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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 ms

t_ref

duration of refractory period in ms

t_spike

point in time of last spike in

capacitance

picofarads (pF)

C_m

capacitance of the membrane in pF

current

picoamperes (pA)

I_e

constant input current in pA

conductance

nanosiemens (nS)

g_L

Leak conductance in nS

g_K

Potassium peak conductance in nS

g_Na

Sodium peak conductance in nS

spike rates

spikes/s

modulation frequencies

herz (Hz)

frequency

frequncy in Hz

voltage

millivolts (mV)

V_m

Membrane potential in mV

E_L

Resting membrane potential in mV

V_th

Spike threshold in mV

V_reset double

Reset potential of the membrane in mV

V_min

Absolute lower value for the membrane potential in mV

E_ex

Excitatory reversal potential in mV

E_in

Inhibitory reversal potential in mV

E_Na

Sodium reversal potential in mV

E_K

Potassium reversal potential in 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 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