Jm. Fellous et al., Frequency dependence of spike timing reliability in cortical pyramidal cells and interneurons, J NEUROPHYS, 85(4), 2001, pp. 1782-1787
Pyramidal cells and interneurons in rat prefrontal cortical slices exhibit
subthreshold oscillations when depolarized by constant current injection. F
or both types of neurons, the frequencies of these oscillations for current
injection just below spike threshold were 2-10 Hz. Above spike threshold,
however, the subthreshold oscillations in pyramidal cells remained low, but
the frequency of oscillations in interneurons increased up to 50 Hz. To ex
plore the interaction between these intrinsic oscillations and external inp
uts, the reliability of spiking in these cortical neurons was studied with
sinusoidal current injection over a range of frequencies above and below th
e intrinsic frequency. Cortical neurons produced 1:1 phase locking for a li
mited range of driving frequencies for fixed amplitude. For low-input ampli
tude, 1:1 phase locking was obtained in the 5- to 10-Hz range. For higher-i
nput amplitudes, pyramidal cells phase-locked in the 5- to 20-Hz range, whe
reas interneurons phase-locked in the 5- to 50-Hz range. For the amplitudes
studied here, spike time reliability was always highest during 1:1 phase-l
ocking, between 5 and 20 Hz for pyramidal cells and between 5 and 50 Hz for
interneurons. The observed differences in the intrinsic frequency preferen
ce between pyramidal cells and interneurons have implications for rhythmoge
nesis and information transmission between populations of cortical neurons.