Study Guide 8: Neuromodulation and Circadian Rhythm

These flashcards cover key concepts related to neuromodulation and circadian rhythms, including the functions of specific systems, mechanisms of circadian generation, and implications for sleep and health.

What are diffuse modulatory systems?

Systems of neuromodulators that modulate levels of excitability in the CNS through volume transmission.

What are the four major diffuse modulatory systems?

Norepinephrine, Serotonin, Dopamine, and Acetylcholine.

What behaviors are associated with activation of the noradrenergic system?

Regulation of attention, arousal, sleep-wake cycles, learning and memory, anxiety, pain, mood, and brain metabolism.

What is the role of the serotonergic system in the brain?

Involved in sleep/wake cycles and stages, mood control, consciousness, and motivation.

What is a consequence of degeneration in the dopaminergic system?

It can result in Parkinson's disease.

What is the primary function of the cholinergic system?

Its functions are not completely understood, but it is implicated in arousal, sleep-wake cycles, learning, and memory.

Why might drugs affecting neuromodulatory systems have multiple side effects?

They act on many receptors throughout the brain and CNS, and may unintentionally influence other receptors.

How is a circadian rhythm generated?

It is generated by the suprachiasmatic nucleus (SCN), which regulates rhythmic activities throughout the body.

What role do ipRGCs play in circadian rhythms?

They respond to light independently of rods and cones and send signals to the SCN for entraining circadian rhythms.

What are the effects of poor adaptation to night-shift work?

It could lead to disruptions in the immune system, endocrine system, and overall bodily functions.

What scheduling pattern would improve night-shift worker performance?

Block scheduling of 1-2 months per shift allows the SCN and bodily functions to adjust properly.

What causes the EEG signal during sleep?

It is caused by the electrical activity of groups of neurons, primarily through calcium ion flow in cortical pyramidal neurons.

What characterizes the architecture of a night's sleep?

Includes multiple stages with specific EEG patterns, cycling every 90 minutes, with REM sleep proportion increasing throughout the night.

What is the endogenous source of melatonin?

The pineal gland, which increases melatonin production in the evening and during sleep.

Why is eliminating exposure to blue light before sleep recommended?

Blue light activates ipRGCs, which influence the SCN; avoiding it promotes better sleep hygiene by enhancing melatonin production.

What are diffuse modulatory systems?

Neuromodulator systems that act through volume transmission to modulate CNS excitability.

List the four major diffuse modulatory systems.

Norepinephrine, Serotonin, Dopamine, Acetylcholine.

What does the noradrenergic system regulate?

Attention, arousal, sleep-wake, learning, mood, pain, metabolism.

What does the serotonergic system regulate?

Sleep/wake cycles, arousal, mood, emotional behavior.

What is the dopaminergic system involved in?

Voluntary movement, Parkinson’s disease, reward and reinforcement.

What functions are associated with the cholinergic system?

Arousal, learning, memory; involved in Alzheimer's disease.

Why do drugs targeting neuromodulatory systems have many side effects?

They act on widespread receptors in different brain/body regions, often nonspecifically.

What brain structure generates the circadian rhythm?

The suprachiasmatic nucleus (SCN).

How does light entrain circadian rhythms in the SCN?

Via ipRGCs signaling through the retinohypothalamic tract.

Do rods and cones play a role in circadian entrainment?

Not essential; ipRGCs can function without rods and cones.

Would SCN neurons be sensitive to body temperature?

Yes, directly or via synapses to temperature-sensitive neurons.

Why is dim light ineffective for night-shift adaptation?

ipRGCs are weakly activated, leading to insufficient SCN entrainment.

What are consequences of poor adaptation to night-shift work?

Disrupted SCN output, immune, endocrine, and ANS dysfunction.

Which shift schedule is better for circadian alignment?

Block scheduling (e.g., 1–2 months per shift) allows better SCN adjustment.

What causes EEG signals during sleep?

Ion flow through cortical pyramidal neurons; recorded from scalp.

Describe the stages of sleep and their EEG features.

Stage 1: theta; Stage 2: sleep spindles/K complexes; Stage 3: delta; REM: fast, random.

How does REM proportion change during the night?

REM increases while deep sleep (Stage 3) decreases.

What is the source of endogenous melatonin?

The pineal gland.

How does melatonin help with jet lag?

It mimics endogenous melatonin to help reset circadian rhythm.

Why avoid blue light before bed?

ipRGCs are activated by blue light, reducing melatonin and increasing SCN firing, disrupting sleep.