Figure 3.
Proximodistal Differences of Theta and Gamma Activity of CA2 Pyramidal Cells
(A) Intracellular recordings obtained simultaneously to multisite LFP signals allowed evaluation of oscillatory behavior of different cell types around CA2. Note the poor theta rhythmicity of spontaneous firing in a proximal PCP4+ CA2 cell but consistent phase-locking preference with theta cycles at SLM. Note also clear hyperpolarization during sharp-wave (SPW) ripples.
(B) Neurochemical classification of cells shown in (A) and (C).
(C) Single-cell and LFP recordings from head-restrained rats.
(D) Power spectrum of the intracellular membrane potential recorded during LFP theta in different cell types. Cells are ranked according to their proximodistal location within each group. Data from n = 5 CA3 cells (green), n = 10 CA2 cells (red), and n = 9 CA1 cells (blue).
(E) Individual single-cell data of theta and gamma power of membrane potential oscillations.
(F) Representative examples of single-cell autocorrelation and phase-locking firing to theta and gamma waves recorded at SLM. Cells are ranked according to their proximodistal location.
(G) Proximodistal distribution of the modulatory strength for theta and gamma for cells recorded under urethane (filled circles; 24 cells) and in drug-free conditions (open circles; 3 cells). The discontinuous line indicates the 95% confidence interval. Note the separate cluster of poorly modulated cells (arrowhead).
(H) Distribution of the modulatory strength as a function of the cell distance within SP (0 is the superficial limit).
(I) Theta phase firing preference of single cells measured against the SLM signal. The circular distribution significance is indicated.
(J) Theta phase firing preference of cells plotted as a function of their deep-superficial location.
(K) Phase firing preference of single cells represented against the CA1 SP signal (note the reversal of the theta wave along the CA1 layers).
(L) Potential mechanisms may include proximodistal and deep-superficial microcircuit organization and the influence of different theta generators.