L.2.4 Flashcards
What are brain rhythms
Brain rhythms are patterns of brain activity that align with environmental and biological changes
how do brain rhythms relate to environmental factors?
these rhythms are influenced by factors such as temperature, day/night cycles, and tides.
What are some examples of brain rhythms?
Brain rhythms include sleep-wake cycles, breathing patterns, steps while walking, and stages of night sleep
What is the function of an Electroencephalogram (EEG)?
An EEG measures brain activity, particularly useful for detecting abnormal brain rhythms
How does an EEG detect brain activity?
- 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.
Why are EEGs good for detecting epilepsy?
The synchronized firing of many neurons produces a large enough signal to be detected on the scalp
Why is it difficult to record EEG signals from deeper brain layers?
harder to detect their signals via EEG, as the signal needs to travel through several cortical layers to reach the scalp.
What are the basic requirements for signal detection in EEG?
- Population Synchrony
- Parallel Alignment:
What is population synchrony
A large group of neurons must fire synchronously to generate a strong enough electrical field
What is parallel alignment
Neurons must be aligned in parallel to combine their electrical signals effectively.
What happens when neurons fire in synchrony for EEG signal generation?
- When neurons fire synchronously, it creates a strong, detectable EEG signal with high amplitude
- allows the signal to be measured effectively at the scalp
What happens when neurons fire irregularly,
- the EEG signal becomes weak because increases and decreases in electrical activity cancel each other out
how does irregular neuron firing affect EEG signals?
low amplitude and meaningless signals.
What factors influence the amplitude of EEG signals?
- Number of active neurons:
- Total excitation level in neurons
- Timing of activity
How does the number of active neurons influence amplitude of EEG signals
More active neurons generate a stronger signal.
How does the total excitation level in neurons influence amplitude of EEG signals
Higher excitation levels contribute to a stronger signal.
How does the timing of activity influence amplitude of EEG signals
More synchronous firing of neurons results in a stronger signal.
What does the alpha rhythm in EEG indicate
- the alpha rhythm (8-13Hz) occurs when a person is awake but has their eyes closed
- moderate synchronization without visual input
What does the beta rhythm in EEG indicate
- The beta rhythm (14-60Hz) occurs during mental activity and attention, especially when the eyes are open
- associated with active thinking and sensory processing
Why is the amplitude low for beta rhythm
The amplitude is lower, as brain activity is less synchronized
What do theta waves in EEG indicate
Theta waves (4-7Hz) indicate drowsiness, sleep
Why do theta waves have moderate amplitude
synchronization changes.
What do delta waves in EEG indicate
Delta waves (<4Hz) occur during deep, non-REM sleep.
What are the amplitude of delta waves like
They have very slow frequency and high amplitude due to synchronized neurons, as minimal external environmental processing occurs