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Carmelo M Vicario Reward and Punishment: what somatosensory intra-oral activity can tell about the value of goods

Final Report Summary - REWARDING THE TONGUE (Carmelo M Vicario Reward and Punishment: what somatosensory intra-oral activity can tell about the value of goods.)

The aim of the current proposal was investigating the groundbreaking hypothesis that the motor representation of the tongue (i.e. the Motor Tongue Area-MTA) might serve as cortical key structure for detecting the activity of the reward system via non-invasive brain stimulation. In particular, we investigated whether a change in the activity of reward system, along the reinforcement-punishment continuum, might influence the excitability of the MTA neurons. This hypothesis has been made according to several theoretical/experimental works in non human primates suggesting that the MTA is a cortical region directly connected with several key regions of the reward system in no human primates. To this purpose, we recorder Motor Evoked potential from the tongue of several groups of participants while manipulating different type of reward/punishment related outcomes (e.g. monetary win and loss; exposure to attractive/appetizing vs. disgusting/aversive outcomes; ethical violation outcomes). Overall, the main results of this work suggest that the MTA excitability is a physiological measure selectively sensitive to aversion related experiences (i.e. disgust, aversion, ethical violations) including social and moral disgust. No effect is reported in response to reward related outcomes (e.g. monetary reward; appetizing foods), although other evidence suggests that the experience of craving affects the MTA excitability.
From the anatomo-functional point of view, the evidence of a link between the excitability of the MTA and the reward system activity suggests might be provided of a direct connectivity with the reward system, similarly to what has been reported in non human primates.
The evidence that the MTA excitability is sensitive to aversion provides also interesting insights to the current debate about the origin of morality. In particular, the results suggest that social and moral disgust might be evolved from sensory (primary) disgust.
Finally, the existence of a functional link between the MTA and the reward system provides support to a further hypothesis that might have important implications for clinical practice and, more in general, for the European Sanitary System. It provides the rationale for the suggestion that the MTA might be a cortical target for the modulation of reward system via non-invasive brain stimulation.
This might open the road to new research protocols for the treatment of clinical disorders characterized by deranged reward system activity such as, for example, eating disorders, pathological gambling, alcohol abuse.