Flashing Light, Sound Restore Memory in Alzheimer's Mice (opens in new tab)

Are you sure that wasn't just from having to go outside to buy it?

Older fluorescent lights (those run off a magnetic current limiter, or "ballast") flickered at 120Hz if they were connected to a 60Hz power source. Every time the voltage declined below a level needed to maintain a discharge, the lamp went out. That happened twice in every full sine wave of primary power.

Whether you could see the flicker depended on the phosphor luminous decay time. If the phosphors on the inside of the bulb (which glow when excited by the UV-rich plasma discharge) had a rapid luminous decay curve, you could perceive the 120Hz flicker if you scanned your eyes across a lit bulb. The afterimage on your retina was a dashed line, the dark parts being the "too little voltage" portions of the sine wave.

You can use the afterimage trick to check out duty cycle dimming of car tail and brake lights. If they're chopped slower than ~1KHz, the smeared retinal afterimage will be chopped. Don't do this if you're moving in traffic.

I’d expect them to be an integer multiple of mains frequency, so 50 or 60 Hz.

Flourescent lights need much higher frequency. They're typically >= 22 kHz.

> plaques are the "root cause

The amyloid hypothesis has been pretty popular for ~25 years, and it's pretty clear that the plaques have something to do with Alzheimers, but it's been a absolute disaster as a treatment target. It feels very much like treating a fever by slathering the patient in antiperspirant.

Biogen announced this morning that they're giving up on Phase III trials of aducanumab, an antibody that was supposed to target and remove the plaques (their stock is doing...badly as a result). https://www.reuters.com/article/us-biogen-alzheimers/biogen-...

There were two other big failures last year here too, as this nice little Nature News piece describes: https://www.nature.com/articles/d41586-018-05719-4

[3] is definitely not 40hz. 40hz is in the sub-bass range, which this clearly isn't. I'm not at home in my studio right now, so I can't measure what it is, but if I was to guess it would be around 200hz.

The ones that are 20hz might make you feel a bit weird because there's not much amateur audio equipment that would do anything other than distort at that low end of the frequency range.

It does say binaural though, so maybe it's panning left/right at 40hz rather than playing a sound-wave at 40hz. If that's the case it's not the same as what the article states: "40 hertz tone".

Here's an online tone generator [1] that will play a sine-wave at 40hz.

[1] https://www.szynalski.com/tone-generator/

That first video definitely is giving me a strange sensation too, it's like my ears and nose are vibrating in response to the "beats" of the audio.

Nature is hardly the top of the crust these days with regards to academic oversight.

I can recall quite easily that a while back they published an article confirming ESP, and then refused to publish a replication of the same paper stating no results.

Because the first one sells issues and the second one doesn't.