L12_Learning___Memory_Annotated

Lecture Overview

• Topic: Learning & Memory (PSC 101 - Bio Psych)

• Date: February 20th, 2025

Learning Objectives

• 12.1: Categorize information as declarative or nondeclarative memory.

• 12.2: Explain the role of the hippocampus in memory consolidation and the experience of individuals with damaged hippocampi.

• 12.3: Predict post-synaptic changes due to long-term potentiation (LTP) following strong stimuli and defend its role as a cellular mechanism for learning.

• 12.4: Explain memory storage in the brain.

Memory Categories

• Memory is complex, consisting of a network of neural processes to encode information.

• Can be categorized based on:

  • Length of time (Immediate, Short-term, Long-term)

  • Information encoded

12.1 - Memory Categories: Time

• Immediate memory: lasts fractions of a second to seconds.

• Short-term memory: lasts seconds to minutes.

• Long-term memory: lasts days to years.

12.1 - Short-Term Memory

• Temporary storage of information lasting seconds to minutes.

• Information must be consolidated into long-term memory.

12.1 - Long-Term Memory

• Information from short-term memory consolidates into long-term memory.

• Can be recalled for hours to years

Types of Long-Term Memory

• Declarative Memory: Available to consciousness (daily episodes, words and their meanings, history).

• Nondeclarative Memory: Generally not accessible to consciousness (motor skills, associations, puzzles).

Examples

• Declarative: Recall of a history fact.

• Nondeclarative: Learning to tie shoes through practice.

Nondeclarative Memory

• More poorly understood than declarative memory; locations for memory consolidation less clear.

• Involves brain areas like cerebellum, basal ganglia, and premotor cortex.

Declarative Memory

• The focus of this lecture. Well-understood and easier to describe.

Case Study: Henry Molaison (HM)

• Subject of a significant study on human memory after bilateral temporal lobe removal.

• Surgery reduced seizures but led to severe memory deficits.

Implications of HM's Case

• Revealed the hippocampus's importance for memory.

• Determined affected and unaffected memory types (short-term memory, recall from before surgery, nondeclarative skills).

• Anterograde Amnesia: Inability to create new declarative memories post-surgery.

Hippocampus Function

• Important for declarative memory consolidation.

• Not essential for short-term memory, nondeclarative consolidation, or recall.

Long-Term Potentiation (LTP)

• A leading cellular mechanism for learning; involves lasting synaptic changes.

• Occurs in the hippocampus, signifying enhanced synaptic strength following strong stimulation.

LTP Process

• Associated with synaptic plasticity; greater post-synaptic response from consistent pre-synaptic stimuli.

• Involves NMDA and AMPA receptors, leading to various cellular responses and increased EPSPs (excitatory post-synaptic potentials).

Summary of LTP Mechanisms

1. Strong stimuli activate NMDA receptors, allowing Ca2+ influx.

2. Second messengers are activated, prompting gene expression.

3. Genes cause long-term synaptic changes promoting learning.

Memory Storage Insights

• The hippocampus is not necessary for long-term memory recall or storage.

• Declarative memories are stored in a distributed manner across the brain using areas that processed the initial information.

Senses and Memory

• Recalling a stimulus activates the sensory areas used during initial encoding.

Hippocampal Connections

• The hippocampus communicates with networks related to senses, executive function, emotions, etc.

Conclusion on Memory Storage

• Declarative memories are widespread across the brain and utilize the same regions for processing and recalling information.

• The hippocampus is a hub for these connections.

Learning Goals in Depth

12.1: Categorize information as declarative or nondeclarative memory.

• Declarative Memory: This type of memory is conscious and relates to facts and events. It's divided into two types: episodic (personal experiences) and semantic (general factual knowledge).

• Nondeclarative Memory: This type is unconscious and involves skills and behaviors, such as how to ride a bike or play a musical instrument. Examples include procedural memory (motor skills) and priming (exposure influencing response).

12.2: Explain the role of the hippocampus in memory consolidation and the experience of individuals with damaged hippocampi.

• The hippocampus is crucial for consolidating new declarative memories. It helps transfer information from short-term to long-term memory.

• Individuals with damaged hippocampi often experience anterograde amnesia, which means they cannot form new declarative memories following the damage. However, their existing long-term memories and nondeclarative skills like riding a bicycle may remain intact, highlighting the hippocampus's specific role in the consolidation of declarative memories.

12.3: Predict post-synaptic changes due to long-term potentiation (LTP) following strong stimuli and defend its role as a cellular mechanism for learning.

• Long-term Potentiation (LTP) is characterized by the strengthening of synapses based on recent patterns of activity. When a synapse is stimulated repeatedly, effectively enhancing neurotransmitter release and increasing receptor density, post-synaptic changes occur, leading to a stronger response upon subsequent stimulations.

• LTP is considered a cellular mechanism for learning because it represents a change that is consistent with synaptic plasticity, thus facilitating memory storage and retrieval subsequent to learning experiences.

12.4: Explain memory storage in the brain.

• Memory storage is not localized to one specific area of the brain; instead, declarative memories are believed to be distributed across various regions corresponding to the qualities of the information.

• Activation of the memory trace involves the same sensory regions engaged during the initial experience, meaning the encoding and recollection processes utilize overlapping neural circuits, thus revealing the interconnected nature of memory storage and sensory systems.