Slide 1:1 The Nature of Learning Perceptual learning A type of learning that involves learning to recognize things, not what to do when they are present. Perceptual learning can involve learning to recognize entirely new stimuli, or it can involve learning to recognize changes or variations in familiar stimuli


Slide 2:2


Slide 3:3


Slide 4:4 Classical Conditioning Classical conditioned emotional responses US, UR, CS, CR US= foot shock URs= freezing, increased blood pressure, hormonal responses (adrenaline) in response to foot shock CS= tone URs = freezing, increased blood pressure, hormonal responses (adrenaline) in response to tone Acquisition Repeated pairing of the US and CS lead to the ability of the CS to elicit the emotional response by itself.


Slide 5:5 Classical Conditioning Classical conditioned emotional responses Brain Mechanisms Information about the CS (tone) is sent from the ears to the lateral nucleus of the amygdala. Information about the US (shock) is sent from the somatosensory cortex to the lateral nucleus of the amygdala. The axons of the neurons in the lateral nucleus project to the central nucleus of the amygdala. Stimulation of the central nucleus results in the emotional responses. Before conditioning, the synapses between the lateral nucleus and the somatosensory system are strong and the synapses between the ear and the lateral nucleus are weak. Repeated pairings strengthen the weak synapses according to Hebb’s law.


Slide 6:6 Classical Conditioning Classical conditioned emotional responses Brain Mechanisms Evidence Lesioning of the lateral nucleus results in the inability to learn a conditioned response. Electrical activity in neurons that responded to the tone CS increases in neurons that did not initially respond to the tone. Pharmacologically inhibiting the lateral nucleus results in the inability to learn a conditioned emotional response. LTP has been demonstrated in the lateral nucleus and this has been linked to increased responsiveness to auditory information. NMDA antagonists block the learning of conditioned emotional responses.


Slide 7:7 Classical Conditioning Classical conditioned emotional responses Brain Mechanisms Evidence LTP in the lateral nucleus of the amygdala also produces AMPA upregulation. Implications for Anxiety Disorders


Slide 8:8


Slide 9:9 Instrumental Conditioning Reinforcement: Neural circuits involved in reinforcement Medial forebrain bundle (MFB) A fiber bundle that runs in a front-back direction through the basal forebrain and lateral hypothalamus; electrical stimulation of these axons is reinforcing. Ventral tegmental area (VTA) A group of dopaminergic neurons in the ventral midbrain whose axons form the mesolimbic and mesocortical system; plays a critical role in reinforcement. Nucleus accumbens 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 reinforcement and attention.


Slide 10:10


Slide 11:11


Slide 12:12 Instrumental Conditioning Reinforcement: Neural circuits involved in reinforcement Brain Mechanisms The circuits involved in operant conditioning must detect the presence of a reinforcing stimulus and strengthen the synapses between the neurons that detect the discriminitive stimulus (that is the condition in the presence of which the organism can be reinforced; i.e. the presence of the lever press). Reinforcement occurs when the mesolimbic DAergic detect a reinforcing stimulus and cause the activation of the VTA neurons. Synaptic rearrangments occur that strengthen the connections between neurons of the mesolimbic DAergic pathway and the neurons involved in detecting the discriminative stimulus via LTP-dependent processes.


Slide 13:13 Instrumental Conditioning Reinforcement: Neural circuits involved in reinforcement Brain Mechanisms DA release by the MFB, especially the other pathway, the mesocortical DAergic pathway, appears to be critical for instrumental learning. DA release results in the release of glutamate which, as we described earlier can result in LTP.


Slide 14:14 Relational Learning Human anterograde amnesia Anterograde amnesia Amnesia for events that occur after 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 retain information encountered after the trauma. Korsakoff’s syndrome Permanent anterograde amnesia caused by brain damage resulting from chronic alcoholism or malnutrition.


Slide 15:15 Relational Learning Human anterograde amnesia Retrograde amnesia Amnesia for events that preceded 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 prior to the brain trauma.


Slide 16:16 Relational Learning 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.


Slide 17:17 Relational Learning Human anterograde amnesia Consolidation The process by which short-term memories are converted into long-term memories. 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.


Slide 18:18 Relational Learning Human anterograde amnesia Declarative memory Memory that can be verbally expressed, such as memory for events in a person’s past. Nondeclarative memory Memory whose formation does not depend on the hippocampal formation; a collective term for perceptual, stimulus-response, and motor memory.


Slide 19:19 Relational Learning Episodic and semantic memories Episodic memories Memory of a collection of perceptions of events organized in time and identified by a particular context. Semantic memories A memory of facts and general information.


Slide 20:20 Relational Learning Hippocampal formation A forebrain structure of the temporal lobe, constituting an important part of the limbic system; includes the hippocampus proper, dentate gyrus, and subiculum. Primary input to the hippocampal formation is from the entorhinal cortex.


Slide 21:21 Relational Learning Anatomy of anterograde amnesia 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. 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.


Slide 22:22


Slide 23:23 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 navigational task.


Slide 24:24


Slide 25:25 Relational Learning in Laboratory Animals Place cells in the hippocampal formation Place cell A neuron that becomes active when the animal is in a particular location in the environment; most typically found in the hippocampal formation.


Slide 26:26