Biomedical Engineering Reference
In-Depth Information
(a) Neuron
(b) Assembly
(c) Population
(d) Ensemble
FIgURE 2.3:
Levels of abstraction of neuronal representation. (a) Recordings from a single neuron.
(b) A single electrode recording from multiple neurons. (c) Spike raster plots from a population of neu-
rons indicating the time of action potentials. (d) Firing rates from an ensemble of neurons.
the action potentials of several neurons (an assembly) appear aggregated in the time series captured
by one microelectrode. Here, multiple action potentials can be observed with different heights and
widths. The concept of cell assembly was proposed by Hebb [
52
] in his topic
The Organization of
Behavior
, where the assembly served as a diffuse group of cells acting in a closed system that delivers
facilitation to other system. In multielectrode recordings, there are many (100 are typical) chan-
nels of neural data that can translate into hundreds of neurons probed. One of the difficult aspects
