Differential taste coding of salt and acid by correlative activities between taste-sensitive neuron types in rat gustatory cortex.
Using a multi-electrode recording technique, the present study aimed to elucidate the role of broadly-tuned taste-sensitive neurons in the rat gustatory cortex in discriminating between salt and acid. A majority of taste-sensitive neurons (94/119 neurons; 78%) were classified as NaCl (N)-, HCl (H)- or NaCl and HCl (NH)-best neurons. Of 63 neuron pairs (94 neurons), 31 showed significant peaks and/or troughs in their cross-correlograms (CCs) during taste stimulation periods. During NaCl stimulation, the incidence of significant correlation and the mean frequency of correlated discharges (FC) in the N/N and NH/NH pairs were higher than those in the other best-taste pairs. In contrast, during HCl stimulation both indices in the N/N or H/H pairs were very low, while those in the NH/NH pairs were high. These results suggest that (1) correlated activities between N-best neurons and those between NH-best neurons play a significant role in taste quality coding of salt, and that (2) correlated activities between NH-best neurons may be important for sour taste coding as well. Peak formation in CCs tended to be more frequent in the homo-types (N/N, H/H and NH/NH pairs) than in the hetero-types (N/NH, N/H and H/NH pairs). In contrast, troughs were observed mostly in the hetero-types. Inhibitory interaction in hetero-type pairs together with coactivation in homo-type pairs may enhance taste discrimination by taste-sensitive neuron populations.
Yokota
T
T
Department of Physiology, School of Dental Medicine, Aichi-Gakuin University, 1-100 Kusumoto, Chikusa, Nagoya, 4648650 Japan. tyokota@dpc.aichi-gakuin.ac.jp
Eguchi
K
K
Satoh
T
T
D000465:Algorithms; D000818:Animals; D003627:Data Interpretation, Statistical; D004594:Electrophysiology; D006851:Hydrochloric Acid / Q000494:pharmacology*; D008297:Male; D008839:Microelectrodes; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride / Q000494:pharmacology*; D013003:Somatosensory Cortex / Q000187:drug effects / Q000502:physiology*; D013268:Stimulation, Chemical; D013649:Taste / Q000502:physiology*
D012965:Sodium Chloride; D006851:Hydrochloric Acid