Physiological Psychology

1. Learning and Memory I Physiological Psychology

2. Learning, Memory, Amnesia, and Brain Functioning • An early influential idea regarding localized representations of memory in the brain suggested physical changes occur when we learn something new. • One popular idea was that connections grow between areas of the brain.

3. Types of learning and memory • Ivan Pavlov researched classical conditioning. Now known as Pavlovian conditioning. • Pairing of two stimuli changes the response to one of them. • Presentation of a conditioned stimulus (CS) is paired with an unconditioned stimulus (US). • US automatically results in an unconditioned response (UR). • After several pairings, response can be elicited by the CS without the US, which is known as a conditioned response (CR).

4. What is being learned in Pavlovian conditioning. • Associations are being formed • CS-US associations • Pavlovian conditioning allows us to establish relationships among stimuli in our world.

5. In operant conditioning, responses are followed by reinforcement or punishment that either strengthen or weaken a behavior. • Reinforcers are events that increase the probability that the response will occur again. • Punishment are events that decrease the probability that the response will occur again. • Operant conditioning allows us to learn about the consequences of our behavior. • Behavior is shaped.

7. Pavlov believed that conditioning strengthened connections between the CS center and US center in the brain. • Karl Lashley (1920’s – 1950’s) – the search for the engrams • physical representations of what had been learned. • Believed that a knife cut should abolish the newly learned response.

9. Lashley’s studies attempted to see if disrupting certain connections between cortical brain areas would disrupt abilities to learn associations. • Found that learning and memory did not depend on connections across the cortex • Also found that learning did not depend on a single area of the cortex.

10. Lashley proposed two key principles about the nervous system: • Equipotentiality – all cortical areas can substitute for each other as far as learning is concerned. • Mass action – the reduction in learning is proportional to the amount of tissue destroyed, and the more complex the learning task, the more disruptive lesions are. • the cortex works as a whole, not as solitary isolated units.

11. Thompson and colleagues - engram for Pavlovian conditioning is located in the cerebellum, not the cortex. • During conditioning, changes occur in cells of one nucleus of the cerebellum called the lateral interpositus nucleus (LIP). • Note: a change in a brain area does not necessarily mean that learning necessarily took place in that area.

12. Fig. 13-4, p. 388

13. Suppression of activity in the LIP led to a condition in which the subject displayed no previous learning. • As suppression wore off, the animal began to learn at the same speed as animals that had no previous training. • But suppression of the red nucleus also led to a similar condition. • Later assumed that the learning did occur in the LIP, as it was the last structure that needed to be awake for learning to occur.

14. Consensus now is that Pavlovian conditioning is not isolated to one brain area. • Instead, depends on the modality of what is being learned • E.g., nictitating membrane is cerebellum • E.g., fear conditioning takes place in amygdala

15. Hebb (1949) differentiated between two types of memory: • Short-term memory – memory of events that have just occurred. • Long-term memory – memory of events from previous times. • Elaborated by Atkinson and Shiffrin • Sensory memory • Short-term memory • Long-term memory

16. Sensory memory exists within the senses themselves • very short (about 0.5 seconds) • Vision: iconic memory • Hearing: echoic memory

17. Short-term Memory • An immediate memory for stimuli that have just been perceived • The content of consciousness • Like RAM on a computer • Duration: 20-30 seconds • Can be maintained: rehearsal • Capacity • Miller’s magical number: 7±2 chunks of information • Displacement within STM

18. Long-term Memory • More permanent memory • Like the hard-drive of the computer • Duration is permanent • Capacity is seemingly endless • Common approach: split into different types of LTM • Atkinson-Shiffrin model as an integrated model • Sensory memory  STM  LTM

19. Atkinson-Shiffrin model as an integrated model • Sensory memory  STM  LTM

20. Later research has weakened the distinction between STM and LTM. • Some memories do not qualify as distinctly short-term or long-term. • Working Memory • Proposed by Baddeley as an alternative to short-term memory. • Emphasis on temporary storage of information to actively attend to it and work on it for a period of time.

21. Three major components of working memory include: • Phonological loop – Stores auditory input • Visuospatial sketchpad – Stores visual input. • Central Executive – Directs attention and determines which items to store.

22. Testing memory • The delayed response task is a test of working memory which requires responding to a stimulus that one heard or saw a short while earlier. • Increased activity in the prefrontal cortex during the delay indicates storing of the memory. • The stronger the activation, the better the performance.

24. Decline in WM • Older people often have impairments in working memory. • Changes in the prefrontal cortex assumed to be the cause. • Declining activity of the prefrontal cortex in the elderly is associated with decreasing memory. • Increased activity is indicative of compensation for other regions in the brain.

25. Amnesia is the loss of memory. • Studies on amnesia help to clarify the distinctions between and among different kinds of memories and their mechanisms. • Different areas of the hippocampus are active during memory formation and retrieval. • Damage results in amnesia.

26. Patient HM is a famous case study in psychology who had his hippocampus removed to prevent epileptic seizures. • Afterwards Patient HM had great difficulty forming new long-term memories. • STM or working memory remained intact. • Suggested that the hippocampus is vital for the formation of new long-term memories.

27. Henry Gustav Molaison (February 26, 1926 – December 2, 2008), famously known as HM • H.M., was an American memory disorder patient who was widely studied from late 1957 until his death.[1][2]His case played a very important role in the development of theories that explain the link between brain function and memory, and in the development of cognitive neuropsychology, a branch of psychology that aims to understand how the structure and function of the brain relates to specific psychological processes. Before his death, he resided in a care institute located in Windsor Locks, Connecticut, where he was the subject of ongoing investigation.[3] His brain now resides at UC San Diego where it was sliced into histological sections on December 4, 2009

28. Fig. 13-5ab, p. 391

29. Patient HM showed massive anterograde amnesia after the surgery. • Two major types of amnesia include: • Anterograde amnesia – the loss of the ability to form new memory after the brain damage occurred. • Retrograde amnesia – the loss of memory events prior to the occurrence of the brain damage.

30. Patient HM had difficulty with declarative and episodic memory. • Episodic memory: ability to recall single events. • Declarative memory: ability to put a memory into words. • Patient HM’s procedural memory remained intact. • Procedural memory: ability to develop motor skills (remembering or learning how to do things).

31. Patient HM also displayed greater “implicit” than “explicit” memory. • Explicit memory – deliberate recall of information that one recognizes as a memory. • Implicit memory – the influence of recent experience on behavior without realizing one is using memory.

32. Research in differences in hippocampus size has revealed conflicting results. • Some evidence suggests that a smaller hippocampus is associated with better memory performance. • Hypothesis is that apoptosis improves hippocampus functioning. • Generally, hippocampus activity is more associated with memory performance than is the size.

33. Research of the function of the hippocampus suggests the following: • The hippocampus is critical for declarative (especially episodic) memory functioning. • The hippocampus is especially important for spatial memory. • The hippocampus is especially important for configural learning and binding.

34. Research in the role of the hippocampus in episodic memory shows damage impairs abilities on two types of tasks: • Delayed matching-to-sample tasks – a subject sees an object and must later choose the object that matches. • Delayed non-matching-to-sample tasks– subject sees an object and must later choose the object that is different than the sample.

36. Damage to the hippocampus also impairs abilities on spatial tasks such as: • Radial mazes – a subject must navigate a maze that has eight or more arms with a reinforcer at the end. • Morris search task – a rat must swim through murky water to find a rest platform just underneath the surface.

37. Hippocampus damage also impairs configural learning and binding. • Configural learning – learning in which the meaning of a stimulus depends on what other stimuli are paired with it. • Animals with damage can learn configural tasks but learning is slow. • Indicates hippocampus is not necessary for configural learning, but is involved.

38. Evidence suggests that the hippocampus is important in the process of “consolidation”. • Consolidation is the process of strengthening short-term memories into long-term memories. • Damage to the hippocampus impairs recent learning more than older learning. • The more consolidated a memory becomes, the less it depends on the hippocampus.

39. Reverberating circuits of neuronal activity were thought to be the mechanisms of consolidation. • Consolidation is also influenced by the passage of time and emotions. • Small to moderate amounts of cortisol activate the amygdala and hippocampus where they enhance storage and consolidation of recent experiences. • Prolonged stress impairs memory.

40. Review of types of learning • Pavlovian conditioning • Learning to associate two objects together • Operant or instrumental conditioning • Learning about the consequences of behavior • How is learning represented in the brain? • Search for the engram • What about at the level of the neuron? • Learning as neural plasticity

41. Hebbian learning • Donald Hebb (1949) - When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A's efficiency, as one of the cells firing B, is increased.

42. Nonassociative learning • Habituation – Reduction in response to a stimulus upon repeated presentations • Examples • Living near a train track • Working in a smelly environment • http://go.owu.edu/~deswartz/videos/habituation.mov • Habituation is learning • Not sensory adaptation or fatigue • Can last over long periods of time (long-term habituation)

44. Sensitization • Opposite of habituation • Increased response with repeated stimulation. • Intense and salient stimuli • Examples: • Pain response • Annoying sounds • Fear-potentiated startle • Everyday examples?

45. Habituation and sensitization in Aplysia