Chapter 12 Learning and Memory: Basic Mechanisms

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Description: Chapter 12 Learning and Memory: Basic Mechanisms

Chapter 12 Learning and Memory: Basic Mechanisms
Chapter 12 Learning and Memory: Basic Mechanisms This multimedia product and its contents are protected under copyright law. The following are prohibited by law: any public performance or display, including transmission of any image over a network preparation of any derivative work, including the extraction, in whole or in part, of any images any rental, lease or lending of the program. Copyright © 2008 Pearson Allyn & Bacon Inc.

Synaptic Plasticity: Long-term potentiation and Long-term Depression
Chapter 12 Outline The Nature of Learning Synaptic Plasticity: Long-term potentiation and Long-term Depression Perceptual Learning Classical Conditioning Instrumental Conditioning Relational Learning Copyright © 2008 Pearson Allyn & Bacon Inc.

1. _____________________: the ability to recognize familiar stimuli.
Studies of the biology of learning has produced learning categories that differ somewhat from those used in most General Psychology courses. Learning: the process by which experience changes the nervous system, and hence changes behavior. 1. _____________________: the ability to recognize familiar stimuli. Facial recognition & the ability to identify “strangers” Accomplished by changes in the association cortex. Copyright © 2008 Pearson Allyn & Bacon Inc.

Learning 2. Stimulus-response learning: establishing connections involved in perception and those involved in movement. Learning to automatically ____________________________________________________________________________________________________. Classical conditioning Operant conditioning (3?) Motor learning: most skilled movements involve practice designed to “improve” the relationship between _________________, batting practice, learning to drive a car or ride a bicycle. Copyright © 2008 Pearson Allyn & Bacon Inc.

Learning (4 or 3?). _____________________: learning the relationships between individual stimuli. Learning the locations of objects in a room Learning the locations and relationships of the structures that compose the limbic system. Episodic learning: sequences of events Copyright © 2008 Pearson Allyn & Bacon Inc.

The Nature of Learning Classical conditioning
A learning procedure; when a stimulus that initially produces no particular response is followed several times by an unconditioned stimulus that produces a defensive or appetitive response. This type of learning involves: Unconditioned stimulus (US) Unconditioned response (UR) Conditioned stimulus (CS) Conditioned response (CR) Copyright © 2008 Pearson Allyn & Bacon Inc.

Classical Conditioning
Classical Conditioning Copyright © 2008 Pearson Allyn & Bacon Inc.

The Nature of Learning ______________
The hypothesis proposed by Donald Hebb that the cellular basis of learning involves strengthening of a synapse that is repeatedly active when the ___________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

The Nature of Learning Instrumental conditioning (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; also called operant conditioning. Copyright © 2008 Pearson Allyn & Bacon Inc.

The Nature of Learning Reinforcing stimulus
An ______________stimulus that follows a particular behavior and thus makes the behavior become more frequent. Punishing stimulus An ______________stimulus that follows a particular behavior and thus makes the behavior become less frequent. Copyright © 2008 Pearson Allyn & Bacon Inc.

Overview of Learning Systems
Copyright © 2008 Pearson Allyn & Bacon Inc.

Memory Formation Neural circuits that contain memories are probably established by strengthening some synapses, and weakening others. At a behavioral level: ______________may be produced by weakening synapses (or strengthening inhibitory inputs). ________________may be produced by strengthening synapses (or weakening inhibitory inputs). Copyright © 2008 Pearson Allyn & Bacon Inc.

Learning and Synaptic Plasticity
Induction of long-term potentiation Long-term potentiation A long-term increase in the excitability of a neuron to a particular synaptic input caused by repeated high-frequency activity of that input. Hippocampal formation A forebrain structure of the temporal lobe, constituting an important part of the limbic system; includes the _____________________________________________________________________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Induction of long-term potentiation Population EPSP An evoked potential that represents the EPSPs of a ________________. Multi-unit recording. Long-term potentiation can follow the Hebb rule. It can last for several months. A. Stimulate preforant path (entorhinal cortex), a burst of several seconds of stimulation. B. Potentiation observed by a larger population of EPSP responses in dentate gyrus (lasts for months). Copyright © 2008 Pearson Allyn & Bacon Inc.

Hippocampal formation & long-term potentiation

Induction of long-term potentiation Associative long-term potentiation A long-term potentiation in which concurrent stimulation of weak and strong synapses to a given neuron generates _____________________________________________________________________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Associative long-term potentiation.

Role of NMDA receptors NMDA receptor A specialized ionotropic glutamate receptor that controls a calcium channel that is normally blocked by Mg2+ ions; involved in long-term potentiation. Dendritic spike Normally only axons can produce action potentials. However, ___________________________________________________________________________________________. An action potential that occurs on the ___________ of some types of pyramidal cells. Copyright © 2008 Pearson Allyn & Bacon Inc.

Synaptic strengthening only occurs if ___________________________________________________________________. Molecules of the neurotransmitter must bind with receptors in a depolarized dendritic spine. Copyright © 2008 Pearson Allyn & Bacon Inc.

Depolarization evicts the Mg2+ ion and unblocks the calcium channel
Depolarization evicts the Mg2+ ion and unblocks the calcium channel. The NMDA receptor requires both the _____________________________________________________________________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Role of NMDA receptors The special properties of NMDA receptors account for long-term potentiation and its associative nature. Q: How does the postsynaptic membrane change as a result of long-term potentiation? A: _________________________________________________________________________________________. AMPA receptor An ionotropic glutamate receptor that controls a sodium channel; when its open, it produces EPSPs. Copyright © 2008 Pearson Allyn & Bacon Inc.

Growth of AMPA receptors after LTP.

Mechanisms of synaptic plasticity How does the influx of calcium ions into the dendritic spine result in the insertion of additional AMPA receptors? CaM-KII Type II calcium-calmodulin kinase, an enzyme that must be activated by calcium; may play a role in the establishment of long-term potentiation. Nitric oxide synthase An enzyme responsible for the production of nitric oxide. Copyright © 2008 Pearson Allyn & Bacon Inc.

Entry of Ca2+ into the spine causes the synthesis and release of NO which serves as a second messenger to increase glutamate release. LTP requires protein synthesis, __________________________________________________________________ This results in larger excitatory postsynaptic potentials. Copyright © 2008 Pearson Allyn & Bacon Inc.

Long-term depression Long-term depression (LTD) A long-term decrease in the excitability of a neuron to a particular synaptic input caused by stimulation of the terminal button while the postsynaptic membrane is hyperpolarized. The combined effect of LTP and LTD (in associated circuits) are believed to be necessary for ________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Perceptual Learning Perceptual learning
A type of learning that involves _____________ It provides subjects with the ability to perform an appropriate behavior in an appropriate situation. Perceptual learning can involve learning to recognize entirely new stimuli, or it can involve learning to recognize changes or variations in familiar stimuli. “I like your new hair style”. Copyright © 2008 Pearson Allyn & Bacon Inc.

Perceptual learning involves changes in synapses in the inferior temporal cortex.

the picture will activate the “memory” for the sound.
If an association is formed between pictures and sounds (a barking dog & a photo of a dog), the picture will activate the “memory” for the sound. Copyright © 2008 Pearson Allyn & Bacon Inc.

Classical Conditioning
Follows the model for long-term potentiation and perceptual learning paradigm. In the formation of conditional emotional responses (foot-shock & tone) the amygdala receives inputs from the auditory and somatosensory systems. Weak synapses (auditory) input are strengthened via association with strong synapses (painful stimulus) via the Hebb rule. _______________ move into the dendritic spine. Copyright © 2008 Pearson Allyn & Bacon Inc.

Instrumental Conditioning
Operant conditioning must begin in the sensory association cortex where perception takes place and end in the motor association cortex where movement is controlled. Reinforcement: Neural circuits involved in reinforcement Medial forebrain bundle (MFB) A fiber bundle that runs in a rostral-caudal direction through the basal forebrain and lateral hypothalamus; electrical stimulation of these axons is reinforcing. This is not the only ___________ area in the brain, _____________________________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Instrumental Conditioning and Motor Learning
Reinforcement: Neural circuits involved in reinforcement Ventral tegmental area (VTA) A group of _______________neurons in the ventral midbrain whose axons form the mesolimbic and mesocortical system; plays a critical role in reinforcement. There may be more than one reward system, but this is an important system involved in reward. Copyright © 2008 Pearson Allyn & Bacon Inc.

Basal ganglia connections involved in controlling automatic complex motor behaviors (e.g. driving a standard transmission automobile). No longer have to think about it. Copyright © 2008 Pearson Allyn & Bacon Inc.

Instrumental Conditioning and Motor Learning
Reinforcement: Neural circuits involved in reinforcement _______________________ A nucleus of the basal forebrain near the septum; receives dopamine-secreting terminal buttons from neurons of the ventral tegmental area and is thought to be involved in ___________________________. Electrical Stimulation of the VTA reward center or administration of cocaine, food or sex causes release of ___________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Nucleus accumbens & Ventral Tegmental Area

Relational Learning Human anterograde amnesia _______________ amnesia
Amnesia for events that occur _______ some disturbance to the brain, such as head injury or certain degenerative brain diseases. A person with anterograde amnesia can remember events in the past and those that occurred just prior to the trauma; however, they cannot ________________________________________________________________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Reinforcement Systems
A. Must detect the presence of the reinforcing stimulus. B. Must strengthen the connections between the detection of the S+ and the instrumental response. Reinforcement occurs when neural circuits detect a reinforcing stimulus, and cause the activation of _______________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Reinforcement Reinforcement is not automatic because it also depends on the ______ of the animal (food is a reward only if the subject is hungry). The prefrontal cortex appears to turn on the reinforcement system when it determines that the ongoing behavior is likely to bring the subject ___________________. Prefrontal cortex projections to VTA secrete glutamate which causes VTA to greatly increase dopamine secretion in N. accumbens. Copyright © 2008 Pearson Allyn & Bacon Inc.

Relational Learning Human anterograde amnesia
Unable to learn new information. ___________amnesia Amnesia for events that ___________ some disturbance to the brain, such as a head injury or electroconvulsive shock. People with retrograde amnesia may not be able to recall events in the past or events that occurred just _______________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Relational Learning Human anterograde amnesia
________________ syndrome Permanent anterograde amnesia caused by brain damage resulting from chronic alcoholism or malnutrition. Unable to form _____________. ______________ The reporting of memories of events that did not take place without the intention to deceive, seen in people with Korsakoff’s syndrome. When asked about recent events subjects fabricate a possible truth, rather than say I don’t know. They appear to believe in what they are saying. Temporal lobe damage may produce the same effect (H.M.) Copyright © 2008 Pearson Allyn & Bacon Inc.

Relational Learning Human anterograde amnesia Short-term memory
Immediate memory for events, which may or may not be consolidated into long-term memory. Long-term memory Relatively stable memory of events that occurred in the more distant past. Copyright © 2008 Pearson Allyn & Bacon Inc.

Broken drawings, patients with anterograde amnesia are capable of learning that set I stilumli correspond to set V stimuli, and other kinds of perceptual and motor learning tasks. They cannot talk about their experiences. The consolidation process does not work for _________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Relational Learning Human anterograde amnesia Declarative memory
Memory that can be ________________, such as memory for events in a person’s past. Nondeclarative memory Memory whose formation does not depend on the _______________________; a collective term for perceptual, stimulus-response, and motor memory. Copyright © 2008 Pearson Allyn & Bacon Inc.

Relational Learning Anatomy of anterograde amnesia
Damage to the hippocampus & associated regions cause anterograde amnesia. A. Perirhinal cortex (__________________________) A region of limbic cortex adjacent to the hippocampal formation that, along with the parahippocampal cortex, relays information between the entorhinal cortex and other regions of the brain. Copyright © 2008 Pearson Allyn & Bacon Inc.

Relational Learning Anatomy of anterograde amnesia
B. Parahippocampal cortex (_____________________) A region of limbic cortex adjacent to the hippocampal formation that, along with the perirhinal cortex, relays information between the entorhinal cortex and other regions of the brain. Copyright © 2008 Pearson Allyn & Bacon Inc.

NMDA Receptors in the _______________
Enhance the ability of subjects to learn quickly via long-term potentiation. However, these receptors and associated neurons are sensitive to metabolic disorders. Disturbances that result in high release of glutamate allow high levels of calcium to enter the cell, and the high levels of calcium are toxic to the neuron. Hippocampus is important for the consolidation of declarative memories including the “order” in which events occurred, and the “contex” of their occurance. Copyright © 2008 Pearson Allyn & Bacon Inc.

Hippocampal Formation

Greater hippocampal activation results in better free recall

Declarative memory has two components.
Relational Learning Declarative memory has two components. A. _____________________ Memory of a collection of perceptions of events organized in _______________________________________________________________________________. B _________________ memories A memory of facts and general information. Copyright © 2008 Pearson Allyn & Bacon Inc.

Relational Learning Spatial memories
Bilateral medial temporal lesions produce the most profound impairment in spatial memory, but significant deficits can be produced by damage that is limited to the right hemisphere. Functional imaging studies have shown that the right hippocampal formation becomes active when a person is remembering or performing a __________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Virtual reality navigation and activation of the right hippocampus.

Relational Learning in Laboratory Animals
Place cells in the hippocampal formation _______________ A neuron that becomes active when the animal is in a particular location in the environment; most typically found in the hippocampal formation. Firing rates of place cells appear to reflect where the subject _________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Place cells fire in accordance to where a subject expects or believes that it is located.

Relational Learning in Laboratory Animals
Memories can be _______________________________________________________________________________. Reconsolidation A process of consolidation of a memory that occurs subsequent to the original consolidation that can be triggered by a reminder of the original stimulus; thought to provide the means for modifying existing memories. Copyright © 2008 Pearson Allyn & Bacon Inc.

Targeted knock-out mutations produce fewer NMDA receptors, and impair relational learning

Enhanced long-term potentiation is seen in these modified mice.
Targeted mutations can also produce genetically “smart” mice that show an increase in the production of NMDA receptors. Enhanced long-term potentiation is seen in these modified mice. They learn the Morris water maze faster than normal mice. But they may be more ____________________________________________________________________________________. Copyright © 2008 Pearson Allyn & Bacon Inc.

Neurogenesis in the hippocampus
Stem cells in the subgranular zone of the adult hippocampus divide and give rise to granule cells which migrate to the dentate gyrus. Rats trained on the relational task in the Morris water maze ______________________________________ in the dentate gyrus. These new neurons participate in learning. Many new connection have to be established for this new tissue to benefit the organism. Thus this process takes time. The volume of the posterior hippocampus is larger in London taxi drivers than in control subjects (2 years of training to receive a license). Copyright © 2008 Pearson Allyn & Bacon Inc.

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