How Parkinson's disease affects the brain

Biomedical engineer Sri Sarma, PhD, explains how brain waves and rhythms influence movement in people with Parkinson’s disease. Watch this video to learn more.

Transcript

00:00

SRI SARMA: When we generate movements, your brain constructs a motor program. You can think of that as sort of a sequence of rules that

00:08

are going to initiate-- basically, control your muscles so that you can generate the movement that you intended to move.

00:14

[MUSIC PLAYING]

00:23

The more complicated the movement, the more information in that program. So if you think of information in terms of bits,

00:31

like one bit of information can tell you something that's a yes or a no, a binary information, right?

00:37

So if I have 10 bits, I have two to the 10 in terms of codes I can implement.

00:44

So in a normal human being, the way a bit can be encoded in the brain is through oscillations, a specific frequency

00:54

of oscillation. So if there's a dominant rhythm, say, in the 10 Hertz band, think of a radio. You have a dominant rhythm in the 10 Hertz band.

01:01

That might carry information. If it's there, that's like a 1 in your bit. If it's not there, that's a 0.

01:07

So for example, in movements, the very coarsest information is move or don't move. So there might be a rhythm in the 30 to 80

01:15

Hertz called the gamma band. This has been shown by many scientists in the motor areas, which is if there is this dominant gamma

01:23

rhythm in certain parts of the motor signal, that's prokinetic. That's information to say, you should move.

01:30

But when you see lower frequency oscillations rhythms in these areas in the 10 to 30 Hertz band, that's akinetic, saying stop.

01:38

That's like the brake. Now, when you're normal, you're always going between stopping and going, stopping and going, actuating and not actuating certain muscles.

01:46

And the brain can carry all these different rhythms so that you have lots of bits to communicate this information.

01:53

Now what happens in Parkinson's disease, the analogy, if I take it to the disease state, is that you lose bits.

01:59

Now, what happens, what people have shown, is that there is a dominant 10 to 30 Hertz rhythm that exists in various parts

02:07

of the circuit, the beta rhythm, the beta band, pathology. That's there in Parkinson's disease, which is essentially-- it's almost think of it

02:15

as it's always saying stop. Put on the brake. Put on the brake. And it's hard to overcome this pathological rhythm

02:21

in these patients to now move to the move like the gamma ray region with higher oscillations because you have

02:28

this pathological rhythm in the brain, in the circuit, that's constantly there. Although there's still lots of questions to be answered,

02:36

I would say the cleanest analogy is that you lose bits of information that can be communicated in the brain that will then control your muscles when you move, and that's the disease.