hippocampus lecture 3

Question 1

Quiroga et al., (2005)

Answer 1

• Patients with pharmacologically resistant epilepsy implanted with electrode to detect onset of seizures
• target areas in the medial temporal lobe, including the hippocampus.
• present large number of visual stimuli
• sparse response to abstract concepts, invariant of picture type.
• suggests generalisation from hippocampal place cells to more general concepts - episodic memory

Question 2

Episodic memory Tulving (1972)

Answer 2

episodic memory recieves and stores infrmation about temporal spatial relations

Question 3

Episodic like memory (Clayton and Emory, 2015)

Answer 3

Behavioural criteria for episodic memory without requiring the conscious experience

1. Content :What where when.
2. Structure: bound together to discriminate memories
3. future deployement: use information to generalise across episodes.

Question 4

Why are networks of place cells important

Answer 4

relation between spatial information may be stored in the connections between place cells, similarly relations between more abstract concepts may be stored in CA3 of humans.

Question 5

What is synaptic plasticity

Answer 5

Synaptic plasticity refers to changes in synaptic strengths.
Spike timing dependent plasticity:
- if neuron A fires a little before B it will strengthen the connecttion from A to B.

Question 6

How do we organise the timing of action potentials

Answer 6

Oscillations reflect behavioural states

• Neural EEG activity or local filed potential
• oscillations reflect a temporal organisation of large networks of neurons
• provide a reference like a clock

Question 7

what is the main wave length of oscillations in the hippocampus

Answer 7

Theta oscillations

Question 8

What is a spike phase

Answer 8

Spikes (ap) do not occur a randon time but relative to a phase of the oscillattion. (180 degrees). IF it prefers a phase the we call this phase locking,

Question 9

Phase locking in hippocampal place cells?

Answer 9

Theta oscillations, place cells, phase precession. = systematic precession or advancement of the spike phase relative to an oscillation.

Question 10

How might information about spatial locations be stored in place cells.

Answer 10

Phase precession
overlapping place fields.
A fires briefly before B due to direction of walking place fields overlap causing them to fire briefly before= strenghtens connections

• sequences of places can be considered a simple form of an episode.

Question 11

What is the difference between episodic and episodic like memory?

Answer 11

episodic memory requires conscious awareness

eppisodic like memory involves the behvaioural components

Question 12

What are the three criteria for episodic like memory?

Answer 12

1. content
2. structure
3. flexible deployment

Question 13

what is a spike phase?

Answer 13

the preferred firing phase of a neuron relative to the oscillations of a group of neurons.

Question 14

why is the timing of action potentials important for memory?

Answer 14

Spike timing dependent plasticity could underly the formation of sequences of places.