Single retinal ganglion cell evokes the activation of L-type Ca(2+)-mediated slow inward current in frog tectal pear-shaped neurons.
The dendrites of neurons from many regions of the nervous system contain voltage-sensitive channels that generate persistent inward currents. We have recently suggested that a slow negative wave (sNW), extracellularly observed in the frog tectum during the burst discharge of a single retinal ganglion cell, can be generated as a result of the persistent inward current in dendrites of tectal pear-shaped neurons. The aim of this study is to substantiate this hypothesis by simulation using a quasi-reconstructed pear-shaped neuron with bistable dendrites and experimental investigation of the sNW. In the experiments, the discharge of a single retinal ganglion cell was elicited by an electrical stimulation of the retina. The evoked electrical activity of the tectum was recorded using a carbon-fiber microelectrode inserted into tectum layer F. We found the following: (1) Slow inward current or plateau potential in bistable dendrites is reflected in the extracellular space as a sNW. (2) The sNW evoked by the burst discharge of a single retinal ganglion cell projecting to frog tectum layer F is generated by the activation of L-type calcium channels in the dendrites of pear-shaped neurons. (3) A few pear-shaped neurons may be suprathresholdly excited during the development of the sNW.
Baginskas
Armantas
A
Laboratory of Neurophysiology, Institute for Biomedical Research, Kaunas University of Medicine, Eiveniu 4, Kaunas LT 50009, Lithuania.
Kuras
Antanas
A
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D001001:Anura / Q000033:anatomy & histology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008959:Models, Neurological; D009474:Neurons / Q000145:classification / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D012165:Retinal Ganglion Cells / Q000502:physiology*; D013477:Superior Colliculi / Q000166:cytology*
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D009543:Nifedipine