Learning and Memory

Learning and Memory

1. Lifelong adaptation of the brain to the environment

2. Enable appropriate response to new situations

3. Memory

   • Declarative (explicit)
     • Memory for facts and events
     • Available for conscious recollection
     • Easy to learn, easy to forget
     • Types...
       • Long term memory
         • Recalled after long period of time
       • Short term memory
         • Last for a short period of time (seconds and hours)
         • Vulnerable to disruption (trauma, ECT)
     • Medial temporal lobe, cortex
   • Nondeclarative (implicit)
     • Not available for recollection
     • Requires repetition over long time and is less likely to be forgotten
       • Procedural memory
         • Skills
         • Habits
         • Striatum
       • Learned emotional response
         • Amygalda
       • Classical conditioning
         • Cerebellum

4. Amnesia

   • Loss of memory and learning ability
   • Causes
     • Concussion
     • Tumour
     • Stroke
     • Alcoholism
     • Encephalitis
   • Types
     • Dissociated amnesia
       • No other deficits
     • Retrogade and anterograde
     • Transient global amnesia

5. Flow of Information

   • Within the medial temporal lobe
   • Hippocampus -> Cortical association areas -> Parahippocampal region -> Hippocampus (repeat)

6. Brain Parts Related to Learning and Memory

   • Hippocampus
     • Spatial memory
       • Place cells
     • Working memory
       • Related to ongoing behaviour
     • Relational memory
       • Ties together things happening at the time of memory storage
   • Diencephalon
     • Lesions to this...
       • Accidental
         • Preservation of short term memory
         • Preserved old memories
         • General intelligence
         • Difficulty in forming new declarative memory
         • Retrograde amnesia
       • Korsakoff's syndrome
         • Confusion
         • Confabulation
         • Memory impairments
         • Apathy
   • Striatum
     • Lesions to this...
       • Inability to form habits
       • Declarative memory relatively spared
       • Huntington's disease
         • Difficulty in learning tasks that require a motor response associated with a stimulus
       • Parkinson's disease
         • Difficulty in weather forecasting task
   • Prefrontal Cortex
     • Self awareness
     • Complex planning
     • Problem solving
     • Working memory
     • Lesions to this...
       • Deficit in performing complex memory tasks
         • Wisconsin card-sorting task
       • Difficulty in planning and organising behaviours
       • Behaviour appropriate for various situations
   • Other...
     • Parietal
       • Lateral intraparietal cortex
     • Temporal cortex
     • Lesions to these...
       • Auditory and visual working memory deficits

7. Hebb Theory

   • Related to memory
   • Engram of an object
     • Assembly of cortical cells activated by the external stimulus
   • Cell assembly
     • Reciprocally interconnected
       • Short term memory
     • Fire together, wire together
       • Long term consolidation

8. Models of Learning

   • Modifications of synaptic transmission
   • Synaptic modifications triggered by neuronal activity
   • Alterations of existing synapses

9. Ageing

   • Loss of neurones
     • 10-20%
     • Causes
       • Reactive oxygen radical
       • Hormonal changes
         • Oestrogen/thyroid
       • Accumulation of toxic chemicals
         • Homocysteine
       • Accumulation of insults
         • Vascular etc.
     • Especially limbic areas
   • Age-related vulnerability of certain neuronal populations
     • Changes in synaptic plasticity
     • Synaptic plasticity makes neurones vulnerable to insults