Biomedical Engineering Reference
In-Depth Information
d
n
4
t
3
n
g
|
7
Figure 3.20
MEA retinasensor. (A) An explanted retina is placed on an MEA with the
ganglion cell side (RPE, retinal pigment epithelium; PR, photoreceptor;
IN, interneurons; GC, ganglion cells). The light stimulus is projected
through the transparent MEA and retina onto the photoreceptors.
Ganglion cell activity and retinal field potentials (microERG) are recorded
by the substrate-integrated microelectrodes (*). (B) View through an
MEA on a retinal segment (white arrow) from a chicken retina. The
broken line marks the border of the pigment epithelium. (C) microERG
with a-, b-, c- and d-wave of a chicken retina, evoked by full-field white
light, impulse duration 500 ms, 0.5Hz. Grey curve denotes a single sweep,
0.5 Hz to 2.8 kHz, the black line five sweeps averaged, filtered 0.5-100 Hz.
(D) Spike activity (insert), extracted from the grey curve shown in (C) by
off-line filtering at 200Hz to 2.8 kHz. The spikes were extinguished
by 100 mM TTX. (E) Drug action on a light-evoked microERG.
2-Aminophosphonobutyric acid (AP4), a blocker of the on-signal pathway
in the retina, resulted in the disappearance of the b-wave (*) that mainly
reflects retinal Muller cell and bipolar cell activity. B-wave amplitude is
restored after washing out the drug. Light pulses 500ms, 0.5Hz.
74
(Reprinted by kind permission of Springer.)
n
3
.
form, the MEA retina sensor is suitable for drug testing over several hours,
depending on the reversibility of tested drug effects, but long-term monitoring
of drug effects is also possible.
References
1. P. L. Nunez and R. Srinivasan, Electric Fields of the Brain: The Neuro-
physics of EEG, 2nd ed., Oxford University Press, Oxford, 2006.
2. G. R. Holt and C. Koch, J. Comput. Neurosci., 1999, 6, 169.
