On Sun, 28 Feb 2010 07:46:34 -0800 (PST), "Peter H."
<pjwholm from yahoo.es> wrote:
>On 26 feb, 21:57, Kalman Rubinson <k... from earthlink.net> wrote:
>Great. Perhaps Prof. Llinas is our man. I wonder whether he might
>perhaps be willing to give you a written answer by email and allow you
>to post it here. If not, please take good notes.
Well, I will talk to him this week and let you know. Email is
unlikely as our conversations are in person.
>And above all, please don´t forget that the issue of the presumed deep
>nucleus cells is only an interesting side point, but not at the core
>of what really is vexing me. The core of what is vexing me I have
>emphasized in the last paragraph of my second response to you (of
>02-25-10, starting with "And this is really the crucial point
>here..."). And condensing the issue even more, the most central of my
>questions is precisely: How do the Purkinje cell axons get to the deep
>nuclei of the cerebellum? Do they go around or through the molecular
>layer? (since according to what one can see at Brainmaps, the
>molecular layer is *in between* the Purkinje cells and the deep
>nuclei)
What I see there is what I have always seen. The Purkinje cell layer
has the molecular layer superficial to it and the granular layer deep
to it. Thus, the Purkinje axons access the nuclei by passing directly
through the granular layer.
>Now, since the granular cells are supposedly located on the same side
>of the molecular layer as are the Purkinje cells, I would of course
>also like to know how the Mossy Fibers reach them.
?? Mossy fibers enter the granular layer from below (white matter) and
terminate in that layer. I do not see the problem.
> But -without the
>intention to offend you here- it appears to me that you are not very
>familiar with cerebellar circuity.
No offense taken but I have the same feeling about you. There is a
simple diagram of cerebellar anatomy/circuitry on p.185 of the 6th
edition of "Berne & Levy Physiology" which I and a colleague have
created, as we have authored the chapters on the nervous system. We
do not claim this diagram as proprietary as it is based on the work of
many.
>Thus, in order to avoid any further
>confusions, when talking to Prof. Llinas I would like you to limit
>yourself exclusively to the questions at the end of the last
>paragraph. So when you see Prof. Llinas the next time, please keep the
>term "PURKINJE CELL AXONS" in your mind constantly (where do they
>run?), and please do not talk to him about *anything* else but just
>that.
Again, why is this an issue? They pass through the granule cell
layer.
>P.S.: This is a postscript, in order to not distract you from the main
>issue as defined above in this post. But as far as those presumed deep
>nucleus cells are concerned, I have become aware of various issues
>surrounding them.
>>A) In the bottom hemisphere on 205 we are dealing with a dispersed but
>uniformly spherical population of cells, which is visible only on this
>slide in this series (e.g. on the right side of the right arm of the
>"U", as I wrote in my post of 02-24). And it disperses itself
>throughout the entire posterior white matter of this hemisphere.
>Surprisingly, this population cannot be detected in the top hemisphere
>on this slice.
I note that, too.
>B) The neuronal population of the deep nuclei is by no means as
>homogenous as is this spherical cell population in question: The deep
>nuclei contain a rich mixture of elongated, triangular and even y-
>shaped neurons.
Agreed.
>C) I have looked for this spherical cell population on the slices 0398
>to 0276 of the very detailed sagittal Nissl series (280 slides) of
>Macaca Mulatta, but couldn´t find it. And setting the scale bar at 184
>microns you can´t miss it.
If you say so. I scanned a few other sections and reached the same
conclusion.
>So now I am wondering about whether I might not have been wrong in my
>initial assumption, that these cells might be deep nucleus neurons -
>even though in my opinion they quite obviously are neurons and not
>glia. Could they perhaps be an individual unilateral ideosyncrasy of
>the specimen used for these horizontal cuts?
>>At any rate, this population intrigues me, but it does not vex me. So
>please *do not* talk to Prof. Llinas about this spherical cell
>population, since it obviously *does not* consist of Purkinje cells.
>This is only an interesting side issue related to the connectivity
>between the molecular layer and the deep nuclei. And what worries me,
>is that in your last conversation with him you already seem to have
>gotten on the wrong track. Because when I wrote on 02-26 that "you
>should also show them these cells", I only said that because I had an
>incling that you confused these spherical cells with Purkinje cells
>("many large cells deep to the granular layer" you wrote on 02-25).
>So please don´t talk to him about this spherical cell population - but
>about what I have said above this postscript.
OK.
