Is a Brain Wave Actually a Wave?

[pabloweigandt]

Can I say, by any means, that a "brain wave" is, in fact, a wave of some kind?

 

[jim mcnamara]

If this refers to EEG - An electroencephalogram (EEG) is a recording of brain activity that shows wave forms - then maybe. What are you referring to?

 

[phinds]

Can I say, by any means, that a "brain wave" is, in fact, a wave of some kind?

If you would learn how to use Google, you could answer simple questions like this by yourself:

 

[jim mcnamara]

@phinds - good EEG graphic

 

[CoolMint]

Can I say, by any means, that a "brain wave" is, in fact, a wave of some kind?

It is electricity. 0.01 to 0.02 volts(detected at the scalp). You should be able to measure it with a good brand multimeter and proper suction cups.

[Mentor Note -- see the following posts for corrections to the incorrect information in this post]

 

[Fra]

It is electricity. 0.01 to 0.02 volts(detected at the scalp). You should be able to measure it with a good brand multimeter and proper suction cups.

I wish EEG signals was that strong but they are not, not even more easily measured ECG signals is that strong, and the typical EEG bands are <44Hz and looks like noise, and too fast to read off a multimeter. The most common measurements does a FFT and looks just at the energy in the various EEG bands. Individual transients in the time domain, often need ensemble averaging of repeated recordings to emerge from both physiological noise and externally induced noise.

(see handbook of psychophysiology, the chapter on EEG)

/Fredrik

 

[phinds]

It is electricity. 0.01 to 0.02 volts(detected at the scalp). You should be able to measure it with a good brand multimeter and proper suction cups.

SUUURRRRRE it is. That's why EEG machines only cost $50,000 and up.

 

[berkeman]

Thread closed temporarily for Moderation and cleanup...

 

[berkeman]

It is electricity. 0.01 to 0.02 volts(detected at the scalp). You should be able to measure it with a good brand multimeter and proper suction cups.

Okay, after some post deletions (persistent misinformation from CoolMint) and cleanup, the thread is reopened. @CoolMint has also been banned from replying in this thread going forward.

Just to clarify the level of EEG signals (which I do have good experience designing circuitry to measure):

https://www.google.com/url?sa=t&rct...lArousal.pdf&usg=AOvVaw1Zna1QlytXncEFWRjXGwLS

 

[tech99]

Professional monitoring equiopment is specially designed to ensure safety. It is very important to not connect electrical equipment to the body for experiments such as EEG and ECG because slight leakage currents from the equipment can endanger the body.

 

[Mister T]

Can I say, by any means, that a "brain wave" is, in fact, a wave of some kind?

When we measure something, and the magnitude of that something oscillates with some kind of regularity, we typically call it a wave. It's just an oscillating magnitude.

 

[sophiecentaur]

When we measure something, and the magnitude of that something oscillates with some kind of regularity, we typically call it a wave. It's just an oscillating magnitude.

You beat me to it. I've always thought that they're signals and not waves. I started thinking about the velocities and frequencies involved and it's a "how long is a piece of string" question. I looked at good old Wiki about this. The speeds that the impulses travel vary a lot - from 0.5m/s to 120m/s which is much slower than EM waves in free space.
Whether you'd see an actual wave (i.e. would you be aware of maxes and mins) travelling along the nerve fibre i.e. an observable 'wavelength'. You need to use the so called wave equation c=fλ for the wavelength. The highest frequencies are 30Hz so, depending on which 'waves' travel at the slowest speed, I guess you could actually get an impulse travelling along a long neuron (like the leg) and the time delay could be significant but, within the brain, it's probably just potentials varying in time.
I then thought of electronic circuits (much faster velocity of course) and realised that the combinations of size and signal frequency can mean virtually no phase delay over a wire or many cycles of phase.
The brain is a very smart structure so I imagine that its 'design' takes care of delays when it needs to.

 

[sophiecentaur]

It's worth pointing out that any change in a variable (i.e. a signal) takes time to propagate from one point to another and that delay implies some sort of wave. I guess the term 'waves' in brain waves is just due to the appearance of the wavy lines of recording ink on the old encephalographs.
In real life, about the only waves we observe directly are water waves.

 

[Mister T]

I guess the term 'waves' in brain waves is just due to the appearance of the wavy lines of recording ink on the old encephalographs.

Or a display on a computer screen. We do this with lots of other things. Like in the sleep apnea world we look at graphs of air flow in and out of your lungs versus time. The graph looks like a wave so a lot of people call it a wave.

Note that in the case of an object undergoing simple harmonic motion we concern ourselves with graphs of the position of the object versus time. The graph is a sine wave, but we are careful not to call it a wave because we want to distinguish it from an actual wave.

It's easier to "explain" using math.

$x=A \sin \omega t$

versus

$y=A \sin (kx \pm \omega t)$

 

[sophiecentaur]

Or just give k a value of zero. no change on the (undrawn) x axis.