Stable visual perception is maintained despite the frequent saccadic eye-movements that disrupt the visual input. One hypothesis for this compensation is that advanced knowledge of the impending saccade is provided by an internal copy, a corollary discharge (CD) signal, of the motor command. This copy is utilized to distinguish self-generated sensations from environmental disturbances and reflects properties of the original motor command. However, the influence these mirrored characteristics exert in determining the source of a disturbance and its impact on visual perception is currently unknown. The research objective of this application is to determine the consequences of CD variability on the ability to make accurate perceptual judgments of trans-saccadic changes in the visual scene, and establish that defects in CD transmission underlie the visual perceptual disorders in neurological disease. The central hypothesis of this research is that (1) the CD of saccadic eye-movements of different amplitudes and directions reflect the properties of the original motor command and (2) patients with CD transmission disruption, such as in Schizophrenia, will demonstrate a reduced ability to perceive trans-saccadic visual scene variations. The research uses human psychophysics and the known neuroanatomy of the saccadic eye-movement system to dissect the way the brain continuously incorporates the changing sensory information that results from our own actions into a stable visual percept. The hypothesis of the application has been formulated on the basis of strong preliminary data that show the ability to utilize CD to detect trans-saccadic visual scene alterations in normal human subjects weakens with increasing variance in the CD signal and is also influenced by the direction of the saccadic eye-movement, as predicted from the source of the CD and motor command. The long-term goal of the research is to understand the role of corollary discharge in visual perception and movement control with the objective of contributing to the diagnosis and treatment of diseases that result from CD transmission deficits. The expected outcomes of the research is to provide evidence that perceptual judgments.;of trans-saccadic changes is influenced by the variability reflected in the CD signal, and that this detection ability is diminished when CD transmission is degraded in Schizophrenia. This contribution is significant because in addition to diagnostics, the majority of the internal signals in the brain that do not represent sensory or motor information are presently inaccessible, and it is likely that diseases that impair higher cognitive function affect these circuits, as in Schizophrenia. CD is one of the few internal signals that is experimentally accessible and, through its study, an enhanced understanding of these signals and their transmission can be achieved.
PUBUC HEALTH RELEVANCE Corollary discharge, an internal copy of a motor command made within the brain, is utilized in neural processes that require advanced knowledge of the upcoming movement, such as the maintenance of visual stability. This duplicate reflects properties of the original motor command, and the results from the proposed experiments will provide a link between the characteristics mirrored in this internal copy and systematic changes to visual perception. This contribution is significant because it will advance the understanding of visual processing and allow the design of diagnostics and therapy for the perceptual disorders in Schizophrenia, characterized by a diminished ability to distinguish self generated sensations from environmental disturbances.
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