Article

Gamma band activity in the developing parafascicular nucleus.

Center for Translational Neuroscience, Dept. of Neurobiology and Developmental Sciences, Univ. of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Journal of Neurophysiology (impact factor: 3.32). 11/2011; 107(3):772-84. DOI:10.1152/jn.00677.2011 pp.772-84
Source: PubMed

ABSTRACT The parafascicular nucleus (Pf) receives cholinergic input from the pedunculopontine nucleus, part of the reticular activating system involved in waking and rapid eye movement (REM) sleep, and sends projections to the cortex. We tested the hypothesis that Pf neurons fire maximally at gamma band frequency (30-90 Hz), that this mechanism involves high-threshold voltage-dependent P/Q- and N-type calcium channels, and that this activity is enhanced by the cholinergic agonist carbachol (CAR). Patch-clamped 9- to 25-day-old rat Pf neurons (n = 299) manifested a firing frequency plateau at gamma band when maximally activated (31.5 ± 1.5 Hz) and showed gamma oscillations when voltage-clamped at holding potentials above -20 mV, and the frequency of the oscillations increased significantly with age (24.6 ± 3.8 vs. 51.6 ± 4.4 Hz, P < 0.001) but plateaued at gamma frequencies. Cells exposed to CAR showed significantly higher frequencies early in development compared with those without CAR (24.6 ± 3.8 vs. 41.7 ± 4.3 Hz, P < 0.001) but plateaued with age. The P/Q-type calcium channel blocker ω-agatoxin-IVA (ω-Aga) blocked gamma oscillations, whereas the N-type blocker ω-conotoxin-GVIA (ω-CgTx) only partially decreased the power spectrum amplitude of gamma oscillations. The blocking effect of ω-Aga on P/Q-type currents and ω-CgTx on N-type currents was consistent over age. We conclude that P/Q- and N-type calcium channels appear to mediate Pf gamma oscillations during development. We hypothesize that the cholinergic input to the Pf could activate these cells to oscillate at gamma frequency, and perhaps relay these rhythms to cortical areas, thus providing a stable high-frequency state for "nonspecific" thalamocortical processing.

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Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

25-day-old rat Pf neurons
 
cholinergic agonist carbachol
 
firing frequency plateau
 
gamma band
 
gamma band frequency
 
gamma frequencies
 
high-threshold voltage-dependent P/Q-
 
higher frequencies
 
N-type blocker ω-conotoxin-GVIA
 
N-type calcium channels
 
N-type currents
 
P/Q-type calcium channel blocker ω-agatoxin-IVA
 
P/Q-type currents
 
Pf gamma oscillations
 
Pf neurons fire maximally
 
power spectrum amplitude
 
rapid eye movement
 
reticular activating system
 
stable high-frequency state
 
thalamocortical processing
 

Nebojsa Kezunovic