Genetics, anatomy and biochemistry of behavior

1. Genetics, anatomy and biochemistry of behavior

2. There is a genetic component to the etiology of various psychiatric disorders and personality traits. • ---studies. • Pedigree studies use--Family tree • Family risk studies—compare how frequently the disorder occurs in the relatives • Twin studies monozygotic dizygotic • If genetic component present concordance rate higher in monozygotic twins.

3. Neuroanatomy • Cns and pns • Cerebral hemispheres • Right nondominant hemisphere- perception • Left dominant h---language function • Pns----symp / parasymp ns

4. Location of lesion and the resultant effect produced. • Temporal lobe • Frontal lobe • Parietal lobe • Occipital • Ras • Basal ganglia

5. Neurotransmission • Receptors-- pre & post synaptic • Presynaptic and postsynaptic receptors are proteins present in the membrane of the neuron that can recognize specific neurotransmitters. • 1-the changeability of number or affinity of receptors for specific neurotransmitters (neuronal plasticity) can regulate the responsiveness of neurons. • 2-second messengers. When stimulated by neurotransmitters, postsynaptic receptors may alter the metabolism of neurons by the use of second messengers, which includes cAMP

6. Neurotransmitters • Biogenic amines • Catecholamines,indolamines, ethylamines, • Quarternary amines • monoamine theory of mood disorder hypothesizes that lowered monoamine activity results in depression. • Metabolites of the monoamines are often measured in psychiatric research and diagnosis because they are more easily measured in body fluids than the actual monoamines.

7. Dopamine—a catecholamine, is involved in the pathophysiology of schizophrenia, parkinson disease, & mood disorders, • Synthesis-the aminoacid tyrosine is converted to the precursor for dopamine by the enzyme tyrosine hydroxylase. • dopaminergic tracts,-the nigrostriatal tract is involved in the regulation of muscle tone and movement. • --this tract degenerates in parkinsons disease. • --treatment with antipsychotic drugs, which block postsynaptic dopamine receptors receiving input from the nigrostriatal tract, can result in parkinsonism like symptoms.l

8. mesolimbic mesocortical tract—may have a role in expression of mood since it projects into the limbic system, which is involved in emotional behavior. • Nor epinephrine—mood, anxiety, learning & memory.nor adrenergic neurons synthesize dopamine.dop-beta hydroxylase converts it to norepinephrine. Dop neurons mostly pesent in locus ceruleus • Serotonin—indolamine –mood, sleep, impulse control • Synthesis—tryptophan convertred to serotonin-(5 ht) by tryptophan hydroxylase---mostly present in dorsal raphe nucleus

9. Histamine—affected by psychoactive drugs. blockade leads to sedation & increased appetite • Acetyl choline—transmitter used by nrve-skeletal-muscle junctions. degeneration of cholinergic neurons—dementia of alzemers, downs syndrome, sleep disorders. cholinergic neurons synthesize ach from acetyl co- A. • Acetyl choline esterase breaks it down to choline & acetate. blocking ache can delay progression of dementia. • Gaba, glycine, glutamate.

10. Amino acid neuro transmitters • GABA, Glycine & glutamate • GABA –principal inhibitor neurotransmitter in brain • Closely involved in the action of antianxiety drugs & babiturates • Glycine inhibitory—works on its own • Glutamate-excitatory neurotransmitter-associated with epilepsy, schizophrenia

11. Neuropeptides • Endogenous opioids • Enkephalins and endorphins are opioids produced by the brain itself. • Placebo effects mediated by endogenous opioid system

12. Neuropeptide • Schizophrenia—cholecystokinin • Mood disorder- somatostatin, oxytocin, vasopressin • Huntington disease-somatostatin & subs p • Dementia of alzheimir type -somatostatin • Anxiety disorder substance p--cck • Pain & aggression- substance p