Introduction

1980 ◽  
Vol 290 (1038) ◽  
pp. 3-4 ◽  
Keyword(s):  
Visual System ◽  
Visual Processing ◽  
Royal Society ◽  
Computational Models ◽  
Shape Recognition ◽  
External World ◽  
Physical World ◽  
The Subject ◽  
Contrast Discrimination ◽  
The Brain

There is a long-standing tradition of research on vision in Great Britain that goes back at least as far as Newton. The Royal Society is therefore a most suitable venue for a conference on the Psychology of Vision, and it is no accident that two of our distinguished guests from North America are British subjects. In the first 30 years of this century the Gestalt movement brought about a revolution in our ways of thinking about vision, but the subject then remained rather stagnant for two decades. In more recent years, dramatic discoveries and radical new insights have been forthcoming from three different directions. First, neurophysiologists have laid bare some of the highly systematic wiring that subserves the early stages of the processing of the visual input. Secondly, psychologists and psychophysiologists have uncovered some of the intricacies of the mechanisms that underlie such functions as acuity, contrast discrimination, motion detection and stereopsis. It is becoming possible to put together results from these two directions and to show how mechanisms inferred from psychophysical observations are instantiated in known neurophysiological circuits. The two sets of results indicate that visual processing is both more complex and more elegant than had been suspected 50 years ago. Thirdly, the advent of the digital computer has made it possible to build rigorous computational models of the visual system, to explore and to specify more adequately the nature of the task that the visual system must perform, and to demonstrate precisely how the constraints imposed by the nature of the physical world and of its optics make it possible for the brain to use the patterns of light impinging on the retinae to form a useful representation of the external world. Although this last enterprise may strike some as speculative, it has already led to insights into the nature of vision that have changed our ways of looking at the problems and have made the theories of shape recognition put forward in the 1950s and 1970s, including those of one of us, look extremely superficial.

Lantern Demonstration of Gross Lesions of the Cerebrum

1901 ◽  
Vol 47 (199) ◽  
pp. 729-737 ◽  
Author(s):  
Joseph Shaw Bolton
Keyword(s):  
Cerebral Cortex ◽  
Dura Mater ◽  
Royal Society ◽  
Mental Disease ◽  
Post Mortem ◽  
Pyramidal Layer ◽  
Gross Lesions ◽  
The Subject ◽  
The Brain ◽  
Morbid Conditions

This demonstration was a further report on the subject laid before the Association at the meeting at Claybury in February last, viz., the morbid changes occurring in the brain and other intra-cranial contents in amentia and dementia. In a paper read before the Royal Society in the spring of 1900, and subsequently published in the Philosophical Transactions, it was stated, as the result of a systematic micrometric examination of the visuo-sensory (primary visual) and visuo-psychic (lower associational) regions of the cerebral cortex, that the depth of the pyramidal layer of nerve-cells varies with the amentia or dementia existing in the patient. At the meeting of the Association referred to it was further shown, from an analysis, clinical and pathological, of 121 cases of insanity which appeared consecutively in the post-mortem room at Claybury, that the morbid conditions inside the skull-cap in insanity, viz., abnormalities in the dura mater, the pia arachnoid, the ependyma and intra-cranial fluid, etc., are the accompaniments of and vary in degree with dementia alone, and are independent of the duration of the mental disease. Since that date the pre-frontal (higher associational) region has been systematically examined in nineteen cases, viz., normal persons and normal aments (infants), and cases of amentia, of chronic and recurrent insanity without appreciable dementia, and of dementia, and the results obtained form the subject of the present demonstration. A paper on the whole subject will shortly be published in the Archives of the Claybury Laboratory.

Heidegger’s Reading of Descartes’ Dualism

1998 ◽  
pp. 57-64 ◽  
Author(s):  
A. Kadir Çüçen
Keyword(s):  
External World ◽  
Physical World ◽  
Modern World ◽  
Traditional Epistemology ◽  
The World ◽  
Subject And Object ◽  
The Subject ◽  
Technological Orientation

The problem of traditional epistemology is the relation of subject to external world. The distinction between subject and object makes possible the distinction between the knower and what is known. Starting with Descartes, the subject is a thinking thing that is not extended, and the object is an extended thing which does not think. Heidegger rejects this distinction between subject and object by arguing that there is no subject distinct from the external world of things because Dasein is essentially Being-in-the-world. Heidegger challenges the Cartesian legacy in epistemology in two ways. First, there is the modern tendency toward subjectivism and individualism that started with Descartes' discovery of the 'cogito.' Second, there is the technological orientation of the modern world that originated in the Cartesian understanding of the mathematical and external physical world.

XIII. On certain functions of the spinal chord, with further investigations into its structure

1853 ◽  
Vol 143 ◽  
pp. 347-356 ◽  
Keyword(s):  
Royal Society ◽  
Nerve Roots ◽  
Exact Relation ◽  
Spinal Nerves ◽  
Object A ◽  
Physiological Importance ◽  
Spinal Chord ◽  
The Subject ◽  
The Brain ◽  
Difficult Subject

When I had the honour of laying before the Royal Society my former researches on the structure of the spinal chord, I intimated an intention of preparing another communication on the structure of the medulla oblongata and cerebellum; but as many important points in the minute anatomy of the chord still remained in obscurity, I thought it advisable to make them first the subject of special inquiry, as far as the new method I employed would enable me to proceed. Moreover, as all investiga­tions into the structure of any organ have, or ought to have, for their object a clearer and better knowledge of its functions, I have undertaken also to communicate in this paper whatever physiological deductions may appear to follow from my observa­tions. Having no particular theory to support, and being influenced in these inquiries by no other feeling than the simple desire to elicit truth, the greatest care has been taken to verify my facts, and caution has been exercised in drawing conclusions from them. It is a question of great interest and physiological importance, whether the roots of the spinal nerves belong exclusively to the spinal chord, or whether part of them ascend within either the white or the grey columns, and form the channels by which impressions are transmitted to and from the brain. On account of its interest and importance, I have employed much time and labour in endeavouring to arrive at some well-grounded and settled conclusion on this very difficult subject, having devoted to it alone many hours daily for nearly five months. So extremely intricate, however, is the internal structure of the chord; so numerous are the planes in which the nerve-roots enter the grey substance; and so various are the directions which they pursue within it, that notwithstanding the perfect transparency of my prepara­tions, and the sharp outline which their fibres retain, my efforts to determine the exact relation between these roots and the white and grey columns appeared for some time almost hopeless; but by varying my dissections according to the exigencies of each case of difficulty, I succeeded in arriving at several results which I believe will be considered important.

scholarly journals Single circuit in V1 capable of switching contexts during movement using VIP population as a switch

2020 ◽  
Author(s):  
Doris Voina ◽  
Stefano Recanatesi ◽  
Brian Hu ◽  
Eric Shea-Brown ◽  
Stefan Mihalas
Keyword(s):  
Visual System ◽  
Visual Processing ◽  
Visual Space ◽  
Cell Types ◽  
Flexible Architecture ◽  
Multiple Cell ◽  
Context Dependent ◽  
Spatio Temporal ◽  
Context Integration ◽  
The Brain

AbstractAs animals adapt to their environments, their brains are tasked with processing stimuli in different sensory contexts. Whether these computations are context dependent or independent, they are all implemented in the same neural tissue. A crucial question is what neural architectures can respond flexibly to a range of stimulus conditions and switch between them. This is a particular case of flexible architecture that permits multiple related computations within a single circuit.Here, we address this question in the specific case of the visual system circuitry, focusing on context integration, defined as the integration of feedforward and surround information across visual space. We show that a biologically inspired microcircuit with multiple inhibitory cell types can switch between visual processing of the static context and the moving context. In our model, the VIP population acts as the switch and modulates the visual circuit through a disinhibitory motif. Moreover, the VIP population is efficient, requiring only a relatively small number of neurons to switch contexts. This circuit eliminates noise in videos by using appropriate lateral connections for contextual spatio-temporal surround modulation, having superior denoising performance compared to circuits where only one context is learned. Our findings shed light on a minimally complex architecture that is capable of switching between two naturalistic contexts using few switching units.Author SummaryThe brain processes information at all times and much of that information is context-dependent. The visual system presents an important example: processing is ongoing, but the context changes dramatically when an animal is still vs. running. How is context-dependent information processing achieved? We take inspiration from recent neurophysiology studies on the role of distinct cell types in primary visual cortex (V1).We find that relatively few “switching units” — akin to the VIP neuron type in V1 in that they turn on and off in the running vs. still context and have connections to and from the main population — is sufficient to drive context dependent image processing. We demonstrate this in a model of feature integration, and in a test of image denoising. The underlying circuit architecture illustrates a concrete computational role for the multiple cell types under increasing study across the brain, and may inspire more flexible neurally inspired computing architectures.

scholarly journals Predictive coding as a unifying principle for explaining a broad range of brightness phenomena

2020 ◽  
Author(s):  
Alejandro Lerer ◽  
Hans Supèr ◽  
Matthias S.Keil
Keyword(s):  
Visual System ◽  
Computational Model ◽  
Predictive Coding ◽  
Gain Control ◽  
Physical World ◽  
Input Image ◽  
Visual Illusions ◽  
Contrast Effects ◽  
Dynamic Filtering ◽  
The Brain

AbstractThe visual system is highly sensitive to spatial context for encoding luminance patterns. Context sensitivity inspired the proposal of many neural mechanisms for explaining the perception of luminance (brightness). Here we propose a novel computational model for estimating the brightness of many visual illusions. We hypothesize that many aspects of brightness can be explained by a predictive coding mechanism, which reduces the redundancy in edge representations on the one hand, while non-redundant activity is enhanced on the other (response equalization). Response equalization is implemented with a dynamic filtering process, which (dynamically) adapts to each input image. Dynamic filtering is applied to the responses of complex cells in order to build a gain control map. The gain control map then acts on simple cell responses before they are used to create a brightness map via activity propagation. Our approach is successful in predicting many challenging visual illusions, including contrast effects, assimilation, and reverse contrast.Author summaryWe hardly notice that what we see is often different from the physical world “outside” of the brain. This means that the visual experience that the brain actively constructs may be different from the actual physical properties of objects in the world. In this work, we propose a hypothesis about how the visual system of the brain may construct a representation for achromatic images. Since this process is not unambiguous, sometimes we notice “errors” in our perception, which cause visual illusions. The challenge for theorists, therefore, is to propose computational principles that recreate a large number of visual illusions and to explain why they occur. Notably, our proposed mechanism explains a broader set of visual illusions than any previously published proposal. We achieved this by trying to suppress predictable information. For example, if an image contained repetitive structures, then these structures are predictable and would be suppressed. In this way, non-predictable structures stand out. Predictive coding mechanisms act as early as in the retina (which enhances luminance changes but suppresses uniform regions of luminance), and our computational model holds that this principle also acts at the next stage in the visual system, where representations of perceived luminance (brightness) are created.

Brain World or Life World? Critique of Neuroconstructivism

2021 ◽  
pp. 144-156
Author(s):  
Thomas Fuchs
Keyword(s):  
External World ◽  
Point Of View ◽  
Phantom Limb ◽  
Rubber Hand ◽  
Life World ◽  
Body Experience ◽  
The World ◽  
Spatially Extended ◽  
The Subject ◽  
The Brain

From a neuro-constructivistic point of view, the brain creates an internal simulation of the external world which appears as the phenomenal world in consciousness. This view presupposes in particular that the subjective body and the organic or objective body belong to two fundamentally different worlds, the mental and the physical. The spatiality of the subject-body must then be declared an illusion, for example by referring to dissociations of the subject- and object-body as in the rubber hand illusion or the phantom limb. However, this alleged virtuality of body experience can be refuted by the intersubjectivity of perception, which confirms the co-extensivity of subject-body and object-body. Subjectivity thus proves to be as embodied as it is spatially extended, that means, as bodily being-in-the-world.

scholarly journals On the nature of sleep

1837 ◽  
Vol 3 ◽  
pp. 179-180
Keyword(s):  
External World ◽  
Muscular Fibre ◽  
Natural Consequence ◽  
Vital Function ◽  
Spinal Marrow ◽  
The Subject ◽  
The Law ◽  
The Mind ◽  
The Brain ◽  
Do So

The author intends the present paper as a continuation of his in­quiries into the relations subsisting between the nervous and muscu­lar systems, which form the subject of his former papers, but which would be incomplete without the consideration of their condition during sleep. With this view he proposes to determine the particular organs, on the condition of which this peculiar state of the system depends; the laws by which it is governed ; and the influence it has upon other parts of the system. The necessity of intervals of repose applies only to those functions which are the medium of intercourse with the external world, and which are not directly concerned in the maintenance of life. The organs subservient to these two classes of functions may be viewed as in a great degree distinct from one an­ other. The brain and spinal marrow constitute alone the active por­tions of the nervous system. The law of excitement, which regulates the parts connected with the sensorial functions, including sensation, volition, and other intellectual operations, and the actions of the vo­luntary muscles, is uniform excitement, followed by a proportional exhaustion; which, when occurring in such a degree as to suspend their usual functions, constitutes sleep j all degrees of exhaustion which do not extend beyond the parts connected with the sensorial functions being consistent with health. On the other hand, the law of excitement of those parts of the brain and spinal marrow which are associated with the vital nerves, and are subservient to the vital func­tions, is also uniform excitement; but it is only when this excitement is excessive that it is followed by any exhaustion; and no degree of this exhaustion is consistent with health. The law of excitement of the muscular fibre, with which both the vital and sensitive parts of the brain and spinal marrow are associated, namely, the muscles of respi­ration, is interrupted excitement, which, like the excitement of the vital parts of these organs, is, only when excessive, followed by any degree of exhaustion. The author conceives that the nature of the muscular fibre is everywhere the same; the apparent differences in the nature of the muscles of voluntary and involuntary motion de­pending on the differences of their functions, and on the circumstances in which they are placed: and he concludes, that, during sleep, the vital, partaking in no degree of the exhaustion of the sensitive system, appears to do so simply in consequence of the influence of the latter on the function of respiration, the only vital function in which these systems co-operate. The author proceeds to make some observations on the cause of dreaming, the phenomena of which he conceives to be a natural consequence of the preceding proposition. In ordinary sleep, the sensitive parts of the brain, with which the powers of the mind are associated, are not in a state of such complete exhaustion as to preclude their being excited by slight causes of irritation, such as those which accompany the internal processes going on in the system. The sensorium is the more sensible to the impressions made by these internal causes, inasmuch as all the avenues to external impressions are closed, and the mind is deprived of the control it exercises, during its waking hours, over the train of its thoughts, by the help of the perceptions derived from the senses, and the employment of words for detaining its ideas, and rendering them objects of steady attention, and subjects of comparison.

scholarly journals V. On the modifications of the spectrum of potassium which are effected by the presence of phosphoric acid, and on the inorganic bases and salts which are found in combination with educts of the brain

1880 ◽  
Vol 30 (200-205) ◽  
pp. 278-286 ◽  
Keyword(s):  
Nitric Acid ◽  
Phosphoric Acid ◽  
Royal Society ◽  
Potassium Salt ◽  
Extraction Process ◽  
Dilute Solution ◽  
Metaphosphoric Acid ◽  
Quantitative Analyses ◽  
The Subject ◽  
The Brain

Among the results of a large investigation on which I have for many years been engaged in regard of the chemistry of the brain, I had been led to conclude that the so-called “ protagon” of Oscar Liebreich is not a definite chemical body, but is a variable mixture of several bodies. This conclusion of mine (which agrees with opinions expressed on the same subject by Strecker, Diaconow, and HoppeSeyler) was published by me in 1874, and endeavours to controvert it have since then been made, on several occasions, by Dr. Arthur Gamgee. Last summer, he brought before the Royal Society his contentions for the chemical individuality of “protagon”; and it fortunately was in my power shortly afterwards to publish evidence, which, I believe, those who will take the trouble to follow it will find quite unanswerable, that Dr. Gamgee’s contentions were mistaken.§ Part of my evidence to that effect consisted in showing by quantitative analyses that Dr. Gamgee’s so-called “ protagon” contains 0·7 per cent, of potassium; secondly, that in connexion with trifling differences in the extraction process, the proportion of potassium in different specimens of “protagon” can be made to range from a trace to 1·6 per cent.; thirdly, that with the variable quantities of potassium the quantities of phosphorus and other ingredients will also vary. In the last published number, No. 200, p. 111, of the “Proceedings of the Royal Society,” I find that Dr. Gamgee has recently brought the question again under notice of the Society, and that, in doing so, he especially rests his case upon the following statement made by his colleague, Professor Roscoe, on the subject of some examinations, which, at Dr. Gamgee’s request, he had made for him: see “ Proceedings,” vol. xxx, p. 113:—“I have examined spectroscopically for potash a sample of protagon furnished me by Dr. Gamgee, and labelled ‘Protagon, twice recrystallised, Blankenhom.’ I could not detect any potash by the spectroscope in the incinerated mass from 0·1 grm. of substance. With the carbonised mass obtained from 1·0 grm. of substance I obtained the potasssium line ( α ) very faintly, and from comparative experiments with a dilute solution of a potassium salt I estimate the quantity of potash in 1 grm. of the substance Lot to exceed 1/20 mgrm. The carbonised residue of 1 grm. of protagon was carefully oxidised with pure nitric acid, when a small quantity of fused metaphosphoric acid remained after ignition. The residue weighed 0·0278 grm., corresponding to 1·08 per cent, of phosphorus.— (Signed) H. E. Roscoe.”

scholarly journals XIV.—Of the Fourth and Sixth Nerves of the Brain;—being the concluding paper on the distinctions of the Nerves of the Encephalon and Spinal Marrow

1839 ◽  
Vol 14 (1) ◽  
pp. 237-241 ◽  
Author(s):  
Charles Bell
Keyword(s):  
Optic Nerve ◽  
Royal Society ◽  
Circular Muscle ◽  
Complex Nature ◽  
Spinal Marrow ◽  
The Subject ◽  
The Brain ◽  
Royal Society Of London

Interesting as theoptical properties of the eye have been to philosophers in every age, there are conditions of this organ which are no less curious, and which have not had their share of attention.In the year 1823, I introduced the subject to the Royal Society of London, nearly in the terms I am now using, but there is much more in the subject than I then conceived, although I see no reason to change the mode of contemplating it.The eight muscles of the eye, and the five nerves, exclusive of the optic nerve, which pass to them, imply the complex nature of the apparatus exterior to the globe, and I fear it is too plain that the subject has not been satisfactorily treated.It is chiefly with respect to the protecting motions of the eye that the difficulty occurs, for I hope the dependence of the proper organ of vision on the voluntary muscles of the eye, has been proved and acknowledged.Permit me to draw the attention of the Society to what appears a very simple piece of anatomy, the circular muscle which closes the eyelids, orbicularis palpebrarum.

scholarly journals Wiring Up Vision: Minimizing Supervised Synaptic Updates Needed to Produce a Primate Ventral Stream

2020 ◽  
Author(s):  
Franziska Geiger ◽  
Martin Schrimpf ◽  
Tiago Marques ◽  
James J. DiCarlo
Keyword(s):  
Visual System ◽  
Visual Processing ◽  
Ventral Stream ◽  
Visual Object ◽  
Visual Object Recognition ◽  
Visual Stream ◽  
Ongoing Research ◽  
Ventral Visual Stream ◽  
And Behavior ◽  
The Brain

AbstractAfter training on large datasets, certain deep neural networks are surprisingly good models of the neural mechanisms of adult primate visual object recognition. Nevertheless, these models are poor models of the development of the visual system because they posit millions of sequential, precisely coordinated synaptic updates, each based on a labeled image. While ongoing research is pursuing the use of unsupervised proxies for labels, we here explore a complementary strategy of reducing the required number of supervised synaptic updates to produce an adult-like ventral visual stream (as judged by the match to V1, V2, V4, IT, and behavior). Such models might require less precise machinery and energy expenditure to coordinate these updates and would thus move us closer to viable neuroscientific hypotheses about how the visual system wires itself up. Relative to the current leading model of the adult ventral stream, we here demonstrate that the total number of supervised weight updates can be substantially reduced using three complementary strategies: First, we find that only 2% of supervised updates (epochs and images) are needed to achieve ~80% of the match to adult ventral stream. Second, by improving the random distribution of synaptic connectivity, we find that 54% of the brain match can already be achieved “at birth” (i.e. no training at all). Third, we find that, by training only ~5% of model synapses, we can still achieve nearly 80% of the match to the ventral stream. When these three strategies are applied in combination, we find that these new models achieve ~80% of a fully trained model’s match to the brain, while using two orders of magnitude fewer supervised synaptic updates. These results reflect first steps in modeling not just primate adult visual processing during inference, but also how the ventral visual stream might be “wired up” by evolution (a model’s “birth” state) and by developmental learning (a model’s updates based on visual experience).

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