Spinal connections of ventral-group bulbospinal inspiratory neurons studied with cross-correlation in the decerebrate rat

摘要: We examined the synaptic connections from ventral-group bulbospinal inspiratory neurons to upper cervical and phrenic intercostal motoneurons in decerebrate rats using cross-correlation. Inspiratory were recorded medulla (n=28) at level of obex upper-cervical segments (C1 C2) spinal cord (n=29) 18 vagotomized, paralyzed, ventilated, decerebrated rats. The identified by their firing pattern antidromic activation C7. Whole-nerve recordings made bipolar electrodes central cut ends C5 nerve external internal nerves various thoracic levels. Cross-correlation histograms computed between these detect short time scale synchronizations indicative connections. (n=20), activities nerve, all showed peaks (mean half-amplitude width±SD, 1.1±0.3 ms) latencies latency±SD, 2.0±0.6 suggestive monosynaptic excitation. (n=33), neurons, displayed four (12%) halfamplitude 0.9±0.1 latencies(mean 1.8±0.6 excitation, six (18%) 1.4±0.4 near zero excitation fro m a common source. (n=34), levels (T2-8), 2.5±0.5 latency 4.5±1.1 oligosynaptic (n=42) Although size decreased with segmental separation, displacement did not increase separation displacement±SD, 0.6±0.6 as would be expected if resulted descending source such ventral-groupbulbospinal neurons. conclude that make motoneurons, few but are via interneurons.