Stimulants Nicotine Chapter 5 Pages 133 144 Primary psychoactive and addictive agent in tobacco Complex action short puffs stimulating effect long puffs depressant effect Acts as agonist of acetylcholine activates muscles main NT in PNS because it moves muscles increases alertness Addictive withdrawal symptoms include nervousness anxiety drowsiness lightheadedness headaches Relapse probability is high related closely to cancer Puts extra wear and tear on important systems such as the cardiovascular system more likely to develop heart problems Primary psychoactive drug in coffee Produces arousal alertness and decreased sleepiness Acts as agonist of dopamine and acetylcholine by increasing their release in the synaptic cleft Withdrawal symptoms include headaches fatigue anxiety shakiness and craving Very common addiction Caffeine Psychedelics cause perceptual distortions of objects time self often accompanied by euphoria Addictive Their use correlates with neural damage LSD similar to serotonin bind to serotonin receptors Ecstacy MDMA causes release of dopamine and serotonin kills serotonin neurons in monkeys Angel dust PCP produces schizophrenia like symptoms in humans hallucinations Inhibits glutamate receptors antagonist Increases activity in dopamine pathways agonist Marijuana Dried and crushed leaves and flowers of Indian hemp plant Major psychoactive ingredient THC Particularly concentrated in the dried resin of the plant hashish Given to assassins so they would go and kill someone THC acts as agonist of NT anandamide and 2 AG by binding to their receptors cannabinoid receptors directly bind widely distributed in CNS usually receptors are only found in certain regions of CNS Anandamide and 2 AG may play important role in the regulation of mood memory appetite and pain perception Addiction Withdrawal symptoms are associated with stopping use anxiety irritability stomach cramps Not much evidence to suggest that it s a portal drug much more likely that other drugs within the same class will lead to addiction rather than a drug from another class addiction to pain killers leads to other opiate use Definition preoccupation with obtaining drug compulsive use of drug high tendency of relapse after quitting Withdrawal Avoidance Hypothesis Major factor in development of addiction is that person is trying to avoid the experience of withdrawal symptoms Withdrawal negative reaction when drug use is stopped Definitely an important factor especially in maintaining addiction but hypothesis can t explain all addictions Does not explain use of drug before dependence develops which takes awhile Different areas of the brain seem to be involved in withdrawal and addiction PeriVentricular PeriAqueductal Gray cluster of neurons thought to be involved with addiction Midbrain Inject drug opiate into this center of the brain until dependence was developed remove it distress displayed demonstrate that this area is involved with withdrawal Modified allow rat to press lever to self inject the drug never happened showed that region was involved with withdrawal but not addiction of a substance Ventral Tegmental Area midbrain Mice quickly learned how to press lever to self inject the drug addiction If the effect of the drug was blocked expected distress which never happened no withdrawal Medial Forebrain Bundle Nucleus Accumbens axons Network known as MesolimboCortical Dopamine System VTA MFB NA experience addiction through this System s true adaptive function was the reward system network geared to reward any stimuli not just drugs let people know what s good and bad evolution Ex of when used win a million dollars get married sex special rare moments biologically advantageous situations Drugs hijack this system to make people feel this good for no reason create gap between person s experience and the world Knowing what s good and bad more towards the innate side rather than the learning side of the spectrum Nucleus Accumbens NAcc Rich in dopamine receptors Double dissociation Nearly all abused drugs increase dopamine levels in NAcc Reducing dopamine level in NAcc decreases rewarding effects of drug Increase in dopamine in NAcc may be the neural basis for rewarding basis for rewarding effect of drugs MDS may be part of a general reward system Electrical stimulation of the Medial Forebrain Bundle is rewarding in rats Increase dopamine levels in NAcc Involved in rewarding effects for behaviors of basic importance sex feeding Increase dopamine level in NAcc both humans and not HOWEVER Apparent paradox lower number of dopamine receptors in drug users possible innate trait reward deficiency syndrome vulnerability to drug abuse Lower number of receptors make their reward experience less therefore more likely to seek a way to enhance their experience Dopamine activity in MDS cannot account for all addictions Benzodiazepines affect glutamate and GABA levels not dopamine May continue to use drugs even when the effects are no longer pleasurable withdrawal avoidance hypothesis Possible important role in learning Just seeing drug paraphernalia can evoke craving in drug addicts Dopamine levels in MDS may act as teaching signals emphasizing importance of relevant stimuli spike in dopamine production after heroin other drug injected quickly go back down even though drug is still in system Doesn t explain all addictions but it explains a lot Ending Dependence on Drugs Overcoming withdrawal symptoms Difficult with nicotine and opiates Potentially life threatening with alcohol Fighting against relapse Pharmacological Treatments Agonist treatments Freud quit cocaine addiction but could never quit smoking cigars Replace addicting drug with another that has a similar effect that is supposedly safer less likely to overdose and access is controlled by a medical professional provide lower amount of substitute to manage withdrawal and quit both drugs Methadone for heroin addiction Nicotine gum kind of more principal than exact definition Not really that effective although been used for a long time Criticisms get individual addicted to something else not getting to the root of the problem Positives patient has accepted remission better than doing nothing