Week 3 Notes: Mind Reading (Electrophysiology)

Functional Imaging & Electrophysiology

  • Comparison of Methods:
    • Electrical Methods:
    • Examples: EEG (Electroencephalography), SUA (Single Unit Activity).
    • Characteristics: Fast response times.
    • Metabolic Methods:
    • Examples: fMRI (Functional Magnetic Resonance Imaging), PET (Positron Emission Tomography).
    • Characteristics: Slower response times compared to electrical methods.

Spike Recording

  • Types of Recording:
    • SUA (Single Unit Activity): Records activity from a single neuron.
    • MUA (Multiple Unit Activity): Records activity from multiple neurons.
  • Recording Environments:
    • Extracellular Recording: Conducted in vivo, often in freely moving subjects.
    • Intracellular Recording: Conducted in laboratory studies, usually in controlled environments.

Neural Coding

  • Types of Neural Coding:
    • Specificity Coding: One neuron corresponds to one specific concept or idea.
    • Example: "Jennifer Aniston cell" demonstrates this theory, as specific neurons fire in response to known faces or concepts.
    • Population Coding: A concept is represented by a pattern of firing across multiple neurons.

Motor System & Brain-Computer Interfaces (BCI)

  • Motor Areas:
    • M1 (Primary Motor Cortex): Responsible for executing movement.
    • M2 (Secondary Motor Areas): Responsible for planning movements.
  • Neuronal Firing:
    • Neurons exhibit preferred directions, meaning they fire more when the movement aligns with their favored direction of activity.
  • Brain-Computer Interface Functionality:
    • BCIs use signals from these areas to control robotic limbs or digital cursors.

EEG, ECoG, and LFP

  • EEG (Electroencephalography):
    • Non-invasive method using electrodes placed on the scalp.
  • ECoG (Electrocorticography):
    • Invasive method that requires a direct connection to the brain surface.
  • LFP (Local Field Potentials):
    • Involves deep brain recordings to capture local neural activities.

Signal Analysis

  • Fourier Transform:
    • A mathematical transformation that converts signals from the time domain to the frequency domain.
  • Spectrogram:
    • A visualization tool that displays how the frequency of a signal varies with time.
  • Alpha Wave:
    • Typically oscillates around 10 Hz; associated with states of relaxation, often observed when a person closes their eyes.