Hippocampus Memory systems Learning Set of processes by
Hippocampus Memory systems
Learning • Set of processes by which experience creates enduring changes to neural circuits, changing behavior • Resulting changes are memories
Creating a memory • Sensory memory • Capacity? • Duration? • Location? • Short-term memory • Capacity? • Duration? • Location? • Long-term memory • Capacity? • Duration? • Location? • Process by which sensory input becomes a long-term memory?
Using memories • Retrieval • Reconsolidation • Are memories stable and consistent over time?
Classifications of memory • Declarative memory - • Nondeclarative memory -
Brain regions involved in declarative memory • Hippocampus • Mammillary bodies • Damage or removal prevents consolidation of new long-term memories • Amygdala adds emotional valence
Brain regions involved in models of non-declarative memory • Priming • Cortex • Skill learning • Cortex to Basal ganglia
Brain regions involved in models of non-declarative memory • Classical conditioning – Eye-blink conditioning • Cerebellum • Convergence spot of incoming auditory (tone) and trigeminal (corneal air puff) input • Source of (eyeblink) output to cranial motor nuclei Trigeminal nucleus Auditory nucleus Cerebellum Cranial motor nucleus
Brain regions involved in models of non-declarative memory • Instrumental learning – Appetitive conditioning • Nucleus accumbens • Convergence spot of incoming forebrain signals (discriminative stimulus and recent behavior) and ventral tegmental input (reward) • Source of (motor behavior) output to striatum Forebrain areas (contextual cues, recent behaviors) Ventral tegmental area (reward) Nucleus accumbens (“That felt good”) Striatum (behavioral motivation)
Hippocampus Long-term potentiation
Mechanisms of learning – Synaptic plasticity • Example: Long-term potentiation (LTP)
Initiating long-term potentiation • LTP depends on influx of Ca++ into the postsynaptic cell • Where can Ca++ enter the postsynaptic cell? • What keeps Ca++ from entering all the time? • What two simultaneous events will allow Ca++ to enter the cell? • What happens once Ca++ enters the cell?
Changes supporting long-term potentiation • Calcium activates _______, resulting in: -
LTP characteristics • Synaptic strengthening is limited to those synapses where calcium entered the post-synaptic cell • Once long-term potentiation has been induced:
Hippocampus Damage and memory loss
Amnesia • Who was H. M. ? • What happened to him? • Anterograde amnesia • Retrograde amnesia • Brain regions critical for: • Working memory? • Consolidation? • Storage? H. M. died in 2008, age 82
Korsakoff’s syndrome • Damage to: • Cause? Early damage Late damage
Alzheimer’s disease • Most common cause of dementia • Abnormal proteins: • Damage to: • Resulting memory loss?
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