L8 Declarative memory

Question 1

types of declarative memory?

Answer 1

episodic (memories) and semantic (facts)

Question 2

how does declarative memory become procedural

Answer 2

we have an initial hippocampal cognitive map - a place. Over time, we develop a ‘procedural’ memory - a striatal (Caudate nucleus) response

Question 3

Eichenbaum experiments

Answer 3

1st:
- measured place cell firing at with left and right turns - concluded hippocampus not only involved in spatial navigation but also guiding future behaviours
2nd: relational memory
- association between memories relies on MTL
- used A-E odour rewards

Question 4

What could be shown with Eichenbaum’s relational memory experiment?

Answer 4

• hippocampal lesions in had no effect with learned or end-anchored pairs, but did with BD
• Suggest hippocampus lies in the organisation of relationships between memories

Question 5

what was Eichenbaum’s ‘memory space’ hypothesis?

Answer 5

episodic memories represented as a sequence of events and places
activity of each cell in this network encodes a small segment of the episode

Question 6

how can patterns of info be orchestrated into a memory?

Answer 6

• auto-associative network (a–>a–>a)
• heteroassociative network (a–>b–>c)

Question 7

HOW IS A MEMORY REPRESENTED?

Answer 7

BY A SUBSET OF PYRAMIDAL NEURONS FIRING IN SYNCHRONY

Question 8

HOW CAN MULTIPLE ITEMS BY ACTIVATED SEQUENTIALLY AND COMBINE?

Answer 8

THETA AND GAMMA RHYTHMS

Question 9

THETA AND GAMMA SPEEDS

Answer 9

THETA SLOW
GAMMA FAST

Question 10

HOW MANY ITEMS CAN THETA HOLD?

Answer 10

7+/-2, SAME AS STM BUFFER

Question 11

WHAT EVIDENCE SUPPORTS GAMMA THETA IN MEMORY

Answer 11

• THETA PHASE PRECESSION THEORY
• RAT ON PLANK RUNNING TO AND FRO
• CELLS FIRE AT PEAK OF THETA WAVE ON LEFT SIDE
• AS RAT MOVES RIGHT, CELLS FIRE AT LATER PARTS OF THETA WAVE
• PLACE CELLS FIRE MOST STRONGLY IN CENTRE OF PLACE FIELD AT THETA ‘TROUGH’

Question 12

HOW DOES THETA PHASE PRECESSION WORK

Answer 12

• RAT MOVES THROUGH DIFF PLACE FIELDS
• FIRING RATE FOR ANY PLACE INCREASES THEN DECREASES, AND OVERLAPS
• SOME FIRE AT SAME TIME, AND CHANGES OVER TIME IN RELATION TO ONGOING THETA RHYTHM
• SO ANIMAL KNOWS WHERE IT IS

Question 13

THETA PHASE PRECESSION IN MORE DETAIL PLS

Answer 13

• CELL FIRING (GAMMA) IS ‘PACED’ BY THETA
• CURRENT POSITION IS MARKED BY CELLS CURRENTLY FIRING AT THETA TROUGH
• PAST LOCATIONS BY EARLIER FIRING CELLS, AND FUTURE LOCATIONS BY LATER-FIRING CELLS
  THUS, GAMMA MODULATED THETA-PHASE PRECESSION ALLOWS RAT TO PREDICT FUTURE LOCATION AND ENCODE NEW INFO INTO EPISODIC MEMORY RELATIVE TO PAST AND PRESENT LOCATION

Question 14

GOOD BIT OF EVIDCENCE FOR THETA PHASE PRECESSION?

Answer 14

MORE AND MORE ITEMS INCREASE WAIT BY 30MS
WHICH IS AROUND 38Hz
WHICH IS FREQUENCY OF GAMMA BOSH
ALSO PEOPLE WITH GOOD RECALL SHOW CLEAR LINK BETWEEN POWER OF GAMMA THETA COUPLING