Chapter 12 Learning Memory Outline Non Associative Learning Habituation Sensitization Associative Learning Classical Conditioning What is Learning Relatively long lasting change in an organism s behavior or thought as a result of experience What is Learning Distinct from Reflexes or Instincts Involuntary response to stimuli Automatic complex behavior Mating or parenting behavior Types of Learning Non associative learning involves change in the magnitude of response to environmental events Habituation Sensitization Associative learning involves a connection between two elements or events Classical conditioning Instrumental conditioning Habituation Decrease in strength or occurrence of behavior after repeated exposure to stimulus Orienting Response Innate reaction to novel stimuli Purpose Allows organism to focus on learning new or important information Sensitization Experience of one startling stimulus heightens responding to subsequent stimuli Acoustic Startle Response shock dishabituates response Purpose Allows organism to focus on potentially dangerous stimuli Learning with Aplysia Invertebrate learning offers a simpler system in which to isolate neurobiological correlates of learning Simple nervous system 20 000 neurons Neuronal development hardwired Identifiable individual neurons Learning with Aplysia The gill withdrawal reflex occurs when touching the siphon produces a retraction of the gill Habituation in Aplysia Less glutamate released onto motor neuron Habituation in Aplysia Sensitization in Aplysia Shocking the head or tail results in an enhanced gill withdrawal reflex following siphon touch Serotonin interneuron release promotes enhanced glutamate sensory neuron release Sensitization in Aplysia Shocking the head or tail results in an enhanced gill withdrawal reflex following siphon touch Long term Changes in Habituation and Sensitization Control Aplysia have 1300 axon terminals on sensory neurons Aplysia experiencing sensitization have 2800 terminals Aplysia experiencing habituation have 800 terminals Outline Non Associative Learning Habituation Sensitization Associative Learning Classical Conditioning Classical Conditioning Formation of connections or associations between related sensations emotions or thoughts Pavlov Identified and developed an empirical approach for studying classical conditioning Classical Conditioning An unconditioned stimulus US is a biologically relevant stimulus An unconditioned response UR is an unlearned reaction to the US A conditioned stimulus CS is an initially neutral stimulus that acquires the ability to signal important biological events A conditioned response CR is a learned reaction to the CS Classical Eyeblink Conditioning Best understood form of classical conditioning behavior and neural substrates Acquisition of eyeblink CR Eyeblink Conditioning Neural Circuit Eyeblink Conditioning Neural Circuit LTD LTP Long term Potentiation Depression NMDA receptor activation leads to changes in synaptic efficacy i e AMPA receptors which gate sodium are inserted LTP or removed LTD from the terminal Long term Potentiation Depression NMDA receptor activation leads to changes in synaptic efficacy i e AMPA receptors which gate sodium are inserted LTP or removed LTD from the terminal Interpositus cell activity LTP dependent increase in neuronal firing across trials CS US NMDA receptor activation leads to changes in synaptic efficacy i e AMPA receptors which gate sodium are inserted LTP or removed LTD from the terminal Eyeblink Conditioning Interpositus cell activity LTP dependent increase in neuronal firing across trials Neuronal activity in IP corresponds to generation of eyeblink CR suggesting IP neurons drive the behavioral response First training session Fourth training session CS US Eyeblink Conditioning Neural Circuit Timing LTD Purkinje cell activity Sole output from cerebellar cortex Inhibitory releases GABA onto IP neurons Decrease in firing rate due to LTD First training session Purkinje cell activity Sole output from cerebellar cortex Inhibitory releases GABA onto IP neurons Decrease in firing rate due to LTD Fourth training session IP excitation generates CR Purkinje cell dis inhibition enables proper timing of blink CR Extinction of eyeblink CR Presentation of CS in absence of US Extinction of Eyeblink CR Not simple unlearning New opposing response acquired Learned response is unexpressed Spontaneous Recovery CR recovers with passage of time Renewal CR is context specific Reinstatement US reminder reinstates CR Behavior and neural circuit conserved across most mammalian species Eyeblink Conditioning in Humans Lateral interpositus nucleus