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It can be used to measure the thermally stimulated depolarization of molecules within a material. One method of doing so is to place the material between two electrodes, cool the material in the presence of an external electric field, remove the field once a desired temperature has been reached, and measure the current between the electrodes as ...
Depolarization increases the Na + current through the persistent channels, resulting in a lower rheobase; hyperpolarization has the opposite effect. The strength-duration time constant increases with demyelination, as the exposed membrane is enlarged by inclusion of paranodal and internodal membrane.
Chronaxie is the tissue-excitability parameter that permits choice of the optimum stimulus pulse duration for stimulation of any excitable tissue. Chronaxie (c) is the Lapicque descriptor of the stimulus pulse duration for a current of twice rheobasic (b) strength, which is the threshold current for an infinitely long-duration stimulus pulse.
Normal functioning of the central nervous system entails a summation of synaptic inputs made largely onto a neuron's dendritic tree. These local graded potentials, which are primarily associated with external stimuli, reach the axonal initial segment and build until they manage to reach the threshold value. [ 5 ]
When, at the end of a sinoatrial action potential, the membrane repolarizes below the I f threshold (about −40/−50 mV), the funny current is activated and supplies inward current, which is responsible for starting the diastolic depolarization phase (DD); by this mechanism, the funny current controls the rate of spontaneous activity of ...
Laser stimulation highlights differences in thermal characteristics between areas containing defects and areas which are defect-free. As the laser locally heats a defective area on a metal line which is carrying a current , the resulting resistance changes can be detected by monitoring the input current to the device.
This inward flow of sodium leads to a short term depolarization of the postsynaptic neuron and an EPSP. While a single depolarization of this kind may not have much of an effect on the postsynaptic neuron, repeated depolarizations caused by high frequency stimulation can lead to EPSP summation and to surpassing the threshold potential. [9]
The rate of change for an h gate is much slower than that of an m gate, therefore if one precedes a sub-threshold voltage stimulation with a hyperpolarizing prepulse, the value of h may be temporarily increased, enabling the neuron to fire an action potential.