Fukushimas Neocognitron
There has been an explosion of effort and innovation in the field of ANNs since the original work of Rosenblatt and Widrow. It is not the purpose here to describe the evolution of modern ANNs or the details of their operation. Instead, this section will examine the general properties of one of the more biologically inspired ANN systems, the neocognitron. Fukushima, whose model of a static pattern recognition system based on the vertebrate retina was introduced in Section 7.1.3, went on to...
Feature Extraction by Optic Lobe Units of Crustaceans
The visual information processing characteristics of crustacean CEs has been shown to be similar in many ways to that performed by nonflying insects. Crustacean CEs have, in general, seven retinula cells per ommatidium Waterman, 1961 . Crustaceans e.g., crabs, lobsters, crayfish are unique in that their CEs are at the ends of stalks that can be moved by the animal to track moving objects over a limited range, or be moved to a protected position if the animal is threatened. Insect CEs are, of...
Motoneurons
A vertebrate motoneuron is a good example of a unipolar neuron. Its cell body lies in the spinal cord. Dendrites branching, treelike processes arise from the soma and serve as points for synaptic inputs from presynaptic excitatory and inhibitory neurons. Analog epsp and ipsp transients are summed in space and time on the dendrites to determine a generator potential at the point where the axon joins the soma. This region is also called the spike generator locus SGL because it is where the...
Info Uuh
FIGURE 8.0-2 Schematic of a 32-bit PRBN generator built by the author. The random square wave, n t , has zero mean. n t is low-pass-filtered to generate a continuous, bandwidth-limited Gaussian noise, Vn t . 9nn x is periodic in T i.e., 9nn x lt m x T . However, in this system, T gt At or N gt 1, so the periodicity in lt nn x will be neglected and the continuous Fourier transform CFT of Equation 8.13, m ra calculated. This is easily shown to be Onn CO a2 N l N 22 - 2naVN 5 8.14 Considering the...
Electrical Synapses
Chemical synaptic action is always accompanied by small delays associated with NT release, diffusion and binding, and the time it takes ion gate proteins to open and ions to move in or out of the postsynaptic membrane PSM . The capacitance of the PSM must also be charged or discharged to realize an epsp voltage transient. Electrical synapses allow the depolarization or hyperpolarization of the presynaptic neuron to be directly coupled to the postsynaptic neuron without delays. Electron...
Chemical Synapses
At the ends of the terminal arborizations of the presynaptic nerve axon are the bulbs or boutons of chemical synapses. Each synaptic bulb is from 1 to 2 im in diameter it is filled with many spherical, synaptic vesicles containing neurotransmitter, some of which are in intimate contact with the membrane of the bulb facing the synaptic cleft or gap Eccles, 1964 . The vesicles are from 20 to 60 im in diameter and are constantly being made by the metabolic machinery in the bulb and axon terminal....
Table of Contents
1.1.2 Vertebrate Peripheral Sensory Neurons 1.2 Electrical Properties of Nerve Membrane 1.2.1 The Source of UM Electrical Parameters 1.2.2 Decremental Conduction on Dendrites The Space Constant 1.2.3 Active Membrane The Nerve Spike 1.2.4 Saltatory Conduction on Myelinated Axons 1.3.4 Quantal Release of Neurotransmitter 1.4 Models for the Nerve Action Potential 1.4.1 The 1952 Hodgkin-Huxley Model for Action Potential Generation 1.4.2 Properties of the Hodgkin-Huxley Model 1.4.3 Extended...
Rosenblatts Perceptron
One of the first ANNs, the Perceptron, was developed by Rosenblatt 1958 1962 . His Mark I perceptron was a pattern recognition system that could learn to recognize simple visual patterns presented to its compound eye receptor plane, which contained 400 CdS photosensors in a square, 20 x 20 array. This perceptron had available a total of 512 connections with adjustable weights. The weights were varied by motor-driven potentiometers. The connections could be set by a patch panel, and were usually...
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FIGURE 8.2-7 The reversed, conditional expectation, Rxy t , calculated from a single fiber in a cat auditory nerve. Noise bandwidth was 200 to 2000 Hz the noise input for 4403 spikes was processed. The peak sinusoidal frequency response for this unit was 1.5 kHz. From DeBoer, E. and Kuyper, P., IEEE Trans. Bio. Med. Eng., 15 3 169, 1968. 1968 IEEE. With permission from IEEE. Taking the inverse LaPlace transform of H s yields its weighting function or impulse response, h t h t --e-at sin bt 9 ,...
Retinula Cells and Rhabdoms
The number of retinula cells in an ommatidium vary among arthropod species. Damselflies Zygoptera have only four retinula cells per ommatidium Mazokhin-Porshnyakov, 1969 , as do beetles coleoptera Meyer-Rochow, 1975 . There are eight retinula cells in each ommatidium of dragonflies odonata and in flies diptera . However, bees generally have nine, one of which is a smaller, eccentric cell Laughlin, 1975 Gribakin, 1975 . The horseshoe crab, Limulus, a chelicercate, has ten retinula cells plus a...
WiDROws ADALINE and MADALINE
The ADALINE for ADAptive LINear Element was developed by Bernard Widrow and colleagues 1985 1962 1960 for use as a pattern classifier ANN, similar to the perception. Multilayer assemblies of ADALINE units were called MADALINES Many ADALINES . Except for its improved w training algorithm, an ADALINE was essentially a single-layer perception. In the early 1960s, Widrow's Ph.D. student, W. C. Ridgway, III 1962 , found a means to obtain non-linear separability in classifying inputs, x. A two layer...
Saltatory Conduction on Myelinated Axons
A morphological adaptation of vertebrates that increases the spike propagation velocity on their axons is myelinization. An electron micrograph of the cross section of a myelinated axon is shown in Figure 1.2-5 from a rat sciatic nerve, x 52,000 . Where the axon is wrapped in the myelin tape, two important changes occur in the cable parameters. Because of the insulation of multiple, close-packed layers of UM, gm decreases, perhaps by a factor of 1 64. Because of the effective thickening of the...
Simulink
Simulink runs with Matlab both are products of The Math Works, Natick, MA. Simulink is now at v3.0 11 99 different versions of Matlab and Simulink run on PCs with Windows 95, 98, or NT4.0, or on Macs or UNIX platforms . Simulink is an icon-driven, dynamic simulation package that allows the user to represent a nonlinear dynamic process with a block diagram. As the block diagram is built, the user has to specify numerical values for the parameters in the blocks, and, of course, the...
Info Bjs
FIGURE 4.5-4 Results of a simulation of the RI system when symmetrical inhibitory feedback is used. Same trace numbering as in Figure 4.5-3. Note that the output neurons fire two pulse bursts, in phase. Same simulation parameters except Do3 Do4 1. FIGURE 4.5-5 Results of a simulation of the RI system when asymmetrical inhibitory feedback is used. Same trace numbering as in Figure 4.5-3. The N1 firing is completely inhibited by N2, which becomes dominant. Same simulation parameters except Do3 1...
Functional morphology of the compound eye of the bee
FIGURE 5.1-3 Schematic of a radial cross section of an ommatidium of a worker bee. Perpendicular cross sections through the retinula cells on the right. Key CL, corneal lens CC, crystalline cone SPC, secondary pigment cell PPC, primary pigment cell VC, retinula cell Rh, rhabdom 9VC, the ninth visual eccentric cell OC, the optical stopper formed by pigmented extensions of the four cone cells. Nature has designed this ommatidium to trap and deliver as much light as possible to the rhabdoms where...
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The PDS at the output of the linear filter is yy fi XX H jffl G2lo for o - B lt fi lt o B The autocorrelation function of the narrowband noise at the filter output is found from r t I G2l ejraTdra I ejCTdc I ejCTdc 8.2-28
Figure P26
dpr a b p-q b-a dprestimates pr over 0 . a 2r ms Give the spike responses of the RPFM spike generator for a. A pulse of pressure p t Po U t - U t - 20 . The pulse is 20 ms in duration Po 3 psi. Let a 2, b 3 r ms. b. A pressure sine wave of varying frequency p t Po sin 2nf t . Let Po 3 psi and let 0.05 f 5 cycles ms. Plot the steady-state spike frequency vs. f. 2.7. It is known that the primary response of some animals' photoreceptor cells is hyperpolarization upon illumination, while absorption...
Chemoreceptors
Two major classes of chemoreceptors exist in animals external and internal. Internal chemosensors sense quantities such as pH and pO2 in the blood or extracellular fluid. External chemoreceptors sense a wide spectrum of molecules that figure in an animal's life. External chemoreceptors are examined first. External chemoreceptors are sensory neurons that respond to specific molecules in the air as gases, liquids, or solids in vapor phase, or solids suspended as aerosols . Aquatic and marine...
Vertebrate Peripheral Sensory Neurons
Vertebrate peripheral sensory neurons are generally described by their sensory ending anatomy. They may or may not be myelinated. Parameters sensed are heat T above ambient body temperature , cold, pain, touch, pressure, strain muscle tension , and muscle length. Chemoreceptors for taste, odor, pH, pO2. etc. , photoreceptors rods and cones , and hearing receptors hair cells are generally considered to be part of the large receptor arrays having direct connection with the vertebrate brain....
Review Of The Anatomy And Physiology Of The Vertebrate Retina
The retinas of all vertebrates follow a general anatomical pattern. Located on the rear, inside surface of an eyeball, it has ten anatomical layers. Starting from the vitreous humor, the layers are 1 internal limiting membrane 2 optic nerve axon layer 3 ganglion cell layer about 5 x 105 per eye in the frog 4 inner plexiform layer 5 inner nuclear layer 6 outer plexiform layer 7 outer nuclear layer 8 external limiting membrane 9 sensory cells about 106 rods and cones in the frog 10 pigment...
Review Of Characterization And Identification Means For Linear Systems
Because neural system identification and systems-level modeling are very broad subjects in which many workers have developed a variety of approaches, one cannot hope to review them all in this chapter. However, those classical approaches that have had some impact on neural systems will be examined. Many schemes have been devised by systems and control engineers for the characterization of single-input single-output SISO linear systems, including those exhibiting nonminimum phase transfer...
The JPST Diagram
The poststimulus firing time PST diagram is a well-known neurophysiological tool that is used to illustrate adaptation and habituation in a single responding neuron. Every time a stimulus is given, the time base is triggered on a storage oscilloscope when the neuron fires, the spike is discriminated and the z-axis beam intensity is brightened to make a dot to mark the event on the CRT face. On the next stimulus, the trace is stepped up and another sweep is started, etc. This process builds a...
The Torsional Vibrating Mass Gyro
A schematic of a single, torsional vibrating mass angular rate sensor is shown in Figure 2.7-2. This structure is analogous to one haltere. This particular example 1 introduces and illustrates Lagrange's method of analyzing complex, dynamic bio-mechanical systems Cannon, 1967 2 allows extension of the analysis of a single, torsional, vibrating-mass, angular-rate sensor to a paired structure in which the masses vibrate 180 out of phase a crude model for the paired halteres of a complete FIGURE...
The LeeSchetzen Approach to White Noise Analysis
Lee and Schetzen 1965 showed how the terms of the Wiener functional series may be estimated through cross-correlation or cross-power spectrum techniques to arrive at a useful, general, quantitative model for a nonlinear dynamic system. Marmarelis and Naka 1973a extended the Lee-Schetzen method of white noise analysis to nonlinear systems with two inputs and one output, and have applied this approach to describing the dynamics of signal processing in the catfish retina. They also analyzed the...
A Model for epsp Production Based on Chemical Kinetics
The ballistic shape of the epsp can also be modeled by a simple, nonlinear, chemical kinetic model. In this case, consider a nicotinic acetylcholine ACh synapse in which two molecules of ACh must bind to a subsynaptic receptor site in order for the ion channel to open, depolarizing the SSM. Stated in terms of a chemical reaction, a bolus of ACh is released by the presynaptic action potential, and it diffuses across the cleft to the receptors. There, at every receptor, two transmitter molecules...
Ampullary Receptors
The ampullae of Lorenzini AoL found in sharks, skates, and rays were rst discovered by Marcello Malpighi in 1663 they were described in detail by Stephano Lorenzini in 1678, and bear his name. Anatomically the AoL are relatively simple structures. A jelly- lled canal projects through a pore in the skin. The surface pores of the AoL on the face of a shark give it the appearance of having acne. The canal jelly has a high conductivity due to its high content of Cl- and K ions it is probably...
T2
FIGURE 2.3-9 Block diagram of a theoretical type 0 control loop for a spindle designed to keep the steady-state output instantaneous firing rate, r2, constant. Note that the CNS output to the spindle ys motor fiber is proportional to some re ro - r2, re 0 if ro - r2 lt 0. FIGURE 2.3-9 Block diagram of a theoretical type 0 control loop for a spindle designed to keep the steady-state output instantaneous firing rate, r2, constant. Note that the CNS output to the spindle ys motor fiber is...
Directionally Sensitive Neurons in the Frogs Brain
Reddy 1977 examined single visual units found in the frog's brain exhibiting directional sensitivity DS to moving visual objects. Reddy made extracellular recordings from visual units in the tectum, thalamus, and cerebellum using glass-coated Pt Ir microelectrodes. Only 9 of the motion-sensitive units found in these sites were truly DS. A DS unit by definition fires at a maximum rate for an object having constant speed in a preferred direction PD . The neuron fires at slower rates for...
Eye Morphology
LaCourse 1981 examined the structure and ultrastructure of Mytilus in detail using light and transmission electron microscopy. He found that there were pigment cells in close membrane association with the PRCs. The arrangement between PRCs and pigment cells was irregular. The PRCs were unpigmented. Their distal ends were covered with many microvilli and one or more cilia with the 9 2 arrangement of microtubules in their axonemes. Figure 2.8-3 is an artist's schematic of a slice through the...
Quantal Release of Neurotransmitter
In 1952, Fatt and Katz, using extra- and intracellular recording from the subsynaptic membrane of resting muscle, observed what they called spontaneous miniature endplate potentials SMEPPs Katz, 1966 Eccles, 1964 . These SMEPPs were transient depolarizations of the membrane under the motor end plate having the same time course as a muscle twitch potential caused by the arrival of a single motoneuron spike at the motor end plate. The SMEPPs occurred randomly at a mean rate of about one per...
Electrical Properties Of Nerve Membrane
The basic structure of the unit membrane UM covering all nerve cells is the ubiquitous lipid bilayer, found on cells everywhere in the animal kingdom. The lipid bilayer is about 7.5 to 10 nm thick how thick it appears under the transmission electron microscope often depends on the fixation techniques used to prepare the specimen . The lipid bilayer is composed of facing ordered arrays of phospholipid cholesterol molecules. The fatty acid radicals on the molecules are hydrophobic and face each...
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FIGURE 2.2-2 A Anatomical schematic of the connections of various cells within the olfactory bulb. Anatomically, there are five layers in the olfactory bulb OB . Shepherd 1970 observed that there is congruence between cells of the vertebrate retina and olfactory lobe cells. Retinal horizontal cells are analogous to OB periglomerular cells, and retinal amacrine cells are analogous to OB granule cells. There are no cells analogous to retinal bipolar cells in the OB, but the long primary dendrite...
Lateral Inhibition In The Eye Of Limulus
Much of the early work on CE vision was done by Hartline 1949 , Hartline and Ratliff 1957 1958 , Ratliff et al., 1963 1966, and Tomita 1958 on the lateral eyes of the horseshoe crab, L. polyphemus. Limulus, a chelicercate arthropod, has two relatively simple, CEs and is an ideal subject to study the basic anatomy, organization, and neural signal processing of a primitive CE. Limulus eyes are elipsoidal bulges on the sides of the animal's dorsal carapace, about 12 mm long by 6 mm wide. Each...
Anatomy Of The Arthropod Compound Eye Visual System
This section examines the structure of an interesting, ubiquitous, neuro-sensory array, that of the arthropod CE. The most important arthropod classes include insects, crustaceans, and arachnids. Other animals either have primitive photoreceptor arrays, or in the case of vertebrates and certain mollusks including the octopi and the squids have two sophisticated camera eyes, each with a single lens that focuses an image on a neuro-sensory array, the retina. Compound eyes, as the name suggests,...
Mechanoreceptors
Mechanoreceptors are specialized sensory neurons that transduce the mechanical parameters of force or stretch of muscle fibers or tendons to spike frequency muscle spindles, Golgi tendon organs, Mytilus anterior byssus retractor muscle stretch receptors . They also sense the bending of specialized hairs trichoid hairs of arthropods, tricobothria, tricholiths in a particular range of directions, or the angle of one limb segment with respect to the next segment chordotonal organs . Other...
A Lorentz Force Mechanism in Vertebrate Photoreceptors
In the dark, the cell membrane of the outer segment of a vertebrate rod or cone has a heavy leakage current density of certain positive ions into the cell through gated cation channels embedded in the cell membrane. 80 of the current is carried by Na , 15 by Ca , and 5 by Mg ions. The inward leakage current is balanced by active outward pumping of Na , etc., by metabolic pumps in the inner segment of the cell. When light is absorbed by the photopigment molecules on the disks inside the outer...
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FIGURE 5.1-5 Transmission electron micrograph of a cross section of a bee ventral ommatidium showing the rhabdom in the proximal part of the dark-adapted ommatidium. Key ES, extracellular space PG, pigment granule PEC, principal endoplasmic cysternae SLP, secondary pigment cell M, mitochondria CB, cytoplasmic bridges. Arrows show the directions of diffusion between SLP and the cytoplasm of the visual cell, and between ES and PEC. From Gribakin, F.G., in The Compound Eye and Vision in Insects,...
Gravity Receptors Of The Cockroach Arenivaga Sp
This section shows that the tricholith gravity sensors of the cockroach Arenivaga sp. are an excellent example of a small receptor array. Tricholiths have been shown to respond to the position of the cockroach with respect to the Earth's gravity vector. Only four large identi able interneurons carry spatial orientation information from the tricholith arrays to the animal's CNS where it is processed by many interneurons. Willey 1981 recorded from single, position-sensitive neurons in the...
Electroreceptors
Electroreceptors are specialized neurons that, in an aquatic or marine environment respond to the presence of an electric eld or , equivalently, a voltage gradient across them . They are found in the skin of certain sh and in the beak of the duck-billed platypus, the only mammal having this sensory modality. Underwater electric elds can be subdivided into two classes those that are constant dc or slowly varying up to 50 Hz , and those high-frequency elds arising from special electrogenic organs...
Eye Movements and Visual Tracking in Flies
The preceding section demonstrated that the visual systems of flies are richly endowed with at least two types of DS visual neuron, and several preferred directions. It is reasonable to assume that these neurons carry information to the complex motor centers that stabilize flight. In the visual systems of other arthropods, e.g., crustaceans, which have movable eyes on eyestalks, visual DS units control eye movements Burrows and Horridge, 1968 Horridge and Burrows, 1968 . Insect eyes are...
Integral And Relaxation Pulse Frequency Modulation Models For The Spike
How the SGL of a spiking neuron behaves approximately as a voltage-to-frequency converter VFC , driven by a positive generator potential GP that is the spatiotemporal sum of epsps and ipsps has been described. As seen from the discussion of the HH model equations in Section 1.4, spike generation is a nonlinear process. There is a minimum GP below which a neuron will not fire, and the steady-state spike frequency is a nonlinear saturating function of the GP. To model spike generation...
Simnon
Simnon was developed at the Department of Automatic Control at the Lund Institute of Technology, Sweden in the late 1980s. The program in its early versions V1.0 to V3.2 was written to run under DOS on PCs. A simple, algebraic input script was used. The author found in 1988 that Simnon v2.0 was particularly well suited for simulation of compartmental pharmacokinetic systems, chemical kinetic systems, and physiological regulators and control systems because its input modality is in the form of...