Lecture 8-Brain & Circadian Rhythmn Flashcards
What factors are known to contribute to the development of Alzheimer’s and vascular dementia?
Neuroinflammation and oxidative stress are key contributors to the development of Alzheimer’s and vascular dementia.
How does obstructive sleep apnea contribute to Alzheimer’s disease and vascular dementia?
Obstructive sleep apnea disrupts glial clearance, causing a buildup of amyloid-beta and tau proteins, linked to Alzheimer’s disease and vascular dementia.
What is the role of glial cells in brain health, and what do they clear out?
Glial cells play a critical role in maintaining brain health by clearing out toxic metabolites, such as amyloid-beta 42 (Aβ42) peptide, which is implicated in Alzheimer’s disease.
What is Vascular Dementia and what causes it?
Vascular dementia is a type of dementia caused by impaired blood flow to the brain, often due to strokes or other vascular conditions.
What is the consequence of inadequate clearance of Aβ42 in the brain?
Inadequate clearance of Aβ42 in the brain can lead to the accumulation of amyloid plaques and tau proteins, both of which are associated with the development of Alzheimer’s disease.
What is the function of the glymphatic system in the brain?
Functions as a waste clearance system that uses perivascular channels formed by astroglial cells to eliminate soluble proteins and metabolites from the central nervous system.
Compare Sleep EEG and awake EEG
Sleep EEG slow and rhythmic; awake EEG is fast and irregular.
What is the role of the AQP4 protein in the brain’s waste clearance process?
The AQP4 protein functions as a water-transporting channel, facilitating the movement of metabolic waste across the blood-brain barrier into veins for clearance.
What is a circadian rhythm and how does it typically manifest in the presence of day-night cues?
A circadian rhythm is a natural, internal process that regulates the sleep-wake cycle and repeats roughly every 24 hours
How does the absence of external cues affect the body’s circadian rhythm?
Without external cues, the body’s circadian rhythm persists, but the wake-sleep cycle may fluctuate based on the individual’s internal biological clock, which may not perfectly align with the 24-hour solar day.
When does the core body temperature start to decrease in relation to circadian rhythms?
The core body temperature begins to decrease in the early evening, following the circadian rhythm.
How does the secretion of growth hormone change throughout the day according to circadian rhythms?
Growth hormone levels begin to increase in the early evening, in alignment with circadian rhythmicity.
What role do photosensitive retinal ganglion cells (RGCs) play in signaling circadian light changes?
Photosensitive retinal ganglion cells (RGCs) detect changes in light intensity, playing a crucial role in signaling circadian light changes to the brain
What happens to photosensitive RGCs when the light intensity increases?
Increasing light intensity triggers a burst of action potentials in photosensitive RGCs.
What role does the hypothalamus play in relation to photosensitive RGCs?
The hypothalamus is involved in processing physiological responses like sleep-wake cycles and hunger, and it works in conjunction with RGCs to regulate these responses.
Explain the process through which light signals from the environment are processed by the brain to regulate the body’s internal clock,
1)Light enters the eye and is detected by retinal ganglion cells.
2) These cells send the light signal to the hypothalamus, specifically the suprachiasmatic nucleus (SCN).
3)The SCN is the body’s master clock. It processes the signal and sends information to other parts of the brain.
One key area it communicates with is the pineal gland, which is involved in producing melatonin
4) The signal from the SCN also travels down the spinal cord and back up to the pineal gland through a pathway involving the superior cervical ganglion.
5) These pathways help the body adapt to the day-night cycle, influencing sleep, wakefulness, and other bodily functions.
Describe how genes are connected in the regulation of the circadian rhythm.
Genes interact in a feedback loop to control the circadian rhythm, with their proteins regulating the cycle by interacting with each other.
How does light influence the circadian rhythm at the molecular level?
Light affects the transcription of clock genes, leading to the production of proteins like CLOCK and BMAL1. These proteins form complexes that control the expression of other genes like PER and CRY, establishing a 24-hour feedback cycle
Where are Pyramidal Cells located and what to they generate?
Located in the deeper layers of the cortex, generates the electric fields that provide the source of current for EEG?
What is the outcome of oscillatory rhythms between neurons in the thalamus and cortex, and what kind of activity does it involve?
Oscillatory rhythms between thalamic and cortical neurons produce changing electrical fields, driven by synaptic activity, resulting in a negative superficial extracellular space relative to deeper cortical regions.
What characterizes the synchronous activity during deep sleep?
Deep sleep is characterized by synchronous activity, particularly delta waves in the EEG (Electroencephalogram).
In the pyramidal cell layer below an EEG electrode, what happens when neurons receive irregular or out-of-phase synaptic inputs?
Irregular or out-of-phase synaptic inputs to neurons lead to low-amplitude, high-frequency brain activity, resembling the waking state (beta activity).
If the pyramidal cells receive synaptic inputs that are synchronous or in phase, what type of EEG waves would you predict?
Low frequency. high amplitude, as seen in delta waves during stage IV sleep.
What are EEG oscillations the result of?
Result of synchronized electrical activity in neurons, driven by reciprocal interactions between excitatory and inhibitory neurons within neural circuits.
