4. Function of the Hippocampus

Question 1

phase precession in CA1

Answer 1

• phase precession is the same when the animal walks in the opposite direction
• this recoding of place fields can change through different layers of the cortex

Question 2

temporal sequences

Answer 2

• N1 > N2 > N3 imprinted in CA3 network, what now?
• related to remembering sequences, completing a pattern or planning
• can reactivate sequence just by activating N1 (remembering - where to go in rat)
• Diba and Busaki (2008)

Question 3

Diba and Busaki (2008)

Answer 3

• recorded from 13 different place cells whilst rat runs back and forward down a path to food
• before moving, the place cells are activated in the order they fired when moving down the path to food = forward replay
• at the end of the path (at the food), the rat activates the place cells in the order they were just activated (most recently activated to first activated) = reverse replay
• idea that when the rat gets to the food reward there is a release of dopamine and an association is made between the reverse replay activation of place cells (just a hypothesis)

Question 4

forward replay

Answer 4

before moving to food, rats place cells are activated telling him where to go

Question 5

reverse replay

Answer 5

when at the food, the place cells are played in reverse (with last place cell active firing first)

Question 6

hippocampal firing patterns and memory

Answer 6

relationship between mechanism and memory

• storage = during activation of place fields the sequence is stored in CA3
• recall = reactivation of place cell sequence and end and beginning of traverse
• consolidation = reactivation of place cell sequence to other brain regions (during sleep)
• Lee and Wilson (2002)

Question 7

Lee and Wilson (2002)

Answer 7

found that rats reactivated the place cell sequence during sleep

Question 8

what is mental time travel?

Answer 8

ability to recollect specific past events/episodes to anticipate future needs and motivational states

Question 9

what is mental time travel characterised by?

Answer 9

Tulving (2005) - in humans, by 2 features of consciousness

1) the ability to re-experience past events and pre-experiencing possible future events
2) the awareness of being the order of memories and forethoughts

• • cant empirically study this in animals as there is no accepted behavioural marker for consciousness
• so we focus on behavioural criteria for episodic cognition without a requirement of conscious experience
• use prospective aspect of episodic like memory (Clayton and Emery, 2015)!!!

Question 10

Clayton anf Emery (2015) - prospective

Answer 10

3 criteria:

1. content = anticipating what will happen, when and where based on previous experience
2. structure = what, when, where components are bound together (important for distinguishing between events e.g. time they happened)
3. flexibility = interaction with semantic (relating to meaning) knowledge

• future planning occurs independent of current motivational states and includes a novel action

Question 11

Clayton et al (2003)

Answer 11

mental time travel in Western Scrub Jays

• episodic memory = what happened, when and where
• future planning = what will happen, where and when
• birds were taught that worms would degrade over time, but peanuts wouldn’t
• they have a natural drive to cash food in various locations
• 4h = no food has gone bad so bird will go for the favoured worm
• 24h = worms have gone bad so should go for the nuts
• semantic knowledge = worms will go bad (3.) - must think about what will happen to their cashed food
• birds that were taught about the worms didnt even bother looking at them in 24h condition, went straight to the peanuts, but in 4h condition went for worms
• in both controls, birds try to cash the worms and try to find eat them in both conditions (but they are degraded)
• they know what WILL happen to the worms

Question 12

Avian Cognitive Neuroscience Lab, University of Bochum

Answer 12

Dr. Rose. (findings not released)h

• new paradigm to study storage and recall of episodes in Jackdaws
• hexagonal area which has touch screens and feeders
• visual stimuli displayed on screen, sequence of events is taught to the jackdaws (different at each touch screen but must remember sequence of symbols)
• idea for storing what-where-when episodes (colour, location, order)
• wireless recordings during task performance
• does phase precession take place during storage?
• is there sequence replay during recall?