Memory and consciousness

Human verbal and visual memory; awareness of memory

Aim Learning

unconscious motor learning conditioning

conscious memory of place

Biology of Memory neural “substrate”

Self v non self awareness

Types of learning Perceptual learning

recognise stimuli you have seen before Motor learning Stimulus-response learning

classical conditioning instrumental (=operant) conditioning

Relational learning episodic spatial

First: motor learning and the cerebellum

Motor learning

Cerebellum

Vestibuloocular reflex VO reflex to stabilize image on retina

when head moves eyeball muscles rotate eye to

compensate no sensory feedback gain has to be exactly 1

Control of VO reflex

Inf Olive

Purk cellgain = E/H = -

hair cell vestibular nucleus optic motor neuron

accessory optic tract

VO gain need Cerebellum

prism left on

prism on

prism off

- -x- - intact

no cerebellum

cats rotated on platform in dark

Control of VO reflex without cerebellum, cannot adapt adaptation during aging and disease

Types of learning Perceptual learning

recognise stimuli you have seen before Motor learning Stimulus-response learning

classical conditioning instrumental (=operant) conditioning

Relational learning episodic spatial

Next: one trial classical conditioning

Classical conditioning food - bell

Pavlovian fear conditioning

CS conditional stimulus US

unconditional stimulus noxious stimulus – eg electric shock

learnt fear response autonomic NS; eyes dilate, blood

pressure rises, heart rate up; hormonal response

Single trial last for years

Amygdala initial stimulus associated with high

levels of adrenaline and corticosterone NMDA receptors in amygdala required

for fear learning – role for LTP

NMDA antagonists / GluR knockoutsprevent acquisition of learning

Consolidation fear conditioning, then ECS

(electroconvulsive shock)

ECS soon after, memory never formed ECS after 24hr, memory fixed

requires protein synthesis soon after stimulus

Generic feature of memories

ReConsolidation fear conditioning, then ECS

ECS soon after, memory never formed ECS after 24hr, memory fixed ECS after reactivating memory,

memory lost requires NMDA receptors and protein

synthesis soon after reactivation stimulus

Long / short term memory STM requires protein synthesis

amygdala Aplysia Honeybee Fruityfly hippocampus

• relational memory

Let’s try it…

STM test

Cortex activity in learning word list

difference in memory effect

Short term memory different sensory

modalities are associated with different areas of the cortex during STM

STM is distributed

Types of learning Perceptual learning

recognise stimuli you have seen before Motor learning Stimulus-response learning

classical conditioning instrumental (=operant) conditioning

Relational learning episodic spatial

Now on to: Relational learning

Amnesia retrograde amnesia

inability to remember something which happened before brain damage

anterograde amnesia Korsakoff’s syndrome – alcohol abuse cannot form new memories tell a fable when asked for recent

events (rather than say don’t remember)

HM hippocampus removed bilaterally remember sentences by rehearsal learn motor skills recall old memories do mental arithmetic

cannot identify by name new people

cannot recognise surroundings

Hippocampus is not location of long term memory

HM would not know how to dress himself

not location of short term memory could not carry out a conversation

site for consolidation of memory

HC active in learning areas of brain which correlate with

rehearsal - learning list of words PET scan while playing word list test words learnt correlate

hippocampus

This leads to: declarative memories

explicitly available to conscious recall as facts, events or specific stimuli (=explicit M)

maybe verbal (as in declare) non-verbal – e.g. as video recall

non-declarative memories not necessarily conscious =implicit M

Hippocampal organisation RB stroke – hippocampus has high

NMDA receptors and very sensitive to ischaemia

amnesia lost CA1 neurons of hippocampus

CA1 CA1

HC Place cells taxi drivers

enlarged CA1 region Rat place cells Induce LTP in

CA1/CA3 neurons → new place cells

CA1 conditional NMDA knockout – longer to learn Morris water maze rat running in

triangular path

Summary so far amygdala : Pavlovian fear conditioning

short / long term memory reconsolidation

hippocampus crucial to memory cognitive maps of the environment consolidation phase

clinical animal models (CA1, CA3?, LTP)

Next: where do we Find LTM ?

Lashley rat exploration

Cortex as I/O of Hc

Summary so far amygdala : Pavlovian fear conditioning

short / long term memory reconsolidation

hippocampus crucial to memory cognitive maps of the environment consolidation phase

STM associated with cortex does not require hippocampus

Finally – memories in the future?

Prospective memory

imagining episodes in the futureDoes this look familiar?

Frontal regions for “self” DB, amnesiac who lost experience of

own past but not non personal past

Lesion data ventromedial frontal damage → lossof personal future time perspective

dorsolateral frontal damage

non-frontal damage.

fMRI Data Big difference

between Clinton/self

Small difference between future/past

Summary to end amygdala : Pavlovian fear conditioning

short / long term memory reconsolidation

hippocampus crucial to memory cognitive maps of the environment consolidation phase

STM associated with cortex does not require hippocampus

frontal region for prospective memory

Happy Christmas !!