Abstract

Introduction and General Methods

VTA DA response to auditory and visual stimuli.

Varying stimulus intensity and conditioned properties of the stimulus

Discussion
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Mesolimbic dopamine (DA) activity has been conceptualized as a reward signal, transmitting information about the appetitive motivational properties of environmental stimuli. However, relations between altered DA activity and attention-related clinical deficits, such as those seen in ADD and schizophrenia, suggest a more general role for DA as a signal of stimulus salience. We recorded the single-unit activity of DA neurons residing in the ventral tegmental area (VTA) in freely moving cats during the presentation of 1 ms (fast rise-time) auditory stimuli. Ventral tegmental DA neuronal activity was dramatically elevated either by a) increasing the intensity of the auditory event (varying dB), or b) pairing an auditory event with a reward stimulus (milk delivery). Because the DA neurons were sensitive both to physical changes in stimulus salience (auditory volume), and to the conditioned reward properties to the auditory event, mesolimbic DA neurons appear to signal the salience of environmental stimuli, regardless of whether that salience is derived from physical properties of the stimulus or from conditioned reward properties of the event.

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Presentation Number SAhorvitz0345
Keywords: dopamine, vta, attention, electrophysiology, sensory