Artificial Neural Networks: Concepts

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Questions and Answers

What is the primary motivation behind the development of artificial neural networks?

  • To replicate the computational speed of conventional digital computers.
  • To simulate the linear processing capabilities of the human brain.
  • To create a simpler alternative to traditional computer programming.
  • To mimic the unique information processing capabilities of the human brain, which differs significantly from conventional digital computers. (correct)

Which of the following is an example of a task that the human brain performs significantly faster than a powerful computer?

  • Perceptual recognition, such as recognizing a face. (correct)
  • Performing repetitive logical operations.
  • Executing complex mathematical calculations.
  • Storing and retrieving large amounts of data.

What is the role of plasticity in the context of neural networks and the developing nervous system?

  • To enable the system to adapt and modify its structure based on its environment. (correct)
  • To limit the network's ability to adapt to new information.
  • To accelerate the processing speed of the network.
  • To maintain a fixed structure within the network.

How is knowledge stored within a neural network?

<p>By adjusting the strengths of the connections between neurons, known as synaptic weights. (D)</p> Signup and view all the answers

What is the purpose of a 'learning algorithm' in the context of neural networks?

<p>To modify the synaptic weights of the network to achieve a desired objective. (B)</p> Signup and view all the answers

What does the term 'generalization' refer to in the context of neural networks?

<p>Producing accurate outputs for inputs not encountered during the training phase. (D)</p> Signup and view all the answers

Why is nonlinearity considered an important property of neural networks?

<p>Many real-world signals are inherently nonlinear, and the network must be able to model them accurately. (A)</p> Signup and view all the answers

What is the main principle behind 'supervised learning' in neural networks?

<p>The network refines its synaptic weights based the input signal and a corresponding desired output. (B)</p> Signup and view all the answers

What does 'adaptivity' refer to in the context of neural networks?

<p>The capability to adjust synaptic weights in response to environmental changes. (A)</p> Signup and view all the answers

What is the 'stability-plasticity dilemma' in the context of adaptive neural networks?

<p>The conflict between adapting to new information and maintaining stability by not responding to spurious disturbances. (A)</p> Signup and view all the answers

In pattern classification, what is the benefit of a neural network providing an 'evidential response'?

<p>It provides information about the confidence level of the decision, allowing for the rejection of ambiguous patterns. (D)</p> Signup and view all the answers

How do neural networks inherently handle 'contextual information'?

<p>By allowing every neuron to be potentially affected by the global activity of all other neurons in the network. (E)</p> Signup and view all the answers

What does 'fault tolerance' mean in the context of hardware-implemented neural networks?

<p>The capacity for the network to continue functioning even if some neurons or connections are damaged. (C)</p> Signup and view all the answers

What is a key advantage of implementing neural networks using Very-Large-Scale Integration (VLSI) technology?

<p>VLSI provides a means of capturing complex behavior in a highly organized and hierarchical manner. (C)</p> Signup and view all the answers

In what sense do neural networks exhibit 'uniformity of analysis and design'?

<p>The same notation and fundamental building blocks (neurons) are used across different applications. (B)</p> Signup and view all the answers

How do neurobiologists utilize artificial neural networks in their research?

<p>As a tool for interpreting and modeling neurobiological phenomena. (D)</p> Signup and view all the answers

What function does the vestibulo-ocular reflex (VOR) serve?

<p>To maintain visual stability by making eye rotations opposite to head rotations. (C)</p> Signup and view all the answers

What is the main function of the retina?

<p>To convert an optical image into a neural image for transmission to the brain. (B)</p> Signup and view all the answers

What are 'neuromorphic integrated circuits' designed to mimic?

<p>The structure and function of the human retina. (B)</p> Signup and view all the answers

In the three-stage model of the human nervous system, what role do 'receptors' play?

<p>To convert stimuli from the body or environment into electrical impulses. (B)</p> Signup and view all the answers

How does the human brain compensate for the relatively slow rate of operation of individual neurons?

<p>By using a staggering number of neurons with massive interconnections. (A)</p> Signup and view all the answers

What is the function of synapses in the brain?

<p>To mediate the interactions between neurons by converting electrical signals to chemical signals and back. (D)</p> Signup and view all the answers

What are the two main mechanisms by which plasticity is achieved in the adult brain?

<p>The creation of new synaptic connections and the modification of existing synapses. (D)</p> Signup and view all the answers

What is the role of action potentials in neuronal communication?

<p>To transmit signals over long distances along the axon without signal degradation. (B)</p> Signup and view all the answers

What is a 'neural microcircuit'?

<p>An assembly of synapses organized into patterns of connectivity to produce a specific functional operation. (B)</p> Signup and view all the answers

What are 'topographic maps' in the context of brain organization?

<p>Organized regions that respond to incoming sensory information in a spatially ordered manner. (A)</p> Signup and view all the answers

According to the material provided what is the most appropriate characterization of the artificial neurons used to build neural networks today?

<p>They are extremely primitive compared to those found in the brain. (C)</p> Signup and view all the answers

What are the three basic elements present in the model of an artificial neuron?

<p>A set of synapses with associated weights, an adder (linear combiner), and an activation function. (B)</p> Signup and view all the answers

What is the role of the 'bias' in an artificial neuron?

<p>To increase or decrease the net input of the activation function. (A)</p> Signup and view all the answers

According to the material, what is the relationship between the 'induced local field' and the 'linear combiner output' in a neuron when a bias is applied?

<p>The induced local field equals the sum of linear combined output and bias. (B)</p> Signup and view all the answers

What type of transformation is applied to the output of the linear combiner by the bias?

<p>An affine transformation. (B)</p> Signup and view all the answers

What is the function of the 'activation function' in an artificial neuron?

<p>To introduce non-linearity into the neuron's output and limit its amplitude. (A)</p> Signup and view all the answers

What is another term used for 'activation function'?

<p>Squashing function. (C)</p> Signup and view all the answers

What is the McCulloch-Pitts model?

<p>A simple neuron model with a threshold activation function. (A)</p> Signup and view all the answers

Why is differentiability an important feature of activation functions in neural network theory?

<p>Allows the use of gradient-based learning algorithms (A)</p> Signup and view all the answers

What is the main difference between a deterministic and a stochastic model of a neuron?

<p>Deterministic models have a precisely defined input-output behavior, while stochastic models have a probabilistic interpretation. (C)</p> Signup and view all the answers

In the context of a stochastic neuron, what does the 'pseudotemperature' control?

<p>The noise level and uncertainty in firing. (A)</p> Signup and view all the answers

What are the three basic rules that dictate the flow of signals in a signal-flow graph?

<p>Signal flow direction, node signal summation, and signal transmission independence. (D)</p> Signup and view all the answers

What is the key characteristic of an 'architectural graph' of a neural network?

<p>It describes the network layout, showing how neurons are interconnected. (D)</p> Signup and view all the answers

In a feedback system, what is the role of the 'open-loop operator'?

<p>To characterize the combined effect of the forward and feedback paths. (C)</p> Signup and view all the answers

What is a key difference between feedforward and recurrent neural networks?

<p>Recurrent networks have feedback loops, while feedforward networks do not. (C)</p> Signup and view all the answers

In the context of network architectures, what does the term 'single-layer' refer to in a single-layer feedforward network?

<p>The output layer of computation nodes (neurons). (D)</p> Signup and view all the answers

What is the purpose of 'hidden layers' in a multilayer feedforward neural network?

<p>To intervene between the external input and the network output, extracting higher-order statistics from the input. (A)</p> Signup and view all the answers

What does it mean for a neural network to be 'fully connected'?

<p>Every node in each layer is connected to every node in the adjacent forward layer. (A)</p> Signup and view all the answers

What distinguishes a recurrent neural network from a feedforward network?

<p>It has at least one feedback loop. (D)</p> Signup and view all the answers

According to the material provided, what does 'knowledge' refer to?

<p>Stored information or models used to interpret, predict, and respond to the world. (B)</p> Signup and view all the answers

Flashcards

The Human Brain

A highly complex, nonlinear, and parallel computer that can organize its structural constituents (neurons) to perform computations much faster than digital computers.

Neural Network

A machine designed to model how the brain performs a task, often implemented with electronic components or software.

Neural Network (Adaptive Machine)

A massively parallel distributed processor made up of simple processing units that has a natural propensity for storing experiential knowledge and making it available for use.

Synaptic Weights

Interneuron connection strengths used to store the knowledge acquired by the network.

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Learning Algorithm

The procedure used to modify the synaptic weights of a network in an orderly fashion to attain a desired design objective.

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Generalization

The neural network’s production of reasonable outputs for inputs not encountered during training (learning).

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Nonlinearity (NN)

A property of neural networks where an interconnection of nonlinear neurons creates a nonlinear network, important for processing inherently nonlinear signals.

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Supervised Learning

Modifying synaptic weights using labeled training examples to minimize the difference between desired and actual responses, creating an input-output mapping.

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Adaptivity

The built-in capability of neural networks to adjust their synaptic weights in response to changes in the surrounding environment.

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Stability–Plasticity Dilemma

The challenge of ensuring an adaptive system remains stable and doesn't overreact to spurious disturbances.

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Evidential Response

A design feature allowing a neural network to provide confidence levels about its decisions, useful for rejecting ambiguous patterns.

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Contextual Information

A property where knowledge is represented by the structure and activation state of a network, allowing it to naturally process contextual information.

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Fault Tolerance

The potential of a neural network to maintain performance even when neurons or connections are damaged, due to the distributed nature of information storage.

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VLSI Implementability

The suitability of neural networks for implementation using very-large-scale-integrated (VLSI) technology due to their massively parallel nature.

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Neural Microcircuit

A set of synapses organized into patterns of connectivity to produce a functional operation of interest; analogous to a silicon chip.

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Topographic Maps

Maps organized to respond to incoming sensory information, often arranged in sheets such that stimuli from corresponding points in space align.

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Neuron (Artificial)

An information-processing unit that is fundamental to the operation of a neural network.

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Synapses (Artificial)

A set of connecting links, each characterized by a weight or strength, that multiplies the input signal.

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Activation Function

A function that limits the amplitude range of the output signal of a neuron to some finite value.

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Bias (in Neurons)

An externally applied input that increases or lowers the net input of the activation function, affecting the neuron's output.

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Threshold Function

An activation function that outputs one of two values (e.g. 0 or 1) based on whether the input is above or below a threshold.

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Sigmoid Function

A type of activation usually used in the construction of neural networks that exhibits a balance between linear and nonlinear behavior.

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Stochastic Model of a Neuron

A neural model where the decision for a neuron to fire is probabilistic, based on the induced local field and a pseudotemperature parameter.

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Signal-Flow Graphs

Networks of directed links interconnected at nodes, used to portray the flow of signals in a neural network.

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Synaptic Links

Links governed by a linear input-output relation where the node signal is multiplied by a synaptic weight.

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Activation Links

Links governed by a nonlinear input-output relation, typically represented by a nonlinear activation function

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Architectural Graph

A directed graph describing the layout of a neural network, focusing on signal flow from neuron to neuron and omitting details inside individual neuron and

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Feedback

When the output of an element influences the input to that element creating closed paths for signal transmission.

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Infinite Impulse Response (IIR) Filter

A system where the output is an infinite weighted summation of present and past samples of the input signal, controlled by a weight 'w'.

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Unfolding a Feedback System

Approximating a feedback system with a feedforward system, achieved by truncating the series representation; only practical when the feedback system is stable.

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Single-Layer Feedforward Network

A neural network architecture where neurons are organized in layers, with an input layer projecting directly onto an output layer, a feedforward-only network.

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Multilayer Feedforward Network

A feedforward neural network with one or more hidden layers between the input and output layers, enabling the network to extract higher-order statistics from its input.

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Fully Connected Network

A neural network where every node in each layer is connected to every other node in the adjacent forward layer.

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Recurrent Neural Network

A neural network with at least one feedback loop, where the output of a neuron can influence its own input or the inputs of other neurons.

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Knowledge

Stored information or models used to interpret, predict, and appropriately respond to the outside world.

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Training Data

A set of input-output pairs used for training a neural network, consisting of an input signal and the corresponding desired response.

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Generalization (Learning)

Successful performance of a trained network on test patterns not seen during training, demonstrating its ability to apply learned knowledge to new situations.

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Rule 1 of Knowledge Representation

Patterns drawn from similar classes should produce similar representations inside the network, leading to classification in the same class.

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Rule 2 of Knowledge Representation

Items to be categorized as separate classes should be given distinctly different representations within the neural network.

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Rule 3 of Knowledge Representation

If a certain feature is significant, a large number of artificial neurons should be allocated to the representation of that item in the neural network.

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Rule 4 of Knowledge Representation

If prior information and invariances are available, they should be incorporated in the design of a neural network to ease learning and simplify design.

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