Electrode stimulation

Use of caffeine has also been recommended to lower the threshold in patients who do not experience an adequate seizure (104,105 and 106). One report, however, found that caffeine appeared to produce neuronal damage in rats receiving ECS (107). Because adenosine may have neuroprotective effects, one postulated mechanism is the ability of methyixanthines (e.g., caffeine, theophylline) to block adenosine receptors. On a positive note, studies have not found a difference in cognitive disruption between patients receiving ECT with or without caffeine (108). Although the implications of the animal data for humans are not clear, and because shorter seizures may be effective in some patients, a conservative approach would be to augment with caffeine only when seizure duration is less than 20 seconds and response is inadequate ( 38). Alternatively, it may be appropriate to switch to BILAT electrode placement or from methohexital to etomidate when UND electrode stimulation produces inadequate seizure duration (even at maximal stimulus intensity) and response is insufficient ( 97, 98). 

Many new tools, such as sensors, electrodes, stimulators, and detailed instruction sets of how to use them, are expected to become available in the future. By describing how these tools interact with the underlying neural tissue and modeling this performance, the instruction set allows us to predict how the tools will perform in various situations. Sensors that detect physical movement, pressure, or electrical activity may be used for control or feedback. 

The increase in DA concentration from nanomolar level in extracellular fluid can be provoked by implanting electrodes in the vicinity of axons. Then the concentration changes of DA are measurable by fast cyclic voltammetry. These electrodes stimulate the action potentials. Voltammetric sensors can then be used for monitoring the evoked release of dopamine. The experiment is demonstrated in Fig. 48. When the stimulus is initiated a chemical change is detected within 100 ms. The observed concentration of DA, which is a function of stimulus frequency (60 Hz has been applied), rapidly increases during the stimulation and returns to the baseline once the stimulation ceases. It is evident that a subsecond time resolution is required to observe these events. Further quantitative in vivo measurements are required so that models of the dynamics of this process can be tested [172]. 

Fe(III)-de novo protein/NR, or Fe(III)-de novo protein/Co(II)-reconstituted Mb were cross-linked with glutaric dialdehyde to yield electrically contacted electrocatalytic electrodes. The Fe(III)-de novo protein/NR-electrode assembly was applied for the electrocatalyzed reduction of N03 to N02 and acted as an amperometric NOs" sensor (Fig. 26b), and the Fe(III)-de novo protein/Co(II)-reconstituted Mb integrated electrode stimulated the electrocatalyzed hydrogenation of acetylene dicarboxyhc acid to malic acid. 

Gotman I (1997) Characteristics of metals used in implants. J Endourol 11(6) 383-389 Guyton DL, Hambrecht FT (1973) Capacitor electrode stimulates nerve or muscle without oxidation-reduction reactions. Science 181 74-76... 

The same experimental procedure was repeated with the 9-electrode array configuration. It was also introduced into the synthetic media bath from the bottom. In this case, stimulation was done on each of the 9 electrodes individually, followed by simultaueous stimulation of multiple electrodes in predetermined patterns. For a set of 9 electrodes, analysis of all possible combinations of single and multiple electrode stimulation reveals that the maximum number of patterns is 511. In these experiments, not all 511 patterns were stimulated. A few selected combinations were chosen that were representations of the complex patterns. The characterization of the 9-electrode analog was performed 20 p m above the surfaces of the electrode. 

Fig. 16 Three-dimensional model of the experimental single-electrode analog setup without a probe electrode. Stimulating electrode (left) has a Pt conductor surrounded by glass for insulation. The counter electrode (right) includes a horizontal conducting wire and an insulation support. A section of the glass cladding of the stimulating electrode has been removed to show the inner Pt wire...

Arfin, S.K., and R. Sarpeshkar. 2011. An energy-efficient, adiabatic electrode stimulator with inductive energy recycling and feedback current regulation. IEEE Transactions on Biomedical Circuits and Systems. In press. 

Sit, J.-J., and R. Saipeshkar. 2007. A low-power, blocking-capacitor-free, charge-balanced electrode-stimulator chip with less than 6nA DC error for 1mA full-scale stimulation. IEEE Transactiais on Biomedical Circuits and Systems 1(3) 172-183. 

Figure 15.1. Drosophila embryonic neuromuscular preparation. Top panel) Dissected Drosophila embryo viewed with a scanning electron microscope (SEM) anterior (A) to the left, posterior (P) to the right. The prominent CNS lies along the ventral midline. Bottom panel) Schematic drawing of the four ventral longitudinal muscles in one segment. The CNS, peripheral nerve, and NMJ on these four muscles are drawn. The typical recording configuration involves whole-cell patch-clamp recording from muscle 6 and suction-electrode stimulation of the peripheral nerve.

Direct CNS Stimulation. An alternative to the standard suction electrode stimulation of the peripheral nerve is direct stimulation of the CNS (Nishikawa and Kidokoro 1995). A microelectrode filled with 3-4 M KCl or potassium acetate is inserted into the middle of the ventral ganglion and positive pulses of approximately 2 pA in intensity and approximately 2 msec in duration are delivered (Dietcher et al. 1998). Synaptic transmission is recorded in the patch-clamped muscle in the standard configuration. 

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