Recording of spontaneous activity with photoetched microelectrode surfaces from mouse spinal neurons in culture.

A matrix of photoetched gold conductors integrated into the floor of a tissue culture chamber has been used to record from mammalian spinal cord neurons grown on the insulation layer of the multielectrode plate. Spontaneous activity has been monitored from tissue microfragments less than 150 micrometers in diameter and from thin sheets of spinal cell aggregates. Maximum spike amplitudes of 360 microV with signal-to-noise ratios of 8:1 have so far been achieved and the spontaneous activity maintained for several days. Recording electrode impedances measured between 4 and 7 M omega at 1 kHz. Conductor tips were deinsulated with laser pulses that formed shallow craters 2 micrometers deep and 12 micrometers in diameter. Addition of colloidal gold or platimum black was not necessary to achieve satisfactory recordings.