NEUROLOGICAL MECHANISMS OF LEARNING AND MEMORY

Question 1

ANATOMY OF ANTEROGRADE AMNESIA

Answer 1

PERIRHINAL CORTEX = Region of limbic cortex adjacent to hippocampal formation that relays information between entorhinal cortex and other regions of the brain

PARAHIPPOCAMPAL CORTEX = Region of limbic cortex adjacent to hippocampal formation that shares same general role as perirhinal cortex

Question 2

SPATIAL LEARNING - Role of the Hippocampus

Answer 2

3 Main Subdivisions: CA1, CA2 & CA3
Main Pathways: 1, 2, 3 -> Trisynaptic circuit
1. Perforant Path = entorhinal cortex > debate gyrus
2. Mossy Fibres = granule > CA3 cells
3. Schaffer Collaterals = CA3 > CA1 cells
4. Commissural Path = through fimbria > CA1

Question 3

RELATIONAL LEARNING IN LAB ANIMALS

Answer 3

MORRIS WATER MAZE
= hippocampal place cells
= Rats with hippocampal lesions are always released from the same place - learn this non-relational stimulus-response task
= If released from new position, they swim in an aimless fashion until they finally encounter a platform

= Effects of hippocampal lesions - rats, radial arm maze

- cued learning (informed that arm visited)
- spatial impaired
- perseveration

Question 4

PLACE CELLS

Answer 4

= Single neurones that fire when the rat moves through a specific location (O’KEEFE AND DOSTROVSKY, 1971) - Pyramidal and Granule
= Area where cell fires is its ‘place field’

Question 5

HEAD DIRECTION CELLS

Answer 5

= HDC fire selectively when the animals head is pointed in a particular direction in allocentric space
= HDC and place cells are usually coupled

Question 6

GRID CELLS

Answer 6

= Grid cells (like place cells) show stable spatially constrained firing but with peculiarity that each cell has multiple firing fields positioned in a grid defined by the vertices of tessellated, equilateral triangles

Question 7

WORKING MEMORY ASSESSMENT WITH DELAYED RESPONSE (DR) TASKS

Answer 7

= Basic procedure includes presenting a piece of info (a stimulus), withdrawing that info, then waiting for a period of time and finally, in a choice procedure, representing the original stimulus together with a comparison item

= Lesion studies and electrophysiological data suggest that the hippocampus and the prefrontal cortex play an important role in DR performance