|
Responses to single channel tetanic stimulation (SCTS) on channel 3.
About 15 min after the initial SCTS on channel 54, tetanic stimulation
on channel 3 caused an increase in the spontaneous spike rate.
|
|
| Responses to SCTS on channel 54 monitored on 14 channels. Prior to
tetanic stimulation, spiking activity erupted quasi-periodically across
most of the channels (~23 sec intervals). These episodes represent bursts.
Following tetanic stimulation, the spontaneous periodic spiking was depressed
for over 2 min. |
|
 |
The multi-channel recording environment provides
a wealth of data on the activity of cultured neuronal networks. The 3 figures
show network activity from different segments of an experiment in which
a novel synthesized compound which had been shown to inhibit the enzymatic
cleavage of acetylcholine is applied to a culture grown from dissociated
tissue dissected from embryonic murine frontal cortex. The panels display
multiple simultaneous spike trains of 30 discriminated units, recorded
on 16 channels. The first panel shows a 20-second window of spontaneous
network activity 6 minutes before the initial application of the drug.
The majority of the units are producing single action potentials, with
an occasional burst evident on some units. Panel 2 is shows activity 10
minutes after the concentration of the compound was raised to 50 µM.
The initial 6-8 seconds represents a period of higher-density bursting
and spiking that resolves into a somewhat coordinated pattern of activity
between the majority of units, with very little inter-burst spiking evident,
even on the units that do not burst. The final panel is 40-seconds in length,
and shows the activity 15 minutes after the concentration reaches 100 µM.
The activity is obviously much more coordinated between units. Statistically,
the mean spike rate of the 30 individual units was increased 62% by 100
µM of the drug. However the effect was unit-specific; for example
8a actually decreased spike production, while other units such as 9a increased
their spike rate over 100% and transformed from a predominately spiking
neuron to a predominately bursting one. The constant challenge in a multi-channel
environment is to choose the parameters that most accurately depict the
network behavior. |
 |
 |
|
|
