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Principles of Med Neuroscience > L.2.4 > Flashcards

L.2.4 Flashcards

1
Q

What are brain rhythms

A

Brain rhythms are patterns of brain activity that align with environmental and biological changes

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2
Q

how do brain rhythms relate to environmental factors?

A

these rhythms are influenced by factors such as temperature, day/night cycles, and tides.

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3
Q

What are some examples of brain rhythms?

A

Brain rhythms include sleep-wake cycles, breathing patterns, steps while walking, and stages of night sleep

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4
Q

What is the function of an Electroencephalogram (EEG)?

A

An EEG measures brain activity, particularly useful for detecting abnormal brain rhythms

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5
Q

How does an EEG detect brain activity?

A
  • An EEG involves placing a mesh of electrodes on the head to detect electrical activity from neurons
  • signals are then analyzed to identify abnormal brain patterns.
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6
Q

Why are EEGs good for detecting epilepsy?

A

The synchronized firing of many neurons produces a large enough signal to be detected on the scalp

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7
Q

Why is it difficult to record EEG signals from deeper brain layers?

A

harder to detect their signals via EEG, as the signal needs to travel through several cortical layers to reach the scalp.

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8
Q

What are the basic requirements for signal detection in EEG?

A
  • Population Synchrony
  • Parallel Alignment:
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9
Q

What is population synchrony

A

A large group of neurons must fire synchronously to generate a strong enough electrical field

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10
Q

What is parallel alignment

A

Neurons must be aligned in parallel to combine their electrical signals effectively.

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11
Q

What happens when neurons fire in synchrony for EEG signal generation?

A
  • When neurons fire synchronously, it creates a strong, detectable EEG signal with high amplitude
  • allows the signal to be measured effectively at the scalp
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12
Q

What happens when neurons fire irregularly,

A
  • the EEG signal becomes weak because increases and decreases in electrical activity cancel each other out
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13
Q

how does irregular neuron firing affect EEG signals?

A

low amplitude and meaningless signals.

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14
Q

What factors influence the amplitude of EEG signals?

A
  • Number of active neurons:
  • Total excitation level in neurons
  • Timing of activity
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15
Q

How does the number of active neurons influence amplitude of EEG signals

A

More active neurons generate a stronger signal.

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16
Q

How does the total excitation level in neurons influence amplitude of EEG signals

A

Higher excitation levels contribute to a stronger signal.

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17
Q

How does the timing of activity influence amplitude of EEG signals

A

More synchronous firing of neurons results in a stronger signal.

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18
Q

What does the alpha rhythm in EEG indicate

A
  • the alpha rhythm (8-13Hz) occurs when a person is awake but has their eyes closed
  • moderate synchronization without visual input
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19
Q

What does the beta rhythm in EEG indicate

A
  • The beta rhythm (14-60Hz) occurs during mental activity and attention, especially when the eyes are open
  • associated with active thinking and sensory processing
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20
Q

Why is the amplitude low for beta rhythm

A

The amplitude is lower, as brain activity is less synchronized

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21
Q

What do theta waves in EEG indicate

A

Theta waves (4-7Hz) indicate drowsiness, sleep

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22
Q

Why do theta waves have moderate amplitude

A

synchronization changes.

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23
Q

What do delta waves in EEG indicate

A

Delta waves (<4Hz) occur during deep, non-REM sleep.

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24
Q

What are the amplitude of delta waves like

A

They have very slow frequency and high amplitude due to synchronized neurons, as minimal external environmental processing occurs

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25
Q

What EEG patterns are observed during awake state

A

alpha (eyes closed) and beta (eyes open, active attention)

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26
Q

What EEG patterns are observed during REM sleep

A

Low amplitude and fast activity, indicating unsynchronized brain activity, associated with dreaming

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27
Q

What EEG patterns are observed during non-REM sleep

A

Light sleep: Theta waves.
Deep sleep: Delta waves (slow, high amplitude, synchronized neurons).

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28
Q

What are the 2 ways synchronisation of neurons is generated

A
  • pacemaker activity
  • collective interaction
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29
Q

What is pacemaker activity

A

when certain neurons (pacemakers) generate rhythmic discharges that help synchronise the other cells

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30
Q

What is the collective interaction in neuron synchronisation

A

neurons synchronise their firing based on the activity and rhythm of nearby neurons

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31
Q

How does the thalamus act as an oscillator

A

they have voltage-gated ion channels that enable rhythmic firing without external input

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32
Q

How does the thalamus act as an oscillator during awake state

A

when depolarised, the thalamic neurons exhibit continuous activity

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33
Q

How does the thalamus act as an oscillator during the sleep state

A

when hyperpolarised the thalamic neurons activate low threshold ca2+ channels that produce rhythmic bursts

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34
Q

What are the 3 main functions of brain rhythms

A
  • regulates what sensory information reaches conscious awareness
  • activity coordination of different cortical regions
  • meaningless by product of feedback circuits and connections
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35
Q

Why do prey animals sleep in short bursts

A
  • remain vigilant for survival
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36
Q

Why do dolphins and seals have unihemispheric sleep

A

it allows them to stay alert to environmental threats or come up to the surface to breathe

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37
Q

What is unihemispheric sleep

A

one hemisphere of the brain sleeps while the other remains awake

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38
Q

Why is it important for predatory animals to have uninterrupted sleep cycles

A

for rest and cognitive processing

39
Q

What are behavioural criteria for sleep

A
  • reduced motor activity
  • decreased response to stimulation
  • can easily be interrupted
40
Q

What is the functional importance of the awake state

A

active information processing

41
Q

What is the functional importance of non-rem sleep

A

physical recovery and memory consolidation

42
Q

What is the functional importance of rem sleep

A

consolidating learning

43
Q

What are the functions of sleep and dreaming

A
  • conserves metabolic energy
  • cognition processing
  • mental health
44
Q

What are the characteristics of the awake state in terms of input

A

External input.

45
Q

What are the characteristics of the awake state in terms of modulation

A

Driven by aminergic neurotransmitters like norepinephrine and serotonin.

46
Q

What are the characteristics of the awake state in terms of activation

A

high activation

47
Q

What is the role of histamine in awake state

A
  • contribute to alertness.
  • antihistamines contribute to drowsiness
48
Q

What are the characteristics of non-REM sleep in terms of input

A

Intermediate (some external processing but primarily internal).

49
Q

What are the characteristics of non-REM sleep in terms of modulation

A

Decreased aminergic activity as the brain enters a restful state, with the thalamus beginning to oscillate

50
Q

What are the characteristics of non-REM sleep in terms of activation

A

Moderate to low; thalamic and cortical synchrony increases, reflecting deep rest and energy conservation

51
Q

What are the characteristics of REM sleep in terms of input

A

internal

52
Q

What are the characteristics of REM sleep in terms of modulation

A

Low aminergic activity and high cholinergic activation, especially in brainstem regions.

53
Q

What are the characteristics of REM sleep in terms of activation

A

High cortical activation levels, resembling those seen in wakefulness, which results in rapid eye movements and dreaming characteristic of REM sleep

54
Q

What is anesthesia?

A

a reversible drug-induced absence of sensation and awareness

55
Q

How does anesthesia work?

A

Anesthesia works by using any lipid-soluble agent that depresses the brain in a specific order:

56
Q

What happens if cortex is under anesthesia

A

absence of consciousness and awareness

57
Q

What happens if the spinal cord is under anaesthesia

A

absence of reflexes and movement)

58
Q

What happens if the medulla is under anaesthesia

A

absence of vital autonomic functions like breathing

59
Q

What is meant by range of anesthetics?

A

A diverse range of agents with different chemical structures and mechanisms of action

60
Q

Why is lipid solubility important for anesthetics?

A

Determines the ability of anesthetics to cross the cell membrane (blood-brain barrier).

61
Q

What are 2 ways anesthetics can be administered

A

Can be inhalational or intravenous.

62
Q

What does it mean if anesthetic is more lipid soluble

A

More lipid-soluble agents have a faster onset of action.

63
Q

How do anesthetics interact with membrane proteins?

A

Anesthetics bind to membrane proteins like receptors and regulate neuronal excitability.

64
Q

What happens during the global depression of neuronal activity?

A

Anesthetics cause a global decrease in brain activity, leading to loss of consciousness

65
Q

How do anesthetics stimulate inhibitory receptors?

A
  1. Anesthetics stimulate GABA(A) and glycine receptors in the brain
  2. allows Cl- ions to flow into neurons, causing hyperpolarisation
  3. Hyperpolarisation reduces neuronal excitability, creating a sedative and anesthetic effect.
66
Q

How do anesthetics inhibit excitatory receptors?

A
  1. Anesthetics inhibit nicotinic, serotonin, and glutamate/NMDA receptors
  2. prevents the flow of Ca2+ and Na+ ions into neurons
  3. Reduced neuronal excitability and a lower likelihood of neurons firing
67
Q

What does anaesthesia Inhalation entail

A

Patient breathes in gases; suitable for children and the elderly.

68
Q

What does intravenous anesthesia mean

A

Administered intravenously for quick effect.

69
Q

Name examples of inhalational agents

A

oxygen, nitrous oxide and Isoflurane & other volatile agents

70
Q

Why is oxygen used during anesthesia

A

Maintains breathing during anesthesia

71
Q

Why is nitrous oxide used during anesthesia

A

Provides analgesic and anesthetic effects.

72
Q

Why is isoflurane used during anaesthesia

A

Act quickly, are controllable, and enable smooth anesthesia with fast recovery.

73
Q

What are the cons of oxygen use in anesthesia?

A
  • High concentrations increase fire risk
  • O2 free radicals causing cellular damage.
74
Q

What are the pros of using nitrous oxide in anesthesia?

A
  • Highly soluble (35x more than N2), enters blood fast, and acts quickly.
  • Wears off quickly, making it controllable
75
Q

What are the cons of nitrous oxide use?

A
  • High solubility can expand gas-filled spaces, unsuitable for surgeries with gas buildup risks
  • Not strong enough as an anesthetic alone but effective for pain relief.
76
Q

What are the physical properties of inhalational agents?

A
  • expensive
  • stable over time; resistant to breakdown.
  • Easily converted to gas for inhalation
77
Q

Why is chemical stability important in anesthesia

A

chemical stability ensures reliability over time.

78
Q

Why is vaporability important in anesthesia

A

Vapourisability allows easy delivery during anesthesia.

79
Q

What are the chemical properties of inhalational agents?

A
  • Non-irritant: Gentle on lungs and throat.
  • low blood solubility: Rapid entry and exit from the bloodstream for fast onset and recovery
  • High potency (low MAC): Effective at low concentrations
80
Q

Why aren’t older inhalational agents (like ether and chloroform) used anymore?

A
  • slow onsets
  • Serious side effects (toxicity)
  • Newer agents are safer, more effective, and better controlled
81
Q

how does isoflurorane work?

A
  • Increases GABA activity → hyperpolarization → reduces neuronal excitability.
  • CNS depression, leading to loss of consciousness and sensation during surgery
82
Q

Why is isoflurane important in modern anesthesia?

A
  • Low cost and stability: Makes it accessible and reliable.
  • Controlled anesthesia: Depth can be easily adjusted during surgery.
83
Q

What are the side effects of isoflurane?

A
  • Changes in heart rate and blood pressure.
  • Respiratory depression
84
Q

What is sevoflurane and how does it work?

A
  • Halogenated ether used for general anesthesia
  • Increases GABA activity → hyperpolarization → reduces neuronal excitability
85
Q

What are the side effects of sevoflurane?

A

Agitation and confusion in some patients after waking

86
Q

What are the features of sevoflurane?

A
  • High MAC → higher concentration needed for effect.
  • Non-irritable to airways
  • minimal toxic metabolites
87
Q

Why are intravenous agents preferred for induction?

A
  • Rapid onset: Induces anesthesia quickly.
88
Q

What are the pharmacokinetics of IV anesthetic agents?

A
  • Lipid-soluble: Easily cross cell membranes and enter the CNS.
  • Quickly distribute to various tissues → short-acting process
89
Q

What are the potential side effects of IV anesthetic agents?

A
  • Cardiovascular depression: Reduced heart function.
  • Respiratory depression: Requires careful monitoring during administration
90
Q

What is the function of thiopentone

A

Helps control seizures

91
Q

What are the side effects of thiopentone

A
  • Cardiovascular and respiratory depression, allergic reactions (e.g., anaphylaxis), affects arterial pressure.
  • 10 hours half-life, leading to prolonged presence in the body
92
Q

What are muscle relaxants, and why are they used?

A

Induce muscle paralysis for procedures like intubation, surgery, and mechanical ventilation

93
Q

How do depolarizing muscle relaxants work?

A
  1. Mimics acetylcholine, binding to post-synaptic receptors
  2. Causes rapid, sustained depolarization → muscle contraction → paralysis
  3. Rapid onset and offset due to short half-life
94
Q

How do non-depolarizing muscle relaxants work?

A
  1. Compete with acetylcholine at receptor sites without activating them
  2. Block sodium channel opening → prevent muscle contraction → paralysis
  3. Slower onset and offset

Principles of Med Neuroscience (12 decks)

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