Question

\(\sf\huge \color{#66FF00}{Tutorial}\)
Field: Neuroscience, Neurophysiology.
Topic: States of Brain Activity
Subtopics involved:
Part One:
Sleep, Stages of sleep, Brain waves, Dreams, Fetal Familial Insomnia.

◦◦◦This is practically a summary of topics using 2 human physiology books and 1 neuroscience book + some internet resources.◦◦◦

Answer 1

\(\sf\huge\color{#21ABCD}{What~ is ~sleep?}\)
◦An \(\sf \color{#21ABCD}{unconscious}\) state of a person from which he/she can be aroused by \(\sf \color{#21ABCD}{sensory}\) or other stimulus. By sensory, i refer to touch, vibration, sound, cold and so on.
◦Sleep effects all of our bodily and mental functions starting from \(\sf \color{#21ABCD}{metabolism}\), \(\sf \color{#21ABCD}{muscle~ tone}\), all the way to regulation of \(\sf \color{#21ABCD}{thought ~processes}\).
◦During wakefulness the electroencephalogram (EEG) shows relatively low-voltage, high-frequency, fast activity, showing an active cerebral cortex busy with perception and cognition.

But during sleep the EEG records are quite different.
There are 5 stages of sleep (in some books it can be considered as 4 but i am going with 5 because of wave patterns you will see soon), four of which are : \(\sf \color{#21ABCD}{Slow – wave~ sleep}\); and 5th one is \(\sf \color{#21ABCD}{REM}\) sleep (rapid eye movement)
To distinguish these stages we use:
◦\(\sf \color{#21ABCD}{Electroencephalogram}\) (EEG) for measuring brain activity
◦\(\sf \color{#21ABCD}{Electro–oculogram}\) (EOG) to record eye movements
◦\(\sf \color{#21ABCD}{Electromyogram}\) (EMG) to measure muscle tone

Take a look at how the waves look like in each of these procedures.

Answer 2

The definition of sleep is very important. UNCONSCIOUS yet possible to get the person to wake up by SENSORY stimulus or some other stimuli. In COMATOSE (coma) state, its also unconscious state except the individual cannot be aroused with same types of stimulus like that of sleep state.

Answer 3

Now before we go into stages of sleep, lets take a look at types of waves seen in EEG

◦\(\sf \color{#FF0038}{Alpha}\) – are seen in normal adults when they are awake and in quiet resting state of cerebration. Are absent during deep sleep.
◦\(\sf \color{#FF0038}{Beta}\) – when person’s attention is fully on a specific task/mental activity, alpha waves are replaced by low frequency beta waves.
◦\(\sf \color{#FF0038}{Theta}\) – emotional stress such as disappointment and frustration in adults. Also occur in many brain disorders. (Neurodegenerative)
◦\(\sf \color{#FF0038}{Delta }\)– very deep sleep & in very serious organic brain diseases. It occurs strictly in the cortex independent of activities in lower regions of brain.

Take a look at waves here:

Answer 4

\(\huge\sf \color{#ED9121}{Slow – wave~sleep~ or~ non- REM ~sleep}\)

\(\sf \color{#ED9121}{Stage~ 1}\): transition between wakeful and sleep state – not yet asleep stage.
◦EEG exhibits a decrease in high-frequency activity that characterizes ‘wakefulness’.

\(\sf \color{#ED9121}{Stage ~2}\): first true stage of sleep. EEG exhibits onset of spindle waves and K-complexes.
◦There are slow, synchronized oscillations of neuronal and synaptic activities within thalamus and cerebral cortex.
◦This is followed by gradual inactivation of the brain mechanisms of arousal.
◦Muscle tone decreases; eyes slowly roll back and forth; respiration becomes more regular and slows; body temperature begins to fall.

\(\sf \color{#ED9121}{Stage~ 3}\):
◦Appearance of delta wave oscillations (0.5–4 Hz).
◦Arousal processes keep reducing; synchronization of cortical and thalamic activity continues.

\(\sf \color{#ED9121}{Stage ~4}\):
◦Predominance of delta waves in EEG shows that the person is in state of deep sleep.
◦During stages 3 & 4: respiration continues to be slow and regular; heart rate slows; muscles relax; and body temperature slowly decreases.

Take a look at attached pictures.

Answer 5

\(\huge\sf \color{#967BB6}{REM~ sleep}\)
◦Overall brain metabolism is \(\sf \color{#967BB6}{increased}\) to as much as 20%. EEG shows patters that resemble wakefulness.
◦This cycle keeps going throughout our sleep jumping from one stage to another followed by brief stage of REM sleep
◦As the night progresses, the depth of non-REM sleep \(\sf \color{#967BB6}{decreases}\) and the duration of REM sleep \(\sf \color{#967BB6}{increases}\).
Because of this pattern the \(\sf \color{#967BB6}{dreams}\) that take place in the morning are the ones most often remembered. This type of sleep can be called \(\sf \color{#967BB6}{paradoxical~ sleep}\) because the person can still be asleep despite a quite high brain activity
Which means if you get a dream in the middle of night, you will most probably forget it.

Answer 6

\(\huge\sf \color{#FF9999}{Dream}\)
Inability to remember dreams is one of the mysteries of sleep. Dreams mostly reflect our everyday life events.

Only a small percentage of dreams contain bizarre and fantastic elements.
◦Dreams occur in both REM and non-REM sleep but have different characteristics:

◦\(\sf \color{#FF9999}{REM ~dreams }\)are \(\sf \color{#FF9999}{long}\), primarily \(\sf \color{#FF9999}{visual}\), somewhat \(\sf \color{#FF9999}{emotional}\), and usually are \(\sf \color{#FF9999}{not~ connected ~to ~immediate~ events~ of~ everyday~ life}\).

◦\(\sf \color{#20B2AA}{Non-REM~ dreams}\), however, are \(\sf \color{#20B2AA}{shorter}\), \(\sf \color{#20B2AA}{less~ visual}\), \(\sf \color{#20B2AA}{less ~emotional}\), and are \(\sf \color{#20B2AA}{related~ to~ current~ life~ of ~the~ dreamer}\). (thought-like mental activity can occupy up to 50% of non-REM sleep)

***Events in dreams occur over a period of time that is about as long as they would be in real time*** If your dream state was to be monitored by EEG it would be couple of minutes but you, the dreamer, will feel like it was couple of hours or a day, and that it because indeed in real life the event that took place in your dream would take that much time, but again, it was a dream. :)

Answer 7

\(\huge\sf \color{#FF9999}{Fun ~Fact: (づ￣ ³￣)づ}\)
You know sometimes you see faces in your dream? Like new people and all, or new places. Well they really do exist. You've seen those people in real life, and the places too but your conscious self has forgotten about them as they are not marked as important memories. So yeah, your brain uses preexisting scenes, faces, places to make up movie for you, sometimes with a bizarre and scary genre. How cool is that (๑>ᴗ<๑)

Answer 8

So we talked about sleep, stages of sleep, the waves, dreams and all but
\(\huge\sf \color{#32CD32}{What~ causes ~us ~to~ sleep?}\)
Sleep is believed to be caused by an \(\sf \color{#32CD32}{active ~inhibitory}\) process that is generated in brainstem at level of \(\sf \color{#32CD32}{midpons}\). This level is referred to as cortex that never goes to sleep. Such a cool name (ˆ⌣ˆԅ)
It is assumed that levels below midpons play a big role in inhibition of some brain areas, and this in turn lead to sleep state.
Well, this was a simple way to put it, now lets go into some details, don't be scared my fellow learners :3

Answer 9

\(\sf \color{#BCD4E6}{Raphe~ nuclei}\) in the lower half of the pons and in the medulla

◦ Nerve fibers from this nuclei spread in the brainstem reticular formation; upwards into thalamus and hypothalamus; areas of limbic system & neocortex of cerebrum.
◦ Fibers also go downwards into spinal cord and terminate in sensory region which is posterior grey horn. So it plays role in \(\sf \color{#BCD4E6}{inhibition}\) of incoming sensory signals. [ Please remember this point! Its very important, we'll talk more about it later when we go into pathology in next parts of this tutorial :D ]

◦ Nerve fibers coming from raphe nucleus secrete \(\sf \color{#BCD4E6}{Serotonin}\) as their main neurotransmitter (so it is an \(\sf \color{#BCD4E6}{inhibitory}\) neurotransmitter)

The possible role of serotonin in promoting sleep was found to be true after administering drugs that would block formation of serotonin in animals. It was observed that animals could not sleep for the next several days.

Take a look at the location of raphe nuclei and where fibers go to in this pictures

Answer 10

Extra mini info:
Stimulation of some areas of nucleus \(\sf \color{#682860}{tractus~ solitarius}\) can also cause sleep. (this tract receives different sensory input from viscera and tongue as well as plays role in visceral reflex)

Regions in diencephalon: \(\sf \color{#682860}{rostral ~part~ of~ hypothalamus}\) and some nucleus of \(\sf \color{#682860}{thalamus}\) also play role in promoting sleep. We'll talk about it more in \(\sf\color{#78184A}{Circadian~ rhythms~ and~ Sleep-wake~ cycle}\) tutorial which is coming up next.

Answer 11

so, \(\sf\huge \color{#B7410E}{What~ if~ we ~don′t~ sleep?}\)
Take a look at this video to find out the answer to this question
my dear owls ( ˘ ³˘)❤

https://www.youtube.com/watch?v=P-Kxr52mPic

or a full version

https://www.youtube.com/watch?v=85Geq01QevQ

Answer 12

Take a look at this one too, its for the healthy population, i mean those that don't have Fatal Familial Insomnia :3

https://www.youtube.com/watch?v=qPoZVQvsbW0

Answer 13

-Now this shall be the end of this part of the tutorial-
\(\sf\huge \color{#FF0028}{−To ~Be~ Continued−(๑>ᴗ<๑)}\)

Answer 14

Somy, I wanted to take the 5 month course in college about sleep, but you ruined it.

Answer 15

Well don't read it then? lol

Answer 16

Too late.

Answer 17

It's good though, nice job.

Answer 18

Well let me break it to you then, its a big topic and still being researched so you have a lot more to learn :)

Answer 19

Thanks e.e

Answer 20

No problem :)

Answer 21

Very well done, dear.

Answer 22

Thank you <3

Answer 23

Excellent job, @Somy! :)

Answer 24

There are many complex and even cascading events that occur if we did not sleep. One that immediately comes to mind is the disruption of the formation of melatonin which help promote sleep. It is probably due to the over accumulation of adenosine that did not break down because of lack of sleep (I have to double check) that melatonin formation is hindered. The adenosine over accumulation leads to drowsiness as well. If melatonin is affected, it also lead to the disruption of internal clock regulation - the circadian rhythm - for other cell functions such as replication, repair and other crucial events like other hormone formation and regulation.
The bottom line, that person who is trying not to sleep for prolonged periods of time is doomed.

There is one thing that interests me and I might investigate in the future. This is the relationship of REM and temperature regulation. It is currently documented in literature that during REM, there is a slight decrease in effective regulation of body temperature. The interesting part is what happens to the regulation of temperature in the prolonged lack of sleep. If the hypothalamus is not optimally regulating temperature during REM, would the lack of sleep also reduce the regulation of body temperature. IF both are true, then perhaps we can study where these two non-optimal regulation can converge or intersect. I do not know what kind of uses this study will lead us, but it is something worth probing. truly, your wanna be biologist, a dumb one perhaps.

Answer 25

@hwyl @nincompoop they did study it http://www.herseninstituut.knaw.nl/Portals/0/Department/Someren/pdfs/Sleep_2012_Romeijn.pdf
are you sure about the fact that its during REM though?

Answer 26

I forgot to add this picture when talking about REM

Answer 27

Yes. It is documented in literatures that there is a decrease in thermal regulation during REM as well as SWS.

Answer 28

The interaction between sleep and thermoregulation in adults and neonates
Bach, Veronique et al.
Sleep Medicine Reviews , Volume 6 , Issue 6 , 481 - 492

Answer 29

AHH Good stuff. I will read that file sometime and figure out how to extend the studies.

Answer 30

yeah its quite interesting and in fact it makes sense considering the fact that brain doesnt function all too well if sleep deprived

Answer 31

I do not know if it does not "function all to well," because it is relative. I am looking at it more broadly in terms of systemic interaction and focus on chemical

Answer 32

molecular level eh, gonna be hard; functionally speaking, by not too well i mean unorganized; kinda when you are sleep deprived, your emotional state is horrible, meaning unstable, somehow your brain is more sensitive to minor stimulus that could be ignored or down-regulated in normal state and its like half asleep most of the time; cortex for sure is not doing too well in this state, even memory is not good and constant fatigue; at least thats what i observed
whats the most interesting part of Fetal Familial insomnia was the fact that though the individual looked awake, his eyes were open yet he was in REM state having a dream

Answer 33

i mean in normal cases you have to go through through first 4 stages of sleep then enter REM but in this case the patient goes straight into REM

Answer 34

@Somy This is great! I learned a lot about this in my AP psychology class, but I'm specifically going to take a neuroscience class over the summer and we'll learn the sleep cycle again. I enjoyed reading this: you're very knowledgeable!

Answer 35

Thank you :) @kikuo

Answer 36

Very good explainations Somy!

Answer 37

@MedicalDoctor Thank you sir :D

Answer 38

woah

Answer 39

Good Job Somy! Great post! This should be big help for me in my course. ^.^

Answer 40

are you interested in neuroscience? @somy

Answer 41

yeah its very interesting for me :) @DF001