How do neurons conduct information?
- movement of ions across membrane in response to opening of ion channels.
- inputs induce graded changes in membrane voltage, which are converted to “all-or-none” Action Potential as outputs
what property of AP can demonstrate the intensity of stimulus?
frequency
meaning of “all-or-none”
the amplitude of AP is constant,
independent of magnitude of current used to evoke it.
threshold for AP
~ -40 mV
Excitatory Postsynaptic Potential (EPSP)
a small excitatory event that makes the membrane depolarize, typically by about 10 mV
Inhibitory Postsynaptic Potential (IPSP)
a small inhibitory event that make it harder for the membrane to reach the threshold for an AP
How do EPSP and IPSP translate into changes in AP firing rates?
- EPSP can summate in space or in time to depolarize the neuron to the threshold to fire AP.
- but IPSP can impede the cell from reaching threshold for firing an AP.
another name of action potential
spike
what is EEG
measurements brain activity patterns using an array of scalp electrodes.
Advantages of EEG
- high temporal resolution
- relatively non-invasive
- sensitive to coherent cortical activity in 1-30 Hz range
Limitations of EEG
- poor spatial resolution
2. limited to superficial cortical activity
common electrophysiological techniques:
- EEG recording
- extracellular field recording
- extracellular single unit recording
- intracellular recording (sharp electrode)
- patch clamp recording
4 configurations of patch-clamp recording
- cell-attached recording
- inside-out recording
- whole-cell recording
- outside-out recording (begins with whole-cell recording)
Uses of EEG:
- for the diagnosis and categorization of epileptic seizures.
- for monitoring anesthesia depth.
- diagnosing abnormal brain development in infants.
