Received: by alpheratz.cpm.aca.mmu.ac.uk id NAA20338 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Tue, 23 Jan 2001 13:33:25 GMT From: "Chris Lofting" <ddiamond@ozemail.com.au> To: <memetics@mmu.ac.uk> Subject: RE: ....and the beat goes on and on and on... Date: Wed, 24 Jan 2001 00:41:25 +1100 Message-ID: <LPBBICPHCJJBPJGHGMCIGEBECNAA.ddiamond@ozemail.com.au> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2314.1300 Importance: Normal In-Reply-To: <A4400389479FD3118C9400508B0FF230010D1A65@DELTA.newhouse.akzonobel.nl> Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
> -----Original Message-----
> From: fmb-majordomo@mmu.ac.uk [mailto:fmb-majordomo@mmu.ac.uk]On Behalf
> Of Gatherer, D. (Derek)
> Sent: Tuesday, 23 January 2001 11:40
> To: 'memetics@mmu.ac.uk'
> Subject: RE: ....and the beat goes on and on and on...
>
>
> Chris:
> An intersting 'discovery' lately has been that the zebrafish has
> left/right
> hemisphere processing like we do i.e. KNOWN (left bias) vs UNKNOWN (right
> bias) IOW these patterns are possibly in fundamental neurology PRE
> amphibians/reptiles development.
>
> (oops almost forgot the ref: Liang, J.O. et al (2000) Asymmetric nodal
> signaling in the zebrafish diencephalon positions the pineal organ "
> Development 127, 5101-5112)
>
> Derek:
> But is that what this paper really says? The abstract is:
> _________
> The vertebrate brain develops from a bilaterally symmetric neural tube but
> later displays profound anatomical and functional asymmetries. Despite
> considerable progress in deciphering mechanisms of visceral organ
> laterality, the genetic pathways regulating brain asymmetries are unknown.
> In zebrafish, genes implicated in laterality of the viscera
> (cyclops/nodal,
> antivin/lefty and pitx2) are coexpressed on the left side of the embryonic
> dorsal diencephalon, within a region corresponding to the presumptive
> epiphysis or pineal organ. Asymmetric gene expression in the
> brain requires
> an intact midline and Nodal-related factors. RNA-mediated rescue
> of mutants
> defective in Nodal signaling corrects tissue patterning at
> gastrulation, but
> fails to restore left-sided gene expression in the diencephalon. Such
> embryos develop into viable adults with seemingly normal brain morphology.
> However, the pineal organ, which typically emanates at a
> left-to-medial site
> from the dorsal diencephalic roof, becomes displaced in position. Thus, a
> conserved signaling pathway regulating visceral laterality also
> underlies an
> anatomical asymmetry of the zebrafish forebrain
> ________
>
> There's no evidence that zebrafish have 'left/right
> hemisphere processing like we do'. All that this paper says is that
> zebrafish anatomical brain asymmetry is dependent on the nodal signalling
> pathway.
>
In the review/comment in Trends in Neuroscience we find:
"For example, zebrafish show a left versus right preference in viewing
familar versus novel scenes, respectively" p6 Vol24 No1 January 2001 ...as
we do where the novelty is to what is unknown. In us once it is identified
the next exposure shows more left bias... see Posner's ref I gave to these
differences when we operate....
>
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