Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!usc!snorkelwacker.mit.edu!bloom-picayune.mit.edu!18.70.0.226!lfk From: lfk@eastman1.mit.edu (Lee F. Kolakowski) Newsgroups: sci.bio Subject: Re: Speed of human eye? Message-ID: Date: 11 Feb 91 17:40:35 GMT References: <1436@tau.sm.luth.se> Sender: news@athena.mit.edu (News system) Organization: Mass. Inst. of Tech., Dept. of Chemistry Lines: 48 In-Reply-To: d90-ngp@sm.luth.se's message of 7 Feb 91 15:53:41 GMT On 7 Feb 91 15:53:41 GMT, d90-ngp@sm.luth.se (Niklas Grip) said: > Can anyone tell me how many "pictures/second" a human can see, and if > that's much compared to other animals? The eye does not work like a camera. It has no shutter. Each of the photorecepor cells receives light independently of each other photoreceptor. Now the processed images take on the order of 100 msecs to create. That is measured by presenting subjects with images for different lengths of time and then querying about the content. The speed of the human eye as compared to other animals eyes as a result of the measurement technique cannot be measured the same way. Most vertebrate photoreceptor biochemistry works on the some time scale because the process is virtually the same. 1) Rhodopsin(11-cis) + hv --> Rhodopsin(all-trans) 2) Rhodopsin(all-trans) + Gprotein(GDP) --> Rhodopsin(all-trans)-Gprotein(GTP) 3) Gprotein(GTP) + PDE(inactive) --> Gprotein(GTP)-PDE(active) 4) PDE(active) + cGMP --> PDE(active) + GMP 5) as cGMP levels drop, a cGMP sensitive channel closes This is a simple version of the signal that the brain sees. from fruit flys to fish to frogs to cows to humans the rhodopsin is largely similar -- Frank Kolakowski ======================================================================= |lfk@athena.mit.edu or lfk@eastman1.mit.edu or kolakowski@wccf.mit.edu| | Lee F. Kolakowski M.I.T. | | Dept of Chemistry Room 18-506 | | 77 Massachusetts Ave. Cambridge, MA 02139 | | AT&T: 1-617-253-1866 #include | ======================================================================= ||Desert Storm - Lasers have made this the cleanest *dirty war* ever.|| =======================================================================