neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, development ...

, a population spike (PS) is the shift in electrical potential as a consequence of the movement of ions involved in the generation and propagation of

action potentials An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, c ...

. Population spikes often reflect synaptically induced firing and therefore, they can be classified as a type of field

excitatory postsynaptic potentials In neuroscience, an excitatory postsynaptic potential (EPSP) is a postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential. This temporary depolarization of postsynaptic membrane potential, caused by the ...

.
In some areas of the brain, such as the

hippocampus The hippocampus (via Latin from Greek , 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic system, a ...

, neurons are arranged in such a way that they all receive synaptic inputs in the same area. Because these neurons are in the same orientation, the extracellular signals from the generation of action potentials don't cancel out, but rather add up to give a signal that can easily be recorded with a field electrode.
The PS is usually recorded with an extracellular electrode placed close to neural cell bodies or

axons An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, th ...

. The first interpretations of hippocampal field potentials were developed by

Per Andersen Per Oskar Andersen (12 January 1930 – 17 February 2020) was a Norwegian brain researcher at the University of Oslo. Research by his lab, specifically by Terje Lømo (and Timothy Bliss, who helped characterize the phenomenon years later), led t ...

References

Neurophysiology {{Neuroscience-stub