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Glossary

Common abbreviations in NEST

iaf

Integrate and fire.

gif

Generalized integrate and fire.

cond

Conductance-based.

psc

Post-synaptic current (current-based).

hh

Hodgkin huxley.

rng

Random number generator.

wfr

Waveform relaxation method.

aeif

Adaptive exponential integrate and fire.

ht

Hill and tononi.

pp

Point process.

in

Inhibitory.

ex

Excitatory.

MAM

Multi-area model.

mpi

Message passing interface.

stdp

Spike-timing dependent plasticity synapse.

st

Short term plasticity.

vp

Virtual process.

time

Milliseconds (ms).

tau_m

Membrane time constant in milliseconds (ms).

t_ref

Duration of refractory period in milliseconds (ms).

t_spike

Point in time of last spike in milliseconds (ms).

capacitance

Picofarads (pF).

C_m

Capacitance of the membrane in picofarads (pF).

current

Picoamperes (pA).

I_e

Constant input current in picoamperes (pA).

conductance

Nanosiemens (nS).

g_L

Leak conductance in Nanosiemens (nS).

g_K

Potassium peak conductance in Nanosiemens (nS).

g_Na

Sodium peak conductance in Nanosiemens (nS).

spike rates

Spikes/second.

modulation frequencies

Herz (Hz).

frequency

Frequncy in Hertz (Hz).

voltage

Millivolts (mV).

V_m

Membrane potential in Millivolts (mV).

E_L

Resting membrane potential in Millivolts (mV).

V_th

Spike threshold in Millivolts (mV).

V_reset double

Reset potential of the membrane in Millivolts (mV).

V_min

Absolute lower value for the membrane potential in Millivolts (mV).

E_ex

Excitatory reversal potential in Millivolts (mV).

E_in

Inhibitory reversal potential in Millivolts (mV).

E_Na

Sodium reversal potential in Millivolts (mV).

E_K

Potassium reversal potential in Millivolts (mV).

subthreshold dynamics

Non-spiking backgound activity of the synapses.

refractory period

A time period in which neurons cannot fire. This is due to depolarization.

shotnoise

Fluctuations in ion channels as a result of ionic migration through an open channel.

autapse

A neuron connected to itself.

multapse

A neuron that has (multiple) synapses with another neuron.

spike-timing dependent plasticity

STDP, a form of plasticity which adjusts the connection strength between neurons based on the relative timing of a neurons output and input spikes.

spike train

A sequence of actions potentials. Usually seen as events in integrate-and-fire models.

depressing window

A function that determines how synaptic modification depends on spike-timing (STDP).

dendritic arbor

Dendritic trees formed to create new synapses.

axon

The output structure of a neuron.

Clopath

Refering to the Clopath plasticity rule.

plasticity

The ability of a network to grow or reorganize.

Hodgkin-Huxley

A mathematical model that describes how action potentials in neurons can be generated and how they propagate.

refractory time

A time period in which neurons cannot fire due to depolarization.

Point process

A temporal point process is a mathematical model for a time series of discrete events.

non-renewal process

Point process with adapting threshold eta(t).

rheobase

The minimal current that is required to generate a spike.

reversal potential

The membrane potential at which a neuron causes no net current flow.

time constant

The time it takes for a signal to rise or decay in milliseconds (ms).

See membrane time constant (tau_m) and synaptic time constant (tau_syn) in the model documentation.

Gaussian white noise

A random process with a mean of zero.

sfa

Spike-frequency adaptation.

point neuron

A simple neuron model where its soma along with the membrane potential dynamics are modeled as a resistance–capacitance circuit.

propagator

Matrix used in a numerically integrated dynamical system.

See exact integration page for further information.

synaptic response kernel

Shape of post-synaptic response, commonly an alpha, delta-pulse, or exponential function.

eligibility trace

A property of a synapse, which allows it to be modified for a period of time when some constraints are satisfied.

reversal potential

The membrane potential in which a neuron causes no net current flow.

alpha function

Instance of a synaptic response.

facilitation

Mechanism of making a synapse stronger by increasing the weight.

Opposite to depression.

depression

Mechanism of making a synapse weaker by decreasing the weight.

Opposite to facilitation.

stdp_synapse

Synapse with spike-timing dependent plasticity.

static_synapse

Synapse with a fixed weight.

refractoriness

The time before a new action potential can take place.

renewal process

Spike-time statistical analysis.

spike train

A sequence of action potentials.

spike-frequency adaptation

After stimulation, neurons show a reduction in the firing frequency of their spike response following an initial increase.

GIF

Generalized integrate-and-fire model.

coefficient of variation

Standard deviation divided by the mean.

distal dendrite

The part of the dentrite that is furthest away from the soma.

proximal dendrite

The part of the dentrite which is closest to the soma.

soma

Cell body of the neuron.

psp

Post-synaptic potential.

PSC

Post-synatpic current.

absolute refractory

An interval after a neuron fires a spike to prevent it from firing a spike again.

indegree

Amount of connections to post-synaptic cells.

outdegree

Amount of connections from pre-synaptic cells.

synaptic efficacy

The extent to which a pre-synaptic neuron affects a post-synaptic neuron.

multimeter

A device to record analog quantities (e.g., membrane voltage) of a neuron over time.

events

Spikes are encoded as events in NEST.