Electrical coupling between horizontal cell bodies in the tiger salamander retina

Area of Science:

• Neuroscience
• Retinal Physiology
• Cellular Electrophysiology

Background:

• Horizontal cells are crucial for lateral signal integration in the vertebrate retina.
• Understanding their synaptic transmission is key to comprehending retinal network function.

Purpose of the Study:

• To investigate the mode of synaptic transmission between horizontal cells in the tiger salamander retina.
• To determine if transmission is chemical or electrical.

Main Methods:

• Electrophysiological recordings from visually identified pairs of horizontal cells in vitro.
• Current injection and voltage response measurements to assess cell-to-cell coupling.
• Fluorescent dye injection to trace cell connectivity.

Main Results:

• Electrical coupling between horizontal cells was observed and remained intact under various conditions, including light stimulation and presence of cobalt or acetylcholine.
• Fluorescent dye successfully migrated between connected horizontal cells.
• Apparent coupling increased with light response and in the presence of certain chemicals, explained by changes in input resistance.

Conclusions:

• Synaptic transmission between horizontal cells is primarily mediated by electrotonic conduction, indicating the prevalence of electrical synapses.
• Horizontal cell coupling is robust and functional during retinal processing, contributing to lateral signal spread.