The Brain

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Introduction to Neuroscience: The Brain

Overview

  • The brain is the most complex object in the known universe.
  • Composed of 100 billion neurons, each with 1,000 to 10,000 connections.
  • This lecture covers fundamental structures, neuron communication, and functions of brain regions.

Personal Journey into Neuroscience

  • The speaker’s personal experience with sleep paralysis led to an interest in neuroscience.
  • Discovered the brain’s ability to create vivid hallucinations and experiences.
  • Studied in multiple countries, learning from leading neuroscientists.

Neurons: The Building Blocks of the Brain

  • Neurons communicate through synapses using electrical and chemical signals.
  • Key structures:
  • Soma (cell body): Contains the nucleus and essential organelles.
  • Axon: Sends electrical signals.
  • Dendrites: Receive signals from other neurons.
  • Synapse: Gap where neurotransmitters facilitate communication.
  • Myelin: Fatty substance that insulates axons, speeding up signal transmission.

How Neurons Communicate

  • Electrical impulse (Action Potential) travels down the axon.
  • Neurotransmitters are released into the synapse.
  • Excitatory vs. Inhibitory Signals:
  • Excitatory (e.g., Glutamate) increases neuron firing.
  • Inhibitory (e.g., GABA) decreases neuron firing.

Key Neurotransmitters and Functions

  • Glutamate – Main excitatory neurotransmitter, essential for learning & memory.
  • GABA – Main inhibitory neurotransmitter, crucial for relaxation & focus.
  • Dopamine – Associated with motivation, pleasure, and movement.
  • Serotonin – Regulates mood, emotion, and sleep.
  • Oxytocin – Involved in bonding, trust, and social behavior.
  • Endorphins – Natural painkillers, released during exercise and stress.
  • Acetylcholine – Plays a key role in learning, memory, and attention.

Brain Structures and Functions

Cerebral Cortex (Outer Layer of the Brain)

  • Divided into four lobes:
  • Frontal Lobe – Decision-making, motor control, problem-solving.
  • Parietal Lobe – Spatial awareness, body image, touch processing.
  • Occipital Lobe – Visual processing.
  • Temporal Lobe – Hearing, memory, language comprehension.

Deeper Brain Structures

  • Thalamus – Relay station for sensory information.
  • Hypothalamus – Regulates hormones, hunger, thirst, body temperature.
  • Amygdala – Processes fear, aggression, and emotions.
  • Hippocampus – Essential for memory formation and learning.
  • Basal Ganglia – Regulates movement, habits, and automatic behaviors.
  • Cerebellum – Controls balance, coordination, and procedural memory.

Neural Circuits and Systems

  • Central Nervous System (CNS): Brain + Spinal Cord.
  • Peripheral Nervous System (PNS): Sends sensory & motor information.
  • Somatic Nervous System – Voluntary muscle control.
  • Autonomic Nervous System – Involuntary functions:
    • Sympathetic (Fight or Flight) – Increases alertness, energy.
    • Parasympathetic (Rest and Digest) – Promotes relaxation.

Brain Plasticity and Modularity

  • The brain has specialized modules for different functions (e.g., language, vision, memory).
  • Neuroplasticity: The brain’s ability to rewire itself in response to learning, injury, or experience.
  • Example: Rubber Hand Illusion
  • Demonstrates how the brain integrates body awareness and touch perception.

Conclusion

  • The brain, despite being a soft, jelly-like substance, gives rise to all thoughts, emotions, and sensory experiences.
  • The next lecture will explore Brain and Self, focusing on body image and consciousness.
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