Hippocampus And Spatial Memory Flashcards
What allowed researchers to pinpoint the area of the brain responsible for navigation?
Human data (e.g. patient H.M.)
What are the two major mechanisms for navigation?
Path integration and cognitive map
What type of cells within the hippocampal formation support path integration?
Direction and grid cells
What type of cells within the hippocampal formation support the cognitive map?
Place cells
What type of animal is a good model for path integration?
Ants
What 3 W’s studied navigation of desert ants?
Wittinger, Wehner and Wolff (2006)
Theoretically, what are the two possible ways an ant could navigate back to the nest?
- Remember the path exactly
2. Use motor system and sense of direction (from polarised light) as well as distance travelled
What is the evidence that ants might use their motor system information, sense of direction and distance travelled to navigate back to the nest?
They take the most direct route back to the nest, so they must have a sense of distance traveled, and be able to compute and integrate this information with direction when navigating back to the nest
What were Wittinger, Wehner and Wolff (2006) interested in finding out?
Whether animals actually count their steps back to the nest
What was the main idea of 3W’s experiment
If you make the legs of an ant shorter or longer you can change the distance of the step and thus observe whether ants actually step count
Describe the methodology of the 3 W’s experiment
- Train ants to navigate from nest to source of food
- Modify length of ants legs (short, normal or stilts)
- Let them navigate back to the nest
What were the main findings of the 3Ws experiment?
Normal ants navigated back to the nest fine
Ants with stunk legs stopped before the nest
Ants with stilts stopped after the nest
What did the 3 W’s find happened when they did the same task on the modified ants the next day?
The ants were able to compensate for their modified legs as they travelled the correct distance to the nest
So what type of information do ants use to navigate? What is this evidence of?
They use their own motor information to navigate. This is evidence of path integration
What is a cognitive map?
Internal representation of the outside world based on sensory information
What are the advantages of path integration?
Animals can navigate between locations by integrating linear and angular self motion
What are the disadvantages of path integration
Longer journeys tend to accumulate errors
What are the advantages of a cognitive map
Highly accurate
What are the disadvantages of a cognitive map
Cannot support navigation between locations
What type of navigation is path integration
Egocentric
What type of navigation is a cognitive map
Allocentric
Why is learning to navigate a new environment ‘unsupervised learning’
The animal is not rewarded for learning the layout of the new environment. There is no explicit learning outcome
Who first believed that there were detailed internal maps within the rat brain, and coined the term ‘cognitive map’
Tolman
How did Tolman show that rats use unsupervised learning
Set up a maze experiment whereby one set of rats is trained to retrieve food from the end of the maze, and the other set of rats was just left to explore the maze.
Of the rewarded rats, deviation from the optimal path decreased with time. Rats were operating at s low error rate near the end of the experiment
On the 11th day of the experiment the un-rewarded rats were given food to retrieve.
These rats found the food as easily as the rats that had been trained to retrieve the food. End up performing slightly better due to greater exploration of the maze
Shows that unrewarded rats are learning about the maze
How did Tolman show that rats possess a cognitive map
Used a maze with a series of blockage manipulations.
Rats firstly given free reign on the maze - eventually learn to take the shortest of three possible routes to the food.
Then put in block A - blocks the shortest route, rats take the shortest detour
Then put in block B - blocks shortest route and shortest detour.
Rats take the longest, but only possible, detour.
Evidence of rats using knowledge of maze to guide behaviour