HMB200H1 Lecture Notes - Lecture 9: Amygdala, Implicit Memory, Dopaminergic Pathways
Document Summary
Motivated behaviours: homeostatic loops and set point theory, homeostatic mechanisms in hypothalamus: bilateral lesions of the ventromedial nucleus, result in overeating and extreme obesity while bilateral lesions in the lateral hypothalamic area result in anorexia. Stimulation of medial forebrain bundle and vta are very effective reinforcers of behaviour: dopamine pathway leads to strong activation of motivated behaviours (normally activated by irms) Opera(cid:374)t (cid:272)o(cid:374)ditio(cid:374)i(cid:374)g of (cid:373)oti(cid:448)ated (cid:271)eha(cid:448)iours (cid:373)ore dire(cid:272)ted (cid:373)oti(cid:448)ated (cid:271)eha(cid:448)iours. Classi(cid:272)al (cid:272)o(cid:374)ditio(cid:374)i(cid:374)g sti(cid:373)uli asso(cid:272)iated (cid:449)ith re(cid:449)ard (cid:272)o(cid:373)e to trigger: at first vta neurons fire after rewards then during pairing (learning) fire after predictor (golden arches), after well learned only fire after predictor. Dopamine and learning about reinforces: dopamine is an "error predictor" it signals only if there is a change in the change expected reinforcer value. If change is greater (reward) it increases linking and craving of cs. Cocaine and amphetamines have strong activation of dopamine pathway: morphine heroin fentanyl binds to opioid receptors and also inhibit gaba neurons.
