Week 9 Flashcards
Learning definition
Acquisition of experience
Memory definition
Retention of experience
Learning and memory
Work together to adapt behaviour
Versus stereotypical reflexes
Memory classification
Nature of memory
Duration
Nature-declarative
‘Explicit’
Consciously aware
Able to describe in words
Fades with time
Types:
-semantic :facts
-episodic: events
Nature- non declarative
‘Implicit’ the how
Skills, habits, behaviours less likely to fade over time
Types:
-procedural memory: skills and habits, eg motor tasks
Conditioned responses
-associative reflexes
Emotional responses
-How we feel in a particular environment in particular circumstance based on prior experience
Duration
Sensory memory
-fractions of a second
-function= sensory processing
Short term memory:
-approx 30 seconds
-7+/- items
Working memory- combining new things with stored things
Input-> sensory memory -> short term memory—consolidation—> long term memory
Memory deficit
Forgetting is necessary
Increased age?
-difficulty in acquisition or storage?
—all types of memory?
-lost or difficult to retrieve ?
-synapses not neurones
Amnesia- secondary to pathology: traumatic brain injury, infection, neurodegeneration, resection, stroke
Types of amnesia
-retrograde amnesia: events before trauma. Declarative memory
—usually not complete may be reversible in recovery
-ribots law: recent memories are more likely to be lost than older ones
-anterograde amnesia: inability to form new memories
-A&R may occur independently
Anatomical location of memory
Evidence
-humans with brain injury
-lashley 1920s: experimental lesions= large areas of cortex involved . Wrong
Lettvin 1960s; the grandmother cell hypothesis, every neurone was responsible for a memory. Wrong
Currently: fMRI/lesions-> network involving multiple regions
Anatomical location of memory declarative
Declarative memory
-medial temporal lobes
—lesion
—AD pathology episodic then semantic
Sensory info-> hippocampus (and rhinal cortices) (particularly important for episodic)—consolidation—> neocortex
Can map time of info shifting with location in brain
Korsahoffs syndrome -episodic
Diencephalon
-intact pathways between hippocampus and neocortex important for conversions of short term memory into long term memory
Hippocampus-> hypothalamus-> thalamus-> neocortex
Fornix
Anatomical location memory non-declarative
Non declarative
-procedural
—cerebellum
—supplementary motor area and basal ganglia
-emotional
—amygdala
-working memory
—prefrontal cortex
Case study: HM
Bilateral temporal lobectomy
-severe anterograde amnesia for declarative memories
-childhood memories intact
—TL required for new declarative but not for very old memory
Procedural memory- cerebellum and supplementary motor area and basal ganglia not medial temporal lobe
-so no problem
Working memory: pre frontal cortex and others. Evidence: ADHD, schizophrenia
How do neurones store memories
Neuroplasticity
-change in neurotransmission
-change in synaptic structure
Change in neurotransmission:
-long term potentiation LTP (long term depression)
—declarative
-LTP-> NMDA receptor activation
—calcium entry
-> immediately
->altered kinase activity esp CAMKII eg enhanced AMPA function
> persistence
->changed gene expression
-> more AMPA receptors
activation of NMDA receptors elevates activity of neurones and allows storage info
What’s happening at the synapses
Change physical structure
Axon sprout growth cone
Infinite storage capacity
Synaptic Neuroplasticity
Bad news: plasticity-> maladaptive, increase vulnerability
Memory manipulation
Health and recreational
Pharmacological
-enhancement
-suppressors
—NMDA antagonists eg ketamine
Non pharmacological
-EG CBT?