Rhythmic activity of neurons in the rostral ventrolateral medulla of conscious cats: effect of removal of vestibular inputs.

Barman SM, Sugiyama Y, Suzuki T, Cotter LA, DeStefino VJ, Reighard DA, Cass SP, Yates BJ. Am J Physiol Regul Integr Comp Physiol. 2011 Oct;301(4):R937-46 In most electrophysiological studies of RVLM neurons, animals are either anesthetized (like we do) or decerebrated (like in the half-rat prep). In this paper, they went ahead and examined neurons in conscious/behaving cats, and correlated their activity with carotid blood flow. They found that around 8% of RVLM neurons showed their spiking to be most likely to occur during periods of decreased blood flow (in between heart beats). Their previous work showed that the vestibular system normally suppresses RVLM responses to body rotation in intact/awake rats (think like the Dampney paper where they inhibited the colliculi in order to get sympathetic activation following normally non-stimulating cues). So in this paper, they looked at what removal of vestibular inputs would do the cardiac-linked RVLM activity and found that vestibular removal caused them to have an increased likelihood of finding neurons that showed cardiac related activity. What I find most interesting though, is that their data came in bursts - some days they didn't get any neurons with flow-related activity, while other days up to 60% of the neurons they recorded had it. Maybe that's the problem with my recordings - I just keep picking the wrong days to do experiments... -DH