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Phrenic nerve afferents elicited cord dorsum potential in the cat cervical spinal cord.

Chou YL, Davenport PW - BMC Physiol. (2005)

Bottom Line: A single N1 peak of the CDP was found in the C4 and C7 spinal segments.Three peaks (N1, N2, and N3) were found in the C5 and C6 segments.These results demonstrate PnA activation of neurons in the cervical spinal cord.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiological Sciences, University of Florida, Box 100144, HSC, Gainesville, FL 32610, USA. yangling@ufl.edu

ABSTRACT

Background: The diaphragm has sensory innervation from mechanoreceptors with myelinated axons entering the spinal cord via the phrenic nerve that project to the thalamus and somatosensory cortex. It was hypothesized that phrenic nerve afferent (PnA) projection to the central nervous system is via the spinal dorsal column pathway.

Results: A single N1 peak of the CDP was found in the C4 and C7 spinal segments. Three peaks (N1, N2, and N3) were found in the C5 and C6 segments. No CDP was recorded at C8 dorsal spinal cord surface in cats.

Conclusion: These results demonstrate PnA activation of neurons in the cervical spinal cord. Three populations of myelinated PnA (Group I, Group II, and Group III) enter the cat's cervical spinal segments that supply the phrenic nerve.

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Histogram of the CDP peak amplitudes in the cervical spinal segments (C4 to C7) after phrenic nerve afferent stimulation in cats. N1 is the first peak amplitude observed in the C4 to C7 spinal segments; N2 and N3 are the second and third peak amplitudes only observed in the C5 and C6 spinal segments. * indicates a significant differences between N1 and N2 peaks in the C5 and C6 segmental locations. # indicates a significant difference between N1 and N3 peaks in the C5 and C6 segmental locations. ∞ indicates significant differences between the spinal segments for N1 peak.
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Figure 4: Histogram of the CDP peak amplitudes in the cervical spinal segments (C4 to C7) after phrenic nerve afferent stimulation in cats. N1 is the first peak amplitude observed in the C4 to C7 spinal segments; N2 and N3 are the second and third peak amplitudes only observed in the C5 and C6 spinal segments. * indicates a significant differences between N1 and N2 peaks in the C5 and C6 segmental locations. # indicates a significant difference between N1 and N3 peaks in the C5 and C6 segmental locations. ∞ indicates significant differences between the spinal segments for N1 peak.

Mentions: In all cats, electrical stimulation of the phrenic nerve elicited CDP's recorded at the dorsal surface of C4 to C7 cervical spinal segments, and at rostral, middle and caudal locations within each spinal segment. No CDP was observed in the C8 spinal segment. A primary CDP elicited by stimulation of PnA was observed and recorded in dorsal surface of C4 to C7 cervical spinal segments (Fig. 1). The N1 CDP was recorded in the C4 to C7 spinal segments; whereas three CDP peaks (N1, N2 and N3) were identified only in the C5 and C6 spinal segments (Fig. 2). The distributions of the onset latencies and peak amplitudes of individual cervical spinal cord segments are summarized in (Fig. 3) and (Fig. 4), respectively. The averaged N1 peak latency was 1.7 ± 0.1 ms for all cervical spinal segments. The averaged N2 peak latency was 2.3 ± 0.1 ms and the averaged N3 peak latency was 4.6 ± 0.3 ms in the C5 and C6 segments. The averaged conduction velocity was 94.1 ± 8.6 m/sec for the N1 peak, 70.6 ± 7.5 m/sec for the N2 peak and 35.0 ± 3.8 m/sec for the N3 peak. There was a significant difference between the latencies for N1, N2 and N3 peaks (P < 0.05). The average N1 peak amplitude was 22.8 ± 6.0 μV in the C4 segment and significantly less than the N1 peak amplitude for C5, C6 and C7 spinal segments (p < 0.05). The average N1 peak amplitude was 141.3 ± 12.1 μV in the C5 segment and 146.0 ± 27.2 μV in the C6 segment and not significantly different. The average N1 amplitude was 54.6 ± 30.1 μV in the C7 segment and significantly less than C5 and C6. N2 and N3 peaks were only observed in the C5 and C6 spinal segments and the averaged N2 peak amplitude was 79.2 ± 10.3 μV in the C5 segment and 82.1 ± 6.5 μV in the C6 segment. The averaged N3 peak amplitude was 72.0 ± 4.4 μV in the C5 segment and 69.0 ± 11.3 μV in the C6 segment. The amplitudes of the CDP peaks were significantly different between the N1, N2 and N3 peaks (P < 0.05).


Phrenic nerve afferents elicited cord dorsum potential in the cat cervical spinal cord.

Chou YL, Davenport PW - BMC Physiol. (2005)

Histogram of the CDP peak amplitudes in the cervical spinal segments (C4 to C7) after phrenic nerve afferent stimulation in cats. N1 is the first peak amplitude observed in the C4 to C7 spinal segments; N2 and N3 are the second and third peak amplitudes only observed in the C5 and C6 spinal segments. * indicates a significant differences between N1 and N2 peaks in the C5 and C6 segmental locations. # indicates a significant difference between N1 and N3 peaks in the C5 and C6 segmental locations. ∞ indicates significant differences between the spinal segments for N1 peak.
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Related In: Results  -  Collection

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Figure 4: Histogram of the CDP peak amplitudes in the cervical spinal segments (C4 to C7) after phrenic nerve afferent stimulation in cats. N1 is the first peak amplitude observed in the C4 to C7 spinal segments; N2 and N3 are the second and third peak amplitudes only observed in the C5 and C6 spinal segments. * indicates a significant differences between N1 and N2 peaks in the C5 and C6 segmental locations. # indicates a significant difference between N1 and N3 peaks in the C5 and C6 segmental locations. ∞ indicates significant differences between the spinal segments for N1 peak.
Mentions: In all cats, electrical stimulation of the phrenic nerve elicited CDP's recorded at the dorsal surface of C4 to C7 cervical spinal segments, and at rostral, middle and caudal locations within each spinal segment. No CDP was observed in the C8 spinal segment. A primary CDP elicited by stimulation of PnA was observed and recorded in dorsal surface of C4 to C7 cervical spinal segments (Fig. 1). The N1 CDP was recorded in the C4 to C7 spinal segments; whereas three CDP peaks (N1, N2 and N3) were identified only in the C5 and C6 spinal segments (Fig. 2). The distributions of the onset latencies and peak amplitudes of individual cervical spinal cord segments are summarized in (Fig. 3) and (Fig. 4), respectively. The averaged N1 peak latency was 1.7 ± 0.1 ms for all cervical spinal segments. The averaged N2 peak latency was 2.3 ± 0.1 ms and the averaged N3 peak latency was 4.6 ± 0.3 ms in the C5 and C6 segments. The averaged conduction velocity was 94.1 ± 8.6 m/sec for the N1 peak, 70.6 ± 7.5 m/sec for the N2 peak and 35.0 ± 3.8 m/sec for the N3 peak. There was a significant difference between the latencies for N1, N2 and N3 peaks (P < 0.05). The average N1 peak amplitude was 22.8 ± 6.0 μV in the C4 segment and significantly less than the N1 peak amplitude for C5, C6 and C7 spinal segments (p < 0.05). The average N1 peak amplitude was 141.3 ± 12.1 μV in the C5 segment and 146.0 ± 27.2 μV in the C6 segment and not significantly different. The average N1 amplitude was 54.6 ± 30.1 μV in the C7 segment and significantly less than C5 and C6. N2 and N3 peaks were only observed in the C5 and C6 spinal segments and the averaged N2 peak amplitude was 79.2 ± 10.3 μV in the C5 segment and 82.1 ± 6.5 μV in the C6 segment. The averaged N3 peak amplitude was 72.0 ± 4.4 μV in the C5 segment and 69.0 ± 11.3 μV in the C6 segment. The amplitudes of the CDP peaks were significantly different between the N1, N2 and N3 peaks (P < 0.05).

Bottom Line: A single N1 peak of the CDP was found in the C4 and C7 spinal segments.Three peaks (N1, N2, and N3) were found in the C5 and C6 segments.These results demonstrate PnA activation of neurons in the cervical spinal cord.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiological Sciences, University of Florida, Box 100144, HSC, Gainesville, FL 32610, USA. yangling@ufl.edu

ABSTRACT

Background: The diaphragm has sensory innervation from mechanoreceptors with myelinated axons entering the spinal cord via the phrenic nerve that project to the thalamus and somatosensory cortex. It was hypothesized that phrenic nerve afferent (PnA) projection to the central nervous system is via the spinal dorsal column pathway.

Results: A single N1 peak of the CDP was found in the C4 and C7 spinal segments. Three peaks (N1, N2, and N3) were found in the C5 and C6 segments. No CDP was recorded at C8 dorsal spinal cord surface in cats.

Conclusion: These results demonstrate PnA activation of neurons in the cervical spinal cord. Three populations of myelinated PnA (Group I, Group II, and Group III) enter the cat's cervical spinal segments that supply the phrenic nerve.

Show MeSH