Central circuits mediating patterned autonomic activity during active vs. passive emotional coping

Animals, including humans, react with distinct emotional coping strategies to different sets of environmental demands. These strategies include the ca pacity to affect appropriate responses to "escapable" or "inescapable" stre ssors. Active emotional coping strategies-fight or flight-are particularly adaptive if the stress is escapable. On the other hand, passive emotional c oping strategies-quiescence, immobility, decreased responsiveness to the en vironment-are useful when the stress is inescapable. Passive strategies con tribute also to facilitating recovery and healing once the stressful event is over. Active vs, passive emotional coping strategies are characterised f urther by distinct patterns of autonomic change. Active strategies are asso ciated with sympathoexcitation (hypertension, tachycardia), whereas passive strategies are associated with sympathoinhibitory patterns (hypotension, b radycardia). Distinct neural substrates mediating active vs. passive emotio nal coping have been identified within the longitudinal neuronal columns of the midbrain periaqueductal gray region (PAG). The PAG offers then a poten tially useful point of entry for delineating neural circuits mediating the different forms of emotional coping and their associated patterns of autono mic activity. As one example, recent studies of the connections of orbital and medial prefrontal cortical (PFC) fields with specific FAG longitudinal neuronal columns are reviewed. Findings of discrete orbital and medial PFC projections to different FAG columns, and related PFC and FAG columnar conn ections with specific subregions of the hypothalamus, suggest that distinct but parallel circuits mediate the behavioural strategies and patterns of a utonomic activity characteristic of emotional "engagement with" or "disenga gement from" the external environment. (C) 2000 Elsevier Science Inc.