Learning and Memory

1. Learning and Memory

2. 17 Learning and Memory Functional Perspectives on Memory • There Are Several Kinds of Memory and Learning • Memory Has Temporal Stages: Short, Intermediate, and Long • Successive Processes Capture, Store, and Retrieve Information in the Brain • Different Brain Regions Process Different Aspects of Memory

3. 17 Learning and Memory Neural Mechanisms of Memory • Memory Storage Requires Neuronal Remodeling • Invertebrate Nervous Systems Show Plasticity • Synaptic Plasticity Can Be Measured in Simple Hippocampal Circuits

4. 17 Learning and Memory Neural Mechanisms of Memory (cont'd) • Some Simple Learning Relies on Circuits in the Mammalian Cerebellum • In the Adult Brain, Newly Born Neurons May Aid Learning • Learning and Memory Change as We Age

5. 17 Functional Perspectives on Memory Learning is the process of acquiring new information. Memory is: • The ability to store and retrieve information. • The specific information stored in the brain.

6. 17 There Are Several Kinds of Memory and Learning Patient H.M. suffers from amnesia, or memory impairment. • Retrograde amnesia is the loss of memories formed before onset of amnesia. • Anterograde amnesia is the inability to form memories after onset of a disorder.

7. 17 There Are Several Kinds of Memory and Learning Damage to the hippocampus can produce memory deficits. H.M.’s surgery removed the amygdala, the hippocampus, and some cortex. H.M.’s memory deficit was confined to verbal tasks.

8. Figure 17.1 Brain Tissue Removed from Henry Molaison (Patient H.M.)

9. Figure 17.2 Henry’s Performance on a Mirror-Tracing Task

10. 17 There Are Several Kinds of Memory and Learning Two kinds of memory: • Declarative memory deals with what – facts and information acquired through learning that can be stated or described. • Nondeclarative (procedural) memory deals with how – shown by performance rather than recollection.

11. Figure 17.3 Two Main Kinds of Memory: Declarative and Nondeclarative

12. 17 There Are Several Kinds of Memory and Learning Damage to other areas can also cause memory loss. Patient N.A. has amnesia due to accidental damage to the dorsomedial thalamus. Like Henry Molaison, he has short-term memory but cannot form declarative long-term memories.

13. Figure 17.4 The Brain Damage in Patient N.A.

14. 17 There Are Several Kinds of Memory and Learning Korsakoff’s syndrome is a memory deficiency caused by lack of thiamine – seen in chronic alcoholism. Brain damage occurs in mammillary bodies and basal frontal lobes. Patients often confabulate – fill in a gap in memory with a falsification.

15. 17 There Are Several Kinds of Memory and Learning Two subtypes of declarative memory: • Semantic memory – generalized memory. • Episodic memory – detailed autobiographical memory. Patient K.C. cannot retrieve personal (episodic) memory due to accidental damage to the cortex.

16. 17 There Are Several Kinds of Memory and Learning Three subtypes of nondeclarative memory : • Skill learning – learning to perform a task requiring motor coordination. • Priming – repetition priming – a change in stimulus processing due to prior exposure to the stimulus. • Conditioning – the association of two stimuli, or of a stimulus and a response.

17. Figure 17.5 Subtypes of Declarative and Nondeclarative Memory

18. 17 There Are Several Kinds of Memory and Learning Nonassociative learning involves a single stimulus presented once or repeated. Three types of nonassociative learning: • Habituation – a decreased response to repeated presentations of a stimulus. • Dishabituation – restoration of response amplitude after habituation. • Sensitization – prior strong stimulation increases response to most stimuli.

19. 17 There Are Several Kinds of Memory and Learning Associative learning involves relations between events. • In classical conditioning – Pavlovian conditioning – a neutral stimulus is paired with another stimulus that elicits a response. Eventually the neutral stimulus by itself will elicit the response.

20. 17 There Are Several Kinds of Memory and Learning • In instrumental conditioning – or operant conditioning – an association is made between: • Behavior (the instrumental response). • The consequences of the behavior (the reward).

21. 17 Memory Has Temporal Stages: Short, Intermediate, and Long • Iconic memories are the briefest and store sensory impressions. • Short-term memories (STMs) usually last only for seconds, or throughout rehearsal. Short-term memory is also known as working memory.

22. 17 Memory Has Temporal Stages: Short, Intermediate, and Long Working memory can be subdivided into three components, all supervised by a central executive: • Phonological loop – contains auditory information. • Visuospatial sketch pad – holds visual impressions. • Episodic buffer – contains more integrated information.

23. 17 Memory Has Temporal Stages: Short, Intermediate, and Long • An intermediate-term memory (ITM) outlasts a STM, but is not permanent. • Long-term memories (LTMs) last for days to years.

24. 17 Memory Has Temporal Stages: Short, Intermediate, and Long Mechanisms differ for STM and LTM storage, but are similar across species. • The primacy effect is the higher performance for items at the beginning of a list (LTM). • The recency effect shows better performance for the items at the end of a list (STM).

25. Figure 17.6 Serial Position Curves from Immediate-Recall Experiments

26. 17 Memory Has Temporal Stages: Short, Intermediate, and Long Long-term memory has a large capacity, but can be altered. The memory trace, or record of a learning experience, can be affected by other events before or after. Each time a memory trace is activated and recalled, it is subject to changes.

27. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain A functional memory system incorporates three aspects: • Encoding – sensory information is encoded into short-term memory. • Consolidation – information may be consolidated into long-term storage. • Retrieval – stored information is retrieved.

28. Figure 17.7 Hypothesized Memory Processes: Encoding, Consolidation, and Retrieval

29. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain Multiple brain regions are involved in encoding, as shown by fMRI. For recalling pictures, the right prefrontal cortex and parahippocampal cortex in both hemispheres are activated. For recalling words, the left prefrontal cortex and the left parahippocampal cortex are activated.

30. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain Consolidation of memory involves the hippocampus but the hippocampal system does not store long-term memory. LTM storage occurs in the cortex, near where the memory was first processed and held in short-term memory.

31. Figure 17.8 Encoding, Consolidation, and Retrieval of Declarative Memories

32. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain The process of retrieving information from LTM can cause memories to become unstable and susceptible to to disruption or alteration. Reconsolidation is the return of a memory trace to stable long-term storage, after recall.

33. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain Strong emotions can enhance memory formation and retrieval. Many compounds participate: acetylcholine, epinephrine, norepinephrine, vasopressin, the opioids, and GABA. Drugs that are agonists or antagonists of these can be involved.

34. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain In posttraumatic stress disorder (PTSD), memories produce a stress hormone response that further reinforces the memory. Treatments that can block chemicals acting on the basolateral amygdala may alter the effect of emotion on memories.

35. Box 17.2 The Amygdala and Memory

36. 17 Different Brain Regions Process Different Aspects of Memory Testing declarative memories in monkeys: • Delayed non-matching-to-sample task – must choose the object that was not seen previously. Medial temporal lobe damage causes impairment on this task.

37. Figure 17.9 The Delayed Non-Matching-to-Sample Task

38. Figure 17.10 Memory Performance after Medial Temporal Lobe Lesions

39. 17 Different Brain Regions Process Different Aspects of Memory Imaging studies confirm the importance of medial temporal (hippocampal) and diencephalic regions in forming long-term memories. Both are activated during encoding and retrieval, but long-term storage depends on the cortex.

40. 17 Different Brain Regions Process Different Aspects of Memory Episodic and semantic memories are processed in different areas. Episodic (autobiographical) memories cause greater activation of the right frontal and temporal lobes.

41. Figure 17.11 My Story versus Your Story

42. 17 Different Brain Regions Process Different Aspects of Memory Early research indicated that animals form a cognitive map – a mental representation of a spatial relationship. Latent learning has taken place but has not been demonstrated in performance tasks.

43. Figure 17.12 Biological Psychologists at Work

44. 17 Different Brain Regions Process Different Aspects of Memory The hippocampus is also important in spatial learning. It contains place cells that become active when in, or moving toward, a particular location. Grid cells and border cells are neurons that fire when animal is at an intersection or perimeter of an abstract grid map.

45. 17 Different Brain Regions Process Different Aspects of Memory In rats, place cells in the hippocampus are more active as the animal moves toward a particular location. In monkeys, spatial view cells in the hippocampus respond to what the animal is looking at.

46. 17 Different Brain Regions Process Different Aspects of Memory Comparisons of behaviors and brain anatomy show that increased demand for spatial memory results in increased hippocampal size in mammals and birds. In food-storing species of birds, the hippocampus is larger but only if used to retrieve stored food.

47. 17 Different Brain Regions Process Different Aspects of Memory Spatial memory and hippocampal size can change within the life span. In some species, there can be be sex differences in spatial memory, depending on behavior. Polygynous male meadow voles travel further and have a larger hippocampus than females or monogamous pine vole males.

48. Figure 17.13 Sex, Memory, and Hippocampal Size

49. 17 Different Brain Regions Process Different Aspects of Memory Imaging studies help to understand learning and memory for different skills: • Sensorimotor skills, such as mirror-tracing. • Perceptual skills – learning to read mirror-reversed text. • Cognitive skills – planning and problem solving.

50. 17 Different Brain Regions Process Different Aspects of Memory Imaging studies of repetition priming show reduced bilateral activity in the occipitotemporal cortex, related to perceptual priming. Perceptual priming reflects prior processing of the form of the stimulus.