Cerebellum and Memory: LIP, Hippocampus, and Learning Processes

Cerebellum's Role in Learning

Thompson identified the lateral interpositus nucleus (LIP) in the cerebellum as crucial for learning. Blocking LIP activity during conditioning prevents learning responses. Studies confirm LIP's necessity for learning, retention, and extinction.

Types of Memory

Short-Term Memory

• For recent events, limited capacity.
• Fades quickly without rehearsal (around 20 seconds).

Long-Term Memory

• For older events, vast capacity.
• Can last for years, aided by cues.

Consolidation

Process of crystallizing short-term memories into long-term.

Working Memory (WM)

Brain system for temporary storage and manipulation of information for complex tasks (learning, reasoning). Requires simultaneous storage and processing, linked to prefrontal cortex activity.

Delayed Response Task

A model for testing WM.

Aging and WM

Deficits in aging humans show decreased prefrontal cortex activity.

Explicit vs. Implicit Memory

Explicit memory: Conscious, intentional recollection.

Implicit memory: Unconscious retention affecting thoughts or actions.

Note: Most memory tasks involve both types, with potential switching between procedural and declarative memory.

Hippocampus Hypothesis

Declarative Events

Necessary for declarative (episodic) events.

Spatial Memory

Important for spatial memory, tested with the Morris Water Maze in rodents.

Context

Crucial for remembering event details (time and space).

Hippocampus and Consolidation

Hippocampus is essential for consolidation.

Amnesia

Loss of memory about important personal information, often due to organic causes (brain disease, head injury) or psychological factors (guilt, shame).

Alzheimer's Disease

Early onset AD genes linked to Amyloid-β accumulation, forming plaques in hippocampus and cortex, leading to behavioral deficits. Abnormal tau protein forms tangles, contributing to degeneration.

Synaptic Plasticity

Long-Term Potentiation (LTP)

Increased synaptic response with specificity, cooperativity, and associativity.

Long-Term Depression (LTD)

Sustained decreased synaptic response.