All Lectures PDF

All Lectures Pre-lecture work 1 💡 What is Psychobiology? The study of the biological (both brain and body) mechanisms of normal and abnormal behavior. Behavior in the body is dependent upon body function....

All Lectures Pre-lecture work 1 💡 What is Psychobiology? The study of the biological (both brain and body) mechanisms of normal and abnormal behavior. Behavior in the body is dependent upon body function. The brain is the primary area involved. Organisation of the brain: The hemispheres: All Lectures 1  Left: speech and abstract thinking. It also controls the right side of the body. Right: responsible for image processing, spatial thinking, and movement in the left side of the body. 💡 The left and right sides of the brain connect via nerve fibers. Neurons structure: All Lectures 2  MAIN NEUROTRANSMITTERS: 1. GLUTAMATE 2. DOPAMINE 3. GABA Lecture Notes: 💡 What is Learning? Acquisition of behavioral information. Memory is the retention of information. Learning is important for adaptive behavior Memory gets better with more learning. Law of Diminishing returns: Same effort that one puts into learning generates less additional improvement. Learning curve All Lectures 3  The Rescola-Wagner Rule: ∆V = αβ(λ − V) Highlights the importance of surprise in learning. You learn more when you are surprised. The amount learned is proportional to the amount of surprise of the outcome At the start of learning V is small and Delta V is larger. ❗ As we learn V gets bigger therefore the prediction error reduces. (When V is bigger Delta V is smaller) Supporting evidence - Pavlovian blocking: Blocking occurs when a novel stimulus (no predictive value) is presented together with a well-established CS (predictive value is equal to λ, that is, 1). eg,. 1. X is presented, leads to outcome. 2. X+Y are now presented together. 3. The presence of X blocks knowlegde of Y 4. Assume outcome is only happening because of X and not Y e.g. 1. Tom is allergic to peanuts 2. if he eats peanuts = going hospital 3. Bob offered tom peanuts and kale - he didnt know about Toms allergy - This led to Tom being in the hospital - Bob was shocked. 4. Tom would eat kale again as he knows his allergy reaction was due to the peanuts. 5. But we do not know 100% that he isnt allergic to kale as well. All Lectures 4  6. So knowledge of the peanut allergy blocked the idea of him being allergic to Kale as well. If an outcome is predicted, no learning will take place Supporting evidence - Biological evidence: 1. Hollerman & Schultz: monkey Monkey was presented a visual cue (resulted in the providing of a banana milkshake) Banana milkshake = reward Monkey associated the two. 💡 Researchers examined neurons that use the neurotransmitter dopamine within the ventral tegmental area in the mid brain. Rastor Plot: Each dot represents an action potential of a dopaminergic neuron. Above the plot (skyline) average of how things went. Key: R= reward, CS CS= reward All Lectures 5  Plot 3: Monkey was shown image but the reward was not presented. Results in silence in response in the vta. Plot 1: First time award was presented - no prediction (no association between image and reward yet) - leads to unpredicted behavior. Before the reward was presented there was still brain activity. R presented itself → dots all gathered right after → more action potential. (VTA has action and firing Plot 2: monkey learned that after the image is preseted the reward will be present. No VTA activation as monkey predicted the result of a reward after the imag. There was an elevation of action potential after seeing the screen, VTA activated when monkey thought he was going to get the reward All Lectures 6  Conclusion: If monkey did not predictct the reward after the reward is presented, VTA activated and firing. If monkey predicts the reward, there is no increase in firing. 💡 No prediction = firing in the VTA 2. In humans: → Gathered people and gave a predictable outcome. → They were given water and juice every 20 seconds. 💡 Activity that happens for unpredictable trials doesnt occur for predictable trials. There was greater activity in the Nucleus Accumbens. DopaminergIc projections from the VTA to nuclues accumbens → activity is dependent on elevated firing in VTA. → EVIDENCE THAT THE EQUATION IS CORRECT. Prediction error signals: Do prediction error signals regulate learning? 1. over-expectations will lead to higher predictions. → In this case there is a need to weaken the memory to learn the correct outcome. IN RATS: The experiment: All Lectures 7  A1 sound = reward A2 sound = reward A3 sound = no reward Image = reward Over expectation happens when I present them with the sound and the image. As they will expect double the reward, instead of 2 we present them with just 1 and they dont like this. In the test we see that they spend less time waiting for the reward. Therefore we conclude that: VTA prediction error is inhibited by inactivating the orbitofrontal cortex This shows that the VTA is NECCESSARY in learning. IN BABIES The experiment: 1. show solid object/block 2. show sound it produces 3. make a car go through In the 1st experiment the car doesnt make a sound and stops at the first block. In the 2nd experiment car goes through the first block and found behind second. 💡 The baby did not predict this outcome which led to a reaction. Therefore we conclude that: When prediction errors are high you learn more than when it is low. Summary: All Lectures 8  Learning and memory are important for survival Learning is gradual The Rescorla-Wagner rule explains the shape of learning curves Surprise/prediction error is important in the Rescorla-Wagner rule VTA dopaminergic neurons may signal prediction errors Timescales: Timescales are stages of visual memory. 2 stages of visual memory: 1. Immediate ‘iconic’ memory (