Role of the B�tzinger complex in fastigial nucleus-mediated respiratory responses

Abstract

We have reported that the phrenic neurogram (PN) is modulated by stimulation of the fastigial nucleus (FN) of the cerebellum. The present study was undertaken to search for brainstem site(s) involved in the FN efferent pathway to modulate phrenic nerve activities. Experiments were performed on 35 anesthetized, paralyzed, and ventilated cats, using the PN as the index of the respiratory motor output. Results showed that bilateral electrolytic lesions of the red nucleus (RN), the paramedian reticular nucleus (PRN), or the pontine respiratory group (PRG) had little effect on the ability of FN stimulation to modulate the respiratory output. However, the modulation was abolished by bilateral electrolytic lesions of the Bötzinger complex (BötC). Further studies showed that bilateral chemical inactivation of BötC neurons produced by topical microinjection of kainic acid or cobalt chloride failed to abolish the modulation. We concluded that fibers of passage, not synapses or cell bodies in the BötC, were involved in the modulatory effect of FN stimulation on the PN. The RN, PRN, and PRG appear not to be important in the neural circuitry responsible for the FN modulation of the phrenic activity.

Medial cerebellar nuclear projections and activity patterns link cerebellar output to orofacial and respiratory behavior

“…The rVRC occupies a ventral and lateral position in the medulla and pons (Alheid et al, 2011), a region that did not include terminal labeling from the mDCN in the current study. Moreover, careful examination (via lesion) of certain respiratory sites in the medulla and pons by Zhang et al (1999) indicate that neurons in a key respiratory rhythm-generating nucleus in the rVRC, the Bötzinger complex, are not necessary for mDCN modulatory effects on respiration. Instead, lesions of the Gi disrupted mDCN-dependent mediation of respiratory timing.…”

“…There is strong evidence that the cerebellum modulates respiratory-related motor activity via projections of mDCN neurons to various medullary or pontine regions (Lutherer and Williams, 1986; Gruart and Delgado-Garcïa, 1992; Xu and Frazier, 1995, 1997, 2000; Zhang et al, 1999). However, the pathways by which the cerebellum engages brainstem centers controlling other orofacial movements such as licking or whisking is not known.…”

Cerebellar fastigial nucleus: from anatomic construction to physiological functions

“…Thus, the possible respiratory pathways underlying the FN-mediated respiratory responses were examined by separate ablation of these FN targeted respiratory centers. It has been shown that destruction of neurons within the pontine respiratory groups, Bötzinger complex, and PRN fails to alter respiratory responses induced by FN stimulation [ 92 ]. In contrast, respiratory modulation of FN totally disappeared after selective ablation of bilateral NGC neurons [ 89 ], suggesting that FN-mediated respiratory response depends on the relay of NGC (Fig.…”