Transcript The gustatory pathway - West Virginia University

Taste Receptor Cells
Arise from epithelial cells and
are located on taste buds in the
papillae of the tongue
 Detect different taste qualities
each with a unique
chemosensory mechanism
Salty
Sour
Bitter
Sweet
Umami
Innervated by the primary
afferent fibers of cranial nerves
VII, IX, and X
Cranial Nerves
•Taste buds on the anterior
tongue and palate innervated by
the intermediate nerve (VII)
•Posterior tongue and pharynx
innervated by glossopharyngeal
nerve (IX)
•Epiglottis and larynx innervated
by vagus nerve (X)
•The afferent fibers of these
cranial nerves synapse with
many taste cells between
single or multiple taste buds
•Intermediate nerve afferents
enter the brain stem at the
pontomedullary junction
•Glossopharyngeal and vagus
nerve afferents enter the brain
stem in the rostral medulla
Ascending Gustatory
Pathway
The afferent fibers of the cranial
nerves collect in the rostral solitary
nucleus
Axons ascend ipsilaterally in the
central tegmental tract of the brain
stem and terminate in the
parvocellular division of the ventral
posterior medial nucleus of the
thalamus
From the thalamus, neurons project
to the insular cortex, the posterior
limb of the internal capsule, and the
operculum (primary gustatory areas)
The insular cortex projects to the orbitofrontal cortex
Both cortices are part of the limbic system
The limbic system is responsible for the
behavioral and emotional significance of taste
The gustatory cortex is located
completely beneath the cortical surface.
PET scan – Cortical activation after
presentation of 5% sucrose solution
The Gustatory
System is
Complex
•Much about the system is
still unknown
•Labeled Line Model –
suggests that different
tastes have segregated
pathways to the brain
•Across Fiber Theory –
different tastes are
represented by different
activity across a neural
population