Laterality effects in schizophrenia and bipolar disorder.
There are numerous reports in the literature of lateralised structural cerebral abnormalities and alterations of the corpus callosum in the major psychoses. In the light of these findings the purpose of this study was to directly compare hemispheric differences and callosal interhemispheric transmission (IT) in schizophrenia and bipolar disorder. To do that we tested schizophrenic (SCZ), bipolar disorder (BD) patients and controls in a simple manual reaction time (RT) task with lateralised visual stimuli (Poffenberger paradigm) which enables one to test both laterality effects and IT time. We found an overall slowing of responses with the right hand in schizophrenics but not in bipolar patients, who, like controls, showed no hand differences. This selective slowing down of the right hand is likely to be related to abnormalities of intrahemispheric cortico-cortical connections in the left hemisphere. In contrast, IT time was similar in SCZ and BD patients and did not differ with respect to controls. Two are the novel findings of the present study: first both SZC and BD share a normal IT of visuomotor information despite the presence of callosal abnormalities. Second, an impairment of intrahemispheric left hemispheric processing is present only in SCZ patients. This represents a potentially important clue to a further understanding of the pathogenetic differences between the two major psychoses.
Bellani
Marcella
M
Inter-University Center for Behavioural Neurosciences, University of Verona, Verona, Italy.
Marzi
Carlo A
CA
Savazzi
Silvia
S
Perlini
Cinzia
C
Cerruti
Stefania
S
Ferro
Adele
A
Marinelli
Veronica
V
Sponda
Silvia
S
Rambaldelli
Gianluca
G
Tansella
Michele
M
Brambilla
Paolo
P
D000368:Aged; D000704:Analysis of Variance; D016880:Anisotropy; D001714:Bipolar Disorder / Q000523:psychology*; D003337:Corpus Callosum / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology; D010775:Photic Stimulation; D010812:Physical Stimulation; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012565:Schizophrenic Psychology