Differential impairment of interhemispheric transmission in bipolar disease

Abstract

There is abundant evidence that the cerebral white matter and in particular the corpus callosum show several structural abnormalities in both schizophrenia (SCZ) and bipolar disease (BD). However, which cognitive functions are impaired as a result of these anomalies is still unclear. Previous behavioural tests of interhemispheric crosstalk have shown a differential impairment in SCZ with interhemispheric transmission time, as tested with the Poffenberger paradigm, essentially normal but with an abnormally enhanced interhemispheric summation effect, as tested with the redundant signal effect. The present study was inspired by this discrepancy and by the more general question of a possible overlap between the pathophysiology of SCZ and BD. We tested both SCZ and BD patients in the Poffenberger paradigm and redundant signal effect and found a similar dissociation, namely a normal interhemispheric transfer time and an abnormal redundant signal effect. The only difference between the two groups was a selective slowing of speed of response of the dominant right hand in the SCZ group suggesting an impairment of left hemisphere functions. These results cast further light on the question of common and differential impairments of basic psychological functions in the two diseases.

Similar white matter changes in schizophrenia and bipolar disorder: A tract-based spatial statistics study

“…These findings confirm that inter-hemispheric connectivity is hindered in both the disorders [7], representing a common neural underpinning of major psychoses [35][75][76]. The corpus callosum is known to play a fundamental role by modulating inter-hemispheric communication and cognitive processes [77][78].…”

The Crossed Projection to the Striatum in Two Species of Monkey and in Humans: Behavioral and Evolutionary Significance

“…One difficulty with the above interpretation is that the contra-ipsi latency difference is shorter than the conduction delays between cortical areas of the 2 hemispheres measured electrophysiologically or calculated from anatomical data (Tomasi et al 2012). The differences in the Poffenberger's paradigm are in the order of 3-5 ms (but can be as low as 2.65 ms) (Westerhausen et al 2006;Florio et al 2013) while the cortico-cortical delay calculated from anatomical data is in the order of 10 ms for the in A and E streamlines to areas 9, 9/46D, 46D, 46 V,9/46 V (and 47L ?). In B,F, streamlines to area 6DR (F7), 8,and 6VR (F5).…”

The redundant target paradigm and its use as a blindsight-test: A meta-analytic study

“…One clinical context investigated inter-hemispheric communication in split-brain patients (for a recent meta-analysis see Westerhausen, 2022; for a list of studies see table 1). In more recent years, the application of the RTP extended to psychiatric disorders already associated with disturbed inter-hemispheric communication like schizophrenia (Florio et al, 2008;Florio et al, 2013) or bipolar disease (Florio et al, 2013).…”