Neuroscience 2004 Abstract
| Presentation Number: | 882.14 |
|---|---|
| Abstract Title: | Characterization of electrophysiological and pharmacological properties of locomotor activity related neurons in <I>cfos</I>-EGFP mice. |
| Authors: |
Dai, Y.*1
; Jordan, L. M.1
; Brownstone, R. M.2
1Dept Physiol, Univ Manitoba, Winnipeg, Canada 2NS, 730 William Ave, R3E 3J7, |
| Primary Theme and Topics |
Motor Systems - Pattern Generation and Locomotion |
| Session: |
882. Pattern Generation: Spinal Cord and Other I Poster |
| Presentation Time: | Wednesday, October 27, 2004 9:00 AM-10:00 AM |
| Location: | San Diego Convention Center - Hall A-H, Board # FF17 |
| Keywords: | LOCOMOTION, INTERNEURON, MODULATION |
Although it is well accepted that the spinal cord contains a system of interneurons (INs) capable of producing the locomotor rhythm, little is known about their electrophysiological properties. Here we investigate the properties of these neurons and the modulation of their properties by 5-HT and ACh, transmitter substances known to induce locomotor activity. Fluorescent INs were studied using whole cell patch clamp techniques in spinal cord slices from P4-P8 Cfos-EGFP mice (Brownstone et al, SFN Abs 65.8, 2002) following locomotor activity (walking or swimming 60-90 min). The target areas of study included laminae VII, VIII&X from segment T11-L6. The main properties measured from these neurons include input resistance(Ri),time constant, whole cell capacitance, current(Ith) and voltage threshold(Vth), and the frequency-current(f/I) relation. The EGFP labeled cells could be classified into three types based on firing induced by current injection(n=34): single spike (type 1, n=6), brief firing (type 2, n=7), and repetitive firing (type 3, n=21). The type 1 cells are mainly located in lamina VII&VIII, the type 2 in X, and the type 3 in VII,VIII&X. The type 1 cells show a higher Ith and lower Vth & Ri than those measured from the type 2&3 cells. Bath application (10-40 uM) of 5-HT and/or ACh modulated the firing properties, usually producing a hyperpolarization of Vth, left-shift of the f/I curve, depolarization of the membrane potential(Em), and changes in Ri. Some cells, however, showed hyperpolarization of Em and/or depolarization of Vth. The Em oscillations with peak-to-peak amplitude of ~8 mV and frequency of ~9 Hz are observed in type 3 cells (n=4) after application of 5-HT. Investigation of the locations and axonal projections of the various cell types revealed in this study should allow delineation of functional classes of locomotor INs.
Supported by NIH391313520
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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