taste

stimuli: chemicals dissolved in liquid (saliva)

receptors: taste buds

• located on the papillae (bumps) on the tongue

  • not all papillae have taste buds - center of tongue no buds

• also on top of mouth, cheeks, throat

• replaced every 10 days

four types of papillae, structurally different, but all filiform (center) have taste buds

taste buds have 50-100 receptor cells

each taste cell has microvilli (like dendrites) that stick into taste pore - have receptor sites for chemicals to bind (sweet, bitter, umami) or channels that allow ion to flow in (sour and salt)

more receptors for bitter

Zuker’s lab:

• found using DNA a receptor type that seems dedicated to sour

• not only expressed in mouth but along spinal cord - tasting the CSF?

• sour is acidity, taste receptor could help determine pH of spinal fluid and maintain homeostasis

primary pathway - for identification

• orbital frontal cortex - flavor

• primary gustatory cortex- the insula

secondary pathways

• connections from medulla to hypothalamus (hunger) and amygdala (emotions)

• people w just this show reactions to sour and bitter and is believed to be involved in taste aversion

taste adaptation

• we adapt to tastes

  • taste receptors adapt quickly yo allow new tastes to be experienced - sensory specific satiety

  • brain adaptation a big slower but does not occur - alliesthia

    • can occur to direct stomach stimulation

    • adapting to specific tastes

taste modification

• substances can temporarily change the way taste functions

  • gymnema sylvestre - knocks out ability to taste sweet

  • miracle fruit berries make anything taste sweet

• both thought to affect the way taste receptors fire

flavor processed in orbital frontal cortex

• flavor is comprised of taste (output from the taste receptors) and smell plus other factors (temp, texture, appearance, etc)

• OFC receives input from taste, smell, tactile from mouth, vision, heat/pain from mouth