Hypoglossal motor nerve activity elicited by taste and thermal stimuli applied to the tongue in rats

Takashi Yamamoto, Toshiko Fujiwara, Ryuji Matsuo, Yojiro Kawamura

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Single unit activity of hypoglossal motor nerve fibers which innervate the tongue muscles was recorded in lightly anesthetized non-decerebrate and acute decerebrate rats. The pattern of responses to taste and thermal stimuli applied to the tongue surface was classified into 4 types. The type 1 response is characterized by short-lasting rhythmic burst discharges, the type 2 consists of both the rhythmic burst and tonic discharges, the type 3 is long-lasting tonic discharges and the type 4 shows short-lasting burst or short-lasting tonic discharges. In non-decerebrate rats, most of the fibers (93%) showed no or a few spontaneous firings. Sucrose and NaCl were the most effective stimulants, and 70-80% of the fibers showed the type 1 response to these stimuli. Calculating the correlations between response patterns of the fiber to a pair of the stimuli, sucrose and NaCl, and HCl and quinine produced a similar response profile, respectively. In decerebrate rats, however, about 21% of fibers showed a highly regular spontaneous firing (about 30 Hz). Rhythmic burst responses (types 1 and 2) were not induced, and thermal (especially cold) stimulation elicited much better responses than the taste stimuli. HCl and quinine, but not sucrose and NaCl, produced a similar response profile. These characteristic properties of the response in acute decerebrate rats may in part be attributed to inactivation of a 'rhythmic center' in the brain stem.

Original languageEnglish
Pages (from-to)89-104
Number of pages16
JournalBrain Research
Issue number1
Publication statusPublished - Apr 22 1982


  • chorda tympani
  • electrophysiology
  • hypoglossal nerve
  • taste
  • temperature
  • tongue
  • touch

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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