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Hippocampal neuronal responses during signaled licking of gustatory stimuli in different contexts
Author(s) -
Ho Anh Son,
Hori Etsuro,
Thi Nguyen Phuong Hong,
Urakawa Susumu,
Kondoh Takashi,
Torii Kunio,
Ono Taketoshi,
Nishijo Hisao
Publication year - 2011
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.20766
Subject(s) - licking , taste , umami , neuroscience , chemistry , hippocampal formation , sensory system , psychology , medicine
Abstract Neuroanatomical studies suggest that hippocampal formation (HF) receives information from all sensory modalities including taste via the parahippocampal cortices. To date, however, no neurophysiological study has reported that HF neurons encode taste information. In the present study, we recorded CA1 HF neurons from freely behaving rats during performance of a visually‐guided licking task in two different triangular chambers. When a cue lamp came on, the rats were required to press a bar to trigger a tube to protrude into the chambers for 3 s. During this period, the rats could lick one of six sapid solutions: [0.1M NaCl (salty), 0.3M sucrose (sweet), 0.01M citric acid (sour), 0.0001M quinine HCl (bitter), 0.01M monosodium L ‐glutamate (MSG, umami), and a mixture of MSG and 0.001M disodium‐5′‐inosinate (IMP) (MSG+IMP)], and distilled water. Of a total 285 pyramidal and interneurons, the activity of 173 was correlated with at least one of the events in the task—illumination of cue lamps, bar pressing, or licking the solution. Of these, 137 neurons responded during licking, and responses of 62 of these cells were greater to sapid solutions than to water (taste neurons). Multivariate analyses of the taste neurons suggested that, in the HF, taste quality might be encoded based on hedonic value. Furthermore, the activity of most taste neurons was chamber‐specific. These results implicate the HF in guiding appetitive behaviors such as conditioned place preference. © 2010 Wiley‐Liss, Inc.