Memory systems in mammals Flashcards
Define contextual fear conditioning.
When a subject shows fear in the context of their conditioning. E.g. rats conditioned to associate sound with an electric shock will freeze in fear when placed into the chamber they’re conditioning took place in, even when neither stimulus is present. This is common in PTSD.
What brain structure does contextual fear conditioning rely on?
The hippocampus as memories are involved, e.g. the rat remembers the surroundings.
Define cued fear conditioning.
When the subject displays fear upon exposure to the neutral stimulus they have been conditioned to associate with a noxious one, e.g. the rats are played the sound that usually accompanies an electric shock.
Which brain structure is important in cued fear conditioning?
The amygdala.
a) What is the principle of dynamic polarisation?
b) Who proposed it?
a) That information can only travel in one direction down a neuron.
b) Santiago Ramon y Cajal
a) What is Hebbian theory?
b) Who proposed it?
a) It proposes a mechanism for synaptic plasticity in learning: an increase in synaptic efficacy results from the repeated and persistent stimulation of the post-synaptic neuron by the pre-synaptic neuron.
Basically the more times a pathway is used the stronger it gets.
b) Donald Hebb
Which part of the brain is involved in procedural memory?
The striatum.
Which part of the brain is involved in priming?
The neocortex.
What is the 8-arm maze?
A memory test: mice are placed in a chamber with 8 arms, each with food at the end. The mouse must find all the food and is scored on the number of errors it makes, i.e. whether it returns to previously visited chambers.
What is the Morris water maze?
A memory test: mice are placed into a water bath with a hidden platform. They must swim around the bath until they find the platform to rest on. They cannot see it. When put into the water maze again the mice do not waste time swimming around and remember, using visual cues, where the platform is.
What happens to mice in the Morris water maze when they have had lesions to the hippocampus?
They cannot remember where the platform is.
Define place learning in terms of solving a maze.
One of the main mechanisms in cognitive map theory whereby the subject learns where it is in space by using (visual) cues, e.g. the maze exit is under the window.
Define response learning in terms of solving a maze.
The subject learns how to solve the maze by memorising a particular response, e.g. turn left, turn right, turn right etc.
How can place vs. response learning be tested with mazes?
For example if a maze is a plus shape: start the subject as being north, and you put a reward in the west pointing arm. Assume the subject can see outside of the maze and identify visual cues. Then remove the subject and turn the maze round. If the subject goes west it is place learning, as it has used the external visual cue to orientate itself, or if it was response learning it will have gone east because that’s the response it learned last time.
Early on in maze experiments with rats, what happened when lidocaine was injected into a) the hippocampus and b) the caudate nucleus? c) What does this suggest?
a) Place response was reduced and response responses were increased.
b) There was little effect on either response.
c) The hippocampus is heavily involved in place learning
