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1.
Summary Neural activity is viewed as a stochastic point process, in which information resides in the modulation of a background of spontaneous activity. Characteristic features of the spatial and temporal mapping of sensory signals are discussed. One of the puzzling aspects of neural functioning is the integrity of the signal in its passage toward higher brain centers, in view of the fundamentally noisy response of the individual neuron. It is shown, that a process, we call image stabilization, is a direct consequence of the particular mapping function exemplified by lateral inhibition and adaptation.The research reported in this paper was sponsored by the Aerospace Medical Research Laboratories, Aerospace Medical Division, Air Force Systems Command, Wright-Patterson Air Force Base, Ohio, under contract No. F 33615-67-C-1413 and the Office of Naval Research, contract No. ONR N0001467-A-0378-0001, with Syracuse University Research Institute. Further reproduction is authorized to satisfy needs of the U.S. Government. 相似文献
2.
Gordon Pask 《Bulletin of mathematical biology》1965,27(1):261-273
Systems in which a human subject interacts with an adaptive control mechanism through display and response facilities are
examined. A cybernetic model is discussed, together with supporting experimental data.
The research reported in this paper has been supported by the Air Force Office of Scientific Research, under Contract AF.
61.052.640. (for Cybernetic models for learning) and by the Aerospace Medical Research Laboratories A.F.C.S., under contract
AF. 61.052.402. (for adaptive teaching systems), through the European Office for Aerospace Research. 相似文献
3.
Summary An electron microscopic study of the interganglionic connectives of an orthopteran (Laplatacris dispar) demonstrated that a reaction starts in the sectioned fibers very soon after transection (30 minutes). This reaction is closely similar to that observed in sectioned nerves of vertebrates and consists in the appearance of microvesicles and the proliferation of mitochondria. Sectioned connectives were studied from 30 minutes to 88 hours after section. The reaction mentioned increases progressively during the indicated lapse of time.This research was supported by the United States Air Force under Contract No AF 49 (638) 585 and Grant Af 61-64, monitored by the Air Force Office of Scientific Research, Air Force Research Division of the Air Research and Development Command. 相似文献
4.
H. D. Landahl 《Bulletin of mathematical biology》1961,23(2):159-163
A mechanism is suggested in which a postulated substance can enter a synaptic region only during the simultaneous action of
a conditioned and an unconditioned stimulus. If this substance remains and produces a physico-chemical change, then a consequence
is that the degree of learning will depend on the spacing of conditioning trials and the time constant of the process will
be related to the rate of diffusion or transport of the substance along the axon.
This research was supported by the United States Air Force through the Air Force Office of Scientific Research of the Air
Research Development Command under Contract No. AF 49(638)-414. 相似文献
5.
Robert Rosen 《Bulletin of mathematical biology》1962,24(3):279-290
It is shown informally that Cohn’s theory of Optimal Forms can be construed as a comparative theory, and that when this is
done the celebrated theory of transformations of D’Arcy Thompson follows as a consequence. The implications of this type of
theoretical foundation for the Thompson theory with regard to problems of comparative morphology are discussed, and some suggestions
for the further implementation of the theory are described.
This research was supported by the United States Air Force through the Air Force Office of Scientific Research of the Air
Research and Development Command, under Contract No. AF 49(638)-917. 相似文献
6.
Summary The exact mathematical treatment is given for a non linear equation describing the delayed yes-or-no response to a binary system to external stimulations, in some typical cases of interest. Comparison is made with neurophysiological data on the frequency rate of firings of stimulated neurons; the same equation, however, can be conceivably applied to a vast variety of phenomena. The procedures followed to solve the problems that arise in connection with this equation could be extended to more general types of non linear equations.The research reported in this document has been sponsored in part by the Air Force Office of Scientific Research under Contract no. AF EOAR 65-44 through the European Office of Aerospace Research, OAR, United States Air Force. 相似文献
7.
C. Jone J. E. Trosko C. C. Chang 《In vitro cellular & developmental biology. Plant》1987,23(3):214-220
Summary A normal rat liver epithelial cell line, with phenotype characteristics of “oval” cells (WB-F344), was examined for its ability
to perform gap-junctional intercellular communication as measured by metabolic cooperation. To test for gap-junctional intercellular
communication, 6-thioguanine-sensitive cells were cocultivated with 6-thioguanine-resistant cells. It was found that the recovery
of 6-thioguanine-resistant cells depended on the densities of the 6-thioguanine-sensitive cells. Higher densities of 6-thioguanine-sensitive
cells reduced the recovery of 6-thioguanine-resistant cells. These observations demonstrate that rat liver epithelial cells
could metabolically cooperate, implying they could perform gap-junctional intercellular communication. Two tumor-promoting
organochlorine pesticides, aldrin and dieldrin, were potent inhibitors of metabolic cooperation for these cells, but 12-0-tetradecanoyl-phorbol-13-acetate
and teleocidin, known mouse skin tumor promoters, were not significantly effective in inhibiting metabolic cooperation. The
results suggest that these cells might provide the basis for an in vitro assay specifically to study liver tumor promoters.
Research was sponsored by a grant from the Air Force Office of Scientific Research, Air Force Systems Command, USAF, under
grant AFOSR-86-0084. The U. S. Government is authorized to reproduce and distribute reprints for government purposes notwithstanding
any copyright notation thereon. 相似文献
8.
Harold White 《Bulletin of mathematical biology》1962,24(4):351-359
Quantitative aspects of the photochemistry of visual adaptation are considered. A simplied model is given that fits data on
changes of rhodopsin concentration during and following strong illumination. A variation on Wald’s compartment hypothesis
is shown to fit the quasilinear dependence of log threshold upon pigment concentration. Finally, there is a brief review of
pertinent data on cone pigments.
This research was supported in part by the United States Air Force through the Air Force Office of Scientific Research of
the Air Research Development Command under Contract No. AF(638)-414, and in part by the United States Public Health Service
Training Grant 2G-833. 相似文献
9.
Morphologically identical nerve endings subserve more than one sensory modality. Two possible explanations are: such endings
are functionally different, responding to one type of physical excitation only, or such endings are capable of responding
to more than one type of physical stimulus, but central mechanisms discriminate between different stimuli. A simple network
is described to illustrate how thermal receptors could discriminate between thermal and mechanical stimuli.
This research was supported in part by the United States Air Force Office of Scientific Research of the Air Research and Development
Command under contract No. AF 18(600)-1454. Reproduction in whole or in part is permitted for any purpose of the United States
Government. 相似文献
10.
H. D. Landahl 《Bulletin of mathematical biology》1964,26(1):83-89
A simple avoidance situation is considered in terms of a neural net learning model. Data for the control situation can be
represented by an expression having three parameters which determine the initial and the steady state activities together
with the transient aspects. The introduction of a learning parameter then allows one to calculate satisfactorily the results
obtained in the experimental situation in which shock is applied.
This research was supported in part by the United States Air Force through the Air Force Office of Scientific Research of
the Air Research Development Command under Grant No. AF AFOSR 370-63 and in part by the United States Public Health Service
Grant RCA GM K6 18,420. 相似文献
11.
J. A. Goguen Jr. 《Bulletin of mathematical biology》1964,26(2):121-138
This paper proposes a model for color perception which accounts for variations in the dimension of the space of perceived
colors. The model assumes that there is only one type of cone with only one shape of response curve, but that different cone's
response curves differ by translation. It also assumes that the final discrimination system, learned from originally random
connections, maximizes discrimination in the normal visual environment. Learning mechanisms are discussed, and the form which
the final discrimination system ought to take is plausibly derived. An algorithm for the tristimulus curves is obtained from
this model, and it is shown that a good fit of the empirical data can be obtained.
This work was supported by the Air Force Systems Command, United States Air Force, Contract No. AF33(657)-8681. 相似文献
12.
Harold White 《Bulletin of mathematical biology》1963,25(2):125-139
First a model for theb-wave of the electroretinogram is given. The essential part of the model is the diffusion into the rod-bipolar synapse of
a transmitter substance, followed by the induction of an inhibitor. Making use of this model, adaptation to an illumination
too weak to cause of significant decrease in the concentration of visual pigment is interpreted as due to a decreased effectiveness
of the rod impulse in exciting the bipolar cell. The disparity between threshold changes for very small test spots and for
relatively large spots is explained simply, without invoking any additional physiological mechanisms.
This research was supported in part by the United States Air Force through the Air Force Office of Scientific Research of
the Air Research Development Command under Contract No. AF(638)-414 and in part by the United States Public Health Service
Training Grant 2G-833. 相似文献
13.
Hal Smith 《Journal of mathematical biology》1987,25(2):169-190
In this paper we study the cyclic gene model with repression considered by H. T. Banks and J. M. Mahaffy. Roughly, the model describes a biochemical feedback loop consisting of an integer number G of single gene reaction sequences in series. The model leads to a system of functional differential equations. We show that there is a qualitative difference in the dynamics between even and odd G if the feedback repression is sufficiently large. For even G, multiple stable steady states can coexist while for odd G, periodic orbits exist.This research was supported in part by the Air Force Office of Scientific Research under Contract #AFOSR-84-0376 and by the US Army Research Office under Contract #DAAG29-84-K-0082 相似文献
14.
Summary On the basis of a recent physical theory of many-body problems developped in our Institute, a model of the brain is formulated, and it is shown how some of its typical features, such as learning and memory processes, find therein a natural and simple explanation. In the Appendix a short surview of the necessary mathematical formalism is finally given.A brief outline of the model presented in this paper was unformally given by one of the authors (L.M.R.) at the I.S.P. Neurosciences Research Program; Boulder Colorado, in July 1966.This work has been sponsored in part by: Air Force Avionics Lab., Research and Technology Div., Wright Patterson Air Force, Air Force System Commend-U.S.A.F.-Government of United States of America. Contract No. AF 33(615)-2786. 相似文献
15.
Robert Rosen 《Bulletin of mathematical biology》1961,23(2):165-171
It is shown that a wide variety of structural alterations in both the “metabolic” and “genetic” apparatus of (
, ℜ)-systems can result from specific changes in the environment of such systems. A number of specific examples are investigated
in order to demonstrate the scope of these alterations. Certain biological applications of this discussion are suggested,
including a suggestion for a possible interpretation of the mitotic cycle.
This research was supported by the United States Air Force through the Air Force Office of Scientific Research of the Air
Research and Development Command, under Contract #AF 49 (638)-917. 相似文献
16.
Sadayoshi Kamiya 《Bulletin of mathematical biology》1958,20(4):343-373
A photochemical system is considered which is similar to that of S. Hecht but which includes an intermediate substance between
visual purple and visual white. This intermediate is assumed to change the embrane voltage of the photoreceptors. A simple
model is presented from which one may calculate the frequency of the impulses resulting from the application of light. It
is found that this physicochemicai model enables one to account for a considerable number of physiological phenomena of vision.
Among these are the light and dark adaptation phenomena. By introducing a simple assumption regarding spatial interaction
one can account for some psychological phenomena such as the effect of intensity, light-dark ratio, shape, and area on the
critical flicker frequency. A number of other phenomena are discussed in terms of the model.
This research was supported by the United States Air Force through the Air Force Office of Scientific Research of the Air
Research and Development Command under Contract No. AF 18(600)-1454. Reproduction in whole or in part is permitted for any
purpose of the United States Government. 相似文献
17.
Peter H. Greene 《Bulletin of mathematical biology》1957,19(2):147-156
Interpretations of the mechanisms of perception of contours or of Mach bands have stressed either the role of various spatial
derivatives of light intensity at the retina or the importance of various forms of inhibitory effects between neighboring
retinal elements. Evidence is presented here in support of the latter type of interpretation. It is considered that the brightness
contrast and perceived contours arise from neural elements, each of which is stimulated in proportion to the intensity of
photo-receptor excitation at a point of the retina and inhibited in proportion to the mean intensity in some neighborhood
of that point. The role of the spatial derivatives is best seen as a particular manifestation of the inhibitory mechanism.
Predictions based upon this hypothesis appear to be consistent with experimentally observed evidence.
This research was supported by the United States Air Force through the Air Force Office of Scientific Research of the Air
Research and Development Command under Contract No. AF 18(600)-1454. Reproduction in while or in part is permitted for any
purpose of the United States Government. 相似文献
18.
Robert Rosen 《Bulletin of mathematical biology》1963,25(1):41-50
The environmentally induced alterations in structure of (M, ℜ) which were described previously (R. Rosen,Bull. Math. Biophysics,23, 165–171, 1961) are examined from the standpoint of determining under what circumstances they can be reversed by further
environmental interactions. For simplicity we consider only the case of (M, ℜ)-systems possessing one “metabolic” and one “genetic” component. In the case of environmentally induced alteration of
the “metabolic” component alone, a necessary and sufficient condition is given for the reversibility of the alteration. In
the case of alteration of the “genetic” component, the situation becomes more complex; several partial results are given,
but a full analysis is not available at this time. Some possible biological implications of this analysis are discussed.
This research was supported by the United States Air Force through the Air Force Office of Scientific Research of the Air
Research and Development Command, under Contract no. AF-49(638)-917 and Grant no. AF-AFOSR-9-63. 相似文献
19.
Summary The output distribution function of a non-linear switching element with a Poissonian sequence of impulses at the input is calculated by a straightforward method. The dead time of the element is taken into account. Some limiting properties of this distribution and its mean value are studied.The present research has been sponsored in part by the Air Force Avionics Lab., Research and Technology Div., Wright-Patterson Air Force, Air Force System Command — U.S.A.F. — Government of United States of America, Contract no. AF 33(615)-2786. 相似文献
20.
The effects of area and intensity on the critical flicker frequency, threshold, and reaction time are considered in terms
of neural net theory. An attempt is made to develop a mechanism which can account for the phenomena associated with the empirically
observed laws of Ricco, Granit, Talbot, and Ferry-Porter as well as observations on reaction time and threshold. A simple
model gives results which are substantially in agreement with observation except for a few apparent discrepancies. Experimental
procedures are suggested which can determine whether these are apparent or real.
This research was supported by the United States Air Force through the Air Force Office of Scientific Research of the Air
Research and Development Command under contract No. AF 18(600)-1454. Reproduction in whole or in part is permitted for any
purpose of the United States Government. 相似文献