Taste and SmellGustatory / Olfactory pathways Daniel Vela-Duarte, MD Department of Neurology Loyola University Medical Center July 2012
Smell. Its a warning system to identify potentially toxic food or noxious chemicals. Contributes to various life qualities, provides awareness of many pleasurable sensations, including appreciationof certain foods and beverages and other pleasures.
Olfactory impulses reach the cerebral cortex without relay through the thalamus. Olfaction is unique among sensory systems. From the prepiriform cortex fibers project to the neighboring entorhinal cortex and the medial dorsal nucleus of the thalamus. The amygdaloid nuclei connect with the hypothalamus and septal nuclei.
Clinical Manifestations ofOlfactory Lesions Quantitative abnormalities: loss or reduction of the sense of smell (anosmia, hyposmia) or, rarely, increased olfactory acuity (hyperosmia) Qualitative abnormalities: distortions or illusions of smell (dysosmia or parosmia) Olfactory hallucinations and delusions caused by temporal lobe disorders or psychiatric disease Higher-order loss of olfactory discrimination (olfactory agnosia)
Clinical presentation Bilateral anosmia is a common complaint, and the patient is usually convinced that the sense of taste has been lost as well (ageusia). Parosmia may also be a troublesome symptom in middle-aged and elderly persons with a depressive illness, who may report that every article of food has an extremely unpleasant odor (cacosmia). Sensations of disagreeable taste are often associated cacogeusia).
Differential diagnosisAdams and Victors Principles of Neurology. 9th Ed.
Taste Older notions of a “tongue map,” which implied the existence of specific areas subserving one or another taste, are incorrect. Any one taste bud is capable of responding to a number of sapid substances, but it is always preferentially sensitive to one type of stimulus.