In vivo monitoring of chemically evoked activity patterns in the rat trigeminal ganglion

Abstract

Albeit lacking a sense of smell, anosmic patients maintain a reduced ability to distinguish different volatile chemicals by relying exclusively on their trigeminal system (TS). To elucidate differences in the neuronal representation of these volatile substances in the TS, we performed voltage-sensitive dye imaging (VSDI) in the rat trigeminal ganglion (TG) in vivo. We demonstrated that stimulus-specific patterns of bioelectrical activity occur within the TG upon nasal administration of ten different volatile chemicals. With regard to spatial differences between the evoked trigeminal response patterns, these substances could be sorted into three groups. Signal intensity and onset latencies were also dependent on the administered stimulus and its concentration. We conclude that particular compounds detected by the TS are represented by (1) a specific spatial response pattern, (2) the signal intensity, and (3) onset latencies within the pattern. Jointly, these trigeminal representations may contribute to the surprisingly high discriminative skills of anosmic patients.

Single-neuron responses to intraoral delivery of odor solutions in primary olfactory and gustatory cortex

“…Moreover, our data show that responses to odor solutions in both OC and GC differ in latency from responses to taste solutions that OC responses are driven by respiration and correlated with responses to the same odorants presented orthonasally. These findings argue against gustatory stimulation being the source of responses to intraoral odorants, although the involvement of the trigeminal system cannot be completely ruled out, as is the case in most studies involving odor stimuli (Lübbert et al 2013;Silver and Moulton 1982). Finally, it is possible that odor-specific mouth movements contribute to the observed neural responses.…”

RNA-Seq Analysis of Human Trigeminal and Dorsal Root Ganglia with a Focus on Chemoreceptors

“…Odorant activation leads to chemically evoked activity patterns in the TG and higher order neurons in the brain [22–24]. Most odorant molecules simultaneously stimulate both, the olfactory and the trigeminal system within the nasal cavity.…”

“…It is known that nearly all odorants, particularly at high concentrations, activate intranasal trigeminal nerve fibers and trigeminally innervated respiratory epithelia [ 20 , 21 ]. Odorant activation leads to chemically evoked activity patterns in the TG and higher order neurons in the brain [ 22 – 24 ]. Most odorant molecules simultaneously stimulate both, the olfactory and the trigeminal system within the nasal cavity.…”