Fig. 4.

Field effects of laminar-localized pressure pulse applications of CCh (10 mm) in the entorhinal slice.A, A diagrammatic representation of the recording and application arrangement. Two stationary recording electrodes were located in layers II and V. A pressure pipette was placed consecutively in layers I, II, III, V, and VI and in the angular bundle (AB), and a 10 msec pulse was administered at each point. B, Layer II application (denoted by thevertical line). After only a short delay, small-amplitude epileptiform activity was recorded in layer II. Note the absence of activity in layer V. C, Layer III application. No activity was elicited. D, Layer V application. A long-lasting series of large-amplitude epileptiform events of both long and short duration were elicited in layer V and propagated to layer II. These events are remarkably similar to those engendered by bath perfusion of CCh (see Fig. 1). E, Layer VI application. One short-duration field spike was elicited at a long delay from the onset of the pressure pulse.