Brain research in the 20th century/Electrophysiologic brain research
One of the big influences furthering brain research was electrophysiology.
Since the discovery of bioelectricity, investigations in understanding the nature and function of the electric currents that flow through neural fibers have advanced.
But, utilizing only the ammeters available at the time meant there were limitations to how close they were able to come to understanding its nature and function.
In 1897 Brown invented the Cathode ray oscilloscope and, thanks to this invention, researchers could observe the change of voltage in real time, and they adapted this machine to analyze neural actions.
However, the actual contribution to the development of electrophysiology was a "trigger type oscilloscope" invented in 1946.
By delivering a weak electrical current via an electro-stimulator, a portion of the brain or a specific nerve became stimulated, and researchers observed an electrical response, known as the "action potential", occur concurrently with the stimulus. (Fig.6)
In the early phase of electrophysiology, the action potential was recorded with recording electrodes located external to the cell, before long, various other stimulation electrodes and recording electrodes were developed.
One of those developed in that process were glass micro electrodes less than 1 micron top in diameter, filled with highly-concentrated electrolytes, furthermore, a high input resistance amplifier that could readily detect subtle electrical events was invented.
As a result, researchers were able to insert the point of the electrodes into cells without damaging a single neuron. This electrode enabled the observation of the resting membrane potential, action potential and synapse potential in the cell of a single neuron in real time. This technique rapidly caught on, and become the norm in brain research.
Challenge Quiz
Thanks to the invention of the ( ammeter voltmenter oscilloscope ), one could observe neural action, however, actual viable research started after the invention of the ( step repeat interval trigger ) type.
( Flash potential Firing potential Action potential Conduction potential ) induced when a neural cell is stimulated by an electric current or voltage induced by an electric-stimulator can be measured by electrodes located external to the cell.
Before long, micro electrodes made by thin glass tubes filled with ( mercury lead silver electrolytes ) were invented.
Using these electrodes, the ( resting membrane potential action potential synapse potential ) of single cells became observable in real time.