On 10 Feb 2004, Ken Steele wrote: > > > Braitenberg (1994) describes an answer provided by Ramon y Cajal.
Ken: Is this it? Braitenberg, V. (1984). Vehicles: experiments in synthetic psychology. > Cajal's account was that crossing originated with the visual system [to avoid a discontinuity in the mapping of the visual field] A website provides a brief commentary on Braitenberg's view, and suggests he wasn't too supportive of Cajal's idea. It says there: "Braitenberg notes that there are several possible objections to this argument. First, crossing is sufficient but not necessary for this correction; in Figure 24 Braitenberg provides several alternatives that could serve the same purpose. Second, the argument presupposes that there is an advantage in not having the midline discontinuity. However, this need not be the case. In summary, this is still an open topic. I myself have asked neuroscientists about it, and they have not provided any answers. (Question: Has Braitenberg raised alternative answers in describing his vehicles?) They have noted, though, that it is an excellent question! " Source at http://www.bcp.psych.ualberta.ca/~mike/Pearl_Street/Margin/Vehicles/bi ology.html PubMed tells me that that Capozzoli reference I cited in my previous note (Medical Hypotheses, 26, 1-8) also blames the visual system. Here's what the abstract says: Contralateral central nervous control may be an evolutionary consequence of dependence on the image-forming eye, especially in large organisms. As a result of the topological transformation of the visual stimulus in the pupillary eye, the external environmental hemispace impinges directly upon the contralateral internal organismal hemispace. Selective pressure leads to the development of central connections capable of the most rapid and precise functional association of the internal milieu with the organism's environment. The consequence is contralateral central sensorimotor control. Previous hypotheses are discussed, including those based on bilaterality, binocularity the optic chiasm, and avoidance behaviors. ...whatever that means! Stephen ___________________________________________________ Stephen L. Black, Ph.D. tel: (819) 822-9600 ext 2470 Department of Psychology fax: (819) 822-9661 Bishop's University e-mail: [EMAIL PROTECTED] Lennoxville, QC J1M 1Z7 Canada Dept web page at http://www.ubishops.ca/ccc/div/soc/psy TIPS discussion list for psychology teachers at http://faculty.frostburg.edu/psyc/southerly/tips/index.htm _______________________________________________ --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
