Bio psych2 3

Biological Psychology Lecture Notes

Lecture Overview

• Title: Lecture 02: Short-Term and Working Memory

• Instructor: Dr. Richárd Reichardt

• Email: reichardt.richard@ppk.elte.hu

Key Topics

• Learning and Memory Systems

• Sensory and Short-Term Memory

The Significance of Memory

Memory plays a crucial role in survival, particularly in larger organisms. While simple organisms might utilize random foraging strategies effectively, larger animals face the challenge of food scarcity. As a result, these creatures evolve to integrate memory into their behaviors, allowing them to track food sources more efficiently. This adaptation significantly increases their chances of survival.

Behavioral Manifestations of Learning

• Aplysia Californica:

  • The sea hare exhibits a defensive reflex known as the

    • Gill Withdrawal Reflex: The withdrawal intensity varies and can show:

      • Habituation: Decrease in response intensity due to repeated exposure to a stimulus.

      • Sensitization: Increase in response intensity following a strong or noxious stimulus.

• Forms of Conditioning:

  • Classical Conditioning: Involves forming an association between an unconditioned stimulus and a conditioned stimulus.

  • Operant Conditioning: Based on the relationship between an action and a consequence (reward or punishment).

Distinct Forms of Memory

Humans exhibit various types of memories corresponding to different cognitive functions. We remember events, recognize factual information, and develop skills. The primary distinction in memory systems lies in their operational timeframes.

Memory Systems According to Atkinson & Shiffrin (1968)

• Modal Model: This model categorizes memory into three distinct units according to the duration of information storage:

  • Sensory Memory: Retains information for a few seconds.

  • Short-Term Memory (STM): Holds information for about 15-20 seconds; can persist longer if rehearsed.

  • Long-Term Memory (LTM): Capable of storing information for decades.

Detailed Memory Types

• Long-Term Memory Types:

  • Declarative (explicit):

    • Episodic: Memories of events.

    • Semantic: Factual knowledge.

  • Nondeclarative (implicit):

    • Skill Learning (procedural): Developing abilities.

    • Priming: The exposure to a stimulus influences a response to a subsequent stimulus.

    • Classical Conditioning: Associative learning through paired stimuli.

    • Nonassociative Learning: Habituation and sensitization techniques.

    • Spatial Learning: Knowledge of spatial relationships.

• Brain Regions Involved:

  • Different parts of the brain are responsible for managing various attributes of memory:

    • Medial Temporal Lobe & Neocortex: Crucial for declarative memory.

    • Striatum, Motor Cortex, Cerebellum: Involved in procedural memory.

    • Amygdala: Links emotional responses to memory.

    • Hippocampus and Cortex: Integral for forming new memories.

    • Prefrontal Cortex: Important for working memory.

Memory Processes

• Events must be encoded for memory retention.

• Retrieval of memories is essential.

• Research indicates that newly formed memories can be labile and require consolidation to stabilize over longer durations.

Sensory Memory

• Persistence of Vision: This phenomenon occurs when the perception of light remains even when it’s no longer physically present.

• Classic Experiment:

  • Sperling (1960): Participants viewed letters for 50 ms, and recall was influenced by a tone signaling which row to report. Performance drops substantially with just a second's delay.

• Although its neural basis isn't fully understood, some hypotheses suggest persistent neural activity in sensory cortical areas is responsible for sensory memory generation.

Short-Term Memory

• STM retains information for approximately 20 seconds if rehearsal is not utilized (Peterson and Peterson, 1959).

• Typically, STM can hold 5-9 items, affected by stimulus complexity. Techniques such as chunking can enhance capacity.

Working Memory

• Definition (Baddeley & Hitch, 1974): An advanced form of short-term memory responsible for temporary storage and manipulation of information necessary for complex tasks like comprehension and reasoning.

Research on Memory Tasks

• Delayed Response Task: Participants select from two options to earn a reward, providing insights into short-term memory functionality.

• Neural Basis of STM:

  • Research (Goldman-Rakic, 1990) indicates that lesions in the dorsolateral prefrontal cortex lead to performance decline in memory tasks.

  • Infants show limited memory behavior due to underdeveloped frontal and prefrontal cortex structures until approximately 8 months of age.

  • Notably, experiments demonstrate specific neurons remain active during memory delays, indicating a potential neuronal basis for maintaining information.

Conclusion

• New theories propose that continuous neural activity isn’t strictly necessary for memory retention. Instead, synaptic changes may allow the network to hold previously encountered information.

Next Class Information

• Topic: Long-Term Memory

• Thank you for your attention!