HPC Lecture

Question 1

Define interacting memory systems theory

Answer 1

that there are multiple learning and memory systems in the brain.
These systems are functionally dissociable
Store and acquire information simultaneously in parallel

Question 2

What are the 3 parts to the interacting memory systems theory (IMST)

Answer 2

1. systems have been functionally dissociable (where and what they do)
2. there are non-specific systems involved such as, portion of thalamus leads to encoding, subregions of prefrontal cortex control executive function, etc.
3. systems are specifically designed (ex. how design to perform its function) to represent different relationships (ex. what systems project to the memory systems) among elements of learning
   (intrinsic and extrinsic organization)

Question 3

episodic memory, thought that it is based on formation of….

Answer 3

complex associative representations
construct all different parts of an event into a coherent memory

Question 4

Describe the anatomy of the hippocampus mainly in relation to the episodic memory

Answer 4

receives polymodal sensory information representing the external world (entorhinal cortex is gateway of that info entering and leaving hippocampus)

has horizontal and vertical organization, allows sensory input from neocortex to be distributed throughout hippocampus

can re-activate cortical nodes to represent elements of a previous experience (reactivating cortical regions)

Question 5

What cells are involved in the electrophysiology of the hippocampus

Answer 5

place cells, prospective cells, head direction cells, boundary cells, grid cells, and speed cells

Question 6

Place units were discovered by ___ and ____

Answer 6

O’Keefe and Dostrovsky

Question 7

Define place unit

Answer 7

neurons in the hippocampus that fire when an animal enters specific regions of its environment, called place fields

Question 8

What are the 4 place cell properties

Answer 8

1. location specific firing
2. head direction independent (even if body is pointing one way, only relative to where the head is pointing)
3. non topographic (two neighbouring place cells don’t have neighbouring place fields)
4. independent fields in different environments

Question 9

How long does it take for a place cell to become well established

Answer 9

10 minutes

Question 10

lesions of the ____ or ____ disrupt place unit activity in the hippocampus, both input and output

Answer 10

fornix (connects nodes)
entorhinal cortex

Question 11

what happens if place cells fire at a specific location in relation to a set of spatial cues and then the lights are turned out

Answer 11

use their memory to still fire in the familiar place and remain active

Question 12

place fields are _____ on goals or intended movements

Answer 12

not dependent
(ex. in maze experiment, they will always fire in the same spot even if the “goal” of food is there or not

Question 13

What did the early stage set out to discover about place cells

Answer 13

to understand spatial nature of place cell activity and to understand the electrophysiological phenomenon of them

Question 14

What did the middle stages set out to discover about place cells

Answer 14

discovery of head direction cells (multiple spatial signals getting into the hippocampus)

Question 15

What does the current stage want to discover about place cells

Answer 15

attention turned towards entorhinal cortex - led to discovery of grid and border cells

Question 16

What are the 4 properties of place cell firing fields

Answer 16

1. fields are independent of each other
2. independent of different environments
3. stable over time (create memory)
4. anchored to dominant visual cues

Question 17

unlike place cells, head direction cells are _____ specific and _____ invariant. They strongly depend on the ______ system.

Answer 17

orientation
location
vestibular

Question 18

Define grid cells and their function

Answer 18

within the entorhinal cortex, multiple firing action potentials in clusters that encode abstract spatial structure in the brain and encodes Euclidean space (space of geography in relation to physical space), adds temporal dimension

Question 19

place cell firing patterns are based on ____ input to encode ____ within a specific context

Answer 19

sensory
locations

Question 20

grid cell firing patterns provide a highly efiicient and context independent _____ ____ for path integrations and ___ navigation

Answer 20

spatial metric
vector

Question 21

What is the two state theory of navigation and who created in

Answer 21

Poucet and Muller
information flow depends on animal using landmarks (light) or self-motion (dark) signals to select path through space. (use grid for dark because doesn’t have sensory info to use for place)

Question 22

define boundary cells

Answer 22

fire whenever boundary is at a particular direction and distance from the animals current location

Question 23

define speed cells

Answer 23

in hippocampus and entorhinal cortex that alter firing rates with pace of organism moving. do not code other spatial dimensions. head direction and grid cells help

Question 24

what is “the promise” that resulted from the different stages of research

Answer 24

that it is possible to investigate specialized cells types that work together and spatial mapping is one of the first cognitive functions understood

Question 25

define stereotaxic brain atlas and the surgery

Answer 25

apparatus that allows for precise location of brain sections and there can insert drugs into specific locations

Question 26

What are the 3 types of experimental designs that are associated with stereotaxic surgery

Answer 26

1. site specific brain lesion, recovery, behavioural training
2. training, lesion, recovery, retest, retrain
3. reversible lesion, pharmacology (effects), genetic approach