Electrical activity measurements

Electrical Activity Measurements as a Functional and Neuronal Specific Endpoint... 

The receptors are proteins that cross the cell membranes of olfactory neurons seven times and are related to other types of sensory receptors. For a number of years, a direct proof that these proteins were indeed olfactory receptors was lacking. This was provided in 1998 by Firestein and coworkers, who were able to make electrical activity measurements on a single modified receptor showing differing responses to a variety of odorants... 

Electrical conductivity measurements revealed that ionic conductivity of Ag-starch nanocomposites increased as a function of temperature (Fig.l7) which is an indication of a thermally activated conduction mechanism [40]. This behavior is attributed to increase of charge carrier (Ag+ ions) energy with rise in temperature. It is also foimd to increase with increasing concentration of Ag ion precursor (inset of Fig.l7). This potentiality can lead to development of novel biosensors for biotechnological applications such as DNA detection. 

The spontaneous electrical activity of the brain can be measured by electroencephalography (EEG), a technique that has been widely employed to study neurotoxic effects of chemicals both in humans and in experimental animals. EEG waves represent summated synaptic potentials generated by the pyramidal cells of the cerebral cortex (Misra 1992). These potentials are the responses of cortical cells to rhythmical changes arising from thalamic nuclei. The signals recorded can be separated into frequency bands—faster waves exceeding 13 Hz, and slower ones below 4 Hz. 

The electrocardiogram (ECG) is a non-invasive means of measuring the electrical activity of the heart. The relationship... 

Figure 13.4 Electrocardiogram. The electrocardiogram (ECG) is a measure of the overall electrical activity of the heart. The P wave is caused by atrial depolarization, the QRS complex is caused by ventricular depolarization, and the T wave is caused by ventricular repolarization.

Detection of free radicals can be performed using light absorption, luminescence, oxygen consumption, electrical conductivity, and enzyme activity measurements. A number of examples of relatively common systems are given in Table 1. 

Epilepsy implies a periodic recurrence of seizures with or without convulsions. A seizure results from an excessive discharge of cortical neurons and is characterized by changes in electrical activity as measured by the electroencephalogram (EEG). A convulsion implies violent, involuntary contraction(s) of the voluntary muscles. 

Burdyga T, Wray S 1997 Simultaneous measurements of electrical activity, intracellular [Ca2+] and force in intact smooth muscle. Pfliigers Arch 435 182-184 Burdyga TV, Wray S 1999a The relationship between the action potential, intracellular calcium and force in intact phasic, guinea-pig uretic smooth muscle. J Physiol 520 867-883... 

Reflex action can be objectively examined. Measurement of the so-called electrical conduction velocity of motor nerves gives an indication of whether peripheral nerves have been damaged. Electromyography, or examination of the electrical activity of the muscle, and electroencephalography (EEG) can also be used to detect the presence of neurologic abnormalities. And, at least in animal tests, detailed pathological examination of neural tissue can be performed on animals that are killed. 

Having observed a decrease in appetite and thirst when testing BZ, we decided to measured caloric and fluid intake more precisely in the EA 3443 series. At the incapacitating dose, calories ingested and fluid consumed both dropped by about 40%. Sleep duration, also measured, increased at the lower doses but seemed to drop precipitously at the incapacitating dose. This seeming insomnia, however, was illusory. Delirious subjects appeared physically awake, but were asleep in terms of brain electrical activity - the so-called pseudowakeful state. ... 

A parameter (usually symbolized by P, and often containing a subscript to indicate the specific ion) that is a measure of the ease with which an ion can cross a unit area of membrane by simple (or passive) diffusion through a membrane experiencing a 1.0 M concentration gradient. For a particular biological membrane, the permeabilities are dependent on the concentration and activity of various channel or transporter proteins. In an electrically active cell (e.g., a neuron), increasing the permeability of K+ or CF will usually result in hyperpolarization of the membrane. Increasing will cause depolarization. 

Skin conductance represents changes in the electrical activity of skin. Resting skin conductance level (SCL) and the number of nonspecific fluctuations (spontaneous skin conductance responses [SCRs] seen in a resting state) are thought to reflect arousal. Skin conductance responses are also seen 1 to 3 seconds after stimulus onset, when they index the orienting reflex, which measures allocation of attention to the stimulus. Although SC arousal studies show some consistency, 4 out of 10 showed underarousal in antisocial-spectrum subjects no specific links to violence are reported (Scarpa and Raine, 1997). 

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