Phantom taste

Abstract: Purpose: Our goal was to demonstrate the appearance of phantom tastes and smells (phantageusia and phantosmia, respectively) by use of functional MRI (fMRI) of the brain and to demonstrate the efficacy of drug treatment that inhibited both the subjective presence of these phantoms and the fMRI brain activation initiated by these phantoms. Method: Multislice FLASH MR or echo planar MR brain scans were obtained in two patients with phantageusia and phantosmia in response to memory of two tastants (salt and sweet); memory of two odors (banana and peppermint); actual smell of amyl acetate, menthone, and pyridine; and memory of phantom tastes and smells before and after treatment with thioridazine and haloperidol. Activation images were derived using correlation analysis, and ratios of brain area activated to total brain area were obtained. Results: Prior to treatment, both patients experienced persistent birhinal and global oral obnoxious tastes and smells in the absence of any external stimulus. The fMRI response to memory of phantoms was activation in sensory-specific brain regions for taste and smell, respectively, fMRI activation was greater than for memory of any tastant or odorant or for actual smell of any odor. After treatment with thioridazine or haloperidol, which successfully inhibited each phantom in each patient, fMRI response to phantom memory was significantly inhibited and was significantly lower than for memory of any tastant or odorant or actual smell of any odorant. Conclusion: These results demonstrate that (a) phantom taste and smell can be revealed by fMRI brain activation, (b) brain activation in response to taste and smell phantoms is localized in sensory-specific brain regions for taste and smell, respectively, (c) brain activation in response to memory of each phantom initiated the greatest degree of activation we had previously measured, and (d) treatment with thioridazine or haloperidol inhibited both the presence of each phantom and its associated fMRI brain activation. This is the first study in which phantom tastes and smells have been demonstrated by an objective technique and treatment that inhibited the phantoms was characterized by objective inhibition of fMRI activation. These two patients represent a relatively common group that may be classified as having primary phantageusia and phantosmia distinct from those with phantoms or auras secondary to neurological, migrainous, psychiatric, or other causes.

Abstract: Objective/Hypothesis: Tonsillectomy is among the most commonly performed procedures. As with any surgery, head and neck surgeons must be aware of possible complications and their potential affects. At our smell and taste center, we have been referred several patients in a 6-month period with the complaint of taste distortion after tonsillectomy. We report in this article a patient that complains of taste distortion after a right tonsillectomy for unilateral tonsillar hypertrophy. Study Design: A prospective study documenting taste distortion after tonsillectomy using clinical, subjective, and objective evaluation. Methods: The clinical course of a patient with taste distortion after a tonsillectomy is described. The gustatory function was investigated by conducting electrogustometry and spatial taste testing. Threshold measurements were determined at three left- and three right-side tongue regions: 1) the tongue tip region (innervated by the chorda tympani branch of the facial nerve), 2) the lateral margin of the tongue (anterior to the foliate papillae), and 3) the posterior tongue region (innervated by the lingual branch of the glossopharyngeal nerve). Results: After a complete clinical evaluation and taste testing, it was found that the patient suffered an injury to the right lingual branch of the glossopharyngeal nerve. The close anatomic relationship between the palatine tonsil and lingual branch of the glossopharyngeal nerve makes the nerve vulnerable during tonsillectomy. This injury has caused the patient to suffer ageusia to the right posterior one third of the tongue, compensated by a contralateral phantogeusia (phantom taste) with clinical dysgeusia. The phantogeusia was abolished by application of anesthetic to the area where the phantom was perceived. We propose that the phantogeusia is the result of release-of-inhibition in the contralateral glossopharyngeal nerve. Conclusion: Taste distortion (including, phantogeusia and dysgeusia) after tonsillectomy is rarely reported as a complication but has a significant impact on quality of life. This article examines the taste distortion presence as a complication after tonsillectomy to make head and neck surgeons aware of this serious complication and the pathophysiology of taste distortion.

Abstract: The oral sensation of metallic is a complex experience. Much of our current understanding of metallic sensation is from the investigation of metal salts, which elicit diverse sensations, including taste, smell, and chemesthetic sensations, and therefore meet the definition of a flavor rather than a taste. Due to the involvement of multiple chemosensory systems, it can be challenging to define and characterize metallic sensation. Here, we provide a comprehensive review of the psychophysical studies quantifying and characterizing metallic sensation, focusing on metal salts. We examine the factors that impact perception, including anion complex, concentration, nasal occlusion, and pH. In addition, we summarize the receptors thought to be involved in the perception of metallic sensation (i.e., TRPV1, T1R3, TRPA1, and T2R7) either as a result of in vitro assays or from studies in knock-out mice. By enhancing our scientific understanding of metallic sensation and its transduction pathways, it has the potential to improve food and pharmaceuticals, help identify suppression or masking strategies, and improve the ability to characterize individual differences in metallic sensation. It also has the potential to translate to clinical populations by addressing the disparities in knowledge and treatment options for individuals suffering from metallic taste disorder (i.e., phantom taste or "metal mouth"). Future psychophysical studies investigating the sensory perception of metal salts should include a range of compounds and diverse food matrices, coupled with modern sensory methods, which will help to provide a more comprehensive understanding of metallic sensation.

Abstract: This chapter presents a new taste device for digital taste communication called ‘Thermal Taste Interface’. It produces thermal taste sensations on the tongue purely by modifying the temperature of the surface of the tongue (from 25 to 40 °C while heating and 25 to 10 °C while cooling) within a short period of time. Our results suggested that rapidly heating the tongue produces sweetness, fatty/oiliness, electric taste, warmness, and reduces the sensibility for metallic taste. Similarly, cooling the tongue produced mint taste, pleasantness, and coldness. By conducting another study on the perceived sweetness for sucrose solutions after the thermal stimulation, we found that heating the tongue significantly enhances the intensity of sweetness for both thermal tasters and non-thermal tasters. Also, we found that faster temperature rises on the tongue produce more intense sweet sensations for thermal tasters. This device offers easy customization options such as rapid heating and cooling, different stimulation speeds, extended temperature range (from 4 to 100 °C), and ability to integrate and control using a software. The sections below discuss the development, technical evaluation, user evaluations, and future work of this device. We believe this technology may can the user experiences related to thermal taste in different disciplines including Human-Computer Interaction, New Media Arts, Communication and Medicine.