1 Chapter 12 Learning

2 Three Types of Behavior Reflexes involuntary responses to stimuli. Instincts stereotyped responses triggered by environmental stimuli. Learning a relatively permanent change in behavior due to experience. © Renee Purse/Photo Researchers, Inc.

3 Types of Learning Associative learning involves a connection between two elements or events. Classical conditioning Operant conditioning Nonassociative learning involves change in the magnitude of response to environmental events. Habituation Sensitization

4 Nonassociative learning Habituation The response to steady or repeated (harmless) stimulus decreases over time. Example: You don’t hear your air conditioner after it’s been running awhile. Sensitization The experience of one stimulus heightens the response to a subsequent stimulus. Example: People are “jumpy” following natural disasters, like earthquakes.

5 Using Aplysia Californica to Study Learning The gill is used for breathing. The gill can be covered with the mantle shelf. Waste and seawater are released through the siphon. The gill-withdrawal reflex occurs when touching the siphon produces a retraction of the gill.

6 Using Aplysia Californica to Study Learning Anatomy of gill- withdrawal reflex This reflex can show habituation 6

7 Why does habituation occur? Possible Hypotheses 1. Do sensory neurons in the siphon become less responsive? 2. Does the gill muscle lose its ability to contract? 3. Do changes occur at the synapses between the sensory and motor neurons? Daniel L. Geiger/SNAP

8 Kandel’s Explanation of Habituation Aplysia

9 Kandel’s Explanation Sensitization in Aplysia

10 Kandel’s Explanation Sensitization in Aplysia

11 Long-term Changes in Habituation and Sensitization Normal Aplysia showed 1300 axon terminals on sensory neurons. Aplysia experiencing sensitization had 2800 terminals. Aplysia experiencing habituation had 800 terminals.

12 Associative learning Classical Conditioning Basic Procedure

13 Classical Conditioning in Aplysia

14 Conditioned Emotional Responses and the Amygdala Typical experiment for conditioned emotional response Tone (CS+) followed by shock (UCS) results in reduced feeding (CR) in rats.

15 Conditioned Emotional Responses and the Amygdala Evidence that amygdala involved in this type of learning Lesions of the basolateral nucleus of the amygdala prevent this learning. Recording during training shows an increased response of the amygdala to the tone. Blocking NMDA receptors in the amygdala prevents learning of conditioned emotional responses.

16 Hebb rule The hypothesis that the cellular basis of learning involves strengthening of a synapse that is repeatedly active when the postsynaptic neuron fires.

17 Instrumental learning (operant conditioning): A learning procedure whereby the effects of a particular behavior in a particular situation increase (reinforce) or decrease (punish) the probability of the behavior. Association between a stimulus and a response Not automatic Associative learning

18 Instrumental Learning