BiologicalBasis 7 Spatial Learning slides and notes.pdf

Ian McLarenLecture 7Spatial LearningPSY2304Biological Basis of Behaviour To-day’s questionHow do animals manage to learn where things are? It’s navigation –but with an emphasis on learning.We go about this by:•Studying learning to distinguish one place from another.•Asking how do they do this?•Do t...

Ian McLarenLecture 7Spatial LearningPSY2304Biological Basis of Behaviour To-day’s questionHow do animals manage to learn where things are? It’s navigation –but with an emphasis on learning.We go about this by:•Studying learning to distinguish one place from another.•Asking how do they do this?•Do they learn by smell? Location designated by landmarks in some way? A response that gets them there? Any or all of these? S+ = food_The simple T-maze. How does the rat do it? S+_ S+_ Some possibilities:SMELLOf food or the odour trail left from other runs.PAVLOVIAN CONDITIONED APPROACHIt learns to approach a landmark near the goal (we call this a beacon).INSTRUMENTAL RESPONSEIt learns to turn left –instrumental learning.MAPIt knows the location of the goal, and so finds a path to it. Test in extinctionIt can detect where the food is (odourperhaps)? Yes –it could –but we can prevent that by...Maybe it’s the odourtrail left by the rat? Yes –it could use this as well but...Swap the arms of the T-maze+-“+” = trained side but no food there.S+-SIf it’s following an odourtrail it will now go to the “wrong” side.We can rule out both of these mechanisms and the rat can still solve the problem. As we know it’s not the odour of the food, the trick is to rotate the entiremaze 180 degrees to differentiate between a response based on place and one based on instrumental learning. This approach can also rule out the “odour trail” explanation ifthey show control by place.Working down our list, we can now see that the next possibilities are Pavlovian conditioned approach to a landmark near the goal and instrumental learning to turn left –how do we tell which of these is controlling behaviour? ABS If we’ve established that the rat is heading for a certain point in space, the question then arises of how it is doing that. Is it using a map -or just approaching a specific landmark (beacon)? By taking the landmark away (deletion) we can assess the effect on the rats performance. We can also try altering the configuration (spatial arrangement) of the landmarks. The Radial Arm Maze•Radial Arm Maze experiments with rats.•There is now abundant evidence that rats typically solve this maze by using the external (extra-maze) landmarks.•Rotation tests and landmark deletion / re-arrangement studies all point to this conclusion. Rotation Test:The animals are forced to the 4 arms shown in blue, then the maze is rotated through 45º (or the landmarks are rotated relative to the maze. UVRotation Test:Now the rats are offered a choice between an unvisited arm U(animal has not been down it, there is food at the end, but it’s now at the location that was visited) or a visited arm V(animal has just been down it, no food at end, but is at an unvisited location.) UVThe result is that rats tend to choose the visited arm. In my studies a typical result was that on 32 trials 20 were revisits to previously visited arms. A control test where the maze was not rotated gave only 2 visits to previously visited arms, a highly reliable difference. Suzuki, Augerinosand Black (1980) used a cylindrical testing chamber with discrete landmarks at each arm of the radial maze. They found that rats ‘followed”rotation of the landmarks with respect to the maze, but a re-arrangement of the landmarks relative to one another (what they call landmark transposition which in this case just means swapping some landmarks over) dramatically worsened performance between study and test.These data suggest that rats use configurations of landmarks to define locations in the radial maze, rather than using them as beacons to mark specific locations close by.O’Keefe and Nadel (1978) in their book “The Hippocampus as a Cognitive Map”went further and claimed that animals use a map to navigate, and that the mechanisms for constructing and using this map were located in the hippocampus.O’Keefe was awarded the Nobel Prize in 2015 for his work on Cognitive Maps. card fan light buzzer O'Keefe and Conway 1978 Remove all 4 cues: 6/8 units lose ability to discriminate place field Remove any 2 cues: 3/8 units lose ability to discriminate place field Conclusion: For some units, cues are used in combination to designate a given region such that any 2 cues will define it. card buzzer fan light O’Keefe and Conway (1978) The Morris Water Maze: The apparatus looks like this (plan view). It's raised off the floor and open so that the animal can see around the room.PoolBlack curtainsPlatformABCDA -D are landmarks. PoolSThe rat is put in the pool at a random location along the side (S).ABCD PoolSIt then swims to the platform, at first in a roundabout fashion, later more directly. Animals with hippocampal lesions are impaired at this task, in that they take longer to find the platform and do not exhibit the ability to swim straight to it in the way that controls can.ABCD Blocking in the water maze:A problem for the cognitive map hypothesisTwo groups are trained in the water maze to find a platform on the basis of different sets of landmarks, either ABC or ABCX.Landmark X is then added to ABC in the first group, and more training given.Tests with ABC and ACX reveal how well the animal has learned to use X to find the platform in conjunction with the other landmarks. BlockingControl BlockingRodrigo,T.,Chamizo,V.D.,McLaren,I.P.L.,&Mackintosh,N.J.1997.Blockinginthespatialdomain.JournalofExperimentalPsychology:AnimalBehaviorProcesses,23,110-118. T 1 T 2 G 1 G 2 1 1.5 2 2.5 ABCABXBlockingControlMean Rank: 1=bestThe Blocking Group are worse at using landmark X (see ABX) Summary•If you give a rat the problem of finding food in a maze, then the truth is –it will learn to do that using any method available!•But we can show that it is able to use landmarks, and, more than that, to use configurations of landmarks.•But the learning is still subject to the same learning phenomena we’ve already encountered. It seems there’s one set of principles that govern learning.