3A). This weakens the effectiveness of the nearby synaptic connection, and reduces the firing of neurons that generate the mental representations needed for top-down control. In contrast, high levels of catecholamines strengthen the affective responses of the amygdala, the habitual responses of the striatum, and primary sensory cortical function. Cortisol has been shown to accentuate the effects of catecholamines in the PFC and the amygdala (Barsegyan et al., 2010), thus creating a coordinated stress response. The following reviews catecholamine actions in the PFC and amygdala, and the effects of stress on NE and DA neurons. Pyramidal cell circuits in the dlPFC interconnect on dendritic spines through glutamatergic,

NMDA receptor synapses (Fig. 3; Wang et al., 2013). The functional strength of these synapses is dynamically modulated to rapidly enhance or weaken connections, and thus help to shape the contents and strength of working memory. These DAPT molecular weight very rapid changes in synapse

strength, called Dynamic Network Connectivity, are mediated by feedforward, cAMP-Ca2+ signaling events, which open K+ channels near the synapse to weaken the connection (Fig. 3A; Arnsten et al., 2012). Catecholamines can either inhibit or activate these signaling events to strengthen (e.g. when we are safe) or weaken (e.g. when we are stressed) PFC network function. GSK126 supplier This contrasts with cAMP-Ca2+ signaling actions in more primitive circuits, where increases in cAMP-Ca2+ generally strengthen synaptic connections, e.g. via long-term potentiation. These opposing actions in different brain circuits may help begin to explain why dendrites retract in PFC, but hypertrophy in amygdala,

in response to chronic stress. Thus, understanding the cellular effects of the catecholamines may be especially 17-DMAG (Alvespimycin) HCl important for treatment strategies. The following provides a brief review of DA and NE actions in the PFC. Initial studies of stress effects on PFC function focused on the role of DA, revealing that increased DA stimulation of D1 receptors in the PFC impaired working memory (Arnsten, 1998 and Murphy et al., 1996). Mild stress preferentially increases DA release in the PFC but not in striatum (Deutch and Roth, 1990), likely involving release from “salience” DA neurons that fire to aversive as well as rewarding events (Matsumoto and Hikosaka, 2009 and Bromberg-Martin et al., 2010). Indeed, even a very mild stress such as receiving water instead of juice increases DA release in the primate dlPFC (Kodama et al., 2014). Studies in rats showed that the levels of DA release in PFC during stress exposure correlated with the degree of working memory impairment (Murphy et al., 1996), and that treatments that blocked DA D1 receptors or reduced DA release protected cognitive performance from the detrimental effects of stress in both rats and monkeys (Arnsten and Goldman-Rakic, 1998 and Murphy et al., 1996).