Functional Neuropsychophysiological Asymmetry in Schizophrenia: A Review and Reorientation

Abstract

In reviewing the neuropsychophysiological evidence of functional asymmetry it is proposed that schizophrenia is characterized by a greater dispersion of leftward and rightward asymmetries. The two extremes are represented by active (left greater than right) and withdrawn (right greater than left) syndromes, as is the case with psychometric schizotypy. Syndrome-asymmetry relations extended beyond fronto-temporal systems to include posterior activity, infracortical motoneuron excitability, and individual differences in interhemispheric connectivity and directional biases. Central to these are lateral imbalances in thalamo-cortical and callosal arousal systems, while centrality to schizophrenia follows evidence of reversals in asymmetry with changes in symptom profile, clinical recovery, and neuroleptic treatment. Affinities are found in intact animals from challenge-induced turning tendencies representing coordinated activity of attentional, motor, and reinforcement systems. In both patients and animals, neuroleptics have reciprocal interhemispheric effects, with a bidirectionality that depends on syndrome or endogenous turning preference. Bidirectionality implicates nonspecific thalamic system (NSTS) and not limbic projections. It is proposed that the asymmetries arise from endogenous influences of genes, hormones, and early experience including stressors on NSTS asymmetry, and these underpin approach/withdrawal behavior that is manifested in temperament, personality, and clinical syndrome, and which precedes language development.

DTI and MTR abnormalities in schizophrenia: Analysis of white matter integrity

“…Our findings of CC anisotropy abnormalities are also consistent with other findings in the literature (Agartz et al, 2001;Foong et al, 2001;Ardekani et al, 2003). Moreover, Gruzelier (1999) speculates that information processing deficits in schizophrenia are related to defective interhemispheric communication, mediated by the CC. Another speculation is that, because of the long maturation period for CC myelination, an insult to the developing brain may contribute to a decrease in connectivity between the right and left hemispheres (Njiokiktjien, 1988) and thus might explain the lack of asymmetry between the hemispheres observed in schizophrenia.…”

Abnormal Striatal Dopamine Transmission in Schizophrenia

“…In schizophrenia, dopamine is known to be implicated in functional neuropsychophysiological asymmetry (for a review see [86]). McGowan and colleagues [20] as well as Hietala and co-workers [21] reported that abnormal presynaptic dopamine density (measured by 6-[18F]-fluorodopa uptake) was lateralised to the left in patients with schizophrenia.…”

Schizophrenia and viral infection during neurodevelopment: a focus on mechanisms

“…[134][135][136] Neuroanatomical studies have found differences between schizophrenia patients and controls in the number, density or distribution of neurons between the left and right hemispheres. 8,137,138 Abnormalities of laterality have also been revealed by brain imaging studies measuring subregional tissue volume, blood flow, and metabolism.…”

“…There is an unclear relationship between these structural abnormalities, and the behavioral asymmetries in schizophrenia which are purportedly manifested in motor, sensory, language and cognitive function. 134,135 The idea that these lateralization abnormalities arise during development is gaining support, but little attention has been given to the possible involvement of a viral infection.…”