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Electrophysiology lexicon

For further information on these electrophysiological properties, please view Toledo-Rodriguez et al 2004 which serves as an excellent reference.

Electrophysiology property Common Definition Standardization Criteria Units
input resistance Input resistance measured at steady-state voltage response to current injection Values corrected for differences in units, but are otherwise unchanged. Refer to individual articles for specific definitions and calculation methodologies. MΩ
resting membrane potential Membrane potential at the onset of whole-cell recording Values unchanged from those reported. Refer to individual articles for specific definitions and calculation methodologies. mV
spike threshold Voltage at which AP is initiated (as assessed by measuring rising slope of membrane voltage) Values are unchanged from those reported. Refer to individual articles for specific calculation methodology, such as voltage slope criterion for AP threshold determination or which APs are used to define spike theshold (i.e., evoked using rheobase current, via synaptic input, etc.). mV
spike half-width Calculated as the AP duration at the membrane voltage halfway between AP threshold and AP peak. Most commonly calculated using first AP in train at rheobase. current. Values manually standardized case-by-case to correspond to calculation definition of AP width at half-max amplitude. Since authors use different APs for defining spike half-width (i.e., evoked using rheobase current, via synaptic input, etc.), please refer to individual articles for specific methodology. ms
spike amplitude Voltage indicating height of action potential. Usually calculated as the difference between AP peak and AP threshold voltages. Commonly measured using first AP in train at rheobase current. Values manually standardized case-by-case to correspond to calculation definition of difference between AP peak and AP threshold. Since authors use different APs for defining spike amplitude (e.g., evoked using rheobase current, via synaptic input, etc.), please refer to individual articles for specific methodology. mV
membrane time constant Time constant for the membrane to repolarize after a small current injection of fixed amplitude and duration Values corrected for differences in units, but are otherwise unchanged. Refer to individual articles for specific definitions and calculation methodologies. ms
AHP amplitude Calculated as the voltage difference between AP threshold and AP trough. Commonly defined using first AP in train at rheobase current. Values have been algorithmically standardized to correspond to calculation definition of difference between AP threshold and AHP trough. Since authors use different APs for defining AHP amplitudes (i.e., evoked using rheobase current, via synaptic input, etc.), please refer to individual articles for specific methodology. mV
rheobase Minimum current injected somatically required to fire AP Values corrected for differences in reported units, but are otherwise unchanged. Refer to individual articles for specific definitions and calculation methodologies. pA
cell capacitance Neuron capacitance, typically measured by dividing membrane time constant by membrane resistance Values corrected for differences in units, but are otherwise unchanged. Refer to individual articles for specific definitions and calculation methodologies. pF
spike width Duration of AP, not explictly refered to as half-width Values are unchanged from those reported. Values currently lump multiple measures of spike width which do not explicitly denote spike half-width. Refer to individual articles for definition and calculation methodology. ms
maximum firing rate Maximum observed AP discharge rate Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. Hz
AHP duration Duration of AP after-hyperpolarization, not explicitly referred to by author as either fast or slow Values are unchanged from those reported. Values currently lump a number of calculation metrics, including AHP full duration, AHP rise time, AHP time constant, etc. Refer to individual articles for definition and calculation methodology. ms
sag ratio Ratio between the steady state decrease in the voltage and the largest decrease in voltage following a hyperpolarizing current step. Values manually standardized case-by-case to correspond to common calculation definition. For example, sag ratios reported as a percent difference have been manually adjusted to correspond to a ratio. Refer to individual articles for further definition details. ratio
spike max rise slope Maximum rate of rise of membrane voltage during spike rising phase Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV/ms
adaptation ratio Ratio of durations between early and late AP inter-spike intervals in an AP train Values have been manually standardized to reflect ratio of early to late AP inter-spike intervals. Note however that authors use different early and late inter-spike intervals used in definition calculation which has not been accounted for. Refer to individual articles for specific details. ratio
first spike latency Duration to first AP following a depolarizing current step of fixed amplitude Values are unchanged from those reported. Since authors use different APs for defining first spike latency (e.g., evoked using rheobase current, via synaptic input, etc.), please refer to individual articles for specific methodology. ms
FI slope Slope of the frequency-current relationship Values corrected to reflect differences in units, but are otherwise unchanged. Refer to individual articles for definition and calculation methodology. Hz/nA
sag amplitude Absolute difference between the steady state decrease in the voltage and the largest decrease in voltage following a hyperpolarizing current step. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
spike rise time Time for spike to rise from threshold to peak, usually calculated as 10-90% rise time Values are unchanged from those reported. Values currently lump multiple measures of spike rise time. Refer to individual articles for definition and calculation methodology. ms
fast AHP amplitude Calculated as the difference between AP threshold and AP trough, explictly refered to by author as fast. Values have been algorithmically standardized to correspond to calculation definition of difference between AP threshold and AHP trough. Since authors use different definitions for “fast” and which APs are used for defining AHP amplitudes (e.g., evoked using rheobase current, via synaptic input, etc.), please refer to individual articles for specific methodology. mV
spike max decay slope Maximum rate of rise of membrane voltage during spike falling phase Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV/ms
other A catch-all property to reflect any properties which are not already explicitly defined Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. None
spontaneous firing rate AP discharge rate in the absence of current injection or a stimulus Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. Hz
spike amplitude from resting Voltage indicating height of action potential, calculated as the difference between AP peak and resting or baseline voltages. Commonly measured using first AP in train at rheobase current. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
spike decay time Time for spike to fall from peak to threshold, usually calculated as 10-90% decay time Values are unchanged from those reported. Values currently lump multiple measures of spike decay time. Refer to individual articles for definition and calculation methodology. ms
spike peak Maximum voltage reached during AP Values corrected to reflect differences in units, but are otherwise unchanged. Since authors use different APs for defining spike peak (e.g., evoked using rheobase current, via synaptic input, etc.), please refer to individual articles for specific methodology. mV
adaptation ratio (last/first ISI) Ratio of durations between late and early AP inter-spike intervals in an AP train Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. ratio
medium AHP amplitude Calculated as the difference between AP threshold and AP trough, explictly refered to by author as medium Values have been algorithmically standardized to correspond to calculation definition of difference between AP threshold and AHP trough. Since authors use different definitions for “fast” and which APs are used for defining AHP amplitudes (e.g., evoked using rheobase current, via synaptic input, etc.), please refer to individual articles for specific methodology. mV
slow AHP amplitude Calculated as the difference between AP threshold and AP trough, explictly refered to by author as slow Values have been algorithmically standardized to reflect an amplitude measurement . Since authors use different definitions for “slow” and which APs are used for defining AHP amplitudes (i.e., evoked using rheobase current, via synaptic input, etc.), please refer to individual articles for specific methodology. mV
ADP amplitude Amplitude from first AP onset to maximum voltage, typically more depolarized than the resting membrane potential Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
adaptation percent (1 – first/last ISI) 1 minus ratio of durations between early and late AP inter-spike intervals in an AP train, normalized to a percent Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. ratio
fast AHP duration Duration of AP after-hyperpolarization, explictly refered to by author as fast Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. ms
AHP voltage Calculated as minimum voltage value during an AHP. Commonly defined using first AP in train at rheobase current. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
adaptation ratio (other) Adaptation ratio, percent, index but not otherwise characterizable to an existing sub-definition Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. None
medium AHP duration Duration of AP after-hyperpolarization, explictly refered to by author as medium Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. ms
slow AHP duration Duration of AP after-hyperpolarization, explictly refered to by author as slow Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. ms
adaptation percent (first/last ISI) Percentage of durations between early and late AP inter-spike intervals in an AP train Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. ratio
AHP amplitude from resting Calculated as the voltage difference between resting or baseline voltages and AP trough. Commonly defined using first AP in train at rheobase current. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
adaptation ratio (1 – first/last ISI) 1 minus ratio of durations between early and late AP inter-spike intervals in an AP train Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. ratio
fast AHP voltage Calculated as the AHP absolute voltage, explictly refered to by author as fast. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
spike amplitude from trough Voltage indicating height of action potential, calculated as the difference between AP peak and AHP trough voltages. Commonly measured using first AP in train at rheobase current. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
medium AHP amplitude from resting Calculated as the difference between resting or baseline voltages and AP trough, explictly refered to by author as medium Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
slow AHP amplitude from resting Calculated as the difference between resting or baseline voltages and AP trough, explictly refered to by author as slow Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
medium AHP voltage Calculated as the AHP absolute voltage, explictly refered to by author as medium. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
adaptation percent (last/first ISI) Percentage of durations between late and early AP inter-spike intervals in an AP train Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. ratio
slow AHP voltage Calculated as the AHP absolute voltage, explictly refered to by author as slow. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV
fast AHP amplitude from resting Calculated as the difference between resting or baseline voltages and AP trough, explictly refered to by author as fast. Values are unchanged from those reported. Refer to individual articles for definition and calculation methodology. mV