Affect and colour perception – a neurophysiological approach

Objectives: Patients suffering from mood disorders, frequently report alterations of colour perception. Thus, dysfunctions of the neurobiological transformation of colour perception may be involved in the pathogenesis of affective disorders.

Methods: The neurophysiological technique of Transcranial Magnetic Stimulation (TMS) allows to assess non-invasively the integrity and excitability patterns of cortical and subcortical networks. Using this method we studied ten healthy young subjects under three conditions (no visual stimulation, stimulation with red light, stimulation with green light). Several TMS paradigms (Motor Threshold (MT), Cortical Silent Period (CSP), Paired-pulse Facilitation (PPF), Paired-pulse Inhibition (PPI)) were studied. The TMS paradigms allow to assess different aspects of cortical and subcortical excitability and give insight into the nature and localization of inhibitory and facilitatory processes within neuronal networks.

Results: Visual stimulation had significant effects on motor cortex excitability patterns, demonstrating the potential of TMS to detect changes in visual processing in humans.

Conclusions: TMS may be further developed as an instrument for the assessment of cortical and subcortical excitability changes associated with alterations of colour perception. This may help to elucidate the pathophysiology of affective disorders.