Subject: Rats low frequency hearing From: "Didier Depireux, PhD" <ddepi001(at)UMARYLAND.EDU> Date: Thu, 3 Mar 2005 10:36:45 -0500I may be the only person on this list who never recorded from a rat, but that should not prevent me from making a comment about rat hearing and how thresholds changes from one strain to another... Various people have reported various "lowest audible frequency" for rats, from 250Hz to 1kHz. I understand "threshold" depends on what level you use, but I also notice that Rutkowski et al (Hear Res 181 (2003) p116) don't mention neural responses below 500Hz. On the other hand, I read the review of the whisker system by Chris Moore et al (Neuron 42 (2004) 451-463) and on page 452, they show that whiskers have natural resonance frequencies from 175 to 700Hz. On the other hand, Moore also published a book chapter (top publication in http://web.mit.edu/moore/publications.html ) that shows that whiskers respond to sounds (though he doesn't give any levels that I could find by a cursory reading). Also, whiskers are very very sensitive to displacements. The question then becomes: how much do behavioral audiograms depend on "whisker hearing". Alternatively, would the behavioral audiogram change dramatically if whiskers were by-passed, say by using an etymotic sound delivery system. In Rutkowski et al, sounds are delivered to the ear, so that their measurements correspond only (mostly?) to cochlear hearing. Or maybe one could find responses to whisker stimulation in auditory cortex, in the low-frequency part of the tonotopic axes? And that's the random thought of the day. Didier __ Didier A Depireux ddepi001(at)umaryland.edu 20 Penn Str - S218E http://www.theearlab.org Anatomy and Neurobiology Phone: 410-706-1272 (lab) University of Maryland -1273 (off) Baltimore MD 21201 USA Fax: 1-410-706-2512