Anterior cingulate cortex regulation of sympathetic activity.

the anterior cingulate cortex (ACC) is active in such a wide variety of cognitive and emotional tasks has become an important issue in recent research. In this issue of Brain, Critchley et al. (2003) report changes in heart rate in both cognitive and motor tasks related to the strength of activation in the ACC. They interpret their ®ndings as supporting a view that the anterior cingulate is involved in the regulation of autonomic activity according to the current context of behavior. At the turn of the twentieth century, Broca used the termìimbic' to describe the medial convolution that borders the corpus callosum of each hemisphere. Originally, this term was merely descriptive, implying no function. Later, Broca would ascribe olfactory functions to the limbic lobe, and this suggestion dominated teaching of functional neuroanatomy well into the mid-twentieth century despite a persuasive proposal by Papez in 1937. Based upon the reciprocal connections of the cingulate cortex with the hypothalamus, Papez proposed that the cingulate cortex was involved in the subjective experience of emotions. In the 1940s and 1950s, evidence accumulated from animal as well as human studies of the ACC, which are well cited by Critchley et al. (2003). These studies demonstrated the involvement of the cingulate cortex in motor and autonomic control. For example, from his studies with monkeys Ward (1948) concluded, `It is now clear that area 24 has two main functions. It is the most powerful of the cortical suppressor areas and it is also a potent autonomic effector region' (p. 21). Results from modern studies of the ACC have been divided. On the one hand, results from neuroimaging studies have implicated the ACC in a host of cognitive functions (Posner and DiGirolamo, 1998). On the other, neuroimaging studies have also identi®ed the ACC's involvement in transient mood changes (Mayberg et al., 1999), depression and anxiety disorders (Mayberg et al., 2000; Brody et al., 2001) and the perception of pain (Rainville et al., 1997). Given the ®ndings that relate cognitive processes to the ACC, it is somewhat surprising that lesions to the ACC do not produce massive or consistent cognitive de®cits. Early on, it was recognized that patients with lesions to the frontal lobe, including the ACC, demonstrated normal performance on a host of neuropsychological and intelligence tests (Rylander, 1947; Teuber, 1964). More recent studies have basically con®rmed these early observations, but they also show that patients with ACC …