Physiology 4.3 Flashcards
What is being measured in intracellular recording?
potentials can be measured across the cell membrane
What is being measured in single unit extracellular recording?
potentials can be measured in the extracellular space relative to a common ground and close to a single neuron
What is being measured in field potentials?
potentials can be measured in the extracellular space relative to a common ground and not close to a single neuron; group of neurons
What is being measured in EEG?
potentials can be measured relative to a common ground from the scalp surface; very broad information
How does opening your eye affect an EEG?
dramatic change in electrical field; spike in EEG
How can the signal of an EEG be distorted or attenuated?
disturbance from tissue and bone
Why are there spatial and temporal limits of EEG recordings?
-signals are small
- EEG is mainly a recording of cortical activity
- *hippocampus, thalamus, brainstem do not contribute to EEG
How does the specificity of EEG compare to other intracellular recordings?
- EEG measured in microvolts
- intracellular measured in millivolts
- *intracellular more specific
What does a large EEG signal represent?
amplitude is determined by synchronous firing
What is a normal EEG?
1-30 Hz
20-100 micro volts
alpha: 8-13 Hz
beta: 13-30 Hz
delta: 0.5-4 Hz
theta: 4-7 Hz
What are the alpha waves typical of, what is their amplitude, and where are they recorded?
- typical of relaxed wakefulness
- moderate amplitude
- recorded over parietal and occipital lobules
What are the beta waves typical of, what is their amplitude, and where are they recorded?
- typical of intense mental activity
- lower amplitude
- recorded over frontal areas
What happens when a relaxed subject is alerted?
- EEG transitions from alpha to beta waves
- EEG desynchronizes
What are the theta and delta waves typical of?
-typical of drowsiness and early slow-wave sleep
What is the implication of theta or delta waves present during wakefulness?
sign of brain dysfunction
What is the implication of large, abrupt changes from baseline activity on an EEG?
synchronization of neuronal firing; paroxysmal activity
How does a seizure focus appear on an EEG?
sharp spikes
Which types of oscillations in the brain do drugs typically target to induce sleep?
thalamocortical oscillations
What are additional ways to measure brain activity?
metabolic techniques
FMRI
PET
NIRS (near infared spectroscopy)
