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The claim made here is made that contemporary cognitive neuroscience is riddled with conceptual errors and that they, these philosophers, have demonstrated what these mistakes are. Alleged mistake 1. Neuroscientists say that the brain sees, thinks, makes decisions, processes information, and uses codes and maps, etc. Alleged mistake 2. The brain is merely another organ of the body, the purpose of which is to facilitate the various things human bodies do, such as thinking, walking, seeing, desiring, and interpreting Each of us exists as a whole creature, These philosophers further claim that the proper task for neuroscience is limited to the description of how the brain works as an electro-chemical machine, in terms of neuronal properties and activities.
The task of finding out how all this activity is related to human functions, such as seeing, thinking, feeling, deciding, being conscious, etc. Firstly, it supposes that the only branch of science that is relevant to the matter in hand is neurophysiology to which we can add cybernetics. These studies produce information about the nature of phenomenal consciousness itself, which could not have been obtained by neurophysiological, or brain-imaging, methods.
An account of the nature phenomenal consciousness that fails to mention any of this research, and takes note only of discussions about the meaning of words, is. For linguistic reasons, they claim that all real pains are located in the physical body. They admit that ordinary headaches certainly occur in the head, but that is all—and even these occur in the meninges, and not in the brain. In the first place, most people would say that a pain is a phenomenological event that we experience, and not an ascription derived from our behavior.
Secondly, phantom limb pains are hallucinations not illusions.
In an illusion a normal percept is distorted. Direct Realism is itself incorrect see below. It is also surely relevant that phantom limb pain is often real enough to drive the patient to suicide. Physiological realism holds phantom limbs, and all other bodily sensations that we experience, are located in the body-image that we experience during waking hours, and they are not located in the physical body.
Events in the latter constitute only the causal ancestors of bodily sensations. In the case of vision we can go further. Phenomenologists e. Fitzgerald, ; Libet, ; Schilder ; Teschner ; Wright, describe a visual field in which visual sensations are distributed in the form of a topographic map of that part of the external world being looked at during that instant—as Crick p.
There is now considerable experimental evidence that the visual field is constructed by such a mechanism. The first data was obtained by studies of how vision returns after injuries to the occipital lobe. One might expect after such an injury that vision returns by allowing one at first to see objects fuzzily with later clarification as healing progresses. However, the reality is quite different. The first thing to return is the perception of movement. On looking at a scene the patient sees no objects, but only pure movement usually rotary that occupies the visual field.
Then parts of objects appear—such as the handle of a teacup—that gradually coalesce to form fully constituted phenomenal objects, into which the film colors then enter. This indicates that the three basic cortical mechanisms for computing movement, color and shape have different rates of recovery. It is difficult to see how the theory of Direct Realism can account for this data. This is how the brain allots the appropriate color to an object. The neurocomputations, related to our perception of the color, shape and movement of external objects, are carried out in anatomically separate brain areas.
Recently a series of psychophysical experiments have also shown that, under certain experimental circumstances, the normal brain will allot the wrong color to an object Treisman and Schmidt but see Quinlan They showed that scotomata—the blind patches caused by local injury—are not perceived as patches of nothing, but that the brain fills them in with a continuation of whatever pattern surrounds them.
These workers took two photographs, one of a monkey's face and the second of a leafy tropical jungle.
They converted these into two pastiches each composed of portions of each photo, so that in the location where one photo showed part of the monkey's face the other showed leafy jungle. Then each pastiche was shown separately to each retina, so that retinal rivalry occurred. Under these circumstances, the subject did not see what was actually there—that is the two pastiches alternating—but rather a complete monkey face alternating with a complete leafy jungle. Clearly the brain had suppressed the improbable mixed pastiche in favor of what it was familiar with and thus computed what was more probable.
Many other experiments, based on stimuli such as moving plaid patterns, have shown this phenomenon where the perception of an improbable input is suppressed by the brain, and replaced with the perception of what it computes to be more probable ones. Even more crucial experiments Kleiser, Seitz and Krekelberg have shown that, during a saccade rapid movement of the eye , information coming from the eye is suppressed, and what we see is largely virtual reality created by the brain from processed memory.
These authors expressed it thus:.
Neuron , 79 5 , pp. One is to hold firmly to the claim that philosophy alone can help us to understand consciousness by claiming that the subject matter will always elude material science, either by explicitly embracing dualism or some other metaphysical departure from the scientific world view, such as pansychism, or, by posing questions that only philosophy can solve. A system is informationally encapsulated to the degree that it lacks access to information stored outside the system in the course of processing its inputs. In this broader sense of the term, connections between memory, perception, and consciousness are apparent. PLoS Computational Biology 7 3 , p. Main article: Set psychology.
This demonstrates the phenomenon of saccadic suppression: during saccadic eye movements, visual sensitivity is much reduced. In other words, 'filling in' has a temporal as well as a spatial dimension. This function is based on a widespread neural network, that includes the superior colliculus and parts of the thalamus. The purpose of this would appear to be to suppress the violent swings in the visual input the world swirling round one and resulting severe vertigo that would otherwise result. Since saccades occur very frequently, this means that virtual reality plays a major role in normal everyday seeing.
We now also know something of the mechanism by which the brain effects this function of mixing reality and virtual reality in visual perception. In this the brain uses technology already worked out by television engineers for their own purposes. These engineers found out that the efficiency of digital television transmission can be increased in the following manner.
The scenes televised consist of a focus of attention foreground , where the action is, plus a lot of background, where nothing much happens. The computations on which digital television is based are expensive in terms of computational time and monetary cost. The art of TV engineering is to provide the optimum mixture of these two processes. Interestingly enough the brain does the same.
The balance of these two systems is mediated by the neuromodulator acetylcholine. The cell bodies of these cholinergic neurons are located in the Nucleus Basalis of Meynart that is located in the basal forebrain. The axons of these neurons project to the cortex, where they activate stimulatory nicotinic receptors in layer IV, and also inhibitory muscarinic receptors in layers I and II. Now, when nothing much interesting is happening in the environment, there is a low level of activity in the Nucleus Basalis , in which case the cortico-cortical input to the visual cortex is active mediating virtual reality.
The projection to layer IV then activates stimulatory nicotinic receptors on the bodies of those pyramidal neurons that receive the retinal input, which is thereby promoted. Thus the brain can now expend its energies in analyzing the new stimulus for salience. These are the geometrical patterns that fill the visual field when we look at a flashing stroboscopic light.
My subjects were all psychologically sophisticated faculty members, or graduate students. It is obvious that one experiences the redness of a red veridical sensation, a red after-image, and a red hallucination in the same way, and that we see the redness of an external physical object in a different way—i. The recent evidence, that I have related above as to how vision actually works, shows that this unsubstantiated statement is simply untrue Hardin Experienced colors are generated by neurocomputations.
They exist in the visual field attached to phenomenal objects by specific neural mechanisms, which can be disrupted by certain cerebral lesions, so that these colors leave the phenomenal object and become space or film colors, as described earlier. Colors, as experienced, are not located on the surfaces of external physical objects. Consider also the following reports from people who have taken the hallucinogenic drug mescaline my italics —.
All the colours I have ever beheld are dull compared with these. I was further impressed, not only by the brilliance, delicacy, and variety of the colours , but even more by their lovely and various textures—fibrous, woven, polished, glowing, dull, veined and semitransparent The prevailing tint is blue, but the multitude of shades, each with such wonderful individuality, make me feel that hitherto I have been totally ignorant of what the word colour really means.
The colour is intensely beautiful. Rich, deep, deep, deep, wonderfully deep blue. That is indeed helpful at times—but not in this case. Maps are things you unfold and look at when trying to find your way around. The brain contains nothing like that. However, one can reply that organisms can certainly contain maps that direct their movements. The US Air Force has warplanes that have maps of their target digitally coded into their directing computers that enable them to carry out precision bombing. It is this sense of having a map in its brain that neuroscientists employ. However, Tsien has produced evidence that they do and just, in this instance, what this code is.
By means of a technical tour-de-force he found a group of neurons called a clique in the mouse hippocampus, that respond only to stimuli generated by a potential nest any place to curl up and sleep , regardless of its color, shape and materials it was constructed out of. Other cliques respond to other conceptual inputs. These cliques respond to concepts and not merely to specific stimuli shapes, patterns, colors etc. Tsien then shows that the activity of several cliques can be translated into a string of binary code, which reveals details of what the events the animal has experienced that lead to the formation of specific memories.
So why should we say that the clique is not part of a coding mechanism? They do not say. A further link between seeing and television is provided by the interesting fact that, if we illuminate an analog TV studio with a flashing light, geometrical patterns appear on the TV screen, whose form is determined by the geometry of the scan being used and the ratio of the frequencies of the scan and the flashing light. Duplicate citations. The following articles are merged in Scholar. Their combined citations are counted only for the first article.
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