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  • 1
    Electronic Resource
    Electronic Resource
    An inference upon the neural network finding binocular correspondence (1978)
    Springer
    Biological cybernetics 31 (1978), S. 209-217 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Previously, the authors proposed a model of neural network extracting binocular parallax (Hirai and Fukushima, 1975). It is a multilayered network whose final layers consist of neural elements corresponding to “binocular depth neurons” found in monkey's visual cortex. The binocular depth neuron is selectively sensitive to a binocular stimulus with a specific amount of binocular parallax and does not respond to a monocular one. As described in the last chapter of the previous article (Hirai and Fukushima, 1975), when a binocular pair of input patterns consist of, for example, many vertical bars placed very closely to each other, the binocular depth neurons might respond not only to correct binocular pairs, but also to incorrect ones. Our present study is concentrated upon how the visual system finds correct binocular pairs or binocular correspondence. It is assumed that some neural network is cascaded after the binocular depth neurons and finds out correct binocular correspondence by eliminating the incorrect binocular pairs. In this article a model of such neural network is proposed. The performance of the model has been simulated on a digital computer. The results of the computer simulation show that this model finds binocular correspondence satisfactorily. It has been demonstrated by the computer simulation that this model also explains the mechanism of the hysteresis in the binocular depth perception reported by Fender and Julesz (1967)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337092
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  • 2
    Electronic Resource
    Electronic Resource
    Reticulospinal connections with limb and axial motoneurons (1979)
    Springer
    Experimental brain research 36 (1979), S. 1-20 
    Details
    ISSN: 1432-1106
    Keywords: Reticulospinal ; Excitation ; Inhibition ; Axial motoneurons ; Limb motoneurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses of motoneurons supplying muscles of the forelimbs, hindlimbs, back, and neck to stimulation of the medial pontomedullary reticular formation were studied with intracellular recording in cere-bellectomized cats under chloralose anesthesia. Stimulation of the midline or of a reticular region consisting of nucleus reticularis (n.r.) pontis caudalis and the dorsorostral part of n.r. gigantocellularis produced monosynaptic excitation of ipsilateral motoneurons supplying axial muscles and flexor and extensor muscles in both proximal and distal parts of the limbs. This widespread excitation appears to have been produced by rapidly conducting medial reticulospinal fibers. Stimulation of a second region consisting of n.r. ventralis and the ventrocaudal part of n. r. gigantocellularis produced monosynaptic excitation of ipsilateral neck and back motoneurons but only longer latency, apparently multisynaptic excitation of limb motoneurons. Collision tests indicated that this monosynaptic excitation did not involve fibers descending along the midline. It therefore appears to have been produced by lateral reticulospinal fibers. Reticular stimulation also produced short latency, monosynaptic inhibition of neck motoneurons, long latency, apparently polysynaptic inhibition of limb motoneurons and intermediate latency inhibition of back motoneurons. The latencies and properties of inhibitory responses of back motoneurons indicated that they were produced either disynaptically by fast fibers or monosynaptically by slower fibers. The data indicate that the medial pontomedullary reticular formation can be divided into a number of different zones each with a distinct pattern of connections with somatic motoneurons. These include the dorsorostrally located medial reticulospinal projection area, from which direct excitation of a wide variety of motoneurons can be evoked, the ventrocaudally located lateral reticulospinal projection area from which direct excitation of neck and back and direct inhibition of neck motoneurons can be evoked and the dorsal strip of n.r. gigantocellularis which has direct excitatory and inhibitory actions only on neck motoneurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238464
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  • 3
    Electronic Resource
    Electronic Resource
    Direct excitation of neck motoneurons by interstitiospinal fibers (1978)
    Springer
    Experimental brain research 33 (1978), S. 565-581 
    Details
    ISSN: 1432-1106
    Keywords: Interstitial nucleus of Cajal ; Monosynaptic excitation ; Neck motoneurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Responses of neck motoneurons to stimulation of the interstitial nucleus of Cajal (INC) were recorded intracellularly in cats under chloralose anesthesia. When stimuli were applied within or close to the INC, short latency, monosynaptic excitatory postsynaptic potentials (EPSPs) were evoked in many neck motoneurons. Such EPSPs were not evoked by stimulating mesencephalic regions outside the INC. 2. Stimulation of the ipsilateral INC produced monosynaptic EPSPs consistently in biventer cervicis-complexus (BCC) motoneurons, while such EPSPs were observed in about two thirds of the splenius (SP) motoneurons and half of the trapezius (TR) motoneurons tested. Stimulation of the contralateral INC produced weak monosynaptic EPSPs in about half the BCC motoneurons and in a few SP and TR motoneurons. All types of motoneurons also received longer latency, apparently polysynaptic, PSPs from both INCs. In BCC and TR motoneurons these were mainly EPSPs, in SP, mixed excitatory and inhibitory PSPs. 3. Monosynaptic EPSPs evoked by INC stimulation were not eliminated by acute and chronic parasagittal and transverse lesions placed to interrupt the bifurcating axons of all vestibulospinal and many reticulospinal neurons. No significant collision was observed between EPSPs evoked by INC and vestibular or reticular stimulation. The EPSPs evoked by stimulation of the INC therefore appear to have been produced by activation of interstitiospinal neurons rather than by an axon reflex mechanism. 4. The properties of a number of interstitiospinal neurons were observed while recording extracellularly from the mesencephalon to map the location of the INC. One third of the interstitiospinal neurons activated antidromically from the C4 segment could also be activated antidromically from L1. These lumbar-projecting neurons had conduction velocities ranging from 15–123 m/s. Several interstitiospinal neurons sending axons to the ventral horn of the neck segments were identified and two of these were found to be branching neurons that projected both to the neck and to lower levels of the spinal cord.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235575
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  • 4
    Electronic Resource
    Electronic Resource
    Properties of a new vestibulospinal projection, the caudal vestibulospinal tract (1978)
    Springer
    Experimental brain research 32 (1978), S. 287-292 
    Details
    ISSN: 1432-1106
    Keywords: Caudal Vestibulospinal tract ; Fiber trajectory ; Conduction velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neurons in the caudal portions of the medial and descending vestibular nuclei and in vestibular cell group f that project to the cervical or lumbar spinal cord were located by antidromic spinal stimulation. These caudal Vestibulospinal tract (CVST) neurons have a median conduction velocity of 12 m/sec, which is well below the conduction velocities of typical lateral or medial Vestibulospinal tract (LVST, MVST) axons. The descending fiber trajectories of CVST neurons, determined by comparing thresholds for activation of each neuron from six points in the spinal white matter, were remarkably diverse. Unlike LVST and MVST axons, which are located in the ipsilateral ventral funiculi, CVST axons can be found in both the ventral and dorsolateral funiculi on both sides of the spinal cord. The CVST system is thus both anatomically and physiologically different from the LVST and MVST.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239733
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  • 5
    Electronic Resource
    Electronic Resource
    Interstitiospinal action on forelimb, hindlimb, and back motoneurons (1979)
    Springer
    Experimental brain research 37 (1979), S. 605-608 
    Details
    ISSN: 1432-1106
    Keywords: Motoneuron ; Forelimb ; Hindlimb ; Back
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses of motoneurons supplying muscles of the forelimbs, hindlimbs, and back to stimulation of the interstitial nucleus of Cajal (INC) were recorded intracellularly in cats under chloralose anesthesia. Stimulation of the ipsilateral and contralateral INC evoked predominantly excitatory postsynaptic potentials in these motoneurons. Response latencies and properties of responses to multiple shock stimuli indicated that the responses were evoked by a di- or polysynaptic pathway. Stimulation of the anterior MLF (P2), which should have activated the entire interstitiospinal tract, but few reticulospinal or vestibulospinal fibers, evoked only polysynaptic responses. These results indicate that the INC does not establish direct synaptic connections with limb and back motoneurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236827
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  • 6
    Electronic Resource
    Electronic Resource
    Properties and connections of cat fastigiospinal neurons (1978)
    Springer
    Experimental brain research 32 (1978), S. 1-17 
    Details
    ISSN: 1432-1106
    Keywords: Fastigial nucleus ; Fastigiospinal neurons ; Motoneurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Neurons in the cat fastigial nucleus that project to the upper cervical spinal segments (fastigiospinal neurons) were fired by antidromic stimulation of the contralateral spinal cord. Dye ejection from the recording electrode was used to show that most neurons were in the rostral half of the fastigial nucleus. 2. Fastigiospinal neurons can be excited and/or inhibited by stimulation of forelimb and hindlimb nerves and by stimulation of the vestibular nerve. These inputs converge on many neurons. 3. Antidromic microstimulation was used to trace fastigiospinal axons to the vicinity of motor nuclei in C2-C3. 4. The rostral fastigial nucleus was stimulated in preparations with the medial longitudinal fasciculus transected by a wide lesion that impinged on the medial reticular formation in the caudal medulla, to eliminate some potential axon reflexes. Short-latency EPSPs were recorded in some trapezius and biventer-cervicis motoneurons. In many cases there was little or no occlusion between these EPSPs and others evoked by stimulation of the vestibular nerve ipsilateral to the motoneurons. 5. Movement of the stimulating electrode and placement of this electrode lateral to the fastigial nucleus show that the zone from which low threshold EPSPs can be evoked is localized. 6. Latency measurements and lack of temporal facilitation with double shocks suggest that the EPSPs are monosynaptic. The evidence suggests that they are caused by fastigiospinal fibers terminating on motoneurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237385
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  • 7
    Electronic Resource
    Electronic Resource
    Reticulospinal excitation and inhibition of neck motoneurons (1978)
    Springer
    Experimental brain research 32 (1978), S. 471-489 
    Details
    ISSN: 1432-1106
    Keywords: Reticulospinal ; Monosynaptic ; Excitation ; Inhibition ; Neck motoneurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses of neck motoneurons to electrical stimulation of the pontomedullary reticular formation were recorded intracellularly in cerebellectomized cats anesthetized with chloralose. Stimulation of nucleus reticularis (n.r.) ventralis and the dorsal part of n.r. gigantocellularis evoked short latency, monosynaptic inhibitory postsynaptic potentials (IPSPs) in the majority of motoneurons supplying the ipsilateral splenius, biventer cervicis and complexus muscles and in 25% of motoneurons projecting in the ipsilateral spinal accessory nerve. Monosynaptic IPSPs were also evoked by stimulating the medial longitudinal fasciculus (MLF) but lesion and collision experiments indicated that these IPSPs were independent of those evoked by reticular stimulation. Monosynaptic IPSPs were also occasionally observed following stimulation of the contralateral reticular formation, especially of the dorsal part of n.r. gigantocellularis. Monosynaptic excitatory postsynaptic potentials (EPSPs) were evoked in all classes of neck motoneurons studied by stimulation of n.r. pontis caudalis, gigantocellularis and ventralis. Each reticular nucleus appeared to contribute to this excitation. The excitation was bilateral but large monosynaptic EPSPs were most often seen in motoneurons ipsilateral to the stimulus site. Data indicated that pontine EPSPs were mediated by ventromedial reticulospinal fibers while medullary EPSPs were mediated by ventrolateral reticulospinal fibers. Neck motoneurons thus receive at least three distinct direct reticulospinal inputs, two excitatory and one inhibitory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239548
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  • 8
    Electronic Resource
    Electronic Resource
    A self-organizing neural network with a function of associative memory: Feedback-type cognitron (1978)
    Springer
    Biological cybernetics 28 (1978), S. 201-208 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Previously, one of the authors proposed a new hypothesis on the organization of synaptic connections, and constructed a model of self-organizing multi-layered neural network “cognitron” (Fukushima, 1975). the cognitron consists of a number of neural layers with similar structure connected in a cascade one after another. We have modified the structure of the cognitron, and have developed a new network having an ability of associative memory. The new network, named a feedback-type cognitron, has not only the feedforward connections as in the conventional cognitron, but also modifiable feedback connections from the last-layer cells to the front-layer ones. This network has been simulated on a digital computer. If several stimulus patterns are repeatedly presented to the network, the interconnections between the cells are gradually organized. The feedback connections, as well as the conventional feedforward ones, are self-organized depending on the characteristies of the externally presented stimulus patterns. After adequate number of stimulus presentations, each cell usually acquires the selective responsiveness to one of the stimulus patterns which have been frequently given. That is, every different stimulus pattern becomes to elicit an individual response to the network. After the completion of the self-organization, several stimulus patterns are presented to the network, and the responses are observed. Once a stimulus is given to the network, the signal keeps circulating in the network even after cutting off the stimulus, and the response gradually changes. Even though an imperfect or an ambiguous pattern is presented, the response usually converges to one of the patterns which have been frequently given during the process of self-organization. In some cases, however, a new pattern which has never been presented before, emerges. It is seen that this feedback-type cognitron has characteristics quite similar to some functions of the brain, such as the associative recall of memory, or the creation of a new idea by intuition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344267
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  • 9
    Electronic Resource
    Electronic Resource
    Differential blocking of motor fibers by direct current (1975)
    Springer
    Pflügers Archiv 358 (1975), S. 235-242 
    Details
    ISSN: 1432-2013
    Keywords: Differential Blocking ; α Motor Fiber ; γ Motor Fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Differential blocking of α motor fibers was investigated in single fiber recordings when slowly rising direct current was applied to the gastrocnemius nerve in the cat. 18 out of the 26 (69.2%) L7 ventral root filaments, each of which contained 2–5 single α, or γ motor fibers, or both, showed consecutive blocking from thicker to thinner fibers with increase of polarizing current. In the remaining 8 filaments (30.8%) thicker and thinner fibers were blocked almost simultaneously, or the order was reversed. The relation between the strength of the blocking current and conduction velocity is summarized on 30 α and 41 γ fibers. The blocking current of each single fibers was shown to be inversely proportional to 2.01 power of conduction velocity (correlation coefficient −0.71). A regression line was also drawn for α fibers alone, its correlation coefficient being −0.60. Concerning prolongation of latencies of 82 single fibers (39 α and 43 γ), it was shown that the faster the conduction velocity, the smaller was the prolongation of latencies. In no experiments did the prolongation of latencies of single α fibers exceed the latency range of the mass α volley. Moreover, single α fibers were blocked earlier than or almost simultaneously with the mass α volley.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587220
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