The cerebellar norepinephrine system: inhibition, modulation, and gating.
A series of studies has been conducted to determine the mode of action on the cerebellar cortical circuitry of the norepinephrine (NE)-containing afferents from the locus coeruleus. NE has been known to exert an "inhibitory" action on the background firing observed in Purkinje cells, due presumably to a shift in conductances favoring hyperpolarization. An additional independent action at low threshold appears to be an enhancement of GABA, the inhibitory transmitter of cerebellar interneurons. Recent whole-cell patch-clamp studies on isolated Purkinje cells indicate that exposure to NE increases the chloride current caused by transient pulses of GABA applied iontophoretically. NE applied to Purkinje cells in the parafloccular lobule during stimulation by moving visual patterns revealed the capacity either to "gate" signals initially not expressed, or to amplify the gain of phasic excitations. The control of emergent circuit functions may be the functional consequence of the multiple modulatory functions of NE.
Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas.
D J
DJ
Woodward
H C
HC
Moises
B D
BD
Waterhouse
H H
HH
Yeh
J E
JE
Cheun
D000200:Action Potentials; D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D002531:Cerebellum / Q000502:physiology*; D002712:Chlorides / Q000502:physiology; D000242:Cyclic AMP / Q000502:physiology; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D015640:Ion Channel Gating / Q000502:physiology*; D007478:Iontophoresis / Q000379:methods; D008125:Locus Coeruleus / Q000502:physiology*; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology*; D010775:Photic Stimulation; D011689:Purkinje Cells / Q000502:physiology; D051381:Rats; D015290:Second Messenger Systems; D009435:Synaptic Transmission; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D002712:Chlorides; D005971:Glutamates; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D000242:Cyclic AMP; D009638:Norepinephrine