Lecture 7: Learning and Memory

CLASSICAL CONDITIONING

Extinction

The weakening or disappearance of a learned behaviour when reinforcement is removed.

Desensitization

A process where repeated exposure to a stimulus reduces emotional or physiological response to it

Pavlov’s Proposal (Classical Conditioning)

- There are brain regions that act in response to the unconditioned stimulus, the conditioned stimulus, and the unconditioned response

Pavlovs Dog Experiment (Classical Conditioning)

• Unconditioned Stimulus = Steak → Dog salivates naturally

• Conditioned Stimulus = Bell (paired with steak)

• Eventually, Bell alone → Dog salivates (Conditioned Response)

Karl Lashley ENGRAMS

Reasoned that if memories were connections between brain areas, they could be severed with a knife

Engrams Findings

• Trained rats on mazes, then cut to cortex

• Cuts did not impair performance

• Memory is not localized in one spot

Engrams: Equipotentiality

All parts of the cortex contribute equally to functioning behaviors (e.g., learning) and any part can substitute others

Engrams: Mass Action

The cortex works as a whole and more cortex is better

Modern Search for the Engram – Thompson (1930–2014)

LIP is where learning happens

Red nucleus is needed to show the response

Suppressing LIP = no learning

LIP

memory storage

Red Nucleus

Response Execution

OPERANT CONDITIONING

Operant Conditioning: Skinner Box

• Conditioning chamber used to observe/manipulate behaviour.

• Behavior is strengthened —> reinforcer, weakened—> punisher

Positive and Negative REINFORCEMENT

• Adding something good to increase behaviour ( treat).

• Removing something bad to increase behaviour (no curfew→ good grades).

Positive and Negative PUNISHMENT and REINFORCEMENT

• 
  

  GIVING  (positive)	Positive Punishment  Spanking a child	Positive reinforcement   Giving a child a sticker
  TAKING AWAY (negative)	Negative punishment  Taking away child’s screen time	Negative reinforcement   Excusing a child from completing their chores

Continuous Reinforcement

- The desired behaviour is reinforced every single time it occurs

Intermittent Reinforcement

- Reward or consequence only sometimes after a desired behavior, rather than every time. (slot machine)

Neural Basis of Positive Reinforcement

Involves the:

• dopamine system

• nucleus

• (VTA)

• which are activated when a rewarding stimulus is received, reinforcing the behaviour.

STATISTICAL LEARNING

Statistical Learning

The ability to perceive and learn regularities

■ E.g, in language, such as the speech sounds that comprise a word

Changes in Statistical Learning Across Development

• Basal ganglia & primary sensory areas = early-developing regions

• lit up regions are active during language task

PERCEPTUAL LEARNING

Perceptual Learning

Learning to recognize and respond to stimuli through experience (identifying faces/voices better over time).

RELATIONAL LEARNING

Relational Learning

Involves learning the temporal and spatial relationships among objects and events

( where you parked based on landmarks).

SUBTYPES OF MEMORY

Short-Term Memory

Holds a limited amount of info for a brief time (15–30 s)

Working Memory

A more active form of short-term memory that manipulates and processes info (e.g., doing mental math).

Process of Consolidation

The transformation of short-term memories into long-term ones, mainly involving the hippocampus and strengthened through repetition and sleep.

Long- Term Memory

Memory of facts and events that can be consciously recalled

Long term Memory: Explicit

Refers to the conscious recollection of facts, events, and personal experiences

Long term memory: Episodic

Stores personally experienced events

Long- term Memory; Semantic

stores general knowledge

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Long Term Memory: Procedural/ IMPLICIT

Unconscious memory for tasks/ skills (typing, driving, bike).

Flashbulb Memories

Vivid, detailed memories of emotionally significant events

Eg: big accident

HIPPOCAMPUS

Hippocampus – Role in Memory

• Vital for declarative/episodic memory

• Active during:

  • Memory formation

  • Memory recall

  • Imagining future events

Hippocampus – Visual Spatial Memory

• More years as a taxi driver = larger hippocampal volume

• Shows its role in navigation and memory mapping

Place Cells & Time Cells (located in HIPPOCAMPUS)

Fire in response to spatial locations and temporal information

Grid Cells (HIPPOCAMPUS)

• Located in ERC hippocampus

• Helps with navigation and spatial awareness

BASAL GANGLIA

Basal Ganglia - Role in Memory

• Involved in implicit learning

• Supports learning of patterns, habits, and motor skills

Basal Ganglia Anatomy

■ Striatum

– Dorsal striatum

• Ventral striatum

DISORDERS OF MEMORY

Retrograde Amnesia

Can't remember what happened BEFORE brain injury

HM study : Retrograde Amnesia

• Severe anterograde amnesia (no new episodic memories)

• Some retrograde amnesia

• Working memory intact

• Inability to form new explicit/episodic memories

• Procedural learning remained intact

Anterograde Amnesia

Can't form new memories

Infantile Amnesia

The inability of humans to remember episodic experiences that occurred during the first few years of life ( 0–3 yrs)

→ Immaturity of hippocampal systems

What is Severely Deficient Autobiographical Memory (SDAM)?

can remember facts but can’t relive or recall personal past events, even tho they r healthy.

Aphantasia

Inability to visualize images in the mind’s eye.

Korsakoff’s syndrome

• Caused by thiamine (vitamin B1) deficiency, often from alcoholism

• Brain damage, especially in the dorsomedial thalamus

• Main sign: confabulation (making up stories without knowing)