Transcript What are the biological mechanisms associated with taste?

Psychology 304:
Brain and Behaviour
Lecture 30
1
Preventative Medicine
Check us out
on Facebook!
Wednesday, November 28th, 2012 5:30-7:30pm at Mahoney and Sons
What we do:
This month’s topic
questions:
• Discuss important issues that • Does non-western medicine
affect health care and society
place a greater emphasis on
preventative medicine?
• Apply the social determinants
of health
• Could genetic testing help in
preventing diseases such as
• Meet students from different
high blood pressure or
disciplines!
diabetes?
• Free Food!
• What should MSP cover?
Please note that there is only space for 25 students – so come on time!
The Vestibular System and Chemical Senses
1. What are the biological mechanisms associated with
vestibular perception? (continued)
2. What are the biological mechanisms associated with
taste?
3
By the end of today’s class, you should be able to:
1. review the pathway by which vestibular information is
transmitted from receptors to the brain.
2. describe the vestibulo-ocular reflex.
4
3. describe the structural and functional features of the
receptor organs of the gustatory system.
4. review the pathway by which gustatory information is
transmitted from receptors to the brain.
5. identify the locations of the primary cortex and
secondary cortex for the gustatory system.
5
What are the biological mechanisms associated with
vestibular perception?
• When hair cells in the semicircular canals and vestibular
sacs are stimulated, action potentials are triggered that
pass down axons of the vestibular nerve—a branch of
cranial nerve VIII.
• Vestibular information is relayed from the vestibular
nerve to the vestibular nuclei in the medulla and the
cerebellum. The vestibular nuclei relay the information to
the pons, the thalamus, the motor nuclei of the eye
muscles, and the temporal cortex.
6
TVOR Loop: Vestibulo-Ocular
Reflex Loop
VN: Vestibular nuclei
MN: Motor neurons associated
with the oculomotor, trochlear,
and abducens cranial nerves.
Vestibulo-Ocular Reflex
7
What are the biological mechanisms associated with
taste?
• The function of taste (i.e., the gustatory system) is to
monitor the chemical content of the environment by. The
gustatory system detects chemicals that dissolve in
saliva in the oral cavity.
• The receptors for taste are found on the tongue and in
parts of the oral cavity.
8
• The surface of the tongue is characterized by papillae,
each of which contains numerous taste buds.
• Each taste bud contains 50-150 receptor cells which
extend cilia through a taste pore on the surface of the
taste bud.
9
Cilia
Papillae, Taste Buds, Taste Receptor Cells, and Cilia
10
Papillae and Taste Buds
11
• Tastants stimulate receptor molecules on the surface of
the cilia.
• Each receptor cell detects 1 of 5 tastes: sweet, salty,
sour, bitter, and umami.
• When the receptor cells are stimulated by tastants,
action potentials are triggered that pass down axons of
the facial (front of tongue), glossopharyngeal (back of
tongue) and vagus (back of oral cavity) nerves—cranial
nerves VII, IX, and X, respectively.
12
• Taste information is relayed from the cranial nerves to
the solitary nuclei of the medulla and the ventral posterior
(medial) nuclei of the thalamus.
• The majority of thalamic neurons that receive taste
information subsequently project the information to
the primary gustatory cortex in the somatosensory
cortex. Thereafter, information is projected to the
secondary gustatory cortex in the lateral fissure.
13
Pathway of the Gustatory System
14
• Research suggests that there are individual differences
in taste sensitivity:
Nontasters: 96 papillae per cm2
Medium tasters: 184 papillae per cm2
Supertasters: 425 papillae per cm2
15
The Vestibular System and Chemical Senses
1. What are the biological mechanisms associated with
vestibular perception? (continued)
2. What are the biological mechanisms associated with
taste?
16