Exam II Learning and Memory Learning relatively permanent change in behavior due to increase in knowledge skills due to info stored in brain Memory process by which info is stored in brain Non associative learning change in amnt of response in environmental events Sensitization experience of one stimulus heightens response to a subsequent stimulus o Allows brain to focus on dangerous irritating annoying stimuli o Normal Aplysia reflex Single stimulus to siphon SN releases normal amnts of transmitter MN releases normal amnts transmitter gill retracts o Mechanism for sensitization Facilitating neurons release serotonin causes siphon SN MN to release increased amnts of transmitter gill shows stronger than normal withdrawal Habituation becoming less sensitive to a steady repeated stimulus over time o Aplysia Repeated stimulation reduces gill withdrawal Mechanism for habituation Repeated stimuli sensory neuron release less transmitter motor neuron release less transmitter gill shows weak withdrawal o Calcium channel inactivation Less calcium enters sensory neuron o Smaller EPSPs occur Habituation sensitization cause neural plasticity o Neural plasticity changes in neural pathways synapses from change in behavior environment neural processes Control 1300 axon terminals on sensory neurons Habituation 800 axon terminals Habituation decreases connections of neurons Sensitization 2800 axon terminals Sensitization increases connections of neurons o Always changing Can increase and decrease connections depending on amnt of habituation sensitization Associative learning connection between two elements of events Changes activity in brain areas o Good learning performance specific to brain areas Brain stem Cerebellum Loop of neurons correct behavior Very active when someone is successfully learning Classical conditioning Pavlov s Dogs o Unconditioned stimulus UCS event that gives response without prior o Unconditioned response UCR unlearned reaction to stimulus o Conditioned stimulus CS initially neutral becomes able to signal experience food salivation response bell o Conditioned response CR learned reaction to CS salivation The Office example Eye blink example UCS air puff UCR blink CS tone CR blink Emotion Learning o Emotion increases importance and likelihood of remembering events Flashbulb memories Something surprising happening making someone remember all the small details o 9 11 example PTSD Exposure therapy o Repeatedly guiding patients through traumatic memory in safe setting o Memory becomes less associated with fear Hippocampus amygdala Involved in regulation of emotion o Amygdala lesions decrease learned fear o Fear conditioning Combines spatial hippocampus fear amygdala Can t relearn fear without amygdala Operant conditioning consequences of a behavior shape future performance o Reinforcement good bad Positive increases likelihood of behavior by adding something Negative increases likelihood of behavior by removing something o Punishment Decreases likelihood of behavior o Delayed match to sample Rat example Big Bang Theory Navigation Spatial Learning Morris Water Maze Radial Arm Maze Barnes Maze o Hippocampus Spatial memory PET while navigating familiar setting Right hippocampus more active during accurate navigation Forms virtual map of current space o Place cells that become active when rat in in particular place within immediate environment As environment moves place cell adjusts o Subiculum head direction cells Fire whenever rat s head faces certain direction o Entorhinal grid cells Fire at vertices of repeating grid that covers entire space Brain Changes Learning o Engrams physical trace of each memory in brain o Engrams DON T actually exist o Memories distributed throughout brain in neural networks Assemblies of neurons networked together hold memories Neuron becomes better connected with another neuron after repeated activation Activation gets easier o Hebb Rule If axon of presynaptic neuron is active while postsynaptic is firing synapse b w them strengthens Hebbian Synapses o Repeated persistent stimulation of postsynaptic cell increases synaptic efficacy More receptors channels More dendritic spines More synapses o Long Term Potentiation LTP Develops rapidly Long lasting Creates more efficient synapses Can be triggered in areas associated with memory 3 part process Induction learning Maintenance memory Expression recall o Receptors involved in LTP 2 glutamine channels AMPA receptors o Sodium channels o Depolarize neurons Sodium depolarizes membrane Cause EPSPs NMDAR receptors o Blocked by magnesium at resting membrane potential o Voltage gated depolarized o Calcium channels Unblocked when membrane Calcium entry strengthens synapses LTP increases synaptic strength Pre and post synaptic o Pre calcium entering through NMDARs triggers brief production of nitric oxide Calcium activates complex pathways of protein kinases Turns on genes that make proteins o Post adds extra AMPARs to membrane Long lasting LTP induces structure changes Dendritic spines o Spine growth o Increase in spine number Driving taxi in London builds more spine in hippocampus Menstrual cycle changes Hippocampus spine density decreases after progesterone surge at end Learning stimulates gene expression When a rat explores new environment turns on genes for proteins Arc in hippocampus o Aging decreases amnt of Arc produced LTP increases number of spines Alzheimer s decreases number of spines o Categories of Memory o Working memory Temporary form of info storage Limited in capacity Requires rehearsal o Sensory memory Large capacity Lasts 1 2 seconds o Short term memory Memories that last seconds to hours Fades after a week 5 9 items capacity o Long term memory Memories that you recall after days months years Last indefinitely Unlimited capacity o Memory consolidation o Consolidation brain forms a physical representation of a memory storing Describes process where short term become long term o Medial temporal lobe o Retrieval accessing stored memories o Recalling memories is highly susceptible to modification o Memory distortion illusions occur frequently in humans Mechanisms for consolidation retrieval Increased activation in hippocampus parahippocampal gyrus o Activity levels predict later remembering o NMDA glutamate receptors in hippocampus o Enhances hippocampal activity in emotional Without these rest of system wont work Amygdala memories Brain stem o Acetylcholine o Serotonin o Noradrenaline Temporal