unchanging stimuli. – But when continuous stimuli stop, there is also a
What Are the Basic Sensory Processes?
•No neurons beyond the sensory organs respond directly to events in the
•A neuron in the brain doesn’t respond to the outside world, but
responds to its input from other neurons.
In Gustation (sense of taste), Taste Buds Are Chemical Detectors
•Sense of taste’s job – keep poison out of our bodies, while allowing good
•Stimuli for taste – chemical substances from food that dissolve in
•Taste receptors are part of the taste bud - some people have 500,
where others have 10,000
oEach taste bud has about 50 receptor cells. Microvilli – hair like
structures at the tip of each taste bud, (come into direct contact
with saliva) - when stimulated they send electrical signals to a
brainstem region, called the medulla and from there to the
thalamus and cortex, which ultimately produces the experience
•Primary four flavors - salty, sweet, sour and bitter. – Different taste
buds are spread throughout the whole mouth uniformly.
•Textures affect sensory experience, as to extent to which food causes
discomfort. The entire taste experience occurs in your brain, not your
•Supertasters are people who experience intense taste. – 6 x as many
taste buds as normal tasters.
In Smell (olfaction), The Nasal Cavity Gathers Particles of Odor
•Most direct route to the brain.
•We smell when odorous particles pass into our nose and the upper and
back portions of the nasal cavity. – There they come into contact with
the olfactory epithelium > thin layer of tissue embedded with olfactory
receptors – the particles dissolve in the solution that surrounds the
epithelium and causes a reaction that triggers chemical receptors.
•These nerve impulses convey information to the olfactory bulb (the
brain center for smell, just below the frontal lobe)
•Smell signals go directly to other brain areas, initially bypassing the
thalamus. –Regions in the prefrontal cortex process information about
whether the smell is pleasant, or aversive, the intensity of small is
processed in the amygdala.