Neurobiology of anxiety

I. DefinitionsII. Neuro-anatomical circuitsIII. Neurochemicals

Anxiety- Feeling of apprehension caused by anticipation of danger, which may be internal or external.

Fear-Unpleasurable emotional state consisting of psychophysiological changes in response to a realistic threat or danger.

Phobia-Persistent, pathological, unrealistic, intense fear of an object or situation

Obsession- Persistent and recurrent idea, thought, or impulse that cannot be eliminated from consciousness by logic or reasoning; obsessions are involuntary and ego-dystonic.

all share core symptoms of fear and worry

all basically treated with the same drugs (including many of the same drugs that treat major depression)

what is the difference between major depression and anxiety disorders?

Are all these entities really different disorders?

•GAD- persistent and unremitting yet not severe•Panic- intermittent and catastrophic in an unexpected manner•Phobia- intermittent and catastrophic in an expected manner•PTSD-traumatic in origin and conditioned

Conditioned fear associations

Organising fear responses- rapid and long latency

Innate fear and social behaviour

Organising emotional experience- motor , autonomic,endocrinesystems.

Monosynaptic projections from sensory thalamus to lateral nucleus rapid conditioning(vision+sound+somatic). [subcortical]

Long latency response – highly processed complex sensory stimuli and environmental contexts.[higher cognitive processing]

Extinction resistant memory storage

Plasticity

Hippocampus + Amygdala = spatial contextual conditioning (mental map) (emotion)

Tachistoscope

Facial expression and voice intonation Recall of emotional or arousing memories

Central nucleus = fear, BNST = anxiety

CRH acts on BNST Anxiogenic effect of very

bright light presented for long time

Bigger in males.(hormone related change)

Red. vol = pedophiles, Inhibition of sexual maturity ; disruption shown to attenuate reinstatement of drug seeking behaviour.

Striaterminalis

AMYGDALA

WARRIORS WORRIERS

Perirhinal cortex(anterior) – conveys visual stimuli to amygdala

Temporopolar cortex – emotional salience of actual or anticipated stimuli

mPFC- critical in attenuating fear response Insular cortex – active during developing/

while experiencing disgust. Significant role in interoceptive function especially heartbeat.

GABA Serotonin NE Glutamate Dopamine Voltage gated ion channels NeuropeptideY Galanin CCK

GABA-A and GABA-C ligand gated ion channels. GABA-B –G-Protein linked.

GABA-A – critical role in inhibitory neurotransmission + targets of BZD

Functions vary based on the subunits

α1- sleep, α2 α3-anxiety

Increased turnover in mPFC, amygdala, nucleus accumbens and hypothalamus.

Sensitive to severity of stress(esp in mPFC) Chronic Learned helplessness – decreased

5HT release BZD and Antidepressants prevent decrease of

5HT and learned helplessness. 5HT1A knockout mice – marked anxiety and

fear behaviours.

Fight /flight/freeze response

NE PTSD

Yohimbine – panicogenic

β-blockers and opioids can disrupt reconsolidation of fear memory.

Benjamin james sadock.Virginia alcott sadock.Pedro ruiz.,2009.Comrehensive textbook of psychiatry.9th edition. Lippincott Williams & Wilkins.

Stephen.M.Stahl.2013.Stahl’s essential psychopharmacology.4th

edition.Cambridge university press.

Schiltz K, Witzel J, Northoff G, Zierhut K, Gubka U, Fellman H, Kaufmann J, Tempelmann C, Wiebking C, Bogerts B (2007). "Brain pathology in pedophilic offenders: Evidence of volume reduction in the right amygdala and related diencephalic structures". Archives of General Psychiatry 64: 737–746.

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