spatial navigation

Question 1

cognitive maps

Answer 1

tolman: proposed the idea of a cognitive map in the 1940’s
rats: rapidly switch to alternative path if previous path is blocked
- implied that animals must have spatial knowledge about environment
spatial knowledge:
- like that on a map

Question 2

grid cells, head direction cells and border cells complete a cognitive map

Answer 2

• grid cells fire in a regular hexagonal lattice of locations tiling the floor of the environment
• head direction cell fire on the basis of the direction the head is facing
• border cells fire when the animal is at set distances from navigational boundaries facing in specific direction.

Question 3

If the rodent spatial positioning network a good model of human navigation

Answer 3

• similiar anatomical structures; hippocampal formation, papez circuit
  but there are differences across species;
• damage to human equivalent navigation areas causes memory broader memory deficits

Question 4

difficulty translating to humannavigation studies

Answer 4

• navigation is an inherently mobile task, participants in fmri experiments must remain stationary in the scanner
• memory and planning systems are engages and visual inputs are often present

Question 5

scene perception in the brain

Answer 5

• Epsten and K provided evidence for a region in the visual cortex that preferentially processes scenes
• anatomically, PPA lies along the parahippocampal gyrus and collateral sulcus.

Question 6

the PPA responds to scenes, but not faces or other objects

Answer 6

• scenes include a wide variety of images
• ppa is sensitive to a global spatial geometry/ configuration of scenes.

Question 7

the PPA responds less to scrambles scenes

Answer 7

• PPA’s response is highest to scenes that depict a realist spatial layout
• PPA’s response is lower if the position of the objects in the scene are scrambled

Question 8

Is the PpA responsible for the spatial representation of scenes?

Answer 8

• spatial layout hypothesis: the PPA encodes the global spatial layout of a scene
• the lateral occipital complex (LOC) and fusiform gyrus encode information about the local individual objects in the scene
• consists with consequences of damage to the PPA
• the overall organisation of the scene is lost.

Question 9

distance coding from fMRI adaptation

Answer 9

• 220 color photographs of 10 prominent landmarks from the uni of pen
• ‘subjective’ distances between landmarks were determined for each participants
• Task: subjects identified each landmarks and made a button press once they had done.

Question 10

fMRI in hippocampus like border cells

Answer 10

• fMRI activity in the in the hippocampus scales with the distance between that building and the building shown on the immediately preceeding trial

Question 11

recording from individual cells in human medial temporal and frontal lobes

Answer 11

• presurgical epilepsy paients: each patient had 6 to 14 depth electrodes implanted.

Question 12

recording from place cells in human hippocampus

Answer 12

• evidence for a neural code of human spatial navigation based on cells that respond.
• place-responsive cells were clustered in the huppocampus and compared with amygdala, parahippocampal region and frontal lobes

Question 13

viewpoint-independent direction coding in humans

Answer 13

• previous human studies had found evidence from place-like and grid-like representations but not exclusively to percieved heading
• used fMRI adaptation to distinctive landmarks with one of four facing directions
• participants had to indicated whether the position represented by the static image of the landmark was on the left or the right of the centre point of the maze
• paired images were in the same heading direction or head different headings

Question 14

representation of allocentric heading in the retrosplenial complex

Answer 14

• single brain region in the medial pariatal cortex was modulated by learned heading.
• the representation of allocentric heading acheieved in the RSC

Question 15

using cognitive maps to navigate: fMRI results

Answer 15

• subject learned an unfamiliar layout of the city, fMRI shows hippocampal activity correlates with path distances
• subjects watched 10 movies of layout, and data showed hippocampal activity

Question 16

Brain regions associated with different navigation events

Answer 16

• hippocampal volume changes in taxi drivers who become expert navigators after requiring the knowledge.
• the longer the taxi driver the greater the hippocampal volume

Question 17

hippocampi volume differences between taxi drivers and bus drivers

Answer 17

• greater grey matter volume in the mid-posterior hippocampi in london taxi drivers when compared with london bus drivers
• b) less matter volume in the anterior head of hippocampi in taxi drivers
• taxi drivers= better at spatial nav tasks

Question 18

spatial performance differences between taxi drivers and bus drivers

Answer 18

• ## taxi drivers better than bus at spatial activities