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The MED64 System will allow you to:
- Study the effects of natural or artificially induced rhythmic slow-wave activity.
- Easily examine rhythmic activity of
brain regions from 64 recording electrodes
- Investigate the mechanisms generating
hippocampal g, b and q rhythms
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Example 1:
Carbachol-Induced Oscillations
A. Carbachol-induced beta waves in the
hippocampus measured with a dense electrode
array (150 µm inter-electrode spacing)
B. Sample of spontaneous responses in the
presence of 50 µm carbachol
C. Fast Fourier transformations display the frequency (x-axis) and amplitude (y-axis) of rhythmic activity
D. Current source density analyses of carbacholinduced
activity. The pseudo-colored panels
show the computed current source density in
the region of the electrode array at several time
points during a carbachol-induced oscillation. The outlines of the pyramidal and granule cell fields and their apical dendrites are overlayed.
At time 0 ms, a sink appears in the apical
dendrites of the border between fields CA3 and
CA1 with a corresponding source in the basal
dendrites. The fields merge and intensify and
then dissipate after ~12 ms. At ~20 ms, a source appears in the apical dendrites with a corresponding sink in the basal dendrites. These
expand and intensify before dissipating at ~40 ms, after which an apical sink reappears to reinitiate the cycle.
K. Shimono et al. Origin and distribution of cholinergically induced beta rhythms in hippocampal slices. J. Neurosci. 15, 8462-8473 (2000)
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Example 2: The study of circadian and other biological rhythms as the cultures grown in the probe
can be tested repeatedly day and night.
 
A. A phase-contrast photomicrograph of a cultured SCN slice on the MED probe after
14 d in culture. (20 µm square micro-electrodes with 100 µm inter-electrode spacing)
Scale bar, 150 µm
B. Representative circadian firing rhythms of SCN neurons from Clock mutant and
wild-type mice in slice cultures.
The firing rhythm was expressed in a histogram of the mean firing rate in 15 min. and
double-plotted. The numbers in the right margin of the first lane in each panel were
the scales of firing rate. The circadian periods of these firing rhythms were 28.1 h (left)
and 28.0 h (right) for Clock/Clock, 25.3 h and 24.5 h for Clock/+, and 23.3 h and
23.8 h for +/+ neurons, respectively.
Nakamura, W. et al. Clock Mutation lengthens the circadian period without damping rhythms in individual SCN
neurons. Nature Neuroscience, 5, 399-400 (2002)
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Example 3: Endogenous Hippocampal Beta Rhythm
Acute slices from adult rat hippocampus were prepared on the MED probe. Infusion of carbachol (50mM), an acetylcholinergic agonist, triggered spontaneous beta waves in pyramidal regions in 41/55 slices.
Current source density analysis indicated that during each cycle (panel numbers refer to time during the 42 ms cycle) a sink appeared in field CA3 that extended to CA1 (0-9ms) where it subsided (15ms). This was followed by corresponding sources mirroring the sinks of the previous half cycle, in the same regions (21-36ms).
Based on data provided by G. Lynch (1999), UC Irvine.
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