PSY2304 Biological Basis of Behaviour Lecture 6: Memory PDF

Ian McLarenLecture 6: MemoryPSY2304Biological Basis of BehaviourTo h e a r t h e p r e s e n t a t i o n a s y o u g o t h r o u g h t h e s l i d e s , p l e a s e g o t o t h e S l i d e S h o w m e n u and click on “play from start”. You can also start from the sl...

Ian McLarenLecture 6: MemoryPSY2304Biological Basis of BehaviourTo h e a r t h e p r e s e n t a t i o n a s y o u g o t h r o u g h t h e s l i d e s , p l e a s e g o t o t h e S l i d e S h o w m e n u and click on “play from start”. You can also start from the slide you are on using “play from current slide”. If you want subtitles, then click “always use subtitles”. Finally, you can just look at the slides without hearing me by using the up and down arrows after you open it.What I say in this presentation is either on the slides or in the notes that accompany them (see the notes page in PowerPoint on the View menu). Please click on the slide to advance after I’ve finished speaking or use the forward (and back) arrows to navigate. To-day’s questionsWe’vestudied animal learning -how to get the information in if you like -but what about how to access it again?We’ll look at a number of issues in animal memory in this presentation: Including their ability to remember in the long term, the nature of forgetting (do they lose the information or is it still there somewhere?), and examine the evidence for episodic memory in animals. Memory taxonomy (simplified from human memory theory)•Working memory vs long term memory–Short-term storage vs. long term retention•Episodic vs semantic/reference–My first day at University (What? Where? When?) vs knowing that Rescorla-Wagner is a model of associative learning (how the world works) Forgetting•Nature of forgetting: Target memories could be lost because of –Proactive interference from information acquired PRIOR to target–Retroactive interference from information acquired AFTER target–Decaydue to the passage of time.–We’llconsider evidence for each of these mechanisms for forgetting in the online lecture. Here we are more concerned with whether the forgotten memory is actually erased or simply harder to retrieve. Long-Term Memory•We will consider retention over intervals of hours and days (and longer) rather than minutes.•The big issues here are what transformations in the memory trace take place between original encoding and final storage, and whether memories that are forgotten are lost completely or merely become inaccessible. The last point refers to the idea that forgetting should be considered as a failure to retrieve, the memory is still there, it’s just that the animal is unable to access it under present conditions. Consolidation•The idea here is that the initial memory trace is fragile and relatively short-term, and needs to be transformed (consolidated) into a more durable trace for the long term.•Many studies looking at this idea have used avoidance learning in the shuttle box. In this paradigm the rat (typically) is trained to move from one side to the other to avoid shock. Shuttle Box Physiological disruption of consolidation•Several types of physiological trauma prevent learning if and only if they occur shortly after a stimulus or reward•Examples include ECS(electroconvulsive shock: Duncan 1949), sudden heating or cooling, drugs, concussive impact (American Football). •Thus, after learning a shuttle response to avoid shock, ECS given shortly after training will disrupt performance after a delay, whereas ECS given after that delay and just before test will not be as effective. Avoidance as a function of time interval to ECS 0 2 4 6 8 10 12 14 20 sec 40 sec 60 sec 4 min 15 min 1 hr 4 hr 14 hr Control Time interval Mean avoidance Adapted from Duncan (1949) Retrieval•The animal has to retrieve a memory to make use of it. Many studies indicate that most forgetting should be viewed as a failure to retrieve rather than a loss of storage.•Perhaps the most impressive of these is the class of study that falls under the heading of “Reactivation”. In these experiments memories that are apparently “lost”are successfully retrieved following a reminder treatment.•This type of study poses difficulties for consolidation theory. If a memory has not been consolidated, and hence is lost, how can it later be retrieved? Reactivation study by Gordon (1981) 0 2 4 6 8 10 12 1 2 3 Duration of confinement Median Latency 01575Gordon’s (1981) paper reports this reactivation study in the shuttle box. Times are in seconds. The delay between training and test was three days. Reactivation can also restore memories after ECS (Gordon and Mowrer, 1980). Capacity of animal long-term memory•Capacity of long term memory:–Vaughan & Greene's picture recognition experiment with pigeons:•random pseudoconcepttask: slides of trees arbitrarily divided into positive and negative original training with 40 positives, 40 negatives; •new slides introduced once old ones mastered •successful training up to 640 slides •birds trained with 320 slides were then rested for 2 years; on re-testing there was some forgetting but quick recovery Episodic Memory?•Less clear whether we can claim episodic memory in animals•Roberts (2002) claims that animals are “stuck in time”–they cannot do what Suddendorfcalls “Mental time travel”•Clayton and Dickinson have famously argued that scrub jays can, in fact, do just this. What/where/ when memory in caching jays?(Clayton)•Clayton and Dickinson claim that food-storing birds e.g. scrub jays show true episodic memory•Lab experiments show they can remember:–Whatthey stored (waxworms or peanuts) –recover worms rather than peanuts because they are preferred food–Wherethey stored it (scatter hoarders are very good at this in general)–Whenthey stored it –recover peanuts instead of worms if they stored them more than 4 hours before, because worms are perishable Articles cited•Clayton, N. S., & Dickinson, A. (1999). Scrub jays (Aphelocomacoerulescens) remember the relative time of caching as well as the location and content of their caches. Journal of Comparative Psychology, 113, 403-416.•Clayton, N. S., Griffiths, D. P., Emery, N. J., & Dickinson, A. (2001). Elements of episodic-like memory in animals. Philosophical Transactions of the Royal Society of London, series B: Biological Sciences, 356, 1483-1491.•Cook, R. G., Levison, D. G., Gillett, S., & Blaisdell, A. P. (2005). Capacity and Limits of Associative Memory in Pigeons. Psychonomic Bulletin and Review•Duncan, C. P. (1949).The retroactive effect of electroshock on learning. Journal of Comparative and Physiological Psychology, 42, 32-44. •Suddendorf, T., & Corballis, M. C. (1997). Mental time travel and the evolution of the human mind. Genetic Social and General Psychology Monographs, 123, 133-167.•Vaughan, W. and Greene, S. L. (1984). Pigeon visual memory capacity. Journal of Experimental Psychology: Animal BehaviourProcesses, 10, 256-271. Reading•Pearce 3rd Ed. Ch. 8 &9.•Pearce 2nd Ed. Ch. 6