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Neurology of memory
NATESAN
ANDVARUN
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forms, figures, shapes, objects, ideas,
apprehensions, motions, revolutions: these
are begot in the ventricle of memory, nourishedin the womb of pia mater, and
delivered upon the mellowing of occasion.
Shakespeare, Love's Labour's Lost
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HM, in an interval between psychological tests, he
looked up and said rather anxiously,
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.
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Learning is defined as a relativelypermanent change in performance caused
by experience.
Memory is maintaining the learning
retrieving at later time.
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Memory is a basic function for survival of the
individual and the species. Its functions are
represented in an extensive number of brain
structures
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CLASSIC MODELS OF WORKING
MEMORY
Atkinson and Shiffrin: Short term store and
long term store Baddeley and Hitch: Three Component model
of working memory
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Atkinson and Shiffrin (1968)
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Problems with Atkinson and Shiffrin
model
Model says STS required for entry into LTS
A neurological patient with defective short term memory
(as measured by digit span) showed normal long term
learning. (Shallice and Warrington 1970) Model says length oftime in STS determines
likelihood of LTM storage
Length of time in STM does not necessarily result in
transfer to LTM. Depth of processing is more important(Craik and Tulving, 1975)
Quoting The Handbook ofMemory Disorders
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Baddeley and Hitch (1974)
Working memory(instead of short term memory)
Visualspatial sketchpad Phonological LoopCentral Executive
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Norman and Shollice (1986)
supervisor attentional system(instead of Central executive)
Visualspatial sketchpad Phonological Loop
Superior attentional system
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Miller (1956)
Episodic memory(fourth component of working memory)
Visualspatial sketchpad Phonological Loop
Superior attentional system
Episodic buffer
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Neuroanatomy of the memory
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Declarative
(explicit)
Procedural
(implicit)
Episodic
(working)
Semantic
(reference)
Skills Priming Conditioning Non-associative
Emotional
responses
Motor
responses
Striatum Cortex Amygdala CerebellumReflex
paths
from L.R. Squire, 1987)
MTL:
(para)hippocampal
cortex
& Diencephalon
MTL:
(para)hippocampal
cortex
TYPES OF LONG TERMMEMORY
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The temporal lobe
Left temporal lobe damage typically have
more difficulty learning and remembering
verbal material, such as stories or word lists.
Right temporal lobe damage difficulty with
nonverbal material, such as abstract
geometric patterns, faces, tonal patterns, or
the spatial location of objects..
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MTL & Related Structures
Anterior thalamic
nucleus
Mediodorsal thalamic
nucleus
Cingulate
Gyrus
Fornix
Corpus
Callosum
Alveus of the
hippocampus
SubiculumDentate
gyrus
Parahippocampal
GyrusPes HippocampiAmygdala
PrecommissuralFornix
Postcommissural
Fornix
Anterior
commissure
Septal
nuclei
Mammillary
bodies
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.
Schumann C M et al. J. Neurosci. 2004;24:6392-6401
2004 by Society for Neuroscience
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.
Schumann C M et al. J. Neurosci. 2004;24:6392-6401
2004 by Society for Neuroscience
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Stress, amygdala and memory
Aversive learning or fear conditioning occurs
in central nucleus of amygdala.
The long term memory of this is stored insularcortex.
Stress triggers increase in glucocorticoids and
NA.
The NA increases the arousal.
Glucocorticoids stimulate the amygdala and
improve memory at low stress levels
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CHRONIC,HIGH STRESS LEVELS DOWN-GRADE
THE STEROID RECEPTORS.
POOR MEMORY
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Sagittal view of the
brain showing the
location of the
amygdaloid complex
of nuclei in thetemporal lobe.
Coronal section
through the forebrain
at the leveel of the
amygdala.
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Dorsolateral Prefrontallobes
working memory
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Striatum
Responsible for motor skill learning
caudate nucleus :habit formation
connecting motivational values to
sensory stimuli
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Forgetting
definitive loss of information or the failure in
retrieving it at a certain point in time.
Mechanism of forgetting:- failure of consolidation.
- interferance( proactive / retroactive)
- time decay.
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Biblography
Encyclopedia of the Human Brain, Volume 2.
The Handbook ofMemory Disorders
Second edition - Baddelley Forgetting Sergio Dalla Sala
The new cognitive neurosciences
Second edition - Michael S. Gazzaniga Memory and Brain Systems: 1969 2009
Larry R. Squire The Journal of Neuroscience, October 14, 2009 29(41):1271112716 12711