Interhemispheric transfer in schizophrenics, depressives, and normals with schizoid tendencies.

Abstract

Although several studies suggest that schizophrenics suffer from an impairment in the interhemispheric transfer (IHT) of information, methodological weaknesses in these studies preclude clear interpretation of their results. This study addresses these criticisms in order to provide a clearer test of the IHT theory. Schizophrenics, depressives, normal controls, and normals with schizoid tendencies were assessed on five measures of IHT (verbal and nonverbal dichotic listening, intermanual transfer, bimanual block design, finger sequence repetition) and two measures of unilateral hemispheric processing (lateral eye movements, auditory thresholds). Results consistently failed to support an IHT deficit interpretation of schizophrenia. Schizoid normals had a significantly greater right-ear advantage on verbal dichotic listening than both psychiatric groups, a result suggesting enhanced left-hemisphere activation in schizoid normals. It is concluded that the IHT theory requires stronger empirical substantiation than has been obtained to date to warrant further consideration as a central theory of schizophrenia.

Lateralization of the ‘negative priming’ effect: Relationships with schizotypy and with gender

“…Thus, studies in our laboratory have shown that high and low schizotypal subjects differ in a predictable fashion on a variety of tasks of lateralized psychological function : local/global processing (Rawlings & Claridge, 1984) and linguistic processing, both in the visual modality (Broks, 1984;Rawlings & Claridge, 1984) and in the auditory modality (Broks, Claridge, Matheson & Hargreaves, 1984). These observations have been confirmed by Raine and his colleagues, also using a range of laterality measures (Raine, Andrews, Sheard, Walder & Manders, 1989; Raine & Manders, 1988).…”

Affective-prosodic deficits in schizophrenia: profiles of patients with brain damage and comparison with relation to schizophrenic symptoms

“…Although findings have been variable, including negative results,29 30 taken as a whole there seems to be sufficient data to support the idea that some groups of schizophrenic patients show abnormalities of callosal integration of behavioural functions 28. When present, thinning of the callosum has been associated with late onset, positive symptom schizophrenia that is accompanied by loss of the interhemispheric transfer of information whereas thickening of the callosum has been associated with early onset, negative symptom schizophrenia that is accompanied by possible increases in interhemispheric transfer of information 28…”

Schizophrenia Subgroups Differing in Dichotic Listening Laterality Also Differ in Neurometabolism and Symptomatology

“…Most studies using this test or similar dichotic syllable tests have found reduced or absent right ear (left hemisphere) advantage in schizophrenic patients. [3][4][5][6][7][8][9] There are, however, marked individual differences among patients, with many showing a normal REA. This variability in perceptual asymmetry among schizophrenia patients has been related to symptom differences; for example, REA for dichotic words or syllables was more evident in patients with positive symptoms, in particular auditory hallucinations.…”