Recording methods

Question 1

Single unit electrophysiology?

Answer 1

Uses microelectrodes to record action potentials (there are also other techniques)
Researchers attempt to define the receptive field of neurons to understand how they function
Neurons have a variety of responses and neurons that lie together are often responsive in similar ways (e.g. cells in blobs)
Up the hierarchy of processing, neurons’ response properties become increasingly specialized (e.g. faces)
The approach is invasive and therefore only possible in humans in very rare circumstances (e.g. epilepsy)

Question 2

What is Electroencephalography (EEG)?

Answer 2

Spontaneous EEG contains a mixture of different characteristic brain frequencies
Under rest, these frequencies reflect different cognitive states, e.g., the participant’s wakefulness or attention
Oscillations are also modulated during different cognitive tasks (e.g., memory tasks)
Recorded from the scalp, the electrical potential exhibits a wave- form with time on the x-axis and voltage on the y-axis. Over time, the waveform oscillates between a positive and negative voltage.
Very slow oscillations dominate in deep sleep, or what is called the delta wave. When awake, the oscillations occur much faster when the person is relaxed (alpha)

Question 3

What is Magnetoencephalography (MEG)?

Answer 3

Magnetic, not electric fields
Changes in electric fields are always accompanied by magnetic fields orthogonal to them
Instead of measuring the electric field generated by neural activity, we can also measure the magnetic field
MEG signals can thus be interpreted in very similar ways as EEG signals