10 Pages
Unlock Document

Rutsuko Ito

lec06 lecture overview 1. what do we associate with reward 2. neurochemical substrates of self-administration 3. dopamine function in reward 4. hedonic orofacial reactions to reward 5. incentive salience hypothesis what is reward and why do we work for it? 1. feeling of pleasure (hedonic impact) that accompanies certain acts / experiences 2. to recompense in recognition of someone's behavior or actions 3. anticipatory aspect of reward (pre-reward) vs consumption aspect of reward (post reward) a. different neural basis for the two aspects of reward neural and neurochemical basis of reward 1. experimental approaches a. intra-cranial self stimulation i. animals will work for direct electrical stimulation of certain areas in the brain ii. IC SS b. drug self adminstration i. animals will voluntarily self administer drugs abused by humans accidental beginnings of ICSS 2. rats will lever press at a high rate for electrical stimulation of certain area of the brain a. will do this at the cost of eating and drinking 3. led to beginning of a way of mapping circuitries in the brain responsible for reward ICSS in mice 1. note what the mouse does while it is during the wheel a. it is trying to eat the wheel i. behaviors associated with eating 2. suggests brain regions involved with ICSS responsible for consumatory aspect of reward 3. extinction period  cuts off behavior increase (plateaus) 4. does not build up tolerance 5. eating food  satiation a. will ICSS lead to a satiated state? ICSS positive sites 1. medial forebrain bundle important in reward for self stimulation 2. stimulation of limbic areas did not induce a high response rate of ICSS ICSS punishment sites 1. periventricular system 2. a lot of hypothalamic nuclei other hot spots 1. do not need to memorize 2. illustrates a point that many areas of brain support ICSS 3. may not be exclusively associated with reward neural mechanisms of ICSS 1. high correspondence of medial forebrain bundle with catecholaminergic systems importance of dopamine pathways 2. no effect when stimulating noradrenalinergic systems effect of dopamine manipulations on ICSS 3. increased rates of ICSS (lever pressing for electrical stimulations) 4. systemic amphetamine injection a. systemic  animal gets injection into the (body?) system b. intracerebral  infusing directly into the brain c. results i. makes ICSS more rewarding ii. lever press more 5. systematic pimozide injection a. results i. attenuation of ICSS ii. increases brain stimulation threshold nucleus accumbens dopamine and ICSS 1. dopamine important in governing ICSS behavior 2. micro-infuse dopamine antagonists directly into nucleus accumbens a. led to decreased ICSS i. conclusion: 1. nucleus accumbens is important in supporting ICSS behavior with dopamine rate of ICSS 1. very useful in mapping out reward pathways 2. is it rewarding effects of ICSS that is important or is it something else? a. therefore important to look at rates of ICSS to check for confounding factors drug self administration some of the drugs self administered by animal species interesting features of drug self administration 1. lower doses of a drug results in greater response rates 2. there is titration effect where they self-regulate the amounts they take in (dont usually overdose) a. as if they are trying to maintain constant plasma level of drug b. binges can occur when given unlimited access to drug rate of responding - reward efficacy 1. optimal dose of drug that results in maximizing lever pressing a. doses below optimal dose does not support self-administration b. doses above optimal dose 2. decrease in response rate does not mean reward is going down, it just means they feel more of the drug so they dont need to administer the drug as much importance of dopamine 1. dopamine receptor antagonism shifts the curve to the right a. this means that higher doses are required to maintain the same level of response b. for doses below optimum up to optimum level i. responding is lower than usual c. for doses above optimum level i. responding needs to be higher than normal what do real dose-response curves look like? 2. dopamine receptor antagonism results in more responses past optimum level a. whether it is D1 / D2 / D3 antagonist or agonist it should display the same curve remember 3. effects of DA receptor agonism / antagonism on ICSS and drug self administration are different a. increased ICSS  increased rewarding effects of electrical stimulation b. increased self administration  decreased rewarding effects of drug i. drugs set in protective mechanism  titration mechanism ii. ICSS do not have any protective mechanism  behavior keeps on going neural substrate of reinforcement 4. nucleus accumbens is implicated in self-adminstration behavior a. amphetamine is self administered directly in the nucleus accumbens but not into lateral ventricle i. results 1. amphetamine infusion into nucleus accumbens is driving lever press response (rewarding) 2. amphetamine infusion into lateral ventricle is not driving lever pressing as much drugs and dopamine 1. in vivo microdialysis study 2. many drugs of abuse can cause increase in dopamine release in nucleus accumbens food and dopamine 1. missed this slide hedonia hypothesis of reward and dopamine 2. all forms of reward are mediated by the mesolimbic dopamine system a. different modes of action inducing increases in dopamine i. dopamine is central to the action of these drugs support for dopamine = hedonia 3. dopamine mediates hedonic response for reward (pleasure) 4. conditioned cue preference + context + multiple cues a. pair one of the contexts with drug and another context with no drug i. results 1. spend more time in context associated with drug 2. CPP with amphetamine is attenuated by dopamine lesions of the nucleus accumbens (with 6-OHDA) 3. CPP is induced by amphetamine infusions selectively into the
More Less

Related notes for NROC61H3

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.