I can do it voluntary at any time in any position sitting or standing up, it is a harder while walking since it does take a bit of "physical" concentration.
I would describe it like... first, is a "building up" sensation of something, not a thingly or any other sensation i could describe not even in my first language i could describe it any better than a "building up phase".
Then, i feel... something in the back of my head, cerebrum maybe? Same feeling but greatly intensified, after that the SINGLE electric pulse releases from my that area in my head and goes down and stops about mid way in my back. it also branches to both my arms and while doing so it loses "power", the pulse hardly reaches my elbow, there are so many memories i have when this pulse reaches it its extremely hard to make it go that far.
so, i can make low pulses and strong and lasting pulses at will, altough after doing it for about 2 minutes it gets harder and harder to create strong ones. regardless of intensity they reach the same lenght in both my arms and back.
it doesnt hurt, it doesnt feel nice either, i do remember use this as something to "soothe" myselft as a meditation method since the whole thing feels like a "wave" going up and down in my back.
wich brings the next detail: sometimes, somehow, if i think in direction the direction of this pulse changes. if i think of "down" the pulse starts from behind my head and goes down my spine. if i think of "up" the pulse starts... in the upper section of my back and goes up but is considerably lower intesity, is impossible to make it as strong as the "weak" pulse i can create when i send it down, but i can still feel a direction.. it starts where the nerve system branches to the arms if i am to guess.
after 1 minute of doing it, sometimes when i try to send a pulse it starts from the middle part of my back and spreads SIDEWAYS with no build up sensation... weird right?.
what else... i think thats all. i remember my 5-year-old me asking my parents and my older brother if they can do that and then saying no, i have memories of asking friends and teachers and they dint know either, i just asked my parents and again, they said no.
--------------------------------- WARNING: LONG BACKSTORY ---------------------------------
i have a back story with EXTREME chronic pain.
in a nutshell: in 2012 at my 16 - 17 years i got hit by a car, i dint broke any bones, i lost memories of the accident because my brain protected me, i dint had any brouses or so it seemed, i had yellow brouses.
anyhow, since that incident i had lower back chronic pain that got worse and worse through the years to the point it got so extreme that some drugs (pain killers) dint work.
my insurance doctors started to think i was making it up, in a nutshell they dint want to fix me because of that because in the electro magnetic resonance it dint show anything wrong with me, it was a long fight and many many years of doctoring and going to Mental Hospitals just because the insurance tought i was faking it...
really, there is too much to explain, in a nutshell they made me EVERY. SINGLE. STUDY. just to prove i was faking it and trough time it was shown that eventually i developed a neuropathy in my left leg wich at the end we used that material to sue them and finally pay a surgery that solved 100% my chronic pain.
by the end, i was hospitalized for about 2 months, with the most gruesome, HORRIBLE pain ive ever experienced, it seemed NO DRUG was able to calm me down!! EVERYONE got to see me in the hospital go from enduring a HORRIBLE EXTREME pain to a RAW GRUESOME EXTREME pain and when it got that bad my mental strenght was in the floor and since i was taking medicine for years the doctors feared they would create another problem if giving me stronger pain killers than morphine, at some point the good doctor talked to my parents about if i get worse put me in coma or use sedative when surgeons do surgery, wich my parents replied with a strong NO... i would've said yes to be honest, "time" was not real anymore, i would constantly pass out for 2 months uncontable times a day to another reality or to a "nothingness" because my brain was constantly trying to protect me from the pain trauma/shock.
the middle way solution was a drug called Vallium, in those worst months of pain i had a new "symptom", i would have "pain attacks". EXTREME-MIND BREAKING pain rushing from my back outwards and my body would contract to the center abdomen area (i think it was just me uncontrollably reacting to the pain because eventually i would be so tired that i would seace contracting but continue screaming as my mind shifts between realities)
in the end family and friends payed the surgery, the good doctor who did the surgery said he would do it not through the insurance but in a different place but we would have to pay the entirety of the surgery. the doctor also gave us a big discount because he trusted in me he trusted that my pain was real and it was inhumane for the insurance to made me whait 5 years in bed with horrible pain and call me a liar, doctors who dint believe me then changed his mind down the road through years as i got worse and worse and joined him, helped me in the surgery and then testified, after that we won the demand and got the entirety of the money spent back. i also made it to the national news too, it was a big deal the insurance got a big reputation hit since.
------------ END OF BACKSTORY ---------
so... yeah, now that i feel 0 pain i was thinking... since no one ever knew why i felt pain that bad... is this thing could've been somehow involved? its nerve system related, you know.
Dr. Mario Armando Caloca Pichardo (a.k.a. good doc) installed a thingy called WELLEX in my spine and solved fixed me, he is a family hero =).
my BIG QUESTION IS: CAN YOU DO THAT TOO? you know what that is? do you "activate it" differently? or is this some kind of a syndrome i dont know of?
sorry for make you read this long, you made it, you are the real hero! thanks you.