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Vazey, E. M.

Publications and source records attributed to Vazey, E. M..

3 recordsLinked to original sources

Low affinity noradrenergic signaling promotes passive coping during reinforcement behavior

During stress and in many psychiatric disorders the ability to appropriately recognize and respond to cues to avoid negative outcomes (e.g., injury) and achieve positive outcomes (e.g., food) is disrupted. A critical component of the stress response is increased noradrenergic tone, acting on lower affinity noradrenergic receptors (1 and {beta}). Noradrenergic signaling is essential for cue-driven behavior, yet how noradrenergic components of the stress response impacts positive and negative reinforcement behavior is still unknown. We manipulated noradrenergic receptor (1, 2, and {beta}) activity during an active avoidance and reward seeking task in male and female rats. We found modulating noradrenergic activity on low affinity 1 and {beta} receptors but not 2 receptors disrupted reinforcement behavior. Increased 1, but to a greater extent {beta} receptor activity shifted negative reinforcement behavior away from active avoidance and towards passive coping by increasing decision thresholds. We also found sex differences in the impact of 1 and {beta} noradrenergic activity on reward seeking. Overall, stress related noradrenergic signaling deceased active avoidance behavior by shifting strategy towards passive coping. Reward seeking was more robust in females but not males. Collectively these results identify sex differences in noradrenergic dependent stress response behaviors and highlight low affinity adrenoreceptors as relevant therapeutic targets to mitigate the impact of stress on goal-directed behavior. SIGNIFICANCE STATEMENTWhile we know norepinephrine is a fundamental component of the acute stress response, it is unknown how that stress related noradrenergic receptor activity impacts reinforcement behavior, both positive and negative. Here, we show that stress related norepinephrine signaling is differentially involved in positive and negative reinforcement behavior and directly shifts behavioral strategies from active avoidance to passive coping. These results identify that noradrenergic receptor activity can mediate the transition from adaptive to maladaptive behaviors during stress, especially in the context of negative reinforcement.

neuroscience↗

Sex-dependent noradrenergic modulation of premotor cortex during decision making

Rodent premotor cortex (M2) integrates information from sensory and cognitive networks for action selection and planning during goal-directed decision making. M2 function is regulated by cortical inputs and ascending neuromodulators, including norepinephrine (NE) released from the locus coeruleus (LC). LC-NE has been shown to modulate the signal to noise ratio of neural representations in target regions prior to decision execution, to increase the salience of relevant stimuli. Using rats performing a two-alternative forced choice task after administration of a {beta} adrenergic antagonist (propranolol), we show that action planning in M2 is mediated by {beta} adrenergic signaling. Loss of {beta} adrenergic signaling results in failure to suppress irrelevant action plans in M2 that disrupts decoding of cue related information, delays decision times, and increases trial omissions, particularly in females. Furthermore, we identify a potential mechanism for the sex bias in behavioral and neural changes after propranolol administration via differential expression of {beta}2 receptors across sexes, particularly on local inhibitory neurons. Overall, we show a critical role for {beta} adrenergic signaling in M2 during decision making by suppressing irrelevant information to enable efficient action planning and decision execution.

neuroscience↗

A brainstem-central amygdala circuit underlies defensive responses to learned threats

Norepinephrine (NE) plays a central role in the acquisition of aversive learning via actions in the lateral nucleus of the amygdala (LA)1,2. However, the function of NE in expression of aversively-conditioned responses has not been established. Given the role of the central nucleus of the amygdala (CeA) in the expression of such behaviors3, and the presence of NE projections in this brain nucleus, we assessed the effects of NE activity in the CeA on behavioral expression using receptor-specific pharmacology and cell-and projection-specific chemogenetic manipulations. We found that inhibition and activation of locus coeruleus (LC) neurons decreases and increases freezing to aversively conditioned cues, respectively. We then show that locally inhibiting or activating LC terminals in CeA is sufficient to achieve this bidirectional modulation of defensive reactions. These findings support the hypothesis that LC projections to CeA are required for the expression of defensive responses elicited by conditioned threats.

neuroscience↗