Learning and Memory (neuro)

Question 1

Types of memory

Answer 1

• Learning: acquisition of new information
• Memory: retention of learned information
• Declarative memory (explicit):
  • Facts and events - hippocampus
• Nondeclarative memory (implicit):
  • Procedural memory - motor skills, habits - striatum

Question 2

Types of memory

Answer 2

- Declarative memory (medial temporal lobe; diencephalon):
• facts
• events
- Nondeclarative memory:
• procedural memory (skills and habits, striatum)
• classical conditioning:
- skeletal musculature (cerebellum)
- emotional responses (amygdala)

Question 3

Types of declarative memory

Answer 3

• Working memory:
  • Temporary storage, lasting seconds
• Short-term memories - vulnerable to disruption:
  • Facts and events stored in short-term memory
  • Subset are converted to long-term memories.
• Long-term memories:
  • Recalled months or years later
• memory consolidation: process of converting short term to long term memories

Question 4

Prefrontal cortex and working memory

Answer 4

• Primates have a large frontal lobe.
• Functions of prefrontal cortex: self-awareness, capacity
  for planning and problem solving
• Other brain regions are involved, for example lateral
  intraparietal cortex neuron response in delayed- saccade task

Question 5

Where are memories stored?

Answer 5

• The engram.

- Hebb’s Cell Assembly and Memory Storage

Question 6

Consolidation

Answer 6

• involvement of the medial temporal lobes

Question 7

Information flows through the medial temporal lobe

Answer 7

sensory information -> cortical association areas -> parahippocampal and rhinal cortical areas -> hippocampus -> fornix -> thalamus/hypothalamus

Question 8

Amnesia

Answer 8

• serious loss of memory and/or ability to learn
• causes: concussion, chronic alcoholism, encephalitis,
  brain tumor, stroke

Question 9

Henry Gustav Molaison

Answer 9

• known as HM to neuroscientists
• Feb 26, 1926 - Dec 2 2008
• Had a bicycle accident at the age 9.
• Developed epilepsy (had seizures)
• In 1953 was referred to William Scoville at Hartford Hospital.
• Scoville localised the epilepsy to the right and left medial temporal lobes (MTL) of HM’s brain and removed parts of the right and left MTLs.
• The surgery was effective in reducing occurrence of seizures. However, it had a devastating side effect
• HM lost the ability to form new long-term memories but remembered events before the surgery.
• He was, however, able to learn new motor skills (although he didn’t remember learning them)

Question 10

Spatial memory and place cells

Answer 10

• Learning Morris water maze requires hippocampus.
• Place cells fire when animal is in a specific place.
• Place fields dynamic

Question 11

Two models of memory consolidation

Answer 11

• Standard model of memory consolidation:
  • Information from neocortex areas associated with sensory systems sent to medial temporal lobe for processing
  • Synaptic consolidation, systems consolidation
  • Post consolidation, hippocampus not necessary
• Multiple trace model of consolidation:
  • Hippocampal involvement is continued
  • Multiple memory traces
• Dependent upon synaptic plasticity – ‘the biological process by which specific patterns of synaptic activity result in changes in synaptic strength’

Question 12

Trisynaptic circuit

Answer 12

• The changes in neuronal response can be explained by synaptic plasticity.
• The trisynaptic circuit of the hippocampus is often used in studies of this phenomenon
• Trisynaptic circuit:
  • Information flows from entorhinal cortex, via performant path to the dentate gyrus
  • Mossy fibres originate from dentate gyrus and synapse upon pyramidal neurons in CA3 hippocampal region
  • Axons from CA3 (Schaffer collaterals) synapse upon pyramidal neurons in CA1 hippocampal region

Question 13

Mechanisms of LTP in CA

Answer 13

• Glutamate receptors mediate excitatory synaptic transmission.
• NMDA receptors and AMPA receptors