Page 1: Biological Psychology 2

The Neuroscience of Memory Processes

Page 2: Key Concepts in Memory

The Engram

Long-Term Potentiation

Neural Replay

Page 3: The Substrate of Memory

Where Are Memories Located?

• Early theories suggested memories were linked to an immaterial soul.

• Aristotle compared memories to notes on a wax tablet, indicating a physical aspect to memory.

Page 4: Brain as Memory Store

How the Brain Stores Impressions

• The brain is the physical substrate for memories.

• Memory formation can be explained through associations, which are relationships between impressions.

Page 5: The Engram

Concept of the Engram

• Richard Semon introduced psycho-physiological parallelism where every psychological state corresponds to nervous system changes.

• The mneme represents the memory of an experience.

• A mnemic trace or engram is revisited when a related stimulus is encountered.

Page 6: Distributed Engram

Lashley's Experiments

• Karl S. Lashley studied memory locations in the brain by removing parts of rodent brains.

• Memory degradation increased with more tissue removal; however, the specific area removed did not affect memory retrieval.

Page 7: Hebb’s Rule

Neural Processes of Memory

• Donald O. Hebb's work emphasized synaptic weight changes associated with forming associations.

• Hebb's rule or Hebbian learning describes how synaptic strength increases with concurrent activation of neurons.

Page 8: Key Memory Concepts

The Engram

Long-Term Potentiation

Neural Replay

Page 9: Non-Associative Learning

Habituation and Sensitization

• Eric Kandel’s research focused on changes in membrane potential in relation to presynaptic signals.

Page 10: Gill Withdrawal Reflex

Habituation and Sensitization

• Illustration of tactile and tail stimuli affecting sensory neurons and motor neurons in the Gill withdrawal reflex model.

Page 11: Role of the Hippocampus

Hippocampus and Long-Term Memory

• Case study of H.M. highlighted the hippocampus's central role in long-term memory encoding.

• Distinction observed between declarative and procedural memories.

Page 12: Morris Water Maze Experiment

Significance of the Hippocampus

• Experiment demonstrated that rodents with hippocampal damage struggled with spatial navigation compared to healthy rodents.

Page 13: Long-Term Potentiation (LTP) in the Hippocampus

Bliss and Lømo's Study

• Research revealed synaptic changes in the hippocampus's perforant pathway, showing lasting potentiation effects.

Page 14: Molecular Basis of LTP

Components of Synaptic Transmission

• Overview of synaptic transmission activities involving NMDA and AMPA receptors, calcium ions, and magnesium ions.

Page 15: Induction of LTP

Process Overview

• Detailed sequence of events leading to the induction of long-term potentiation in synapses.

Page 16: Expression of LTP

Enhanced Transmitter Release

• Explanation of how LTP leads to an enhanced release of neurotransmitters and the insertion of new AMPA receptors.

Page 17: Summary of Molecular Basis of LTP

Key Mechanisms

• Role of NMDA and AMPA receptors in glutamatergic synapses and the details of molecular signaling leading to synaptic changes.

Page 18: Behavioral Studies in LTP

Morris Water Maze Results

• Experimental data comparing wild-type and mutant responses in the Morris water maze, highlighting discrepancies in memory performance.

Page 19: NMDA Receptors and Memory

Impairment Studies

• Findings from Tsien et al. (1996) showing genetic deletions affecting performance in memory tasks, supporting the vital role of NMDA receptors in LTP.

Page 20: Key Memory Concepts

The Engram

Long-Term Potentiation

Neural Replay

Page 21: Place Cells in the Hippocampus

Cognitive Mapping

• Identification of place cells in the hippocampus firing in relation to specific locations, connecting to memory consolidation theories.

Page 22: Reactivation of Place Cells

Memory Recall during Sleep

• Place cells exhibit sequential activation correlated with physical travel and reactivation during sleep periods.

Page 23: Electrophysiological Patterns during Sleep

Sharp-Wave Ripples

• Synchronous patterns in place cell activity noted during sleep, associated with sleep spindles and slow-wave features.

Page 24: Active System Consolidation Hypothesis

Hippocampal-Cortical Communication

• The coordinated activity across brain regions suggests a mechanism for memory consolidation through communication between the hippocampus and cortex during sleep.

Page 25: Synaptic Homeostasis

Strength Changes

• Overview of synaptic strength adjustment during sleep, promoting overall memory functions.

Page 26: Sequential Consolidation

Behavioral Memory Manifestation

• Changes in synaptic and system consolidation processes lead to observable memory consolidation behaviors.

Page 27: Memory Consolidation and Creativity

Evolution of Memory

• Sleep is linked with memory strengthening and evolving ideas; processes may lead to novel neural patterns and creative insights (e.g., creative dreams).

Page 28: Conclusion

Thank You for Your Attention

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