Lecture 6 - Spatial cognition and memory Flashcards
O’Keefe and Nadel (1978) conceptualised the hippocampus as a cognitive map - what does this mean and how is it different to response learning?
1) The hippocampus evolved for making storing & using maps of the external world (navigation). It models the external world.
2) The hippocampus is especially crucial for map-based navigation, not for route learning aka response learning (this is purely based on associations, not a conceptual map)
According to O’Keefe and Nadel (1978), does map-making occur automatically?
Yes
The hippocampus notices novelty. What does novelty drive?
Exploration; the purpose of exploration is to build and update maps
What type of memory builds on the system of the hippocampus as a cognitive map?
Episodic
What does map based navigation involve?
Creating new routes through familiar environment e.g. if normal route is closed
Is the hippocampus very different across mammals?
No - it is very similar
Is the hippocampus close to the medial temporal lobe?
Yes
What do the EC and DG do in relation to the hippocampus and cortex?
Serve as gateways separating the cortex from the hippocampus - like a relay station
What is the difference between response learning and place learning?
Response learning - Self-based direction - always turn left
Place learning - Place-based direction - always turn towards the direction of this landmark (requires cognitive map)
How does the case of HM support the role of the hippocampus in spatial memory?
HM had hippocampus removed
HM could not “form an instantaneous cognitive map”
Relied on response learning
What is the spatial navigation double dissociation?
Place learning = hippocampus
Response learning = caudate nucleus
Does the hippocampal formation represent allocentric or egocentric space?
- Allocentric or environment-centred, large scale space - necessary for cognitive map - this can be used in novel situations whereas egocentric representations cannot
- Functions: navigation, long-term memory for scenes, spatial contexts, binds items-in-contexts
Not egocentric - this is more typical of response learning
How were place cells discovered?
O’Keefe and Dostrovsky (1971) and O’Keefe (1976)
Recording individual cells at a time
Animal moves freely, then they drop rice which the animal moves to and investigates
Found individual cells that only respond when animal is in a certain place in the environment
What do place cells do?
Each cell responds similarly to its neighbour
All places in environment that animal has learnt are represented in hippocampus
Place cells signal a specific location from a specific context
If put animal in different environment, same cell starts doing something different - adaptability
Place cells firing together signal a specific location in a specific spatial context
In addition to place cells, what are 4 other types of cells that aid spatial navigation?
Speed cell
Head direction cell
Boundary vector cell
Grid cell
- Could be path integration system - how far into the environment you might have moved e.g. still works when the lights go out - in what direction did you move and how far - identify your own specific position in environment
What happens to performance on Morris Water Maze when rats have hippocampal lesions?
Impaired in finding platform, paths are inaccurate - because allocentric coding is needed
Longer, inaccurate routes
Maguire et al. (1998) studied ppts performance on navigating through a virtual town, while measuring activity with a PET scan. How did people with hippocampal lesions, cortical lesions, and controls perform?
Cortical lesioned and control ppts took an accurate direct path
Hippocampal lesioned ppts took an inaccurate circuitous path
Maguire et al. (1998) studied ppts performance on navigating through a virtual town, while measuring activity with a PET scan.
What did the PET scan show correlated to more bloodflow to the hippocampus?
What other area was involved?
More bloodflow to hip = higher accuracy on task
Navigational accuracy positively correlated with:
Hippocampal activity (r = 0.56)
& with Inferior Parietal activity (r = 0.43)
What was a methodological issue with Maguire (1998)?
Lots of within subject variation
What was the method in Hartley et al. (2003) study of route following and wayfinding?
Town 1 - wayfinding
Training was free exploration for 15 minutes
Town 2 - route following
Training was to follow a fixed route for 15 minutes
There was a non-memory control to follow a visible trial
Brain activity recorded
In Hartley et al. (2003), what were brain activation differences between route followers and wayfinders?
Better navigators use their hippocampus more for way-finding navigation
Better navigators use their caudate less for way-finding navigation
What kind of brain wave comes from electrode recordings in the hippocampus?
Theta oscillation (around 8hz)
This has been found to occur:
during rat exploration of environment (A)
during human virtual exploration of environment (B)
Are cells more likely to fire at the peak of oscillation?
Yes
Cornwell et al. (2008) studied hippocampal theta oscillation when people navigated a virtual morris water maze. What did MEG activity show?
Hippocampal Theta power increases during water maze performance (particularly at beginning of trial)
Therefore,
Hippocampal Theta power at beginning of trial strongly predicts navigational accuracy
Which part of the hippocampus is localised to anxiety and which part is localised to spatial memory?
Anterior hippocampus = anxiety
Posterior hippocampus = spatial memory
What were results of a double dissociation of spatial cognition and anxiety with regards to hippocampal theta? (Cornwell et al., 2012)
Better navigators had stronger theta in posterior hippocampus
More anxious people had stronger theta in anterior hippocampus (this was lower frequency)
Schinazi et al. (2013) had ppts navigate a university campus, learning two routes. In subsequent sessions, ppts learnt connecting routes between them. What gender differences and hippocampal size differences were found?
Overall - males better than females, however not significant hippocampus differences between them
Better map learners had larger right hippocampus (particularly posterior hippocampus)
Do better navigators have larger hippocampi? Is this an increase of grey or white matter volume?
Yes
Grey matter volume
What did Maguire discover about the hippocampi of London taxi drivers?
1) Main result:
Larger posterior hippocampal volume in taxi drivers
(2006: > bus drivers)
2) Smaller anterior hippocampal volume in taxi drivers
(not shown here)
3) Both studies:
The longer time spent as taxi driver, the larger the posterior hippocampus
What was an issue with Maguire’s original taxi driver study?
Cause and effect:
Do people who have largest hippocampus to begin with seek out taxi driving as a career more bc they are good at it, or does hippocampus become larger with experience as a taxi driver?
