The cognitive neuroscience of creative thinking in the schizophrenia spectrum: individual differences, functional laterality and white matter connectivity
Folley, Bradley Scott
A relationship between creativity and psychopathology has been observed for over a century, yet the mechanisms that are responsible for this association are poorly understood. In particular, there is converging evidence to suggest that individuals with personality traits related to schizophrenia may be particularly creative. By studying the neurobiological substrates of creative thinking in populations along the schizophrenia spectrum, the mechanisms responsible for enhanced creativity may be elucidated. This may be helpful in identifying the correlates of creativity common to most individuals, and it may also identify those mechanisms that are particularly salient among schizophrenic and schizotypal individuals. The present series of investigations examined these relationships with four related studies using schizophrenics, schizotypes, and normal controls. A study of individual differences in creative thinking used a novel divergent thinking task to assess group differences in creativity and its relationship with handedness and schizotypy. The functional laterality of creative thinking was investigated using a divided visual field approach to assess group differences in verbal and non-verbal divergent thinking. In addition, functional neuroimaging using near infrared spectroscopy (NIRS) was employed to assess differential prefrontal hemispheric contributions to divergent thinking. The structural connective bases of creative thinking were investigated using diffusion tensor imaging (DTI) indices of white matter in comparison with measures of divergent thinking. Findings support enhanced creative thinking in schizotypy, particularly related to disorganized traits, and preservation of creative thinking in schizophrenia compared to normal controls. Results from the NIRS study suggest that the right prefrontal cortex may provide a salient contribution to the higher creativity scores found in schizotypal individuals, and that schizophrenic individuals and normal controls may process creative thinking similarly, resulting in similar patterns of prefrontal activation and divergent thinking scores. Comparing divergent thinking scores with DTI indices of white matter indicate that strength of axonal direction in callosal fibers may be inversely related to both creative and intellectual thinking processes, possibly indicating reduced bilateral processing. Thus, these studies have demonstrated the plausibility of creativity research using the tools of experimental psychology and cognitive neuroscience.