Figure 6

A, cardiovascular neuron with action potentials synchronized 1: 1 by the light pulses. This neuron was labelled juxtacellularly with biotinamide following its characterization as barosensitive and photoactivated. It is identified by the presence of green fluorescing Alexa 488 (panel Aa). Panel Ab shows that the same neuron (arrow) is immunoreactive for the ChR2-mCherry fusion protein (reporter: red fluorescing Cy3). B, respiratory neuron (post-inspiratory). This neuron was activated by light trains but its action potentials were not synchronized to the light pulses (a: biotinamide; b: ChR2-mCherry). This neuron contained no ChR2-mCherry and was located just dorsal to the cluster of neurons that expressed the transgene, i.e. in the Bötzinger region of the RVLM. Scale bar shown in Aa represents 25 μm in Aa and b and 100 μm in Ba and b. C, computer-assisted plots showing the location of the juxtacellularly labelled neurons. The mCherry-positive cardiovascular neurons are in black and the neurons that did not contain detectable levels of the transgene are in grey. Abbreviations: Amb, compact portion of the nucleus ambiguus. IO, inferior olive; pyr, pyramidal tract. Scale bar 0.5 mm.