The lesser palatine sends signals to the nasal cavity; which is why spicy foods cause nasal drip. The zygomatic sends signals to the lacrimal nerve that activate the lacrimal gland; which is the reason that spicy foods can cause tears. Both the lesser palatine and the zygomatic are maxillary nerves (from the trigeminal nerve). The special visceral afferents of the vagus nerve carry taste from the epiglottal region of the tongue. The lingual nerve (trigeminal, not shown in diagram) is deeply interconnected with the chorda tympani in that it provides all other sensory info from the anterior ⅔ of the tongue. This info is processed separately (nearby) in the rostal lateral subdivision of the nucleus of the solitary tract (NST). NST receives input from the amygdala (regulates oculomotor nuclei output), bed nuclei of stria terminalis, hypothalamus, and prefrontal cortex. NST is the topographical map that processes gustatory and sensory (temp, texture, etc.) info.Reticular formation (includes Raphe nuclei responsible for serotonin production) is signaled to release serotonin during and after a meal to suppress appetite. Similarly, salivary nuclei are signaled to decrease saliva secretion. Hypoglossal and thalamic connections aid in oral-related movements. Hypothalamus connections hormonally regulate hunger and the digestive system. Substantia innominata connects the thalamus, temporal lobe, and insula. Edinger-Westphal nucleus reacts to taste stimuli by dilating and constricting the pupils.Spinal ganglion are involved in movement. The frontal operculum is speculated to be the memory and association hub for taste.The insula cortex aids in swallowing and gastric motility.
Other terms for the astringent sensation are "dry", "rough", "harsh" (especially for wine), "tart" (normally referring to sourness), "rubbery", "hard" or "styptic". Metallicness
A metallic taste may be caused by food and drink, certain medicines or amalgam dental fillings. It is generally considered an off flavor when present in food and drink. A metallic taste may be caused by galvanic reactions in the mouth. In the case where it is caused by dental work, the dissimilar metals used may produce a measurable current. Some artificial sweeteners are perceived to have a metallic taste, which is detected by the TRPV1 receptors. Many people consider blood to have a metallic taste. A metallic taste in the mouth is also a symptom of various medical conditions, in which case it may be classified under the symptoms dysgeusia or parageusia, referring to distortions of the sense of taste, and can be caused by medication, including saquinavir, zonisamide, and various kinds of chemotherapy, as well as occupational hazards, such as working with pesticides. Fat taste
Recent research reveals a potential taste receptor called the CD36 receptor. CD36 was targeted as a possible lipid taste receptor because it binds to fat molecules (more specifically, long-chain fatty acids), and it has been localized to taste bud cells (specifically, the circumvallate and foliate papillae).