Smell and Taste

Sinan Canan, PhD sinancanan@gmail.com

Sense of taste

Jan Bruegel – The Sense of Taste - 1618

Sense of taste – Tongue and taste receptors

Papillae

Sour Salty

Sweet

Bitter

•  Apprx. 3000 taste buds •  Types of papillae

•  Filiform (filum: rope) •  Foliate (folio: leaf) •  Fungiform (fungus-shaped) •  Circumvallate (circum-; around + vallum; wall)

Sense of taste – Tongue and taste receptors

Sense of taste – Tongue and taste receptors

•  Taste perception (combination of 5 basic tastes) •  Sweet-sour-salty-bitter + •  Umami and water receptors

•  Umami- receptors of circumvallate papilla sensitive to amino acids (esp. glutamat), small peptides and nucleotides.

•  Water receptors – Esp. in pharynx… •  Large individual variations; in part genetically determined. •  Number of taste buds decrease with age

Taste perception and discrimination

Mechanism

Taste pathways

Taste pathways

VPM

Nuc. Tractus solitarius

Cortical responses to taste stimulations

Sucrose

NaCl

HCl

Quinine sulphate

Sense of smell (Olfaction)

Olfaction

Olfaction

Olfactory pathways

•  Olfaction •  No relay in thalamus... •  Olfactory epithelium – Olfactory bulb – Cortex

(Entorhinal cortex, amygdala, septum, hypothalamus) •  Olfactory discrimination

•  2,000 to 4,000 chemicals can be identified! •  Discrimination based on receptor activation pattern

•  Number of receptors decline with age

Sense of smell

Smell, Behavior and Memory

•  Pheromones •  Bombyx mori – ‘Bombycol’

•  Identification/choice of mate

•  Identification of the offspring

•  Circadian synchrony •  Olfactory memory

•  Direct cortical connections •  Unmyelinated fibres

Smell, Behavior and Memory

Vomeronasal Organ?

Finished...

The mob has many heads, but no brains....