neurology of memory

8/6/2019 Neurology of Memory

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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

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