Lecture 14 Spatial Navigation Flashcards
(30 cards)
Why do we need to know where objects are located in our visual environment?
To know
* where object is located
* where we are located in the world
Why do we need to know our location in the world?
- navigation,
- episodic memory
- future planning (e.g., finding home or food).
What is a cognitive map?
An internal representation of spatial relationships that allows for flexible navigation.
What did Tolman’s rat experiments demonstrate?
Rats used spatial knowledge to switch paths when blocked, supporting the idea of cognitive maps.
What are place cells and who discovered them?
Neurons in the hippocampus **
that fire* at specific real-world locations; ***
discovered by O’Keefe and Dostrovsky (1971).
What are grid cells and where are they located?
Cells that fire in a hexagonal pattern across environments;
found in the medial entorhinal cortex.
What do head direction cells do?
Fire based on the direction the animal’s head is facing.
What do border/boundary cells do?
Fire at certain distances from navigational boundaries facing specific directions.
Who discovered grid cells and when?
Moser & Moser in 2005; they shared the Nobel Prize with O’Keefe.
Are rodent navigation systems good models for human navigation?
Yes, but with differences—humans have more complex visual systems and broader memory deficits with damage.
Why is it hard to study navigation with fMRI in humans?
Navigation requires movement, but fMRI requires participants to stay still.
What methods are used in fMRI studies of navigation?
Virtual navigation, imagined navigation, spatial memory recall, or viewing relevant stimuli.
What is the parahippocampal place area (PPA)?
A region in the visual cortex that responds preferentially to
scenes over faces or objects.
Where is the PPA located anatomically?
Along the parahippocampal gyrus and collateral sulcus.
What kinds of stimuli does the PPA respond to?
Realistic scenes with spatial layout (e.g., landscapes, cityscapes), not just individual objects.
What is the spatial layout hypothesis?
The PPA encodes the global spatial layout,
while LOC and fusiform gyrus encode individual objects.
What does fMRI adaptation reveal about the hippocampus?
Activity scales with spatial distance between landmarks, not their identity—similar to border cells.
How was distance coding studied in humans using fMRI?
Subjects viewed photos of landmarks;
hippocampal activity correlated with subjective distance between landmarks.
How have individual neurons been recorded in humans for navigation studies?
In epilepsy patients with depth electrodes exploring virtual environments.
What types of neurons were found in humans during virtual navigation?
- Place-responsive cells
- landmark-view responsive cells
especially in the hippocampus.
What is viewpoint-independent direction coding?
Encoding of direction not tied to visual appearance—shown using adaptation to same or different heading images.
What brain area represents allocentric heading in humans?
The retrosplenial complex (RSC), located in the medial parietal cortex.
What did Howard et al. (2014) discover using fMRI in navigational tasks?
- Hippocampal activity positively correlated with Euclidean and path distance to the goal.
- **Path **Distances encoded more posteriorly
- Euclidean Distances encoded more anteriorly
How are distances encoded within the hippocampus during navigation?
Path distance is encoded more posteriorly, Euclidean distance more anteriorly.
