Reference Work Entry

Encyclopedia of Neuroscience

pp 3266-3270

Presynaptic Inhibition

  • Jorge N. QuevedoAffiliated withDepartment of Physiology, Biophysics and Neuroscience, Centro de Investigación y de Estudios Avanzados del I.P.N


Decrease of synaptic effectiveness


Presynaptic inhibition (PSI) refers to a decrease of transmitter release at central synapses. Five decades ago, it was reported that activation of afferent fibers originating in flexors led to depression of monosynaptic group Ia excitatory postsynaptic potentials (EPSPs) evoked on extensor motoneurones in the cat spinal cord [1]. This depression occurred with no detectable changes in the time course of monosynaptic EPSPs, membrane potential or motoneurone excitability [1,2]. It is now known that PSI occurs broadly within the central nervous system of both vertebrates and invertebrates, and that synaptic efficacy at axon terminals from sensory afferents, descending systems or interneurones [3] can be subject to an inhibitory control by a number of neurotransmitters and presynaptic receptors [4].


PSI Associated with Primary Afferent Depolarization (PAD)

PAD as a Measure of PSI in the Spinal ...

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