The biological basis of memory

Gavin Norton

Room 6MO7

Memory storage

Association cortices

Unimodal

Multimodal

Primary motor cortexPrimary motor cortex

Primary somatic sensory cortexPrimary somatic sensory cortex

Primary visual cortexPrimary visual cortex

Primary auditory cortexPrimary auditory cortex

Primary olfactory cortexPrimary olfactory cortex

a - Frontal lobea - Frontal lobe

b - Temporal lobeb - Temporal lobe

c - Occipital lobec - Occipital lobe

d – Parietal lobed – Parietal lobe

Unimodal somatosensory cortex

Size and shape of objects, direction of movement

TouchPressure Temperature

Texture

VibrationProprioception

Tactile discrimination

Unimodal auditory cortex

Auditory perception

Sound frequencySound pitch

Sound timing

Unimodal visual cortex

Visual perception Form and colour

Ventral pathwaysDorsal pathways

Motion and depth

Multimodal cortices further integrate

Somatosensory and visual

Perception of space

Somatosensory and visual

Perception of languageVisual and auditory (Wernickes area)

Visual and auditory

Visual and visual

Visual and visualAdvanced visual perception

Motor and Wernickes

Language expression

Motor and Wernickes

2. Achromatosia, visual 2. Achromatosia, visual agnosiasagnosias

1. Agnosias, apraxias1. Agnosias, apraxias

5. Expressive aphasia/dysphasia5. Expressive aphasia/dysphasia

4. Receptive aphasia/dysphasia4. Receptive aphasia/dysphasia

3. Neglect 3. Neglect syndromesyndrome

6. Prosopagnosia and loss of 6. Prosopagnosia and loss of recall of specific itemsrecall of specific items

11..

22..

33..

44..

55..

66..

Agnosias, apraxiasAgnosias, apraxias

Tactile Tactile agnosiasagnosias

AgraphasthesiAgraphasthesiaa

AstereognosisAstereognosisApraxiasApraxias

Motor (e.g. dressing)Motor (e.g. dressing)

ConstructionalConstructional

Agnosia-disorder of higher sensory analysisAgnosia-disorder of higher sensory analysis

Apraxia-disorder of higher level (skilled) motor functionApraxia-disorder of higher level (skilled) motor function

- can’t identify shapes drawn on hand- can’t identify shapes drawn on hand

- can’t identify objects in hand- can’t identify objects in hand

Visual agnosiasVisual agnosias

Spatial agnosia (optic ataxia)Spatial agnosia (optic ataxia)

SimultanagnosiaSimultanagnosia

- can’t judge - can’t judge distancesdistances

- can’t compare sizes and - can’t compare sizes and shapesshapes

Memory processing

Short-term memory (working memory)

Long-term memory

11..22

.. 33..44

..

1. Spatial working memory1. Spatial working memory

Short-term memory (working memory)

2. Object working memory2. Object working memory

3. Verbal working memory3. Verbal working memory

4. Object working memory4. Object working memory

Long-term memory

Anatomical substrate

Explicit (declarative)

Implicit (non-declarative)

Temporal lobe

Procedural (motor skills)

Basal ganglion

Associative (conditioning

)

Amygdala

Non-associative (habituation and

sensitisation)

?

Hippocampal formation + Hippocampal formation + dentate gyrus and dentate gyrus and

subiculumsubiculum

Medial cerebral cortex

a = frontal lobea = frontal lobe

b = temporal b = temporal lobelobe

c = occipital lobec = occipital lobe

d = parietal lobed = parietal lobe

parahippocampusparahippocampus

hippocampushippocampus

Perirhinal and enterorhinal corticesPerirhinal and enterorhinal cortices

Mamillary body and mamillothamalic tractMamillary body and mamillothamalic tract

Explicit long-term memory

Unimodal and multimodal cortices

Parahippocampal cortex

Perirhinal and enterorhinal cortices

Sensory input Working memory in frontal lobes

HippocampusDentate Subiculum

Mamillary body and mamillothalamic tract

Glutamate

NMDA

Ca2+

Ca2+

AMPA NMDA

Mg2+

Mg2+

Less negative

Ca2+

Ca2+ Sensitises

Increases release

Amnesias and dementias

Short-term memory deficits

Anterograde amnesia

Long-term memory deficits

Retrograde amnesia

Korsakoff’s syndrome