Stages of Sleep
What does an EEG measure?
The synchrony of neuronal activity (net electrical charge produced by neurons increasing or decreasing their activity as a group)
What's a circadian rhythm (+ list at least one potential disruption to circadian rhythms)
A circadian rhythm is the internal biological clock that regulates various physiological processes in a roughly 24-hour cycle.
Things that can disrupt circadian rhythms include: working night-shift, jet lag, excessive exposure to electronics at night, irregular sleep patterns, etc
What is cataplexy?
Cataplexy is a sudden and temporary loss of muscle tone that can be triggered by strong emotions (associated with Narcolepsy type I)
Describe the two types of attention. How do they impact our focus and distraction?
Voluntary attention = conscious control of attention to a specific object or location
Involuntary attention = distraction from your chosen goals
What are the primary characteristics of slow wave sleep (SWS)?
SWS is characterized by high amplitude and low frequency brain waves. It represents deeper stages of sleep.
Which brain region is involved in suppressing wakefulness to facilitate sleep?
The ventrolateral preoptic nucleus is the brain region (inside the hypothalamus) responsible for suppressing the systems that keep us awake.
What neuron deficiency is present with individuals with narcolepsy (especially type I)?
Deficiency of orexin
What is the default mode network?
The default mode network is a network of brain regions that is active when a person is at rest and not focused on the external environment.
How does the amount of time a person stays awake influence their experience of SWS?
The longer a person stays awake, the more slow waves they will experience during SWS, indicating a greater need for restorative sleep.
Where does the Suprachiasmatic Nucleus (SCN) receive its input?
The SCN receives direct input from the retina (specifically light-sensitive retinal ganglion cells), which allows it to respond to changes in light and dark conditions.
What role do orexin neurons play in narcolepsy? (think: sleep-wake cycle)
Orexin neurons help maintain wakefulness and regulating the sleep-wake cycle. The loss of orexin leads to inability to stay awake and alert (sleep attacks)
How do the activity levels of the default mode network change from the evening to early morning?
Activity levels of the default mode network often increase during restful periods in the evening and decline during the night when the individual is asleep.
What happens to neuronal synchronization during REM sleep, and how does it differ from SWS?
During REM sleep, neuronal synchronization decreases, as some nerve cells depolarize while others hyperpolarize, counteracting each other's activity. In contrast, SWS features synchronized activity among neurons, resulting in high amplitude waves.
How do the clock proteins in the suprachiasmatic nucleus contribute to sleep and hormone regulation?
Clock proteins in the SCN help regulate circadian rhythms by going through a roughly 24-hour cycle, which sets the timing for various physiological processes, including sleep-wake cycles and hormone release. These proteins control the expression of other genes involved in maintaining the body's internal clock, ensuring proper timing for activities like sleep, hormone secretion (eg: melatonin), and other functions.
In what ways does the loss of orexin impact REM sleep transitions during the day for individuals with narcolepsy?
Normally, REM (Rapid Eye Movement) sleep is characterized by muscle atonia, which people from acting out their dreams.
With narcolepsy, REM sleep can occur at and leads to individuals experiencing REM sleep-like features while awake. This includes episodes of cataplexy, where muscle tone is lost suddenly. As a result, the physiological regulation during REM sleep is disrupted, which can lead to symptoms like excessive daytime sleepiness and sudden muscle weakness.
In what manner does the hippocampus contribute to memory formation when the brain is in a restful state?
When the brain is in a restful state, such as during quiet wakefulness or sleep, the hippocampus is actively involved in the consolidation of memory (formation of long term memory)