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The human brain is the most complicated human organ so it is hard to examine it completely but based on what we know do you think (or do you know from some source) if a human memory can be removed by emp(electromagnetic pulse) ? (If so do you think it would be pernament or temporary?)

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    $\begingroup$ Given the large number of people who were exposed to atomic bombs in Hiroshima and Nagasaki and subsequent atomic testing in the 50s and 60s and did not lose memory, I doubt EMP could erase memory ( unless you count total brain obliteration ). However, I am not aware of actual studies exposing brains to high EM fields to test memory. $\endgroup$ – user137 Nov 7 '14 at 22:19
  • $\begingroup$ This is perhaps best suited for skeptics.stackexchange.com $\endgroup$ – Bez Nov 7 '14 at 23:17
  • $\begingroup$ reddit.com/r/askscience/comments/z3lkd/… it won't have any effect on neurons $\endgroup$ – inf3rno Nov 8 '14 at 0:12
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    $\begingroup$ I think humans are a less interesting case than electric fish, platypuses, and other such animals. To them, the EMP is probably like a flashbang. I believe there have also been reports of birds being confused by strong electromagnetic fields. $\endgroup$ – Superbest Nov 9 '14 at 19:25
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    $\begingroup$ This isn't a ridiculous idea; Transcranial Magnetic Stimulation is used in research and even has some use as treatment for depression (mayoclinic.org/tests-procedures/…) $\endgroup$ – Gretchen Dec 8 '14 at 16:36
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http://en.wikipedia.org/wiki/Electromagnetic_pulse mentions the following natural sources of EMP, which I have ordered by frequency / period, from the shortest to the longest:

  1. Electrostatic discharge from objects coming into contact (normally too small to be of any concern)

  2. Lightning (milliseconds)

  3. Solar flares (hours.) Such flares cause geomagnetic storms (more on this later.)

Several artificial sources of EMP are mentioned, of which the only ones of interest are military:

  1. Non-nuclear weapons. The page links to a general article on directed-energy weapons, which mentions microwave devices for causing pain and for targeted damaging of electronic equipment.

  2. Nuclear weapons. http://fas.org/nuke/intro/nuke/emp.htm gives more information on this, listing three phases.

The EMP produced by the Compton electrons typically lasts for about 1 microsecond, and this signal is called HEMP. In addition to the prompt EMP, scattered gammas and inelastic gammas produced by weapon neutrons produce an “intermediate time” signal from about 1 microsecond to 1 second. The energetic debris entering the ionosphere produces ionization and heating of the E-region. In turn, this causes the geomagnetic field to “heave,” producing a “late-time” magnetohydrodynamic (MHD) EMP generally called a heave signal.

The same reference also indicates:

...the region where the greatest damage can be produced is from about 3 to 8 km from ground zero. In this same region structures housing electrical equipment are also likely to be severely damaged by blast and shock.

As far as I am aware, memory loss was not a major recorded symptom among the survivors of Hiroshima and Nagasaki. The only recent data for sufferers of EMP would be from victims of lightning stikes. While the frequency spectrum is admittedly different from nuclear weapons, victims of lightning strikes are surely subjected to greater magnitudes of EMP than those who managed to survive nuclear bombings (who suffered many other traumas, such as blast waves and radiation.) Those who survive the immediate physical (burns) and neurological (cardiac arrest) effects of lightning strikes must surely be knocked unconscious and be disorientated when they regain consciousness. But again, I am not aware of medium or long term memory loss being a particular symptom.

It is worth comparing the structure of the brain (a fairly homogenous mass of tissue of high water content, relatively conductive) with the structure of electronic equipment (components of ever smaller size and greater resistance in order to save power, surrounded by a nonconductive medium such as air, and interconnected by wires, which serve to channel voltage.) It is unsurprising that the brain is less subsceptible to electrostatic damage than electronic components (electronics workers have to take precautions in order to avoid damaging sensitive components with static discharges from their bodies and clothing.)

The most widespread damage to equipment caused by EMP is from the long-period pulses, which are channeled by electric cables. These act over distances much larger than the size of the human body.

From the last reference:

...distortion of the geomagnetic field was observed worldwide in the case of the STARFISH test. ... the signal from this process is not large, but systems connected to long lines (e.g., power lines, telephone wires, and tracking wire antennas) are at risk

and

The first recorded EMP incident ... nuclear test over the South Pacific ... resulted in power system failures as far away as Hawaii.

http://en.wikipedia.org/wiki/Geomagnetic_storm mentions cases of damage caused by long period EMP, including electric shocks suffered by telegraph operators during solar flare events.

So in conclusion, any amnesia caused by EMP is likely to be caused by normal biological shock mechanisms to individuals unfortunate enough to be electrocuted, and not by any direct electrical effect on the brain itself.

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  • $\begingroup$ Perhaps it is worth mentioning also people who work on high-voltage electrical transmission lines - they also experience dramatic EM changes (though perhaps less rapidly). While they have many involved procedures to avoid electrocution, I haven't heard of anything beyond some anecdotes of slight headaches or dizziness in terms of impairing brain function. $\endgroup$ – Superbest Nov 9 '14 at 19:23
  • $\begingroup$ @Superbest I think long term exposure to mains and higher frequencies is a separate question. There are a lot of people who campaign against mobile phone masts while hypocritically carrying a mobile phone around in their pocket. I would be cautious about concluding mobile phone masts have ZERO health effects, but the phone you are carrying right next to your body will affect you more than the mast. Years ago I used to get a slight headache after talking for half an hour (my phone was a big brick and it got hot) but I phones have improved since then. $\endgroup$ – Level River St Nov 9 '14 at 19:51
  • $\begingroup$ @steverrill Agreed, but I was referring to alleged headaches experienced by electrical workers when they come near (as in, within a meter or so) high voltage lines. $\endgroup$ – Superbest Nov 9 '14 at 19:54
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The brain is not an electronic device.

An EMP is basically a large amount of electrons flying by all at once. They are negatively charged, and as they pass by they distort your local EM-field (hence the name). This distortion induces current in the wires (a phenomenon known since Faraday) - since most wires aren't made with a large tolerance, the sudden current spike overheats the wire and burns components. In the brain, there are no wires to induce current on.

It is true that electromagnetism plays a role in neuron function, and action potentials can be measured or manipulated with electrodes. However, this is just a consequence of the ion concentration being used for signaling - there is not a flow of electrons across a conducting wire that is driving the process.

Memory is not stored electrically. The two major mechanisms of memory are strengthening of the synapses and the chemical state of the neurons (metabolites and proteins such as cAMP or CaMK, RNA levels, DNA methylation). These aren't very sensitive to electrons moving past - you're essentially trying to catalyze a chemical reaction by applying a strong EM field outside of the beaker.

Also, I suspect the skull and tissue surrounding it may act as a Faraday cage to shield the brain itself from the EM field.

I'm sure it is possible to create an electron flux so heavy that it manages to induce enough current in cells to kill them (or current in your bloodstream to cause cardiac arrest). However, the nuclear explosion that produces this would probably be much deadlier due to other effects, like blast shockwave or gamma rays. So to answer your question, a nuclear EMP would either kill you or not affect your memories, although if you had some exotic, very powerful, very precise pure EMP generator perhaps you could get some sort of stunning effect or give people a headache. I don't think it could erase memories without killing large parts of the brain.

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This isn't a ridiculous idea; Transcranial Magnetic Stimulation is used in research and even has some use as treatment for depression (http://www.mayoclinic.org/tests-procedures/transcranial-magnetic-stimulation/basics/definition/prc-20020555)

In TMS a strong, localized magnetic field can disrupt normal functioning of regions of the brain. For instance it can be used on the visual cortex to cause temporary blindness (actually, can cause a condition called blindsight: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2234142/)

As for memory though, TMS does not seem to be able to cause permanent memory loss (in fact, there is research indicating that it may be able to boost memory). Plus, the magnetic pulse would have to be either extremely strong, or very close, for it to have an appreciable effect.

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protected by Chris May 2 '15 at 6:41

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