Figure 1. Schematic representation of the in vitro embryonic mouse spinal cord preparation used for electrophysiology.

A, dissection procedure. After removing the meninges, the spinal cord is dorsally opened (A1) and positioned in the recording chamber ventral side up allowing direct access to motoneurons. A2, schematic view of coronal section of the opened spinal cord. B, patch-clamp recording of visually identified motoneurons. Partial upper view of the laid down spinal cord (B1). The dashed line indicates the midline (m) with the two symmetric columns of motoneurons, laterally positioned. B2, example of a visually identified motoneuron showing the relative position of puff pipette used to eject pharmacological agents and the patch-clamp pipette. B3, perforated patch clamp recording of a motoneuron. The depolarization is due to pressure ejection of the GABA_AR agonist isoguvacine. d, dorsal zone; m, midline; Mns, motoneuronal column; v, ventral zone.