Abstract
Purpose::
The mammalian retina deconstructs the visual world using parallel neural channels, embodied in about a dozen morphological and physiological types of ganglion cells. [1]. Fundamental questions regarding retinal encoding are thus addressed recording many ganglion cells in parallel.
Methods::
Multi electrode array recording. In this technique, many ganglion cells from an isolated retina are simultaneously recorded by an array of extracellular microelectrodes, while visual stimuli are projected onto the photoreceptor layer. Currently, conventional multi-electrode array technology (with up to 512 electrodes) allows for either the sampling of ganglion cell at low spatial resolution (i.e. recording ~20% of the cells in a retinal patch) or for the recording of most cells in a small patch of 0.04 mm2 [2, 3].
Results::
Here we report the recording of ganglion cell activity in the rabbit retina by a multi-transistor-array (MTA) with 16,000 electrodes [4]. The electrodes cover an area of 1 mm2 with the spatial resolution of 7.8 µm. The current sampling rate is 6 kHz and can easily be increased by skipping recording traces of pre-selected electrodes. The mean extracellular signal amplitude for rabbit ganglion cells is ~ 1 mV while the rms noise is 60 µV only.The electrode density of the multi-transistor array is higher than the ganglion cell density in all mammalian retinas. Every spike is picked up simultaneously by several transistors producing for each ganglion cell a unique spatial activity pattern. Our spike sorting approach- the identification of spike trains of individual cells - takes advantage of this unique spatial pattern.
Conclusions::
In summary, our preliminary results show that a high density multi-transistor-array is well suited to record retinal ganglion cell activity at high spatial and temporal resolution over an extended area of 1 mm2 and the time of many hours.References:1. Masland RH (2001) The fundamental plan of the retina. Nat Neurosci. 4:877-86.2. Segev R, Goodhouse J, Puchalla J, Berry MJ, 2nd (2004) Recording spikes from a large fraction of the ganglion cells in a retinal patch. Nat Neurosci 7:1154-1161.3. Zeck GM, Xiao Q, Masland RH (2005) The spatial filtering properties of local edge detectors and brisk-sustained retinal ganglion cells. Eur J Neurosci 22:2016-2026.4. A. Lambacher, M. Jenkner, M. Merz, B. Eversmann, R.A. Kaul, F. Hofmann, R. Thewes and P. Fromherz (2004) Applied Physics 79, 1607-1611
Keywords: retina: proximal (bipolar, amacrine, and ganglion cells) • electrophysiology: non-clinical • receptive fields