Aberrant prefrontal activity and arousal level correlate with action initiation and response vigor

Orchestrating learned Stimulus-Response (S-R) mappings has been suggested as one of the central functions of the prefrontal cortex (PFC), as evidenced by S-R selective single neuron activity during correct task performance. Prior work – limited however to single neuron examples – has shown that, during errors, the “wrong” PFC neurons were aberrantly activated. Psychologists and cognitive scientists have long speculated that Stimulus-Response selective single neuron activity in the prefrontal cortex relates to the vigor of the behavioral response. This idea has been neither tested nor demonstrated. While movement vigor has been related to activity in neural circuits for action control such as the basal ganglia, the neural correlates that link Stimulus-Response mappings to behavioral response vigor remain elusive. To investigate this question, we trained male rats to perform a Go/NoGo response task while head-fixed on a treadmill. This allowed us to record PFC single unit spiking, as well as response vigor (running speed). We show that aberrant activation of the “wrong” S-R mapping is correlated with initiation of the incorrect response. The vigor of the incorrect response was directly related to the strength of the aberrant stimulus-evoked activity. It has long been postulated that response vigor is linked to arousal systems, but this link has not been thoroughly tested until recently. Here, we observe a direct relationship for pre-trial arousal state and the subsequent response vigor. Our findings provide evidence for the long-standing belief that S-R mappings are directly related to response vigor. Moreover, we provide evidence for the often suggested but rarely tested relationship between arousal and response vigor.