Role of biophysical specialization in cholinergic modulation in neurons of the ventral cochlear nuclei.
In contacting arrays of different types of neurons whose axons have differing targets in the brain stem, the auditory pathway is subdivided into parallel ascending pathways, each of which carries a different type of information. Several distinct arrays of neurons in the ventral cochlear nuclei have anatomical and biophysical specializations which enable them to extract differing facets of acoustic information and to convey it up the auditory pathway. T stellate cells have higher input resistances and have lower firing thresholds than bushy or octopus cells, enabling their firing to be modulated by small currents. Cholinergic currents, driven by neurons in the ventral nucleus of the trapezoid body that are likely to include medial olivocochlear efferents, excite T stellate cells, but have subtle effects on the firing of bushy cells, and have no detectable influence on octopus cells and D stellate cells. We suggest that cholinergic excitation of T stellate cells contributes toward shifting their acoustic dynamic ranges and increasing the encoding of spectral peaks in noisy conditions and in awake animals.
Oertel
D
D
Department of Physiology, University of Wisconsin, 1300 University Avenue, Madison, WI 53706, USA. oertel@physiology.wisc.edu
Fujino
K
K
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001306:Auditory Pathways / Q000187:drug effects; D055592:Biophysical Phenomena; D001703:Biophysics; D002217:Carbachol / Q000494:pharmacology*; D018679:Cholinergic Agonists / Q000494:pharmacology*; D003056:Cochlear Nerve / Q000502:physiology; D017626:Cochlear Nucleus / Q000187:drug effects*; D007473:Ion Channels / Q000187:drug effects; D009415:Nerve Net / Q000187:drug effects; D009474:Neurons / Q000187:drug effects; D017729:Presynaptic Terminals / Q000187:drug effects; D011976:Receptors, Muscarinic / Q000187:drug effects; D011978:Receptors, Nicotinic / Q000187:drug effects
D018679:Cholinergic Agonists; D007473:Ion Channels; D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D002217:Carbachol; D000109:Acetylcholine