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Chapter 12 Learning and Memory © Cengage Learning 2016 © Cengage Learning 2016 Learning • Three categories of learning – Reflexes – Fixed action patterns (instincts) – Learning • Types of learning – Associative learning • Classical and operant conditioning – Nonassociative learning • Habituation and sensitization © Cengage Learning 2016 Reflexes Provide Fast, Reliable Responses © Cengage Learning 2016 Contagious Yawning Might Be a Fixed Action Pattern © Cengage Learning 2016 Habituation and Sensitization • Habituation occurs when an organism reduces its response to unchanging, harmless stimuli • Sensitization occurs when repeated exposure to a strong stimulus increases response to other environmental stimuli © Cengage Learning 2016 Classical Conditioning • Organisms learn that stimuli act as signals that predict the occurrence of other important events • First articulated by Pavlov in 1927 – Conditioned responses (CR) are those behaviors that must be learned – Unconditioned responses (UCR) appear without prior experience to a stimulus © Cengage Learning 2016 The Process of Classical Conditioning © Cengage Learning 2016 Operant Conditioning • Studied by B.F. Skinner • Organisms form connections between a behavior and its consequences that impact the subsequent frequency of that behavior • Reinforcing and punishing consequences increase and decrease likelihood of repeating the behavior © Cengage Learning 2016 Learning at the Synapse • Studying invertebrates gives a rich opportunity to understand changes taking place at the level of the synapse • Frequently studied organisms – Fruit flies – Sea slug (Aplysia californica) © Cengage Learning 2016 Aplysia californica © Cengage Learning 2016 The Neuroanatomy of Aplysia © Cengage Learning 2016 Short-Term Habituation at the Synapse • Habituation in Aplysia – Gill-withdrawal reflex – Reduced activity at synapse between sensory and motor neurons – Direct result of decreased neurotransmitter release © Cengage Learning 2016 Short-Term Sensitization at the Synapse • Sensitization in Aplysia – A stimulus gains the ability to influence more than one neural pathway – Increased neurotransmitter release by sensory neuron © Cengage Learning 2016 Habituation and Sensitization in Aplysia © Cengage Learning 2016 Long-Term Habituation and Sensitization at the Synapse • Long-term habituation training decreases the number of presynaptic terminals of sensory neurons • Long-term sensitization training increases the number of presynaptic terminals of sensory neurons • Both are likely the result of gene expression processes controlled by transcription factors © Cengage Learning 2016 Structural Changes in Synapses Result from Learning © Cengage Learning 2016 Biochemical Correlates of Sensitization in Aplysia © Cengage Learning 2016 The cAMP-PKA-MAPK-CREB Pathway Leads to Long-Term Changes in Behavior © Cengage Learning 2016 Classical Conditioning at the Synapse • Classical conditioning in Aplysia – Sequential activation of sensory neurons by CS and UCS leads to greater neurotransmitter release – Classical conditioning in Lymnaea can occur to both rewarding unconditioned stimuli (food) and aversive conditioning stimuli (electric shock) © Cengage Learning 2016 Classical Conditioning in Aplysia © Cengage Learning 2016 Operant Conditioning at the Synapse • Results when an organism’s naturally occurring behavior becomes more or less frequent in response to its consequences • “Fix” what had been a fairly random pattern of behavior into a more reliable, stereotyped pattern © Cengage Learning 2016 Operant Conditioning in Aplysia © Cengage Learning 2016 Brain Structures and Circuits Involved in Learning • Classical conditioning of threat – “Fear” is a conscious feeling of being afraid – “Threat” is the unconscious mobilization of defensive behaviors • Amygdala plays an important role in the classical conditioning of emotional responses © Cengage Learning 2016 The Amygdala Participates in Threat Conditioning © Cengage Learning 2016 Classical Conditioning of the Eyeblink • Rabbit studies – Nictitating membrane – Interpositus nucleus of the cerebellum is necessary for learning to occur • Human studies – The cerebellum is involved in classical conditioning © Cengage Learning 2016 The Role of Interpositus Nucleus in Classical Conditioning © Cengage Learning 2016 Cerebellar Circuits and Classical Conditioning • The Purkinje cells are perfectly situated to influence the output of the cerebellum • Learning will occur if the climbing-fiber and parallel-fiber synapsing onto a Purkinje cell are activated at the same time • Reduced activity in the Purkinje cells is known as long-term depression © Cengage Learning 2016 Connections within the Cerebellum © Cengage Learning 2016 Trace Conditioning • Delay conditioning – The CS overlaps the UCS – No stimulus-free interval • Trace conditioning – The CS and the UCS do not overlap – A stimulus-free interval occurs – Requires the participation of forebrain areas – Requires conscious, declarative processes © Cengage Learning 2016 Delay Versus Trace Conditioning © Cengage Learning 2016 Extinction • Pavlov described how conditioned responding would gradually decrease, or undergo extinction, when the conditioned stimulus was presented repeatedly without the unconditioned stimulus © Cengage Learning 2016 Types of Memory • Steps in the memory pathway – Encoding – Consolidation – Retrieval – Reconsolidation © Cengage Learning 2016 Information Processing Model • Information flows through a series of stages on its way to permanent storage in memory – Sensory memory – Short-term memory – Long-term memory • Declarative memories (semantic and episodic) • Nondeclarative memories (procedural) • Anterograde amnesia • Engrams © Cengage Learning 2016 Atkinson-Shiffrin Model of Memory © Cengage Learning 2016 Types of Long-Term Memory © Cengage Learning 2016 Brain Structures and Circuits Involved in Memory • Early efforts to locate memory functions – Lashley: engram – Penfield: recordings during surgery for epilepsy • Temporal lobe and memory – H.M.’s anterograde amnesia – The delayed nonmatching to sample (DNMS) test (monkeys) © Cengage Learning 2016 Karl Lashley Observed the Results of Brain Lesions on Maze-Learning Performance © Cengage Learning 2016 The Temporal Lobe and Memory • Evidence of the temporal lobe’s involvement in memory – Case studies of patients with anterograde amnesia • Amygdala appears to play a role in processing emotional memories • The hippocampus involved in the formation of long-term memories © Cengage Learning 2016 Surgical Removal of Henry Molaison’s Temporal Lobe Tissue © Cengage Learning 2016 The Mirror-Drawing Task © Cengage Learning 2016 The Delayed Nonmatching to Sample (DNMS) Task © Cengage Learning 2016 Long-Term Potentiation (LTP) • Provide a basis for learning and memory – The application of a rapid series of electrical shocks to input pathways increases the postsynaptic potentials in their target neurons • LTP as a memory mechanism – Associativity, cooperativity, and synaptic tags • LTP and behavioral memory – Spatial memory; avoidance situations © Cengage Learning 2016 The Hippocampus and Its Associated Structures © Cengage Learning 2016 Long-Term Potentiation (LTP) © Cengage Learning 2016 LTP and the NMDA Receptor © Cengage Learning 2016 The Morris Water Maze Requires Spatial Memory © Cengage Learning 2016 The Diencephalon and Memory • Disruption of the hippocampus and other areas of the temporal lobe results in amnesia • Case studies of patients with diencephalic lesions support the role of this area in memory • Alcoholics and amnestic confabulatory (Korsakoff’s) neurocognitive disorder © Cengage Learning 2016 Damage to the Diencephalon in Patient N.A. © Cengage Learning 2016 Semantic Memory and the Cerebral Cortex • Semantic knowledge is widely distributed in the cortex • Retrieving these distributed memories requires a coordinated effort and the use of “convergence zones” – Left lateral inferior frontal gyrus © Cengage Learning 2016 Semantic Memories Are Widely Distributed © Cengage Learning 2016 Episodic Memory and the Cerebral Cortex • Concept of an independent episodic memory store for our personal experiences • Patients with source amnesia can create new semantic memories but forget how the knowledge was gained originally • Prefrontal areas are involved with longterm management of episodic memories • Use episodic memories to distinguish between fantasy and reality © Cengage Learning 2016 Short-Term Memory and the Brain • Four components of working memory – A central executive – The phonological loop – The visuo-spatial scratchpad – An episodic buffer • The dorsolateral prefrontal cortex (DLPFC) and the anterior cingulate cortex (ACC) play roles in attentional aspects of shortterm memory © Cengage Learning 2016 Object Permanence © Cengage Learning 2016 The Striatum and Procedural Memory • The striatum – Role in forming procedural memories – Basal ganglia • Memories of motor patterns – Nucleus accumbens • Emotional and rewarding correlates of a procedure © Cengage Learning 2016 The Radial Arm Maze © Cengage Learning 2016 The Biochemistry of Memory • Acetylcholine (ACh) is essential to memory functions • Cholinergic activity has different effects in different phases of memory – Increases in the hippocampus are associated with better encoding of new information but consolidation and retrieval of memory appear to be impaired by high cholinergic activity • Glutamate is involved in encoding and consolidation of memories © Cengage Learning 2016 The Effects of Stress and Healthy Aging on Learning and Memory • Stress and healthy aging produce relatively mild but noticeable changes in the way memories are processed © Cengage Learning 2016 Effects of Stress on Memory • The critical variable determining the effects of stress on memory appears to be timing – In the Atkinson-Shiffrin model, memories pass through a series of stages during which they are relatively fragile and open to modification – At each stage, stress and biochemical correlates can have unique effects on how information is encoded, stored, and retrieved © Cengage Learning 2016 Flashbulb Memories Seem More Vivid and Complete © Cengage Learning 2016 Stress Has Different Effects at Different Times in the Memory Process © Cengage Learning 2016 Effects of Norepinephrine and Glucocorticoids on Memory • The lateral nucleus of the amygdala is the target for both norepinephrine and glucocorticoids released by the adrenal glands as a result of stress • The stress-induced actions of norepinephrine and glucocorticoids in the amygdala initiate a “memory formation” state in the prefrontal cortex, the hippocampus, and the caudate nucleus © Cengage Learning 2016 Effects of Glucocorticoids and Norepinephrine on Memories for Stressors © Cengage Learning 2016 The Effects of Healthy Aging on Memory • Cognitive ability of healthy older adults is stable – Comparison of young adults, healthy older adults, those at high risk for Alzheimer’s, and those with Alzheimer’s disease – People compensate for age-related declines in brain function © Cengage Learning 2016 Electronic Games and Healthy Aging © Cengage Learning 2016