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36 Cards in this Set

  • Front
  • Back
Which rhythm repeat time is longer than a day?
Which rhythm repeat time is shorter than a day?
Which rhythm repeat time is about a day?
What causes a circadian rhythm to be 24 hours?
External cues such as sunlight
How long is our circadian rhythm without external cues?
About 26 hours
What stucture acts as our internal clock?
Suprachiasmatic nucleus
How many nuclei are in the SCN?
What happened in experiments where rats were kept in the dark all the time?
They still exhibited regular sleep/wake cycles
What happened when the rat's SCN was obliterated?
The rat lost all semblence of a sleep/wake schedule.
When the mutated Tau was transplanted into a wild-type rat, what was the result?
Loss of circadian rhythm
What exactly about the SCN actually causes the circadian rhythm?
Fluctuations in the firing rate of the neurons in the SCN.
What helps synchronize the neurons of the SCN?
Gap junctions
What NT helps synchronize the SCN?
How many "clock" genes are there and what are their purposes?
1. 4
2. Per & Cry are proteins
3. Clock and BMAL are transcriptional regulators of Per and Cry
What process is very important in the regulation of Per and Cry?
Negative feedback (there is also a positive feedback)
Explain how negative feedback works.
1. As Per and Cry are transcribed in excess they form dimers
2. The dimers then go back and interact with Clock and BMAL. Once a significant amount of Per and Cry dimers have been degraded, Clock and BMAL can cause the transcription of Per and Cry
What happens if you knock-out any of the genes for the internal "clock"?
You no longer have a circadian rhythm.
What substance proves that the clock drives the firing of the neuron and not the other way around.
Tetrodotoxin - blocks the action potentials but when administration ends the clock fires back up
What is the direct pathway from the retina to the SCN?
Retino-hypothalamic tract
What NT released in from the SCN helps in entraining?
Glutamate (along with GABA for rhythm)
If intracellular concentrations of this element are increased, entraining occurs.
Is the output of the SCN diffuse of not?
Very diffuse throughout the cortex
Sleep is a(n) (active/passive) process
What are the two sleep states?
2. REM
What is the best way to look at brain activity during sleep?
What does the EEG look like while we are awake?
High frequency, desynchronized, low voltage
What does the EEG look like while we are in NREM?
Low frequency, high voltage synchronized firing
What does the EEG look like while we are in REM?
Is like the awake pattern but muscles are paralyzed and eyes are moving a lot.
As we age (3)...
1. Sleep less
2. REM stays the same
3. NREM decreases
What maintains wakefulness? What happens with a tumor here?
1. Reticular activating system
2. Coma
What neurons produce NREM sleep?
Thalamocortical neurons
What happens to cause NREM sleep?
1. P-type Ca channels are open allowing bursting to occur
2. Burtsing causes slow wave cortical formations seen as NREM sleep
REM-ON centers release what NT?
REM-OFF centers release what NT?
Nor-epinephrine and Seratonin
What is described as the difference between our need for sleep and the timing mechanism for sleep?
Sleep pressure
Does circadian rhythm really ever change?
Not really