Medical Understanding Vision Inversion: The Myth and Meaning Behind It

[zoobyshoe]

My point is that the image is inverted with respect to other internal maps rather than the external world. We have retinotopic and spatiotopic maps; vestibular, somatosensory and auditory cues etc. We seem to build up several internal representations of space which are integrated in a way which we do not understand. It seems to me that any pathological mechanisms causing an inverted or distorted sense of vision are due to the interaction between these various representations of space rather than due to the relationship between the internal representation and the external world.

After I posted I thought some more and I think I've somewhat figured the pathological inversion out. It's not a lens-like inversion with a concomitant flipping of left and right. It's probably always simply a rotation. Note the case study where the patient experienced degrees of rotation depending on the intensity of illumination. The cases of "inversion" are probably simply this rotation carried to 180 degrees, more or less.

The rotation is probably a normal function, a stabilizing correction that is always at work so that, for example, the world doesn't seem to be rocking back and forth when we walk, or appear to be tilted with slight, and even not so slight tilts of the head. Indeed, when you're lying on your side looking at the room there's no vertiginous sense the room is sideways. Up and Down seem pretty normal even though you, yourself, are sideways.

In these cases of vision inversion by disease this stabilizing effect is probably erroneously hyperactivated, rather than something being subtracted as I first supposed. Otherwise the man with the rotation problem would have seen a mirror flip in the image as well.

 

[russ_watters]

There's no objective up or down. People at the North Pole feel just as normal as people at the South Pole, despite the fact they're in 180 degree conflict about Up and Down. There is objective centripetal acceleration toward the center of the earth, but that direction is specific to exactly where you are on the earth, and different in all locations.

The problem created by inverting glasses is that they selectively take one sense and put it at odds with the other senses, as the Opening Poster suspected.

Perhaps this was made clear already, but you missed the point. This is not about arbitrary labels or conventions due to gravity. Consider left and right instead:

You can close your eyes and touch your left shoulder with your right hand: Left and right wrt you are an objective reality. If your vision is mirrored, you would see your left hand going to your right shoulder, but that won't be what you feel.

 

[zoobyshoe]

My point is that the image is inverted with respect to other internal maps rather than the external world. We have retinotopic and spatiotopic maps; vestibular, somatosensory and auditory cues etc. We seem to build up several internal representations of space which are integrated in a way which we do not understand. It seems to me that any pathological mechanisms causing an inverted or distorted sense of vision are due to the interaction between these various representations of space rather than due to the relationship between the internal representation and the external world.

The first paper I linked to is very interesting:

http://www.neurologia.com/pdf/Web/4403/x030157en.pdf

According to Gonzalo [51], the disorder in the visual direction function is not an autonomous syndrome, but it is connected with the rest of visual functions, and could be present in cases with cerebral lesions in different locations, provided there exists some involvement of visual functions. According to the ‘cerebral gradients’, the densities of the specific functions are extended in gradation through the cortex, so that there would not be a particular localization for such a disorder. In this respect, this author stressed his observations of different degrees of tilted vision in cases with lesions on the left or right parieto-occipital region, on the occipital pole, and also far from the occipital area (e.g., a very anterior parieto-temporal region), showing that the anomaly occur not only in central syndrome but also in the high diversity of the so-called paracentral syndromes. In fact, the cases of tilted or inverted vision reported in the literature are associated to a variety of cerebral lesions.

Direction orientation of things in the visual field is one of many functions that the cortex must perform:

When there is a lesion in the rather unspecific ‘central’ region, the main consequence is a deficit of nervous excitability which would lead to a deficit of integration through the cortex, determined by the lesion magnitude (neural mass lost). This deficit gives place, according to the experiences achieved, to the dissociation or decomposition of normal perception into its components or qualities, in such a way that the most complex qualities, with greatest nervous excitability (and integration) demand, become lost or ‘delayed’ in greater degree than the most simple ones (with lower excitability demand). Sensations usually considered as elementary are then seen to be decomposed into several functions, one of them being the direction function.

The direction has to be integrated with the other elements of vision, and on a different level with other senses. It's of interest to your point that the vision inversion or tilt could be temporarily corrected in some cases by strong stimulation of a different sense:

In the cases studied, it was remarkable that a strong muscular contraction was very efficient at improving the perception, reducing the functional disgregation significantly. This type of muscular ‘reinforcement’ straightened the tilted vision almost instantly, and simultaneously cleared the vision and dilated the visual field (about five times in case M). Figure 7 shows the perceived inclination of a vertical upright test arrow versus muscular contraction in case M [51]. Other types of reinforcement are, binocular summation, in which one eye reinforces the other, as well as tactile and acoustic stimuli, although their effects are far less dramatic than that obtained with strong muscular contraction.

However, there are many mentions of image inversion and reinversion. I couldn't quite sort out which were normal and which pathological. The paper may have been translated from Spanish or written in English by a non-native speaker. At any rate, the language is difficult in places.

I'm interested in the included cases where this image inversion is associated with seizures. Before this Van Gogh was the only case I'd heard of where seizures caused this. I happened to notice also that inverted images are listed as rare manifestations of migraine aura, which, as you're probably aware, can cause all kinds of visual integration problems.
http://www.severe-headache-expert.com/symptoms-of-ocular-migraine.html

 

[JD1]

hia,

try this, place your finger on the side of your nose, next to your eye. Very lightly (dont slip and poke you sen in the eye, because then we can't do the experiment, lol, :-) ) press on the inside of your eye. Notice a black spot appears on the outside of your vision! Because the image is inverted, what appears to be a sensation on the outside of your eye is actually a sensation on the inside!

Not convinced eh, well try this,

Go into a dark room with a friend, and have him or her look at a small light-emitting object, like a candle. If the room is dark enough, you will be able to see up to three images in his or her pupil. The first image (upright and brighter than the other images) is a reflection off the cornea. The second image (upright and very dim) is a reflection off the eye lens. The third image (dim and inverted) is a reflection off the retina. This third image is the image that is sent to the brain!