Stress, Anxiety and Aggression

Stress

A physiological response to perceived threats or aversive situations; can be episodic or continuous. Adaptive in short bursts, harmful if prolonged.

Sympathetic Adrenal Medullary (SAM) System

A stress response pathway where the hypothalamus activates the sympathetic nervous system, causing the adrenal medulla to release epinephrine and norepinephrine, preparing the body for 'fight or flight.'

Hypothalamic Pituitary Adrenal (HPA) Axis

A hormonal stress response system. The hypothalamus releases CRH, triggering the pituitary gland to release ACTH, which stimulates the adrenal cortex to release cortisol.

Glucocorticoids (e.g., cortisol)

Hormones released during stress that increase glucose availability and reduce pain sensitivity; chronically high levels damage the hippocampus.

Chronic Stress

Prolonged activation of the stress response systems; linked to hippocampal damage, impaired memory, and elevated glucocorticoid levels.

Diamond et al. (1999)

A study showing that stressed rats had elevated glucocorticoids, impaired synaptic strengthening, and difficulty with hippocampus

Post Traumatic Stress Disorder (PTSD)

A mental health condition triggered by experiencing or witnessing trauma, with symptoms like flashbacks, hypervigilance, and emotional detachment.

Pavlovian Learning in PTSD

A learning process where neutral cues become conditioned stimuli by association with trauma, leading to conditioned fear responses.

Hippocampus in PTSD

Often smaller in PTSD patients; involved in memory and contextual processing.

Amygdala in PTSD

Becomes hyperactive, resulting in heightened emotional and fear responses.

Prefrontal Cortex (PFC) in PTSD

Shows reduced activity, impairing impulse control and emotional regulation.

Exposure Therapy

A PTSD treatment based on extinction learning; patients are gradually exposed to trauma cues in safe environments to reduce fear responses.

SSRIs for PTSD

Medications that increase serotonin, help restore hippocampal volume, reduce amygdala reactivity, and improve PFC functioning.

Anxiety

A feeling of uneasiness or nervousness, often without a clear threat. Beneficial in moderation, but problematic when excessive or chronic.

Panic Disorder

An anxiety disorder characterized by sudden and intense panic attacks, often with hyperventilation, dizziness, and fear of death.

Generalized Anxiety Disorder (GAD)

Persistent, excessive worry about various aspects of daily life.

Social Anxiety Disorder

A fear of social situations and potential negative judgment, often associated with increased amygdala activity.

Amygdala in Anxiety

Overactive in anxiety disorders, contributing to heightened fear and emotional reactivity.

Prefrontal Cortex in Anxiety

Underactive, leading to poor regulation of emotional responses.

Benzodiazepines (BDZs)

Anxiety medications that enhance GABA activity, calming the amygdala. Risk of sedation and dependence.

Neurosteroids (e.g., XBD173)

Compounds that enhance GABA function without sedation, reducing anxiety and panic symptoms.

SSRIs (e.g., fluvoxamine)

Antidepressants that increase serotonin levels and help manage anxiety by improving mood regulation.

D-cycloserine (DCS)

Enhances NMDA receptor activity and improves the effectiveness of exposure therapy by aiding fear extinction.

Aggression

Behavior intended to cause harm or assert dominance; includes threat displays, defensive aggression, and submission.

Periaqueductal Gray (PAG)

Brain region involved in controlling aggressive behaviors. Dorsal PAG is linked to defensive aggression; ventral PAG to predatory aggression.

Amygdala in Aggression

Regulates emotional and aggressive responses.

Prefrontal Cortex (PFC) in Aggression

Inhibits aggressive behavior; dysfunction here can lead to impulsive aggression.

Serotonin and Aggression

Low serotonin levels are associated with increased aggression. SSRIs and substances like MDMA can reduce aggression.

5 HIAA

A metabolite of serotonin; low levels indicate low serotonin activity and correlate with increased aggression in monkeys.

Aggression as a Reward

In some individuals, aggression is intrinsically motivating or reinforcing, especially when it elevates status or control.

Conditioned Place Preference (CPP) in Aggression

A behavioral model where animals show a preference for environments where they previously engaged in aggression, indicating it's rewarding.

Aggression Self-Administration (SA)

A model where animals will work (e.g. press a lever) to access opportunities to be aggressive, showing aggression is reinforcing.

Nucleus Accumbens (NAc)

Part of the brain’s reward circuitry; activated during rewarding behaviors including food, sex, drugs, and aggression.

Ventral Tegmental Area (VTA) Definition

Releases dopamine into the nucleus accumbens during aggressive encounters, reinforcing aggressive behavior.