Figure 1

Spatial correlation of stimuli determines oscillatory activity in electrosensory neurons. (a) Schematic of experimental stimulation. Single unit activity was recorded from ELL pyramidal cells while one side of the fish was stimulated with an array of four dipoles. Each dipole had a tip spacing of approximately 1.2 cm and the centers of adjacent dipoles were separated by 2.2 cm. Each dipole was 1.5 cm from the skin surface and stimulated roughly $2{\mathrm{c}\mathrm{m}}^2$ of the skin for typical stimulus contrasts ($250\mu \mathrm{V}{\mathrm{c}\mathrm{m}}^{-1}$). This ensured that there was limited overlap of the distinct dipole's electric images on the skin. (b) Spike train power spectra, $S$, when the spatial correlation between the dipoles, $c$, was set to 0 (light curve) and one (dark curve).Reuse & Permissions

Figure 2

Network model simulations and theoretical results for spatial correlation $c=0$ and $c=1$. (a) Spike train power spectra $S$ for the network model given by (2) ($c=0$, open circles; $c=1$, closed circles) and the theoretical result (5) ($c=0$, thin line; $c=1$, thick line). (b) Network raster plots for the simulations shown in (a). The top plot is for $c=0$ and the bottom plot is for $c=1$. The parameters for both the simulations and theory were $v_R=0$, $v_T=1$, ${\tau }_R=0.1$, $\mu =0.5$, $g=-1.2$, $\alpha =3$, ${\tau }_d=1$, $D=0.08$, ${\sigma }^2=0.16$, and ${\mu }^{\prime }=0.3286$. All simulations were integrated via a Euler integration scheme with a time step of ${10}^{-3}$. The plots were rescaled so that the membrane time constant was 6 ms; note that $\omega =2\pi f$.Reuse & Permissions

Figure 3

Oscillation dependence on stimulus correlation and axonal delay. (a) ${\Gamma }_{f_1,f_2,c}$ plotted as a function of $c$ for both $[f_1,f_2]=[2,22]\mathrm{H}\mathrm{z}$ (theory, thin line; simulations, open circles) and $[f_1,f_2]=[40,60]\mathrm{H}\mathrm{z}$ (theory, thick line; simulations, filled circles). Numerical integration of $S$ computed from (5) was done with a fixed interval of $\Delta f=0.1\mathrm{H}\mathrm{z}$, while integration of $S$ determined from simulation of (2) used the fast-Fourier transform discretization step of $\Delta f=0.5\mathrm{H}\mathrm{z}$. (b) $\Gamma$ obtained from spike trains of ELL pyramidal cells for a range of $c$ values. Data were obtained from same experiments as those for Fig. 1. (c) $S$ shown for ${\tau }_d=0.5$ (theory, thin curve; simulations, open circles) and ${\tau }_d=3$ (theory, thick curve; simulations, filled circles). $c=1$ for both curves. All other parameters are as given in Fig. 2.Reuse & Permissions