Brain Function and Measurement Study Notes

Chapter 3: Brain Function and Measurement

3.1 Mapping the Mind

  • Discussion of brain activity measurement and performance comparisons.

    • The brain in action: Understanding how we measure brain function.

    • Comparative analysis between injured and intact brains to infer the functions of the frontal lobe.

Challenges in Brain Measurement

  • Unique Brain Injuries:

    • No two brain injuries are identical, complicating the assessment of specific regions.

  • Longitudinal Studies:

    • Wait six months post-injury to observe degenerative changes.

    • Research using MRI scans before and after a task to identify structural changes.

Research Reliability and Replication

  • Message regarding brain measurement techniques is limited and prone to chance occurrences.

  • Replication Importance:

    • When findings have been replicated multiple times, confidence in results increases.

  • Novel Applications:

    • Caution concerning the application of findings, such as in cases of Parkinson's tremors, which can be beneficial but may carry risks.

Complexity of Brain Functions

  • Spirituality linked to various brain sectors, indicating complex activation during tasks.

  • Misconception: "We only use 10% of our brains" arises from oversimplification of brain usage.

    • Origins trace back to popular notions and media representations.

  • Example: Simplistic interpretations, such as "what is the problem with a specific area of the brain," fail to capture the true complexity of brain functions.

Neural Structures and Functions

  • William James on Myelin Sheath:

    • Myelin sheath is crucial for action potentials.

    • Neuron structure includes axons, cell bodies, and synapse terminals, which connect to other neurons, forming networks.

  • Neurotransmitter Release:

    • Stimulation at axon terminals causes the release of neurotransmitters, impacting action potential generation.

Neurons and Immune Cells

  • Reprogrammed Neurons:

    • Research shows ability for cells to convert into neurons, forming synaptic networks.

  • Microglia:

    • Most abundant immune cells in the brain, star-shaped, connections can be extensive (300,000 to 1,000,000 neurons).

    • Functions include nutrient absorption, waste excretion, and cellular fueling.

Axon Structure

  • Distinction of the axon with a myelin sheath:

    • Yellow membrane that supports electrical activity and enhances signal transmission speed.

Neuron Electrical Activity

  • Aldrin Envelope:

    • Neuron structure enveloped and filled with ion-containing fluid.

  • Resting Potential:

    • Greater concentration of negative ions inside than outside the neuron; creates a polarized state, allowing potential firing.

  • Excitatory Signals:

    • Signals open channels for positive ions to enter.

    • Sufficient excitatory input triggers the action potential, leading to a domino effect down the axon.

Action Potential Dynamics

  • Once initiated, an action potential cannot be stopped; it continues down the axon.

  • Some medical conditions provoke excessive action potentials, leading to continuous firing until reduced.