Inhibition (neuron)

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The phenomenon of inhibition is the influencing of a nerve cell by an impulse that does not stimulate this neuron to form an action potential , but rather inhibits it and thereby weakens the signal transmitted by this neuron.

In the case of synaptically mediated inhibition, a distinction is made between pre- and postsynaptic inhibition.

The opposite of the inhibitory synapses are excitatory, excitatory synapses .


It is best explained with an example, the lateral inhibition in the eye: Directly behind the sensory cells that convert the light into electrical impulses in the eye ( photoreceptors ), the resulting signals are passed on to nerve cells. There, each nerve cell has an inhibitory effect on the signals of the neighboring nerve cells. As a result, for example, weak light (from a gray point) that falls on one sensory cell appears darker when strong light falls on the neighboring sensory cells. To do this, the incoming signal is simply "multiplied by a negative factor" (in truth, another messenger substance is released) and passed on to the neuron connected to the neighboring sensory cell (which is supposed to conduct the signal from the sensory cell towards the brain). As a result, the signal from this neuron is weakened, and the stronger the more light falls into the neighboring cell.

This interconnection increases contrasts in the perceived image long before its signals reach our brain. Such inhibition not only helps us to intensify contrasts, but also to better recognize lines and edges. Horizontal lateral inhibition e.g. B. reinforced as an exclusive inhibitory influence on horizontally adjacent sensory cells z. B. vertical edges in the perceived image (see edge detection ).

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