Quantitative long-term imaging of the functional representation of a whisker in rat barrel cortex.
In this study, we implement chronic optical imaging of intrinsic signals in rat barrel cortex and repeatedly quantify the functional representation of a single whisker over time. The success of chronic imaging for more than 1 month enabled an evaluation of the normal dynamic range of this sensory representation. In individual animals for a period of several weeks, we found that: (i) the average spatial extent of the quantified functional representation of whisker C2 is surprisingly large--1.71 mm2 (area at half-height); (ii) the location of the functional representation is consistent; and (iii) there are ongoing but nonsystematic changes in spatiotemporal characteristics such as the size, shape, and response amplitude of the functional representation. These results support a modified description of the functional organization of barrel cortex, where although a precisely located module corresponds to a specific whisker, this module is dynamic, large, and overlaps considerably with the modules of many other whiskers.
Masino
S A
SA
Department of Psychobiology, University of California, Irvine, 92717-4550, USA.
Frostig
R D
RD
D000818:Animals; D006197:Hair / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D008297:Male; D055095:Optics and Photonics; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012677:Sensation / Q000502:physiology*; D013003:Somatosensory Cortex / Q000033:anatomy & histology* / Q000502:physiology*