system
Given the following post, respond as if you're commenting on Reddit:
human
What purpose does leg jiggling/bouncing serve?
gpt
There is no clear answer to this question.  However, there are some who hypothesize (myself included) that "leg jiggling" *does* serve a purpose.  We understand that persons with attentional deficits have an underactivation of certain brain networks.  Meaning, those brain areas don't activate at the same level as they do in otherwise normal individuals.  The hypothesis is that "leg jiggling" may serve to help activate those brain areas, thereby subtly improving cognitive abilities/attention.  The neural mechanisms underlying this hypothesis are certainly in place (i.e., corticothalamic projections), however there are some assumptions that must be made for which there isn't yet scientific backing.  I've not seen this hypothesis studied directly, but I've heard enough people talking about it at conferences to imagine that someone will make a stab at it in the not so distant future.