Artificial neuron
artificial neuronsMcCulloch–Pitts neuronneuronsneuronnodesMcCulloch-Pitts neuronneuronalactivationelectronic neuronslinear neurons
An artificial neuron is a mathematical function conceived as a model of biological neurons, a neural network.wikipedia


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Neural network
neural networksnetworksnetwork
An artificial neuron is a mathematical function conceived as a model of biological neurons, a neural network.
A neural network is a network or circuit of neurons, or in a modern sense, an artificial neural network, composed of artificial neurons or nodes.

Artificial neural network
artificial neural networksneural networksneural network
Artificial neurons are elementary units in an artificial neural network.
An ANN is based on a collection of connected units or nodes called artificial neurons, which loosely model the neurons in a biological brain.





Sigmoid function
sigmoidalsigmoidsigmoid curve
The transfer functions usually have a sigmoid shape, but they may also take the form of other non-linear functions, piecewise linear functions, or step functions.
A wide variety of sigmoid functions including the logistic and hyperbolic tangent functions have been used as the activation function of artificial neurons.

Warren Sturgis McCulloch
Warren McCullochWarren S. McCullochMcCulloch
The first artificial neuron was the Threshold Logic Unit (TLU), or Linear Threshold Unit, first proposed by Warren McCulloch and Walter Pitts in 1943.
Along with Walter Pitts, McCulloch created computational models based on mathematical algorithms called threshold logic which split the inquiry into two distinct approaches, one approach focused on biological processes in the brain and the other focused on the application of neural networks to artificial intelligence.
Feedforward neural network
feedforwardfeedforward neural networksfeedforward networks
Researchers also soon realized that cyclic networks, with feedbacks through neurons, could define dynamical systems with memory, but most of the research concentrated (and still does) on strictly feed-forward networks because of the smaller difficulty they present.
Neurons with this kind of activation function are also called artificial neurons or linear threshold units.


Walter Pitts
PittsWalter H. Pitts
The first artificial neuron was the Threshold Logic Unit (TLU), or Linear Threshold Unit, first proposed by Warren McCulloch and Walter Pitts in 1943.
It is often called a McCulloch–Pitts neuron.

Neuron
neuronsnerve cellsnerve cell
An artificial neuron is a mathematical function conceived as a model of biological neurons, a neural network.









ADALINE
ADALINE Neural Networkother models
The representation of the threshold values as a bias term was introduced by Bernard Widrow in 1960 – see ADALINE.
It is based on the McCulloch–Pitts neuron.

Backpropagation
back-propagationback propagationbackpropagate
The best known training algorithm called backpropagation has been rediscovered several times but its first development goes back to the work of Paul Werbos.
Consider a simple neural network with two input units, one output unit and no hidden units, and in which each neuron uses a linear output (unlike most work on neural networks, in which mapping from inputs to outputs is non-linear) that is the weighted sum of its input.




Perceptron
Perceptronsperceptron algorithmFeedforward Neural Network (Perceptron)
One important and pioneering artificial neural network that used the linear threshold function was the perceptron, developed by Frank Rosenblatt.
In the context of neural networks, a perceptron is an artificial neuron using the Heaviside step function as the activation function.

Connectionism
connectionistparallel distributed processingconnectionist models
Many earlier researchers advocated connectionist style models, for example in the 1940s and 1950s, Warren McCulloch and Walter Pitts (MP neuron), Donald Olding Hebb, and Karl Lashley.
Logistic function
logisticlogistic curvelogistic growth
It has been demonstrated for the first time in 2011 to enable better training of deeper networks, compared to the widely used activation functions prior to 2011, i.e., the logistic sigmoid (which is inspired by probability theory; see logistic regression) and its more practical counterpart, the hyperbolic tangent.
A popular neural net element computes a linear combination of its input signals, and applies a bounded logistic function to the result; this model can be seen as a "smoothed" variant of the classical threshold neuron.


Function (mathematics)
functionfunctionsmathematical function
An artificial neuron is a mathematical function conceived as a model of biological neurons, a neural network.
Mathematical model
mathematical modelingmodelmathematical models
An artificial neuron is a mathematical function conceived as a model of biological neurons, a neural network.

Excitatory postsynaptic potential
excitatoryEPSPexcitatory postsynaptic potentials
The artificial neuron receives one or more inputs (representing excitatory postsynaptic potentials and inhibitory postsynaptic potentials at neural dendrites) and sums them to produce an output (or activation, representing a neuron's action potential which is transmitted along its axon).


Inhibitory postsynaptic potential
inhibitoryIPSPinhibitory synapses
The artificial neuron receives one or more inputs (representing excitatory postsynaptic potentials and inhibitory postsynaptic potentials at neural dendrites) and sums them to produce an output (or activation, representing a neuron's action potential which is transmitted along its axon).


Action potential
action potentialsnerve impulsenerve impulses
The artificial neuron receives one or more inputs (representing excitatory postsynaptic potentials and inhibitory postsynaptic potentials at neural dendrites) and sums them to produce an output (or activation, representing a neuron's action potential which is transmitted along its axon).









Axon
axonsnerve fiberaxonal
The artificial neuron receives one or more inputs (representing excitatory postsynaptic potentials and inhibitory postsynaptic potentials at neural dendrites) and sums them to produce an output (or activation, representing a neuron's action potential which is transmitted along its axon).





Weighting
weightedweighta balance
Usually each input is separately weighted, and the sum is passed through a non-linear function known as an activation function or transfer function.
Nonlinear system
nonlinearnon-linearnonlinear dynamics
Usually each input is separately weighted, and the sum is passed through a non-linear function known as an activation function or transfer function.

Activation function
activation mapnonlinearity
Usually each input is separately weighted, and the sum is passed through a non-linear function known as an activation function or transfer function.
Transfer function
transfertransfer characteristicchannel transfer function
Usually each input is separately weighted, and the sum is passed through a non-linear function known as an activation function or transfer function.
Piecewise
piecewise continuouspiecewise functionpiecewise smooth
The transfer functions usually have a sigmoid shape, but they may also take the form of other non-linear functions, piecewise linear functions, or step functions.
Monotonic function
monotonicitymonotonemonotonic
They are also often monotonically increasing, continuous, differentiable and bounded.



Continuous function
continuouscontinuitycontinuous map
They are also often monotonically increasing, continuous, differentiable and bounded.

