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Learning and Memory

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  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 (continued) • 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 There Are Several Kinds of Memory and Learning 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., Henry Molaison, suffered from severe epilepsy. Because his seizures began in the temporal lobes, a decision was made to remove the anterior temporal lobes on both sides. H.M.’s surgery removed the amygdala, the hippocampus, and some cortex.

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

  8. 17 There Are Several Kinds of Memory and Learning • Retrograde amnesia is the loss of memories formed before onset of amnesia and is not uncommon after brain trauma. • Anterograde amnesia is the inability to form memories after onset of amnesia. H.M. had normal short-term memory but had severe anterograde amnesia.

  9. 17 There Are Several Kinds of Memory and Learning Damage to the hippocampus can produce memory deficits. H.M. was able to show improvement with motor skills but could not remember performing them (i.e. he could not recall the tasks verbally.). H.M.’s memory deficit was confined to describe the tasks he performed.

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

  11. 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. (Things we are aware that are learned.) • Nondeclarative (procedural) memory deals with how—shown by performance rather than conscious recollection.

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

  13. 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 left dorsal thalamus, bilateral damage to the mammillary bodies (limbic structures in the hypothalamus), and probable damage to the mammillothalamictract. Like Henry Molaison, he has short-term memory but cannot form declarative long-term memories.

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

  15. 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. Patients often confabulate—fill in a gap in memory with a falsification which they accept as true. Brain damage occurs in mammillary bodies and dorsomedial thalamus, similar to N.A., and to the basal frontal cortex.

  16. 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 and severe shrinkage of the hippocampus and parahippocampal cortex; his semantic memory is good.

  17. 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.

  18. Figure 17.5 Subtypes of Declarative and Nondeclarative Memory

  19. 17 Memory Has Temporal Stages: Short, Intermediate, and Long • Iconic memories are the briefest memories and store sensory impressions that only last a few seconds. • Short-term memories (STMs) usually last only for up to 30 seconds or throughout rehearsal. Short-term memory is also known as working memory.

  20. Figure 17.6 Stages of Memory Formation

  21. 17 Memory Has Temporal Stages: Short, Intermediate, and Long Working memory can be subdivided into three components, all supervised by an executive control module: • Phonological loop—contains auditory information • Visuospatial sketch pad—holds visual impressions • Episodic buffer—contains more integrated, sensory information

  22. 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.

  23. 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).

  24. Figure 17.7 Serial Position Curves from Immediate-Recall Experiments (Part 1)

  25. Figure 17.7 Serial Position Curves from Immediate-Recall Experiments (Part 2)

  26. 17 Memory Has Temporal Stages: Short, Intermediate, and Long Long-term memory has a large capacity. Information can also be forgotten or recalled inaccurately.

  27. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain A functional memory system incorporates three aspects: • Encoding—sensory information is passed into short-term memory. • Consolidation—short-term memory information is transferred into long-term storage. • Retrieval—stored information is used.

  28. Figure 17.8 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 Thus, the prefrontal cortex and parahippocampal cortex are important for consolidation. These mechanisms reflect hemispheric specializations(left hemisphere for language and right hemisphere for spatial ability).

  31. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain The engram, or memory trace, is the physical record of a learning experience and can be affected by other events before or after. Each time a memory trace is activated and recalled, it is subject to changes.

  32. 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.

  33. Figure 17.9 Encoding, Consolidation, and Retrieval of Declarative Memories

  34. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain In posttraumatic stress disorder (PTSD, characterized as reliving and being preoccupied by traumatic events), memories produce stress hormones that further reinforce the memory. GABA, ACh, and opioid transmission can also enhance memory formation in animal models. Treatments that can block chemicals acting on the basolateral amygdala may alter the effect of emotion on memories.

  35. Box 17.1 The Amygdala and Memory

  36. 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 disruption or alteration. Reconsolidation is the return of a memory trace to stable long-term storage after it’s temporarily volatile during recall.

  37. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain Reconsolidation can distort memories. Successive activations can deviate from original information. New information during recall can also influence the memory trace.

  38. 17 Successive Processes Capture, Store, and Retrieve Information in the Brain Leading questions can lead to ‘remembering’ events that never happened. ‘Recovered memories’ and ‘guided imagery’ can have false information implanted into the recollection.

  39. Figure 17.10 Are “Recovered” Memories Reliable?

  40. 17 Different Brain Regions Process Different Aspects of Memory Testing declarative memories in monkeys: • Delayed non-matching-to-sample task—a test of object recognition memory, where the subject must choose the object that was not seen previously.

  41. Figure 17.11 The Delayed Non-Matching-to-Sample Task

  42. 17 Different Brain Regions Process Different Aspects of Memory Medial temporal lobe damage causes impairment on the delayed nonmatching-to-sample task. The amygdala is not necessary for declarative memory tasks. The hippocampus (in conjunction with the entorhinal, parahippocampal) and perirhinal cortices, is important for these tasks.

  43. Figure 17.12 Memory Performance after Medial Temporal Lobe Lesions

  44. 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.

  45. 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.

  46. Figure 17.13 My Story versus Your Story

  47. 17 Different Brain Regions Process Different Aspects of Memory Early research indicated that animals form a cognitive map—a mental representation of spatial relationships. Latent learning is when acquisition has taken place but has not been demonstrated in performance tasks.

  48. Figure 17.14 Biological Psychologists at Work

  49. 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. Place cells remap when a rodent is placed in a new environment.

  50. 17 Different Brain Regions Process Different Aspects of Memory Grid cells and border cells are neurons that fire when animal is at an intersection and at the perimeter of an abstract grid map, respectively.