Neurophysiology

Abstract

Sensory systems process information that causes either a sensation or a perception of an event within the body or of the outside world. In sensory transduction a sensory receptor converts one form of energy into an electrical signal, eg, a neuronal action potential. Each receptor is most sensitive to one particular form of energy; this is called its adequate stimulus. Sensory receptors can be specialized endings of sensory (or afferent) neurons, such as mechanoreceptors like Pacinian corpuscles, or separate cells adjacent to sensory neurons, such as vestibular hair cells or photoreceptors. Separate cells produce receptor potentials that release chemical transmitter onto an adjacent nerve terminal of afferent neurons. Generator potentials occur in the specialized or unspecialized ending of the primary afferent neuron itself. Both types of graded potentials trigger action potentials in an adjacent nerve membrane via local circuit currents. Sensory information is transmitted by action potentials over long distances to the central nervous system.