Physiology - Electroencephalography (EEG)
(B7) Questions With Solutions
A flat EEG (no electrical activity) is clinical evidence of death
Patterns of rhythmic neuronal electrical activity recorded are called brain waves (brain
rhythms)
scalp EEG a pair of electrodes are attached to scalp connected to a differential amplifier
•Amplifier will reveal a pattern of voltage fluctuations over time
•Amplitude between -100 µV and +100 µV
•Frequency 0-100 Hz
neural basis of EEG - its a measure of the extracellular current flow from the summated
synchronous activity of many neurons
- The most important source of extracellular flow of ions in brain tissue is triggered by excitatory
and inhibitory postsynaptic potentials
- collects the activity mainly from cell layers that are oriented perpendicular to the surface of the
cortex
, Physiology - Electroencephalography (EEG)
(B7) Questions With Solutions
positive deflection EEG EPSPs in deeper layers and IPSPs in superficial layers
negative deflection EEG EPSPs in superficial layers and IPSPs in deeper layers
can scalp EEGS alone determine cortical synaptic events no
can APs of neurons be detected on the scalp no
- they are asynchronous and too fast to generate detectable potentials
what happens to electrical activity from deeper generators it gets dispersed and attenuated
by volume conduction effects
what activity might scalp EEG indirectly trace The activity from deeper structures may
drive cortical pyramidal neurons
EEG collects its activity from which cell layers cell layers that are oriented perpendicular
to the surface of the cortex (prymidal neurons)
(B7) Questions With Solutions
A flat EEG (no electrical activity) is clinical evidence of death
Patterns of rhythmic neuronal electrical activity recorded are called brain waves (brain
rhythms)
scalp EEG a pair of electrodes are attached to scalp connected to a differential amplifier
•Amplifier will reveal a pattern of voltage fluctuations over time
•Amplitude between -100 µV and +100 µV
•Frequency 0-100 Hz
neural basis of EEG - its a measure of the extracellular current flow from the summated
synchronous activity of many neurons
- The most important source of extracellular flow of ions in brain tissue is triggered by excitatory
and inhibitory postsynaptic potentials
- collects the activity mainly from cell layers that are oriented perpendicular to the surface of the
cortex
, Physiology - Electroencephalography (EEG)
(B7) Questions With Solutions
positive deflection EEG EPSPs in deeper layers and IPSPs in superficial layers
negative deflection EEG EPSPs in superficial layers and IPSPs in deeper layers
can scalp EEGS alone determine cortical synaptic events no
can APs of neurons be detected on the scalp no
- they are asynchronous and too fast to generate detectable potentials
what happens to electrical activity from deeper generators it gets dispersed and attenuated
by volume conduction effects
what activity might scalp EEG indirectly trace The activity from deeper structures may
drive cortical pyramidal neurons
EEG collects its activity from which cell layers cell layers that are oriented perpendicular
to the surface of the cortex (prymidal neurons)
