spike

1. A brief electrical event of 3–25 ms that gives the appearance in the electroencephalogram of a rising and falling vertical line. 2. In electrophoresis, a sharply angled upward deflection on a densitometric tracing.

- ponto-geniculo-occipital s. EEG spikes during REM sleep that arise in the pons and pass to the lateral geniculate body and occipital cortex.

* * *

spike 'spīk n a change (as in voltage) involving a sharp increase and fall or a recording of this: as

a) the pointed element in the wave tracing in an electroencephalogram

b) a sharp increase in body temperature followed by a rapid fall <a fever with \spikes to 103°>

c ) (1) the sharp increase and fall in the recorded action potential of a stimulated nerve cell that during the increasing phase corresponds to an inrush of sodium ions to the interior of the cell and during the decreasing phase corresponds to a slowing of the influx of sodium ions and to an increasing efflux of potassium ions to the exterior (2) ACTION POTENTIAL

spike vt, spiked; spik·ing to undergo a sudden sharp increase in (temperature or fever) usu. up to an indicated level <infected patients spiked fevers as high as 105°F>

* * *

(spīk) a sharp upward deflection in a curve, such as the main deflection of the oscillographic tracing of the action potential wave, the following smaller wave being called the after-potential. See also under potential.