How spontaneous brain activity keeps you alive - Nathan S. Jacobs
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0:07 - 0:11You probably don't need to be told
how important your brain is. -
0:11 - 0:13After all, every single thing
you experience, -
0:13 - 0:15your thoughts and your actions,
-
0:15 - 0:17your perceptions and your memories
-
0:17 - 0:20are processed here
in your body's control center. -
0:20 - 0:24But if this already seems like a lot
for a single organ to handle, -
0:24 - 0:28it's actually only a small
part of what the brain does. -
0:28 - 0:31Most of its activities are ones
you'd never be aware of, -
0:31 - 0:34unless they suddenly stopped.
-
0:34 - 0:36The brain is made up
of billions of neurons, -
0:36 - 0:38and trillions of connections.
-
0:38 - 0:41Neurons can be activated
by specific stimuli or thoughts, -
0:41 - 0:45but they are also often
spontaneously active. -
0:45 - 0:47Some fire cyclically in a set pattern.
-
0:47 - 0:52Others fire rapidly in short bursts
before switching off, -
0:52 - 0:54or remain quiet for long periods
-
0:54 - 1:00until thousands of inputs from other
neurons line up in just the right way. -
1:00 - 1:01On a large scale,
-
1:01 - 1:06this results in elaborate rhythms
of internally generated brain activity, -
1:06 - 1:07humming quietly in the background
-
1:07 - 1:09whether we're awake, asleep,
-
1:09 - 1:12or trying not to think
about anything at all. -
1:12 - 1:15And these spontaneously
occurring brain functions -
1:15 - 1:20form the foundation upon which
all other brain functions rely. -
1:20 - 1:24The most crucial of these automatically
occurring activities -
1:24 - 1:26are the ones that keep us alive.
-
1:26 - 1:29For example, while you've been
paying attention to this video -
1:29 - 1:33spontaneous activity in your brain
has been maintaining your breathing -
1:33 - 1:38at 12 to 16 breaths a minute,
making sure that you don't suffocate. -
1:38 - 1:40Without any conscious effort,
-
1:40 - 1:43signals from parts of your brainstem
are sent through the spinal cord -
1:43 - 1:46to the muscles that inflate your lungs,
-
1:46 - 1:50making them expand and contract,
whether or not you're paying attention. -
1:50 - 1:55The neuronal circuits underlying such
rhythmic spontaneous activity -
1:55 - 1:58are called central pattern generators,
-
1:58 - 2:00and control many
simple repetitive behaviors, -
2:00 - 2:01like breathing,
-
2:01 - 2:02walking,
-
2:02 - 2:04and swallowing.
-
2:04 - 2:08Ongoing neural activity also underlies
our sensory perception. -
2:08 - 2:09It may seem
-
2:09 - 2:12that the neurons in your retina
that translate light into neural signals -
2:12 - 2:14would remain quiet in the dark,
-
2:14 - 2:15but in fact,
-
2:15 - 2:19the retinal ganglion cells
that communicate with the brain -
2:19 - 2:20are always active.
-
2:20 - 2:25And the signals they send are increases
and decreases in the rate of activity, -
2:25 - 2:27rather than separate bursts.
-
2:27 - 2:32So at every level, our nervous system
is teeming with spontaneous activity -
2:32 - 2:36that helps it interpret and respond
to any signals it might receive. -
2:36 - 2:41And our brain's autopilot isn't just
limited to our basic biological functions. -
2:41 - 2:43Have you ever been on the way home,
-
2:43 - 2:45started thinking
about what's for dinner, -
2:45 - 2:48and then realized you don't remember
walking for the past five minutes? -
2:48 - 2:51While we don't understand all the details,
-
2:51 - 2:55we do know that the ongoing activity
in multiple parts of your brain -
2:55 - 2:59is somehow able to coordinate
what is actually a complex task -
2:59 - 3:02involving both cognitive
and motor functions, -
3:02 - 3:05guiding you down the right path
and moving your legs -
3:05 - 3:07while you're getting dinner figured out.
-
3:07 - 3:10But perhaps the most interesting thing
about spontaneous brain function -
3:10 - 3:13is its involvement in one
of the most mysterious -
3:13 - 3:17and poorly understood phenomena
of our bodies: sleep. -
3:17 - 3:20You may shut down
and become inactive at night, -
3:20 - 3:22but your brain doesn't.
-
3:22 - 3:23While you sleep,
-
3:23 - 3:28ongoing spontaneous activity gradually
becomes more and more synchronized, -
3:28 - 3:33eventually developing into large,
rhythmic neural oscillations -
3:33 - 3:35that envelop your brain.
-
3:35 - 3:38This transition to the more
organized rhythms of sleep -
3:38 - 3:43starts with small clusters of neurons
tucked in the hypothalamus. -
3:43 - 3:45Despite their small number,
-
3:45 - 3:46these neurons have a huge effect
-
3:46 - 3:51in turning off brainstem regions
that normally keep you awake and alert, -
3:51 - 3:53letting other parts,
like the cortex and thalamus, -
3:53 - 3:57slowly slip into their
own default rhythms. -
3:57 - 3:59The deeper we fall into sleep,
-
3:59 - 4:03the slower and more synchronized
this rhythm becomes, -
4:03 - 4:09with the deepest stages dominated by large
amplitude, low frequency delta waves. -
4:09 - 4:13But surprisingly, in the middle
of this slow wave sleep, -
4:13 - 4:16the brain's synchronized
spontaneous activity -
4:16 - 4:19repeatedly transitions
into the sort of varied bursts -
4:19 - 4:21that occur when we're wide awake.
-
4:21 - 4:24This is the sleep stage
known as REM sleep, -
4:24 - 4:29where our eyes move rapidly
back and forth as we dream. -
4:29 - 4:33Neuroscientists are still trying to answer
many fundamental questions about sleep, -
4:33 - 4:37such as its role in rejuvenating
cognitive capacity, -
4:37 - 4:38cellular homeostasis,
-
4:38 - 4:40and strengthening memory.
-
4:40 - 4:42And more broadly, they are exploring
-
4:42 - 4:47how it is that brain can accomplish
such important and complex tasks, -
4:47 - 4:51such as driving, or even breathing,
without our awareness. -
4:51 - 4:53But for now, until we are better able
-
4:53 - 4:57to understand the inner workings
of their spontaneous functioning, -
4:57 - 5:00we need to give our brains credit
for being much smarter -
5:00 - 5:02than we ourselves are.
- Title:
- How spontaneous brain activity keeps you alive - Nathan S. Jacobs
- Description:
-
View full lesson: http://ed.ted.com/lessons/how-spontaneous-brain-activity-keeps-you-alive-nathan-s-jacobs
The wheels in your brain are constantly turning, even when you're asleep or not paying attention. In fact, most of your brain’s activities are ones you’d never be aware of … unless they suddenly stopped. Nathan S. Jacobs takes us inside the always active, surprisingly spontaneous brain.
Lesson by Nathan S. Jacobs, animation by TOGETHER.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 05:18
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Jennifer Cody edited English subtitles for How spontaneous brain activity keeps you alive - Nathan S. Jacobs |