Exam 4, Lec 1; Memory and Learning

Memory Categories

• Declarative Memory: Knowledge that can be verbally expressed.

• Non-declarative Memory (Procedural): Knowledge that can be demonstrated through actions.

Temporal Categories of Memory

• Immediate Memory: Holds ongoing experiences for fractions of a second.

• Working Memory (Short-term Memory): Holds information for seconds to minutes to achieve goals; requires attention.

  • Examples:

    • Hunting for objects.

    • Remembering a phone number until written down.

• Long-term Memory: Retains information from days to a lifetime, including important exam information and salient life events.

Temporal Categories of Declarative Learning and Memory

• Immediate Memory

• Working Memory (Short-term Memory)

• Long-term Memory

• Memory Consolidation: Requires rehearsal; facilitated by the hippocampus and parahippocampal (rhinal) cortex.

  • Notable Case: Patient H.M.

Delayed Non-Matching-to-Sample Task

• Used to test object recognition memory in animals.

• Monkeys must identify objects not previously seen, demonstrating the effects of medial temporal lobe damage.

• Task Requirement: Memory of objects over varying delay times.

Serial Position Effects

• Primacy Effect: Better recall of words at the beginning of a list.

• Recency Effect: Better recall of words at the end of a list due to short-term memory retention.

Disorders of Memory

• Amnesia: Loss of memory, can be:

  • Retrograde: Difficulty recalling past information.

  • Anterograde: Difficulty learning new information.

Patient H.M. and Memory Storage

• Underwent bilateral temporal lobectomy.

• Results:

  • Normal IQ, perception, reasoning, motivation.

  • Profound anterograde amnesia; inability to consolidate new long-term declarative memories.

  • Retained old memories pre-surgery.

  • Could form new implicit memories (procedural learning).

Learning Types in Memory

• Patient K.C.: Damage led to loss of personal memory but retained knowledge in other areas.

• Two Subtypes of Declarative Memory:

  • Semantic Memory: General knowledge.

  • Episodic Memory: Detailed autobiographical memories.

Hippocampal Place Cells

• Neurons that activate when navigating known spaces, contributing to spatial memory.

• New contexts lead to new neural representations of space.

Memory and Sleep

• Sleep plays a crucial role in memory replay and consolidation, vital for long-term storage.

Memory Storage Sites and Research

• Karl Lashley's Principle: Memory degradation depends on the amount of cortex damage, not the type.

Subtypes of Memory

• Long-term Memory Types:

  • Declarative (Hippocampus dependent): Semantic and Episodic.

  • Non-declarative (Hippocampus independent): Procedural skills, priming, conditioning.

Role of Synapses in Learning and Memory

• Learning: Permanent behavior changes from experience.

• Involves structural changes in synapses without neurogenesis.

• Neuroplasticity: Allows nervous system adaptability to change and injury.

Long-Term Synaptic Plasticity

• Changes in synaptic strength lasting minutes to years:

  • Long Term Potentiation (LTP): Increases synaptic strength.

  • Long Term Depression (LTD): Decreases synaptic strength.

Alzheimer’s Disease Overview

• Population Statistics: Primarily affects individuals 65 and older; projected increase in cases.

• Disease Progression: Slow progression, average 8 years until death typically from secondary illnesses.

• Symptoms: Characterized by dementia, memory loss, and cognitive decline.

Dementia Defined

• Progressive decline in mental function involving memory, language, and decision-making skills.

• Must show memory impairment plus one of the following:

  • Aphasia, Apraxia, Agnosia, Executive function problems.

Not a Normal Part of Aging

• Previously misclassified as normal; actually caused by disease processes, predominantly Alzheimer’s.

Diagnosis of Alzheimer’s Disease

• Accurate through comprehensive evaluations:

  • Health assessments, memory tests, physical health evaluations, imaging scans (MRI, PET).

Brain Changes with Alzheimer’s Disease

• Features include:

  • Loss of cortices, enlarged ventricles, reduced brain activity.

  • Senile Plaques: Extracellular deposits of beta-amyloid.

  • Neurofibrillary Tangles: Intracellular, associated with abnormal tau protein accumulation.

Pharmacological Treatment Strategy

• Aim to counteract loss of cholinergic neurons by inhibiting acetylcholine degradation.

Anti-amyloid Antibody Treatments

• Strategies involve infusing antibodies to promote removal of amyloid deposits, slowing disease progression.

  • Donanemab: Recent FDA-approved treatment slows early Alzheimer’s progression.