LearningNeuralPlasticityI

LearningNeuralPlasticityI - 11/3/09 I. Overview Learning,...

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Unformatted text preview: 11/3/09 I. Overview Learning, Memory and Neural Plasticity Part 1 1 2 B. The major questions: (1) What are the processes which underlie the formation of memories? (2) What processes determine the strength of learning and memory? (3) Where are the changes underlying learning and memory located? Basic tenet: Learning IS (causes/results from) Brain Changes 3 The engram The thing in the place in the brain which is the memory 4 ----------------------------Where are the changes? ----------------------------- II. Humans with damage involving the hippocampus A.  H.M. (1950's): -bilateral removal of medial temporal lobe including hippocampus to treat chronic severe drug resistant epilepsy. 5 6 1 11/3/09 A. H.M. (1950's) 7 8 H.M. Chronic enduring anterograde (forward moving) amnesia -no new long term memories Only limited retrograde amnesia - interference with (or loss of) previously formed memories "Right now, I'm wondering. Have I done or said anything amiss? You see, at this moment everything looks clear to me, but what happened just before? That's what worries me. It's like waking from a dream; I just don't remember." H.M. Comment made between neuropsychological tests of memory. Milner, B (1970) “Memory and the medial temporal regions of the brain” In:Biology of Memory, pp. 29-50 10 9 On asked to remember the number “584” after 15 min without distractions: “ I have to believe in a world outside my own mind. I have to believe that my actions still have meaning, even if I can't remember them. I have to believe that when my eyes are closed, the world's still there. Do I believe the world's still there? Is it still out there?... The character Leonard in Memento (2000) 11 “It’s easy. You just remember 8. You see, 5, 8 and 4 add to 17. You remember 8, subtract it from 17 and it leaves you 9. Divide 9 in half and you get 5 and 4, and there you are, 584. Easy.” 12 2 11/3/09 On asked to remember the number “584” after 15 min without distractions: “It’s easy. You just remember 8. You see, 5, 8 and 4 add to 17. You remember 8, subtract it from 17 and it leaves you 9. Divide 9 in half and you get 5 and 4, and there you are, 584. Easy.” 1 minute later had no memory of any of this 13 14 15 16 “At the end of the 3 days H.M. was still ‘having a little debate with himself’ about which way to turn at the first choice point.” Normal subjects have error free performance after about 20 trials 17 B. Milner 18 3 11/3/09 Not impaired: IQ procedural learning (e.g., mirror tracing), motor skills perceptual abilities 19 20 Impaired "Knowing that" "memory with record" explicit memory declarative memory Intact "knowing how" "memory without record" implicit memory procedural learning (different words for the similar things) 21 Henry Molaison http://www.boston.com/bostonglobe/obituaries/articles/2008/12/06/ henry_molaison_amnesiac_and_study_subject/ http://www.nytimes.com/2008/12/05/us/05hm.html 1929-2008 22 B. R.B. (1980's) bilateral ischemic damage limited to the hippocampus R.B.'s impairments were less severe than H.M.'s but were similar in nature suggesting that the hippocampus is an important contributor to the lost functions. 23 24 4 11/3/09 CA1 C. Altogether what these studies tell us: CA1 25 26 The engram The thing in the place in the brain which is the memory Humans with damage involving the hippocampus -impairments in converting some short term (explicit/ episodic/ declarative) memories into long-term memories 27 28 Spatial Memory Test III. Hippocampal Place Cells Morris Water Maze Cells that are most active when a rat is in a particular position relative to stable cues in the environment. 29 30 rats ability to learn to swim is impaired if the hippocamus is damaged 5 11/3/09 hippocamus of rats CA1 pyramidal neurons in the hippocampus 31 32 Example of position-specific place cell firing Example of position-specific place cell firing place cells fires more at a certain orientation 33 increases firing significantly and 34 Example of position-specific place cell firing Example of position-specific place cell firing notice the place cell does not care where the rat is pointing. The fire based on where the rat think it is, not where it's looking 35 36 6 11/3/09 Example of position-specific place cell firing Example of position-specific place cell firing 37 38 Example of position-specific place cell firing Example of position-specific place cell firing 39 40 don't confuse place cells with place fields. Place fields is the part of space the cell increases its firing. Place fields of 4 cells in the hippocampus http://www.bristol.ac.uk/synaptic/research/ projects/memory/spatialmem.htm In a particular room, many parts of the room corresponds to a particular cell firing. website about place cells 41 42 7 11/3/09 Place fields of 5 cells that developed in a triangular container Stop Here for Test 3 43 44 8 ...
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This note was uploaded on 01/20/2010 for the course PSY 1 taught by Professor Staff during the Spring '08 term at University of Texas at Austin.

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