<qa>  What is the concept of hypofrontality?Frontal Cortical Hypofunction in Negative Symptoms Refinements in the DA hypothesis have emphasized an imbalance between mesocortical and subcorticalmesolimbic DA activity. Hyperactivity of the mesolimbic DA system has been implicated in the positive symptoms of the illness; hypofunctioning of the mesocortical DA pathway has been implicated in the pathophysiology of negative symptoms Weinberger 1987; Davis et al.1991. The finding of neurophysiologic hypofunction of the frontal cortex during cognitive activation studies in schizophrenic subjects has given rise to the concept of hypofrontality Weinberger et al. 1986; Berman et al. 1986; for review see Weinberger et al. 1994. Furthermore, frontal hypofunction has been linked specifically to negative symptoms irrespective of the severity of positive symptoms in unmedicated schizophrenics Wolkin et al. 1992. 