Abstract
Distinct neural circuits process motivation and attention. Deficits in attention observed in neurological disorders such as ADD/ADHD are associated with disruptions in motivational signaling, suggesting functional interaction between these neural systems. To investigate the influence of motivation on attention, humans and rhesus monkeys were trained to perform a peripheral attention task at psychophysical threshold. Subjects were required to indicate the brief flicker of one of two peripheral cues by making a manual (humans) or gaze shift (monkeys) response to a target positioned in the opposite hemifield. On each trial, one randomly selected peripheral cue was illuminated first, indicating the location of the flicker with 80% validity. The amount of cash (humans) or fruit juice (monkeys) awarded for correct trials was varied independently across blocks. Flicker detection performance was correlated with cue validity, indicating that subjects selectively attended to the early onset location. Elevated motivation was associated with enhanced selectivity for attended versus unattended cues, indicating enhanced visual processing of the attended cue. To investigate the neural basis of the influence of motivation on attention, the activity of single neurons in area LIP was studied while monkeys performed this task. Neuronal activity in LIP was elevated for attended stimuli, and increased reward was associated with enhanced neuronal selectivity for attended versus unattended cues. In high reward blocks, there was a significant correlation between behavioral and neuronal selectivity. These data suggest that neuronal activity in parietal cortex reflects the differential deployment of attention to visual stimuli and that motivation sharpens attentional processing.
NIH-NEI EY013496, The Whitehall Foundation & The Alfred P. Sloan Foundation