Firing properties and dye coupling of neurons in the pigeon nucleus semilunaris.
Our previous study indicated that the nucleus semilunaris in birds is a visual center. The present study using pigeon brain slices shows that 84 semilunar cells examined could be grouped into five types according to responses to depolarizing current injections. Type I cells (early bursting, 44%) fire a single burst followed by regular spiking. Type II cells (regular spiking, 13%) regularly produce spikes, the rates of which are enhanced as currents are increased. Type III cells (bursting, 17%) discharge a series of bursts each consisting of 2-4 spikes. Type IV cells (dual spiking, 15%) evoke both spikes and spikelets. Type V cells (inhibition-following, 11%) are characterized by regular spiking followed by an inhibitory period after current cessation. Morphologically, semilunar neurons have piriform, round, or fusiform somata of 12-23 mum in diameter, which give rise to 2-4 primary dendrites with sparse branches. Dual spiking activity is invariably correlated with dye coupling, and bursting cells have a tendency to be fusiform in shape. Other types of semilunar cells do not show a correlation between their firing patterns and morphological features.
Laboratory for Visual Information Processing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.
Zong-Xiang
ZX
Tang
Shu-Rong
SR
Wang
D000818:Animals; D002450:Cell Communication / Q000502:physiology; D010856:Columbidae / Q000033:anatomy & histology* / Q000502:physiology*; D004558:Electric Stimulation; D005074:Evoked Potentials, Visual / Q000502:physiology; D005456:Fluorescent Dyes; D007365:Intercellular Junctions / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology*; D009474:Neurons / Q000145:classification / Q000166:cytology* / Q000502:physiology; D009924:Organ Culture Techniques; D013477:Superior Colliculi / Q000166:cytology* / Q000502:physiology; D014795:Visual Pathways / Q000033:anatomy & histology / Q000502:physiology*
D005456:Fluorescent Dyes