Limitations of neurobiological approach in neuropsychiatry: DCD and the two visual systems theory

Abstract

The purpose of this review is to address possible limitations of the neurobiological approach to understanding psychiatric disorders. Neurobiological approach helps to resolve the mind-body dualism and develop new assessment and treatment approaches in psychiatry. However, it could be a problem to place too much emphasis on certain aspects of neurobiology, specifically structural neuroanatomy, because of the complexity or comorbidity of neuropsychiatric disorders. Developmental Coordination Disorder (DCD), for instance, is generally related to problems in motor skills and this movement disability is often related to perception. One account, two visual systems theory, relied on functional distinction in brain; ventral stream is responsible for visual recognition (perceptual representation), and dorsal stream is responsible for the guidance of actions. Numerous neuropsychological and neurophysiological studies have suggested that there are two separate visual streams. What then can we understand of DCD from this neuroanatomical approach? Studies are now showing that shape perception is relevant to visually guided action, such as reaching-to-grasp an object. In retrospect, it is not so surprising that we would need information about 3D shape to interact with 3D structure. In this article, I reviewed fundamental findings of two-visual system theory and suggested problems of visually guided action to consider what shape perception implies for the hypothesis that there are two separate visual streams in the brain. Questions raised highlight possible limitations of adopting a structural neuroanatomical approach to account for perception and action effects, and by extent related psychiatric conditions such as DCD. In conclusion, neurobiological approach in neuropsychiatry, while useful, would be limited if it focuses too much on anatomical distinction.