These Notes are not intended to replace your own notes or studying Some words have been taken out and replaced with blanks as per the professor s request Notes for the Final Exam 4 8 When the R O Relation Matters Theories and Neurobiological Mechanisms Neurobiological Mechanisms Multiple systems view There appears to be some subdivision of labor wherein different structures are respon sible for different things Evidence lesioning a structure disrupts a class of learning processes Problem with lesioning a structure it causes a disruption in learning and affects several processes and structures that don t really have anything to do with the learning situation Seeking dissociations Better way of testing multiple memory systems Design a task that generates opposing performance results depending on what pro cesses are affected hold all other things constant Example Performance in a T maze Packard Recall that in a T maze rats learn to turn once to reach a goal box Two explanations for why learning occurs 1 the rats learn to get to the correct spatial location that provides reinforcement 2 they simply learn to turn right After you train them test them from the opposite direction it s a simple way of asking the rat what it learned if it is they should turn right if it is they should go to the correct spatial location that was reinforced As it turns out what the rats do changes as a function of training little bit of training they turn left respond spatially lots of training they turn right respond based on habit in other words early in training they respond according to spatial location 1 of 16 These Notes are not intended to replace your own notes or studying Some words have been taken out and replaced with blanks as per the professor s request and later in training they respond in terms of habit Impact of lesioning hippocampus versus caudate hippocampus lesion they don t respond on the basis of spatial location this shows that the hippocampus is necessary for spatial learning another set of structures basal ganglia specifically the caudate if le sioned gets rid of the habit learning this shows that the caudate is necessary for habit learning Notice here that we keep all the other variables the same so the differ ence MUST be due to the structures affected Thus this task is a double dissociation task Delayed discounting neurobox 6 3 we have more difficult choices to make than turning right or left Choice depends on both reward magnitude and value Magnitude What is it Value Estimate of relative gain both now and in the future what will the reward mean in the long run Requires a form of working memory to evaluate alternatives We know now that there are two separate systems which evaluate reinforcers Habit caudate concerns immediate reward factor magnitude To estimate value we need a form of working memory to weigh differ ences Has to do with executive control Orbitofrontal cortex evaluates long term value Part of the prefrontal cortex Evidence Impact of lesions imaging you don t notice reinforcement contingencies have changed you don t weigh the alternatives you get impulsive you can t delay gratification Studied in the laboratory as delayed discounting do you want 10 now or 100 in 5 min utes 1 day 6 months 2 years the value of a reinforcer declines as a function of how long you have to wait to obtain it Lesioning the basal ganglia caudate improves ability to delay gratification It is thought these findings are particularly relevant to addictive behavior Addicts choose immediate rewards over delayed BOX 7 1 even if the reward is the drug they re addicted to weak executive control choose to do something in the immediate despite the long term adverse effects 2 of 16 These Notes are not intended to replace your own notes or studying Some words have been taken out and replaced with blanks as per the professor s request fMRI delayed reward lights up orbitofrontal cortex immediate reward lights up caudate When Both the S and the R O Relation Matter Basic Properties stimuli SD a signal that tells the animal when an instrumental relationship is in effect example hearing a tone S signals the animal to bar press for food R O The signal SD and the R O both matter Appetitive Tone Food Aversive Tone Shock the instrumental response occurs in the context of specific environmental stimuli the signal is a conditional cue Introduces opportunity for additional forms of learning Setting the occasion to respond Tone Food and Tone Shock are CS US relationships The tone thus ac quires Pavlovian value and becomes a motivator for behavior Chinese idiographs Meaningless symbols to us If asked to sort a stack of them according to which ones you like and which you don t like you ll do it randomly If presented on a computer with half followed by a flashed smiling face you ll choose the idiographs that were followed by the face unaware that you did so a mask of noise is presented after the face so you ll deny having seen it The idiographs attained Pavlovian value by being paired with the smiling face and influenced your actions all without you knowing Factor Theory Stems from the idea that Pavlovian conditioning can influence instrumental behavior Recall avoidance learning there is a negative contingency b w the instrumental re sponse turning the wheel and shock Theory assumes that 2 mechanisms are involved in avoidance learning 1 the signal has a Pavlovian value CS US relationship 2 there is an instrumental reinforcement of the avoidance behavior by the signal It was thought at first that absence of shock is presumably reason that avoidance re sponses occur There s a problem with this explanation how can we say a nonoccurrence is re inforcing It doesn t seem complete something s missing TFT gives a better explanation Early in avoidance training the tone has no value like the idiographs The ani mal learns to perform the instrumental response turning the wheel to turn off shock In those 3 of 16 These Notes are not intended to replace your own notes or studying Some words have been taken out and replaced with blanks as per the professor s request early trials the tone predicts shock the animal thus learns to hate the tone because it means a shock is coming Once the animal learns to do the IR completely what reinforces the behavior is not shock but fear of the tone There s no nonoccurrence here The animal is not responding on the basis of fu ture expectation of an aversive event It is responding because it is afraid of