Cerebral processing of umami: A pilot study on the effects of familiarity.
OBJECTIVE
The identification of umami taste among people is extremely variable. Based on functional magnetic resonance imaging (fMRI) the aim of this study was to investigate changes of brain activation in participants before and after they were familiarized with this peculiar taste.


METHODS
A total of 10 healthy, right-handed subjects (7 women, mean age 25 years) participated in this study. A computer-controlled gustometer was used to deliver the umami stimuli at supra-threshold concentrations. After the first session of fMRI experiments, participants went through two weeks of controlled exposure to umami taste, before the second session of fMRI experimentation.


RESULTS
Results from psychophysical assessment showed that umami became more familiar (p < 0.001) among the participants after the gustatory exposure. No significant differences for pleasantness and intensity were observed before and after umami training. FMRI data showed that a broader central-nervous network was activated before "umami training" as compared to imaging after "umami training". Significant activation was found in the primary and high level sensory specific gustatory area (insula and anterior cingulate cortex) before training, whereas, significant activation was observed in memory retrieval areas (parahippocampal gyrus) after training.


CONCLUSIONS
The main finding of the present study suggests that repeated exposure to umami taste over a relatively short period of time does not produce an increased response at the level of taste primary and secondary areas, but that increased familiarity with umami leads to an increased activation of the parahippocampal gyrus.
Smell and Taste Clinic, Department of Otorhinolaryngology, Dresden, Germany; Clinic for Adult Oral Health Care, Faculty of Dentistry, University of Oslo, Oslo, Norway.
P Bano
PB
Singh
Smell and Taste Clinic, Department of Otorhinolaryngology, Dresden, Germany. Electronic address: thummel@mail.zih.tu-dresden.de.
Thomas
T
Hummel
Department of Neuroradiology, TU Dresden, Dresden, Germany.
Johannes C
JC
Gerber
Department of Otorhinolaryngology, University of Geneva, Geneva, Switzerland.
Basile N
BN
Landis
Smell and Taste Clinic, Department of Otorhinolaryngology, Dresden, Germany.
Emilia
E
Iannilli
D000328:Adult; D002531:Cerebellum / Q000098:blood supply / Q000502:physiology*; D004192:Discrimination, Psychological / Q000187:drug effects; D005260:Female; D005421:Flavoring Agents / Q000494:pharmacology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010865:Pilot Projects; D011601:Psychophysics; D021641:Recognition, Psychology / Q000502:physiology*; D012970:Sodium Glutamate / Q000494:pharmacology*; D013395:Sucrose / Q000008:administration & dosage; D013549:Sweetening Agents / Q000008:administration & dosage; D013649:Taste / Q000187:drug effects* / Q000502:physiology*; D055697:Taste Perception / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
D005421:Flavoring Agents; D013549:Sweetening Agents; D013395:Sucrose; D010100:Oxygen; D012970:Sodium Glutamate
Familiarization; Functional neuroimaging; Human brain; Learning; Memory; Umami