On 28 feb, 17:54, Kalman Rubinson <k... from earthlink.net> wrote:
> On Sun, 28 Feb 2010 07:46:34 -0800 (PST), "Peter H."
(cut)
> >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.
And I can see now that I was wrong in assuming that you are a
beginner. Sorry about that.
> 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.
This means that it was indeed me, who was confused.
Now if, when I wrote in the third paragraph of the starting article of
02-23 that "Between the Purkinje layer and the cerebellar surface you
can see two types of cells, the bigger ones supposedly Granular and
the smaller ones supposedly Glia", you would have responded for
example with "You are wrong: These are Stellate and Basket cells",
then I would have understood. But your "This section looks perfectly
normal to me and comparable to standard descriptions" just didn´t give
me any hint with regard to where I could have gone wrong.
>> >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.
>From the drawings of cerebellar circuity which I have seen, I would
never have concluded that the granular layer is so dense, that even
when setting the scale bar at 23 microns I can barely identify a few
cells within it as such! But of course, its blue color in Nissl stains
should have given away its true nature to me. And then of course, the
almost solid black of this area in Weil stains ought to mean that it
is rich in cells, and not rich in fibers! And how rich it is! It
appears that I have mistaken an extremely cell rich region as cell
poor.
>> > 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.
And your feeling apparently was correct. Shame on me.
> 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.
I haven´t (yet) seen that diagram. But I hope that it is better than
what I have seen so far, i.e. giving an idea of how dense is the
cellular population of the granular layer in comparison to that of the
molecular layer.
At any rate: If what I have written in this post is correct, then my
confusion has been cleared away and there is no real need to talk to
Prof. Llinas (exept perhaps about this weird population of spherical
cells). I am almost sure that I got it right this time, but
nonetheless please tell me whether that is so -or not.
And thanks for your patience.
Peter
