***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Negative symptoms may be associated with dysfunction of the brain reward system in schizophrenia . We used functional magnetic resonance imaging ( fMRI ) to assess the BOLD response in the ventral striatum of unmedicated schizophrenics during presentation of reward-indicating and loss-indicating stimuli . METHODS A total of 10 schizophrenic men ( 7 never medicated , 3 unmedicated for at least 2 years ) and 10 age-matched healthy male volunteers participated in an incentive monetary delay task , in which visual cues predicted that a rapid response to a subsequent target stimulus would result either in monetary gain or loss or would have no consequence . RESULTS Compared to healthy controls , unmedicated schizophrenics showed reduced ventral striatal activation during the presentation of reward-indicating cues . Decreased activation of the left ventral striatum was inversely correlated with the severity of negative ( and trendwise positive ) symptoms . DISCUSSION Reduced activation in one of the central areas of the brain reward system , the ventral striatum , was correlated with the severity of negative symptoms in medication-free schizophrenics . In unmedicated schizophrenic patients , a high striatal dopamine turnover may increase the " noise " in the reward system , thus interfering with the neuronal processing of reward-predicting cues by phasic dopamine release . This , in turn , may contribute to negative symptoms as such as anhedonia , apathy , and loss of drive and motivation Comparative studies have implicated the nucleus accumbens ( NAcc ) in the anticipation of incentives , but the relative responsiveness of this neural substrate during anticipation of rewards versus punishments remains unclear . Using event-related functional magnetic resonance imaging , we investigated whether the anticipation of increasing monetary rewards and punishments would increase NAcc blood oxygen level-dependent contrast ( hereafter , " activation " ) in eight healthy volunteers . Whereas anticipation of increasing rewards elicited both increasing self-reported happiness and NAcc activation , anticipation of increasing punishment elicited neither . However , anticipation of both rewards and punishments activated a different striatal region ( the medial cau date ) . At the highest reward level ( $ 5.00 ) , NAcc activation was correlated with individual differences in self-reported happiness elicited by the reward cues . These findings suggest that whereas other striatal areas may code for expected incentive magnitude , a region in the NAcc codes for expected positive incentive value Rationale Dysfunctional reward processing has been proposed as a main deficit in attention-deficit/hyperactivity disorder ( ADHD ) , which could be modulated by treatment with methylpheni date ( MPH ) . Objectives We examined differences in reward processing in adulthood ( independent of actual ADHD ) depending on MPH treatment during childhood . Methods Eleven males with childhood ADHD treated with MPH , 12 drug-naïve males with childhood ADHD , and 12 controls matched by age , h and edness , and smoking behavior were studied drug-free using functional magnetic resonance imaging . BOLD-responses  were compared during a monetary incentive delay task using an ANOVA design focusing on the ventral striatum during anticipation and the orbitofrontal cortex during outcome . Results Controls , drug-naïve , and treated subjects did not differ significantly in their activations in the ventral striatum and orbitofrontal cortex . Explorative analyses revealed decreased insula activation during outcome of loss avoidance in drug-naïve subjects in comparison to both groups , while treated subjects did not differ from controls . Insula activation correlated significantly positive with harm avoidance in the treated group . Furthermore , comparing subjects with actual ADHD symptoms , remitters and controls we observed decreased putamen activition in ADHD persisters . Conclusions Basal ganglia reward processing seemed to be unrelated to MPH pretreatment , but was related to remission . On the other h and , the revealed differences between treated and drug-naïve subjects with childhood ADHD , i.e. , in the insula , give evidence for more pronounced abnormal activation in reward-associated brain regions in untreated subjects with childhood ADHD and underpin the need of prospect i ve studies on long-term effects of psychostimulant treatment Certain classes of stimuli , such as food and drugs , are highly effective in activating reward regions . We show in humans that activity in these regions can be modulated by the predictability of the sequenced delivery of two mildly pleasurable stimuli , orally delivered fruit juice and water . Using functional magnetic resonance imaging , the activity for rewarding stimuli in both the nucleus accumbens and medial orbitofrontal cortex was greatest when the stimuli were unpredictable . Moreover , the subjects ' stated preference for either juice or water was not directly correlated with activity in reward regions but instead was correlated with activity in sensorimotor cortex . For pleasurable stimuli , these findings suggest that predictability modulates the response of human reward regions , and subjective preference can be dissociated from this response 
    Output:
    
In both anticipation and loss outcome phases , participants showed large and robust activations in the bilateral striatum , ( anterior ) insula , and anterior cingulate gyrus relatively to Loss > Neutral contrast .
Although relatively similar activation patterns were observed during the two event types , they differed in the pattern of prefrontal activations : ventro-lateral prefrontal activations were observed during loss anticipation , while medial prefrontal activations were observed during loss receipt .
Discussion Considering that previous meta-analyses highlighted activations in the medial prefrontal cortex/anterior cingulate cortex , the anterior insula and the ventral striatum , the current meta- analysis highlighted the potential specificity of the ventro-lateral prefrontal regions , the median cingulate cortex and the amygdala in the loss events .