Biopsychology Notes - Chapter 12

Page 1

The Nature of Learning (333-336)

THOUGHT QUESTIONS

Can you think of specific examples of each of the categories of learning described in this section? Can you think of some examples that include more than one category?

KEY CONCEPTS

Learning takes many forms. The most important categories appear to be perceptual learning, stimulus–response learning, motor learning, and relational learning.

The Hebb rule describes the synaptic change that appears to be responsible for stimulus–response learning: If an initially weak synapse repeatedly fires at the same time that the postsynaptic neuron fires, the synapse will become strengthened.

Page 2

Synaptic Plasticity: Long-Term Potentiation and Long-Term Depression (337-344)

Introduction of Long-Term Potentiation

Role of NMDA Receptors

Mechanisms of Synaptic Plasticity

Long-Term Depression

THOUGHT QUESTIONS

The brain is the most complex organ in the body, and it is also the most malleable. Every experience leaves at least a small trace, in the form of altered synapses. When we tell someone something or participate in an encounter that the other person will remember, we are (literally) changing connections in the person’s brain. How many synapses change each day? What prevents individual memories from becoming confused?

KEY CONCEPTS

Long-term potentiation occurs when axons in the hippocampal formation are repeatedly stimulated.

Associative long-term potentiation appears to follow the Hebb rule and understanding it may help us understand the physiological basis of learning.

The special properties of NMDA receptors as both voltageand neurotransmitter-dependent account for associative long-term potentiation.

The entry of calcium into dendritic spines activates enzymes that cause the insertion of AMPA receptors into the postsynaptic membrane and initiate biochemical and structural changes in the synapse. PKM-zeta plays an essential role in this process and is responsible for the establishment of longlasting long-term potentiation.

Page 3

Perceptual Learning (344-346)

THOUGHT QUESTIONS

How many perceptual memories does your brain hold? How many images, sounds, and odors can you recognize, and how many objects and surfaces can you recognize by touch? Is there any way we could estimate these quantities?

Can you think of times that you saw something that you needed to remember and did so by keeping in mind a response you would need to make rather than an image of the stimulus you just perceived?

KEY CONCEPTS

Learning to recognize complex stimuli involves changes in the association cortex of the appropriate sensory modality.

Page 4

Classical Conditioning (346-347)

KEY CONCEPTS

Study of the role of the amygdala and associated structures in learning conditioned emotional responses has furthered our understanding of the physiological basis of classical conditioning.

Page 5

Instrumental Conditioning (347-351)

Role of the Basal Ganglia

Reinforcement

THOUGHT QUESTION

Have you ever been working hard on a problem and suddenly thought of a possible solution? Did the thought make you feel excited and happy? What would we find if we had a microdialysis probe in your nucleus accumbens?

KEY CONCEPTS

The basal ganglia appear to be involved in the retention of learned behaviors that have become automatic and routine.

Electrical stimulation of several parts of the brain— especially the medial forebrain bundle—can reinforce an animal’s behavior.

Reinforcing brain stimulation and natural reinforcers are effective because they cause the activation of neurons in the mesolimbic and mesocortical systems, which release dopamine in the nucleus accumbens, prefrontal cortex, limbic cortex, and hippocampus.

Drugs that block dopaminergic transmission in the nucleus accumbens block the reinforcing effects of electrical stimulation of the brain.

Page 6

Rational Learning (351-365)

Human Anterograde Amnesia

Spared Learning Abilities

Declarative and Nondeclarative Memories

Anatomy of Anterograde Amnesia

Role of the Hippocampal Formation in Consolidation of Declarative Memories

Episodic and Semantic Memories

Spatial Memory

Relational Learning in Laboratory Animals

THOUGHT QUESTIONS

Although we can live only in the present, our memories are an important aspect of our identities. What do you think it would be like to have a memory deficit like H. M.’s? Imagine having no recollection of over thirty years of experiences. Imagine being surprised every time you see yourself in the mirror and discover someone who is more than thirty years older than you believe yourself to be.

KEY CONCEPTS

Damage to the hippocampal formation causes a syndrome of anterograde amnesia, in which people can still learn to perform perceptual, stimulus–response, or motor learning tasks but can no longer learn to find their way in new environments or describe episodes from their lives that occur after the time of the brain damage.

Studies with laboratory animals suggest that the hippocampal formation facilitates relational learning by recognizing contexts and coordinating learning that takes place in other parts of the brain. Place cells play a role in the navigation and memory of spatial contexts.

The hippocampus is involved in reconsolidation (modification of existing memories). Neurogenesis may play a role in hippocampal memory functions.

Page 7

Examples of Declarative and Nondeclarative Memory Tasks

Page 8

Resources