Lecture: Memory and Plasticity in Neuroscience

Introduction

• Presenter: Patrick House, a neuroscience PhD student at Stanford University.
• Focus: Memory and plasticity in the brain.

Overview of Memory

• Key Question: Why do some memories last a lifetime while others fade quickly?
• Context Example: Remembering a story more vividly due to a traumatic event.

Mechanisms of Memory

• Stephen Wiltshire: Autistic savant with exceptional memory capabilities.
  • Challenge: Draw Rome from memory in 60 seconds.
• Neural Mechanisms: Memory believed to occur at the synapse between neurons.
  • Synapse: Space between presynaptic and postsynaptic cells.

Historical Perspective

• Early Theories: Memory was thought to involve the formation of new neurons.
• Discovery of Synapse: Shifted focus to synaptic changes as the basis for memory.

Synaptic Plasticity

• Synaptic Plasticity: Changes in synapse strength related to learning.
• LTP (Long-Term Potentiation): Strengthening of synapse with repeated use.
  • Key Neurotransmitter: Glutamate (excitatory).
  • Hebbian Theory: "Neurons that fire together, wire together."

Role of the Hippocampus

• Hippocampus: Critical for memory formation and LTP.
• HM Case Study: Loss of hippocampi led to inability to form new memories.

Memory Storage and Neural Networks

• Distributed Memory: Memories are not localized to single neurons.
• Neural Networks: Involve complex interactions among numerous neurons.

Modulation of Memory

• Factors Influencing Memory:
  • Emotion: Emotional memories last longer.
  • Stress: Can enhance short-term memory but harm long-term memory.
  • Alcohol: Disrupts LTP and memory.

Signal Processing in the Brain

• Noise vs. Signal: Brain differentiates signal from noise using inhibition.
• Inhibition: Prevents unnecessary signals, sharpens meaningful signals.
  • Lateral Inhibition: Enhances contrast and perception.

Neurogenesis and Plasticity

• Adult Neurogenesis: New neurons are formed in adulthood, challenging past beliefs.
• Plastic Changes: Brain adapts over time, influenced by environment and genetics.

The Autonomic Nervous System

• Central vs. Peripheral: CNS (brain and spinal cord) vs. PNS (peripheral nerves).
• Subdivisions:
  • Somatic: Voluntary movements.
  • Autonomic: Involuntary functions (e.g., heart rate, digestion).

Sympathetic vs. Parasympathetic Systems

• Sympathetic: Fight-or-flight response.
• Parasympathetic: Rest and digest functions.
• Key Neurotransmitters:
  • Sympathetic: Norepinephrine.
  • Parasympathetic: Acetylcholine (ACh).

Integration and Regulation

• Hypothalamus: Central regulation of autonomic functions.
• Limbic System: Emotional regulation impacting autonomic responses.
• Cortex: Higher-order thinking influencing emotional and physiological responses.

Conclusion

• Memory and Plasticity: Complex interaction of synapses, networks, and neural plasticity.
• Autonomic System: Balances sympathetic and parasympathetic activities for homeostasis.

Next Topic

• Upcoming Lecture: Endocrinology.

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