Fig. 12.

Only the transverse signal propagation within deep layer was abolished by parasagittal cut made beneath superficial layer in horizontal slice. A: black dashed line represents a cut made parallel to the layer axis beneath superficial layer. Red and black squares show the sites 0.53 mm anterior and posterior (0.61 mm lateral) to the stimulation electrode, respectively. B: time course of fluorescence changes at red and black square sites in A. C: averaged values of optical signals at positive peaks of fast components at red and black square sites in A, respectively. Note that amplitude of excitatory signals in deep layers under the cut (anterior side, black arrow in A) was significantly smaller [t(4) = 3.08, P < 0.05, asterisk, paired t-test] than that of the intact (posterior side, red arrow in A). In horizontal slices, transverse excitation in deep layers was primarily mediated by neural connections in superficial layers.