BURST ACTIVITY OF VENTRAL TEGMENTAL DOPAMINE NEURONS IS ELICITED BY SENSORY STIMULI IN THE AWAKE CAT

In light of evidence implicating dopamine in the pathophysiology of at tention deficit disorder and schizophrenia, diseases involving attenti onal or sensory processing abnormalities, it was of interest to determ ine whether and how dopamine neurons in the ventral tegmental area res pond to sensory stimuli. The single-unit responses of ventral tegmenta l dopamine neurons were recorded in freely-moving cats during the pres entation of brief, non-conditioned auditory and visual stimuli. Both a uditory and visual stimuli produced neuronal excitation, involving a g reater than 5-fold increase in the probability of burst firing followe d by a period of burst inhibition. The burst nature of the single-unit response suggests that sensory-induced dopamine release at target sit es was disproportionally large relative to the discharge frequency. Wh ile characteristics of the dopaminergic sensory response were similar for auditory and visual stimuli, the response latency was longer for v isual stimuli. The results demonstrate that dopamine neurons in the ve ntral tegmental area, the site of origin for mesolimbocortical dopamin e neurons, are reliably activated by non-conditioned auditory and visu al stimuli.