford, CT 06106, USA. massaf@harthosp.org
Rivkin
Paul R
PR
Kuzu
Cheedem H
CH
Calhoun
Vince D
VD
Kraut
Michael A
MA
Groth
Karyn M
KM
Yassa
Michael A
MA
Hart
John
J
Pearlson
Godfrey D
GD
D000328:Adult; D001931:Brain Mapping; D002908:Chronic Disease; D003072:Cognition Disorders / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D004292:Dominance, Cerebral / Q000502:physiology; D017352:Echo-Planar Imaging; D005260:Female; D006179:Gyrus Cinguli / Q000503:physiopathology*; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010153:Paired-Associate Learning; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time / Q000502:physiology; D012563:Schizophrenia, Paranoid / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D012565:Schizophrenic Psychology; D013223:Statistics as Topic; D013850:Thinking / Q000502:physiology*
D010100:Oxygen