Figure 2. The application of the new electrodes was performed with a conventional conductive and adhesive paste Grass, EC2. The skin-electrode impedance was below 2 kOhm. Simultaneous online digital highpass and lowpass filters -—1 kHz were applied to isolate the high-frequency bursts. During the experiments the subjects were in a comfortable position on a bed in our laboratory.
During continuous stimulation and recording of SEPs and Hz oscillations the subjects were instructed to close their eyes and relax throughout the recording session.
After a ten-minute resting period trials of electrical stimulation were averaged control phase a. Hegu LI-4 : On the dorsum of the hand, between the 1st and 2nd metacarpal bones, in the middle of the 2nd metacarpal bone on the radial side.
The points were punctured perpendicularly after local disinfection of the skin with sterile single use needles 25 x 0. Immediately after inserting the needles the next SEPHz-recording phase b , and two minutes after starting acupuncture the next control measurement were performed phase c.
Five minutes after inserting the needles a manual stimulation of the needle was performed phase d. The stimulation consisted of a combination of rotating and thrusting movements.
A tonifying method was used. The last two recordings were made 15 minutes after inserting the needles phase e and two minutes after removing the acupuncture needles phase f. In addition in one person age 22 years, female a placebo measurement using identical conditions but without inserting the needles in the skin was performed.
Figure 2 shows a typical example of SEPs and Hz brain oscillations in a year-old healthy volunteer. Figure 3 Fig. Note the different digital filters and the different amplitudes in the responses. Figure 3 shows the decrease of amplitudes in Ncomponents and in Hz oscillations after acupuncture at acupoint LI In addition Fig.
There was no change in amplitude or latency after placebo simulated needling. Figure 4 Fig. Note there was no decrease in amplitudes after performing placebo acupuncture.
Figure 5 Fig. Note the significant decrease in Hz amplitude immediately after b and during acupuncture stimulation d in 14 healthy volunteers. The registration of SEPs is a neurophysiologic method which is used increasingly in comatose patients and in intraoperative monitoring. Normal values are necessary to interpret clinical data.
The generation of SEPs has been explored extensively. However, few studies have been performed for the Hz bursts 6 , 7 , 8 , 9 , EEG, magnetoencephalography and electrocorticography recordings have established that the SEP-N20 component is generated by excitatory postsynaptic potentials in area 3b pyramidal cells whereas several source sites for the high-frequency oscillations have been discussed, such as thalamus, thalamocortical fibers or postsynaptic activities in the sensorimotor primary cortex 7.
Although acupuncture has a long history, the mechanisms underlying its effects are still unclear in detail. The neuromonitoring method of SEPs has been adopted in the scientific research of acupuncture since the s 2,3, 11 , 12 , The effects of acupuncture on conventional SEPs are controversial Since the conventional SEP is mediated mainly by fast conducting sensory nerve fibers, the methodology, especially for recording short-latency SEP, may be inadequate for studying acupuncture mechanisms In the case of the long-latency cortical SEPs, there is too little data available to judge the effects of acupuncture Kang and Ma11 for example reported that after manual acupuncture at the Neiguan acupoint no significant difference was detected in the early N20 component.
However in one patient with abnormal SEP the latencies were improved after acupuncture, when acupuncture simultaneously decreased pain Chen and Hung2 studied SEPs evoked by electrical stimulation of the median nerve.
Acupuncture was applied to the point Hegu LI-4 at both hand. They found no significant SEP changes in 16 volunteers.
However, in a study published recently, Wei et al. Here, a statistical model and exemplary data are presented reconciling these seemingly contradictory results.
Methods: A statistical model defined the conditions required to detect added-activity in a set of single-trial SEP. Its predictions were tested by analyzing human single-trial scalp SEP recorded with custom-made low-noise amplifiers. Say you flip a light switch 10 times in a minute kids, don't try this at home. Evenly spaced, the light will be on for 6 seconds, then off for 6 seconds.
For the whole minute, it's on for a total of 30 seconds, and off for 30 seconds, right? Something like this:. On average, the total amount of light in the room is 50 percent of what's possible. You have a maximum light on and a minimum light off each half the time. If you increase how often you switch the light, so fast that you no longer see the light turn on and off, instead of a flashing light bulb, the room will just appear dimly lit.
This is, in essence, how a plasma works. As a plasma TV engineer once told me and I mentioned in the refresh article , plasmas create light with time. To create different shades of gray, the pixel is on or off for more often.
Because our TV system is 60Hz or in some places, 50Hz , and each one of those cycles has to be a complete image -- for example 60 images per second or 50 -- a plasma has to switch the subpixels on and off very rapidly.
You could call these, to steal the modern parlance, Hz. Most plasmas now have While not completely accurate, you can sort of think of it as the TV creates 10 dark images that your brain combines into one, full-brightness, image, 60 times a second. Bottom line As we discussed in "What is refresh rate? Plasmas, by how they work, don't have an issue with motion blur.
The Hz claim by all the current plasma TV manufacturers has to do with how the TVs create an image, but is not images per second. So yes, Hz is a marketing term. However, because plasmas don't require faster refresh rates to produce a clear, sharp image, and this is technically how they work, it's fair to give Panasonic, LG, and Samsung a pass
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