Frontal Brain Injury: Effects on Flexibility, Impulse Control, and Attention

Abstract

Traumatic Brain Injury (TBI) is defined as an impact to the head, penetration of the skull, or rapid deceleration of the skull, resulting in an alteration of brain function or neurological deficit. Cognitive deficits are common following TBI and often go unresolved due to a lack of effective treatments. These deficits often perseverate into the chronic post injury phase, so the development of rehabilitative strategies is imperative. Behavioral flexibility, impulse control, and attention are a few cognitive processes that are commonly affected by TBI. The current research compares these processes between rats with and without a severe frontal brain injury (TBI vs. Sham). Behavioral flexibility was measured with the attentional set shifting task (AST) and probabilistic reversal learning (PbR). Differential reinforcement of low rate behavior (DRL) was used to measure impulse control. Cues associated with correct responding were used compare attention between TBI and Sham rats. The cues also served as an environmental treatment for TBI related deficits. Behavioral flexibility, measured by AST performance, was not affected by TBI, however TBI rats were impaired relative to Sham rats on PbR. Sham rats performed better on DRL when compared to TBI rats, suggesting that impulse control was impaired by frontal TBI. The cue treatment improved performance for TBI and Sham rats on both PbR and DRL. On PbR, cues improved TBI performance to Sham levels. Cues also improved TBI performance on DRL, but not to Sham levels. These data suggest that frontal TBI impairs impulse control and behavioral flexibility. The improvement seen in TBI rats associated with the cue treatment suggest that attention may somewhat intact following a brain injury. In addition, the differential improvement between PbR and DRL performance suggests that TBI related deficits in impulse control may be more difficult to treat than deficits in behavioral flexibility.