Neural adaptation
All sensory and neural systems have a form of adaptation to constantly detect changes in the environment.
[1] There are also mechanoreception systems that use calcium inflow to physically affect certain proteins and move them to close or open channels.
[2] Also, repeated sensory stimulation appears to temporarily decrease the gain of thalamocortical synaptic transmission.
[6] In the late 1800s, Hermann Helmholtz, a German physician and physicist, extensively researched conscious sensations and different types of perception.
He defined sensations as the "raw elements" of conscious experience that required no learning, and perceptions as the meaningful interpretations derived from the senses.
After removing the glasses, "normal vision was restored instantaneously and without any disturbance in the natural appearance or position of objects.
In the absence of fixational eye movements, visual perception may fade out or disappear due to neural adaptation.
The results revealed that visual responses to the repeated compared with novel stimulus showed a significant reduction in both activation strength and peak latency but not in the duration of neural processing.
Moreover, after repeated perception, individuals tend to adapt to sounds to the point where they no longer consciously perceive it, or rather, "block it out".
Moving to a completely different area, such as a quiet countryside, that individual would then be aware of the silence, crickets, etc.
Since this is mechanoreception, different from chemoreception, adaptation of sound from surroundings highly depends on the physical movement of opening and closing of cation channels on the hair cell stereocilia.
Mechanoelectric transduction (MET) channels, located at the tops of stereocilia, are poised to detect tension induced by hair bundle deflection.
Hair bundle deflection generates a force by pulling on tip link proteins connecting adjacent stereocilia.
The human brain can distinguish smells that are unfamiliar to the individual, while adapting to those it is used to and no longer require to be consciously recognized.
[15] Olfactory neurons utilize a feedback system from the levels of Ca2+ions to activate its adaptation to prolonged smells.
An unfamiliar piece of clothing that was just put on will be noticed instantly; however, once it has been worn for a while, the mind will adapt to its texture and ignore the stimulus.
As a result, pain does not usually subside rapidly but persists for long periods of time; in contrast, other sensory information is quickly adapted to, if surroundings remain constant.
[19] This showed that neural adaptation accounts for changes to functional properties of the spinal cord circuitry in humans without affecting organization of the motor cortex.
[24] As a person walks, the body constantly gathers information about the environment and the surroundings of the feet, and slightly adjusts the muscles in use according to the terrain.
The rate of neural adaptation is affected by the area of the brain and by the similarity between sizes and shapes of previous stimuli.
Transcranial magnetic stimulation (TMS) is an important technique in modern cognitive neuropsychology that is used to investigate the perceptual and behavioral effects of temporary interference of neural processing.
Antidepressant drugs, such as those that cause down regulation of β-adrenergic receptors, can cause rapid neural adaptations in the brain.
[27] By creating a quick adaptation in the regulation of these receptors, it is possible for drugs to reduce the effects of stress on those taking the medication.
Due to neural adaptations, however, by early school-age, considerable development to those areas was observed.
[30] This result indicates that proprioceptive information is necessary for some of the neural adaptation that occurs in Drosophila after a leg injury.
