Electricity and the brain

Part 2 of 3 : The neuronal membrane and the establishment of neuronal voltage

The "walls" of neurons (neuronal membrane) are composed of special fats that totally separate the interior of the neuron from the outside. If we take these special fats and place them in the tank mentioned above, they will spontaneously form a sphere with a uniform distribution of minerals (those previously dissolved in the aquarium in part 1) inside and outside the sphere (electrically neutral). We then have a draft of a neuron.

The neuronal membrane contains several proteins that distinguish neurons from all other cells. One group in particular, called pumps or exchangers, transfers one or more atoms to the other side of the membrane (Figure 3). Therefore, if we introduce this group of proteins in the membrane of the example of the aquarium above, one group of proteins will be responsible for removing the sodium atoms inside the neuron, another group will be responsible to concentrate potassium atoms inside the neuron, etc. (Table 1). The net result will be a decrease of positive charges (Na +, Ca2 +) inside the neuron and the inside will be negatively charged, thus forming a potential difference (about -60millivolt) ; this is called the resting potential.

Eric Trudel 

McGill University