The striatum beyond reward: caudate responds intensely to unpleasant pictures.

The involvement of striatum in affective processes has been consistently reported in recent years. However, studies within this field have mainly focused on positive affect, revealing the involvement of striatum in reward situations. The present research aimed to explore the involvement of striatum in negative affect through fMRI. To that aim, participants (n=18) were presented with negative, positive and neutral pictures while they performed an indirect task, a strategy repeatedly recommended to avoid cognitive interferences. Positive and negative stimuli did not differ in their arousal levels, as assessed by participants themselves. Analyses of variance showed that caudate nucleus was sensitive to the emotional content of stimulation, negative pictures eliciting greater caudate responses than positive and neutral. Regression analyses indicated that both valence and arousal content of visual stimuli synergically contributed to explain the activation of caudate, whose strong response to negative pictures supports models proposing striatum as a key element in withdrawal situations.