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Indelibility of Subcortical Emotional Memories

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Indelibility of Subcortical Emotional Memories Joseph E. LeDoux Lizabeth Romanski Andrew Xagorasis Laboratory of Neurobiology Cornell University Medical College – PowerPoint PPT presentation

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Title: Indelibility of Subcortical Emotional Memories


1
Indelibility of Subcortical Emotional Memories
  • Joseph E. LeDoux Lizabeth Romanski Andrew
    Xagorasis Laboratory of Neurobiology Cornell
    University Medical College
  • Summarized by Shauna Overgaard

2
Ivan Pavlov
  • Conditioned Reflexes
  • Conditioned Stimulus (CS)
  • Unconditioned Stimulus (US) Classical
    Conditioning

3
LeDoux et al. 1984,1985,1986,1987, 1988
  • Classical conditioning is mediated by projections
    from the thalamus to the amygdala.

4
Affect
  • Occurs after cognition in a sequential
    processing chain.
  • or
  • At least some aspect of emotional processing
    are organized in parallel to cortical functions.

5
Is this Rule or Exception?
6
Triune Brain Paul MacLean
  • www.kheper.net/topics/intelligen
    ce/MacLean.htm

7
Question and Findings
  • Q Is visual fear conditioning, like auditory
    fear conditioning, mediated subcortically?
  • A 1. Visual conditioning does not depend upon
    the integrity of the visual cortex.
  • 2. Emotional memories established in the absence
    of the visual cortex persisted (resisted
    extinction) for unusually long periods of time.

8
Locations of Auditory and Visual Cortices
  • http//www.newhorizons.org/neuro/diamond_aging.gif

9
Auditory Pathway
Nolte, 2002.  The Human Brain  An Introduction
to its Functional Anatomy, 5th Ed
10
The pathway of electric signals on the optic
nerve to the visual cortex.
  • http//scien.stanford.edu/class/psych221/projects/
    06/cukur/intro_files/image020.jpg

11
Typical Lesion of Visual Cortex
  • LeDoux, J, Romanski, L, Xagoraris, A (1989).
    Indelibility of subcortical emotional memories.
    Journal of Cognitive Science. 1, 238-243.

12
What did LeDoux Do?
  • Four groups of rats were given visual cortex
    lesions (VC) or sham operation (SH).
  • Twenty days later, rats were given either paired
    (P) or random (R) presentations of the CS
    (flashing light) and US (foot shock).
  • SH VC

P n11 R n6
P n10 R n5
13
Method Cont.
  • Fear Conditioning the suppression of drinking by
    the CS
  • Basal Lick Rate time elapsed in completing 5
    licks upon box entrance and 100 licks before CS
    presentation.
  • Licking During CS the difference between the
    latency to complete 100 licks before and after
    the onset of the CS.

14
The difference in time to complete 100 licks
before and after the onset of the CS.
LeDoux, J, Romanski, L, Xagoraris, A (1989).
Indelibility of subcortical emotional memories.
Journal of Cognitive Science. 1, 238-243
15
Results
  • Visual Cortex lesions did not interfere with
    acquisition
  • - With onset of the CS, SH and VC given P
    training stopped drinking.
  • - SH and VC given R training continued
    drinking.
  • Visual fear conditioning is mediated by
    subcortical sensory pathways.

16
Results Cont.
  • With each administration of the extinction test
    the CS suppressed licking less in the sham
    operated group than in the visual cortex lesioned
    group.
  • The performance of the lesioned group, did not
    change significantly over the course of 5 tests.
  • LeDoux, J, Romanski, L, Xagoraris, A (1989).
    Indelibility of subcortical emotional memories.
    Journal of Cognitive Science. 1, 238-243.

17
Results Cont.
  • Extinction was greatly prolonged, if not
    prevented, by cortical ablation.
  • http//www.wilsonsalmanac.com/
    images2/pavlov6.jpg

18
Why no extinction?
  • Amygdala Performs primary role of formation and
    storage/processing and memory of emotional
    reactions. Thalamus

http//www.ibiblio.org/rcip/images/Amy
gdala500_500.jpg
19

20
Implications
  • Lesions of visual cortex may prolong extinction
    by preventing the relay of visual inputs to areas
    such as the frontal cortex and/or hippocampus.
  • Emotional memories established in the absence of
    sensory cortex, probably by way of
    thalamo-amygdala projections, are relatively
    indelible.
  • Emotional behavior may extinguish, but the
    underlying association is not lost.
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