PT  - JOURNAL ARTICLE
AU  - Pelin Avcu
AU  - Ashley M. Fortress
AU  - Jennifer E. Fragale
AU  - Kevin M. Spiegler
AU  - Kevin C.H. Pang
TI  - Anhedonia following mild traumatic brain injury in rats: A behavioral economic analysis of positive and negative reinforcement
AID  - 10.1101/527895
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 527895
4099  - http://biorxiv.org/content/early/2019/01/23/527895.short
4100  - http://biorxiv.org/content/early/2019/01/23/527895.full
AB  - Psychiatric disorders affect nearly 50% of individuals who have experienced a traumatic brain injury (TBI). Anhedonia is a major symptom of numerous psychiatric disorders and is a diagnostic criterion for depression. Recently, anhedonia has been divided into consummatory, motivational and decisional components, all of which may be affected differently in disease. Although anhedonia is typically assessed using positive reinforcement, the importance of stress in psychopathology suggests the study of negative reinforcement (removal or avoidance of aversive events) may be equally important. The present study investigated positive and negative reinforcement following a rat model of mild TBI (mTBI) using lateral fluid percussion. Hedonic value of and motivation for reinforcement was determined by behavioral economic analyses. Following mTBI, the hedonic value of avoiding foot shock was reduced. In contrast, the hedonic value of escaping foot shock or obtaining a sucrose pellet was not altered by mTBI. Moreover, neither motivation to avoid or escape foot shock nor motivation to acquire sucrose was modified by mTBI. Our results suggest that individuals experiencing mTBI may experience more stress because of poor proactive control of stress resulting from reduced hedonic value of avoiding aversive events.