Conditioning Flashcards
What is a conditioned stimulus and give an example of one?
Cs is when a reaction is only produced after training, an example of this would be the bell in Pavlov’s experiments.
What is a unconditioned stimulus and give an example of one?
Is a stimulus that always produces a response, this would be the food in the experiment
What widely used model of classical conditioning works like a perceptron?
Rescorla-Wagner
How does the Rescorla- Wagner model work?
Like a perceptron; bases on the stimulus the animal anticipates a reward and adjusts its prediction according to its accuracy.
If x is a binary value representing the presence or absence of the stimulus, r >0 is the reward; a negative reward corresponds to an aversive event, v is the predicted reward and w the height used by the animal to predict the reward, What are the equations for the reward v and the update rule for w
v=wx
w->w+eta∂x
where ∂ = r-v and eta is the learning rate.
What is the total reward,predicted reward and the learning rule in the Rescorla-Wagner model?
r=sum(xr)
v=sum(xw)
wi->wi+eta∂xi
where ∂=r-v
What is blocking?
Consider conditioning a reward r on a stimulus s1 and then changing so that there are two stimuli used to predict r, s1 and s2; now, when s2 is shown on its own to the animal it does not anticipate the reward. Thus, for example, Pavlov’s dog might be shown a light just before it is fed and will soon salivate when it sees the light; next a light is lit and a bell rung before feeding, now, if the bell is rung on its own, the dog does not salivate; the light has blocked the bell. This is an easy consequence of the Rescorla-Wagner rule since the w for the light already gives a correct prediction of the target and so the w for the bell stays at zero as there is no error. Blocking is not a consequence of other models of conditioning proposed at the same time. It has, however, been observed in behavior
Where is the ventral tegmental area located?
Beside the substantia nigra (SN) in the midbrain
What is the VTA important in?
Cognition, motivation, orgasm, drug addiction, intense emotions relating to ,ove and several psychiatric disorders.
The VTA is believed to play an important role in the reward system.
..
What is Dopamine
A neuromodulator, the level of dopamine alters the dynamics of the synapse: different synapses have different dopamine receptors and so their dynamics might be altered in different ways.
VTA has _ numbers of dopaminergic neurons
Large
Where do half of dopaminergic neurons live?
In the Ventral tegmental area
What type of neuron accounts for 50% of all neurons in the Ventral tegmental area?
dopaminergic
VTA contains a lot of what type of synapse?
Gap junctions
