neurobiology of anxiety
TRANSCRIPT
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.
Brainstem wiki