Spatial Cognition and Memory

HM

Could learn sensorimotor skills in a mirror-tracing task.

But severely impaired spatial memory - couldn’t form an ‘instantaneous cognitive map’.

2 types of spatial learning

1. Place Learning - map-based, depends on hippocampus

2. Response Learning - stimulus-response chain, depends on caudate

Tolman and Lashley theory - rats creating a field map of space

Rats escaped maze and ran over top straight to food box - this motor pattern never been practised/reinforced = suggests rats may not be slaves to S-R conditioning.

Tolman field map (1948)

Knowledge can be flexible and based on cognitive maps.

These mental maps serve wider cognitive functions beyond space and navigation.

Hippocampus as a substrate of a cognitive map

Makes, stores and uses maps of the external world.

Crucial for map-based navigation NOT route learning

• Map-making occurs automatically

Hippocampus recognises novelty - drives exploration that builds and updates maps.

O’Keefe and Dostrovsky (1971) and O’Keefe - put electrode in rat hippocampus

Discovered place cells

Place cells are context-specific (unlike some other spatial cells)

Different place cells cover different areas on a spatial map.

Can bind events to the spatial map (episodic memory link).

Hippocampus contains many different types of place cell - Poulter, Hartley and Lever (2018)

1. Head direction cell - fires whenever head faces a particular direction.

2. Boundary vector cell - fires at a specific distance and direction from a stimulus.

3. Grid cell - mammalian brain divides space into nodes (equilateral triangles)

What are vector trace cells

Boundary vector cells that also remember vectors to stimuli.

Has trace capability (firing can remain even when an object is removed).

Hippocampus function

Spatial memory and episodic memory.

Represents allocentric, large-scale space

Function: navigation, LTM for scenes, spatial contexts, binds items in contexts.

Maguire et al. 1998 🗺 - Human navigation and hippocampal activity (PET) - nav1

Virtual town, subjects can head directly to goal.

More right hippocampal activity = more accurate path

More hippocampal blood flow = better accuracy

More inferior parietal activity = better activity

• H provides allocentric representation of space, right IPC uses this info to compute the correct body turns to enable movement to goal.

Only area sig positively covarying with speed = right caudate nucleus.

Activity in left hippocampus does NOT sig covary with navigation accuracy.

Maguire et al. 1998 🗺 - Human navigation and hippocampal activity (PET) - nav2

Virtual town, direct routes blocked so had to take detours.

Left frontal activation - because requirement for strategy switching.

Maguire et al. 1998 🗺 - Human navigation and hippocampal activity (PET) - interpretations and conclusions

Clear evidence of IDs.

BUT can’t rule out within-subject variance

Wayfinding vs route following (fMRI study) - Hartley et al. (2003)

Better navigators use their hippocampus more for wayfinding (suggests effect mainly driven by IDs).

Better navigators use their caudate more for route following and less for wayfinding.

Cornwell et al. (2008) 💦 - Virtual water maze for humans

Theta power in left anterior hippocampus and parahippocampal cortices increases during water maze performance.

Left anterior hippocampus activity predominantly observed in first half of training - role in early learning.

Posterior hippocampus theta highly correlated with navigation performance.

• Early hippocampal activity predicts navigation performance.

• Greater differential activity in left posterior hippocampus at start of navigation = best average length taken to platform.

Cornwell et al. (2012) 😧 - better mappers use their posterior hippocampus more

Virtual Morris water maze, risked receiving electric shocks before platform.

Better navigators - stronger theta power in left posterior hippocampus (no anterior hippocampal theta related to nav)

More anxious - stronger theta power in left anterior hippocampus

Better map learners have ____ ____ hippocampus - Schinazi et al. (2013)

Larger right hippocampus - particularly posterior H

Woollett and Maguire (2011) 🚕 - Role of experience in larger posterior hippocampi in better navigators

Increased grey matter in posterior hippocampus in those that passed The Knowledge.

No decrease in anterior hippocampus volume (maybe happens after, in response to, posterior increase).

BUT researchers mentioned possible influence of genetic predispositions on spatial mapping functions.