title: Taste intensity modulates effective connectivity from the insular cortex to the thalamus in humans.
abstract: Evaluation of taste intensity is one of the most important perceptual abilities in our daily life. In contrast with extensive research findings regarding the spatial representation of taste in the insula and thalamus, little is known about how the thalamus and insula communicate and reciprocally influence their activities for processing taste intensity. To examine this neurophysiological relationship, we investigated the modulatory effect of intensity of saltiness on connections in the network processing taste signals in the human brain. These "effective connectivity" relationships refer to the neurophysiological influence (including direction and strength of influence) of one brain region on another. Healthy adults (N=34), including 17 males and 17 females (mean age=21.3years, SD=2.4; mean body mass index (BMI)=20.2kg/m(2), SD=2.1) underwent functional magnetic resonance imaging as they tasted three concentrations of sodium chloride solutions. By effective connectivity analysis with dynamic causal modeling, we show that taste intensity enhances top-down signal transmission from the insular cortex to the thalamus. These results are the first to demonstrate the modulatory effect of taste intensity on the taste network in the human brain.
authors.affiliation: Oral Diagnosis & Polyclinics, Faculty of Dentistry, University of Hong Kong, Hong Kong. Electronic address: ndyeung@hku.hk.
authors.forename: Andy Wai Kan
authors.initials: AW
authors.lastname: Yeung
authors.affiliation: Department of Psychology, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan. Electronic address: htanabe@lit.nagoya-u.ac.jp.
authors.forename: Hiroki C
authors.initials: HC
authors.lastname: Tanabe
authors.affiliation: Oral Diagnosis & Polyclinics, Faculty of Dentistry, University of Hong Kong, Hong Kong; Department of Oral and Maxillofacial Radiology, Tokyo Dental College, 2-9-18, Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan.
authors.forename: Justin Long Kiu
authors.initials: JL
authors.lastname: Suen
authors.affiliation: Oral Diagnosis & Polyclinics, Faculty of Dentistry, University of Hong Kong, Hong Kong; Department of Oral and Maxillofacial Radiology, Tokyo Dental College, 2-9-18, Misakicho, Chiyoda-ku, Tokyo 101-0061, Japan. Electronic address: tkgoto@tdc.ac.jp.
authors.forename: Tazuko K
authors.initials: TK
authors.lastname: Goto
mesh_terms: D000284:Administration, Oral; D002540:Cerebral Cortex / Q000502:physiology*; D063132:Connectome / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology*; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D012965:Sodium Chloride / Q000008:administration & dosage*; D013649:Taste / Q000187:drug effects / Q000502:physiology*; D055697:Taste Perception / Q000187:drug effects / Q000502:physiology*; D013788:Thalamus / Q000187:drug effects / Q000502:physiology*; D055815:Young Adult
chemical_list: D012965:Sodium Chloride
keywords: Dynamic causal modeling; Functional magnetic resonance imaging; Insular cortex; Sodium chloride; Taste intensity; Thalamus