what is auditory–tactile synesthesia and why does it happen?


what is auditory–tactile synesthesia and why does it happen?

In: Biology

Auditory-tactile synesthesia is experienced as hearing a sound and having a physical sensation as a result, in addition to hearing it.

Current leading theories for synesthesia include:

A) different centers of the brain (e.g. auditory processing and physical sensation) have more crosstalk than other people, such that an individual will have either an additional involuntary sensory experience (such as feeling sound or hearing colors) or cognitive experience (such as feeling that some numbers are nearer/farther than others).

B) your brain is trained to fire electrical impulses (called action potentials or APs) and part of this process includes an inhibitory period in which the same signals cannot yet fire again (mind you this can be fractions of a second) – in this case, the inhibitory period is disregulated causing excitation to build in centers that communicate with that center of the brain or nearby centers (this is similar to types of epilepsy and effects of certain psychedelics on the brain).

C) a strong association is developed between stimuli and associated thoughts or memories, and your brain established semantic meaning and understanding from a stimulus in ways that other people do not.

Though it is not 100% understood, many researchers believe that synesthesia most often develops in early childhood as a result of the brain starting to develop specialized areas of information processing, often with many synaptic connections in ways that adult brains do not make as easily (this is often why kids can pick up many sports/hobbies/languages/etc. at a young age (6ish, give or take a couple years).

Typically, after those windows of time the brain starts “synaptic pruning” in which certain neutral pathways are eliminated – typically because they aren’t as efficient as others, or they aren’t used as frequently (e.g. many children who speak more than one language at this age can forget all but their primary language if they don’t speak the others very often). In this case, however, certain pathways were never pruned, thereby maintaining a connection between (for instance) auditory processing and physical tactile sensation that others wouldn’t have.