Self And The Phenomenon Of Life: A Biologist Examines Life From Molecules To Humanity

Appendix D: Approaches to Explore the Brain 345

“9x6” b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity

the skull. It  is through EEG that the state of consciousness is conve-

niently recorded. Clinically, it is very useful to detect seizure activity in

the brain.

Electro-corticography (ECoG), also known as intracranial

EEG, is the recording of electrical activity from the exposed surface

of the brain, using multiple electrodes to detect brain areas responsi-

ble for seizure activity, or to detect cortical activity following sensory

stimulation (as in visual cortex with respect to retinal light stimulation).

The same electrodes can be used for stimulation in order to study the

behavioral role of a given cortical area. It is an invasive procedure that

is carried out only in patients during brain surgery (for epilepsy) or in

non-human animals.

Magneto-encephalography (MEG) consists of recording the

magnetic field of the brain surface using a magnetometer place on the sur-

face of the scalp. It has better spatial and temporal resolution than EEG,

making it as sensitive as ECoG without having to remove the skull. Its

superior time resolution makes it a good complement of functional MRI.

Whole brain single cell recording brings animal behavior to

the neuronal level, and contributed such important information as the

pattern-recognition cells (visual cortex), place- and grid-cells (hippo-

campus), and the mirror neurons (premotor cortex). Whole brain mul-

tichannel recording provides information on neuronal interaction and

networking.

In vitro single neuron recording provides information on electrical

potential across cell membrane: post-synaptic potential; axonal resting

and action potentials. Patch clamp (voltage clamp) experiments provide

data on ion flux across axonal membranes during neuronal activity.

Electrical stimulation

Deep brain stimulation (DBS) — Stimulation of selected brain areas is

used for therapeutic purposes, such as in Parkinson’s disease. It has also

been used to study the mental and behavioral correlates of a particular

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