Hallucinations generated in the visual cortex

[Fractal_chaos]

Hi. This is not a question about my health, Im just very very interested and want to learn.
I have some problems understanding a part of "Geometric visual hallucinations, Euclidean
symmetry and the functional architecture of striate cortex" p 325 and I thought it must be some hidden expert in here.
I try to understand how symmetry is generated in the brain when hallucinating.

One of the major aspects described in this paper is
the presumed Euclidean symmetry of V1. Many
systems exhibit Euclidean symmetry, but what is
novel here is the way in which such a symmetry is
generated. Thus, equation (9) shows that the
symmetry group is generated, in large part, by a
translation or shift (math) followed by a
rotation or twist (math). It is the (math)
twist (math) that is novel, and which is required
to match the observations of G. G. Blasdel and
L. Sincich (personal communication) and Bosking
et al. (1997). In this respect it is of considerable
interest that Zweck & Williams (2001) have
introduced a set of basis functions with the same
shift^twist symmetry as part of an algorithm to
implement contour completion. Their reason for
doing so is to bind sparsely distributed receptive
¢elds together functionally, to perform Euclidean
invariant computations. It remains to explicate the
precise relationship between the Euclidean invariant
circuits we have introduced here, and the Euclidean
invariant receptive ¢eld models introduced by
Zweck and Williams.
(iv) Finally, it should also be emphasized that many
variants of the Klu«ver form constants have been
described, some of which cannot be understood in
terms of the simple model we have introduced. For example the tunnel image shown in ¢gure 41
exhibits a reversed retinocortical magni¢cation, and
corresponds to images described in Knauer &
Maloney (1913). It is possible that some of the
circuits beyond V1, for example, those in the dorsal
segment of medial superior temporal cortex (MSTd)
that process radial motion, are involved in the
generation of such images, via a feedback to V1
(Morrone et al. 1995). Similarly, the lattice^tunnel shown in ¢gure 42a
is more complicated than any of the simple form
constants shown earlier.

One intriguing possibility is
that such images are generated as a result of a mismatch between the planform corresponding to
one of the Klu«ver form constants, and the underlying
structure of V1.We have (implicitly) assumed that V1
has patchy connections that endow it with lattice
properties. It should be clear from ¢gures 9 and 10
that such a cortical lattice is somewhat disordered.
Thus one might expect some distortions to occur
Geometric visual hallucinations P. C. Bresslo¡ and others 325
Phil. Trans. R. Soc. Lond. B (2001)
Figure 41. Tunnel hallucination generated by LSD. Redrawn
from Oster (1970).
(a)
(b)
Figure 42. (a) Lattice^tunnel hallucination generated by
marijuana. Reproduced from Siegel (1977), with permission
from Alan D. Eiselin. (b) A simulation of the lattice^tunnel.
Figure 43. Complex hallucination generated by LSD.
Redrawn from Oster (1970).
when planforms are spontaneously generated in such
a lattice. Figure 42b shows a computation of the appearance in the visual ¢eld of a hexagonal roll on a
square lattice, when there is a slight incommensurability
between the two.

As a last example we show in ¢gure 43 another
hallucinatory image triggered by LSD. Such an
image does not ¢t very well as a form constant.
However, there is some secondary structure along the
main (horizontal) axis of the its major components.
(This is also true of the funnel and spiral images
shown in ¢gure 2, also triggered by LSD.) This
suggests the possibility that at least two di¡ering
length-scales are involved in their generation, but
this is beyond the scope of the model described in the
current paper. It is of interest that similar images
have been reported following stimulation with £ick- ering light (Smythies 1960).

If someone could explain this in general what they are (trying) to say I would appreciate it so much.
Pictures are not include so please ignore examples (a) (b), and equations. This is not important.
Im a 3D student so this is just a personal interest.. Thanks to those who took their time to read. (ITS SO INTERESTING!!)
24 year old girl.