The Response of Reward Modulated Activity in Primary Somatosensory Cortex Generated During Performance of a Somatosensory Based Psychophysical Task

Abstract

Reward based modulation of many brain regions have been shown experimentally (Schultz, 2002). Although reward signals were first characterized during investigation of single unit activity within the ventral tegmental area as well as the substantia nigra (Schultz, 1997), a similar reward modulation has since been shown to exist in many areas of cortex as well (Schultz, 2002). These areas include prefrontal cortex & the frontal eye fields (Schultz, 2002). This cortical reward signal has been postulated to regulate several aspects of behavior, including motor learning (Kerr, 2001). While this signal has been well characterized in several cortical areas it has not been sufficiently investigated within the primary somatosensory (S1) cortex. Towards a functional description of reward modulation within S1, I aim to test the hypotheses that 1.) A reward based modulation within the primary sensory cortex exists in-vivo, 2.) This S1 reward based modulation can be decoded in response to altered psychophysical task paradigms including conditioned stimuli predictive of reward and 3.) This signal is further modulated by changes in reward itself; namely the magnitude of the reward, and the probability of reward delivery, and that these changes in reward delivery can further be decoded beyond the presence or absence of reward.