LNv and Morning Anticipation Figure 4. Spontaneous action potential firing and acute physiological light response in large LNv persists in flies expressing Q128- Htt in the LNv. (A) Representative whole cell current clamp recording trace of large LNv in brains of flies expressing Q128-Htt under control of pdfGAL4 driver shows normal action potential firing in the functional absence of PDF+ small LNv. (B) Upon exposure to 7–10 klux light intensity (white bar) firing frequency is significantly higher (3.260.4 Hz) than under darkness (2.260.3 Hz black bar; paired t test, p,0.001). Controls (pdfGAL4/NC1) show similar increased firing frequency under 7–10 klux light intensity of 2.960.4 Hz versus 1.960.3 Hz under darkness (0 klux). Resting membrane potential is also significantly more depolarized in the presence of light (data not shown). Normal spontaneous action potential firing and light responsiveness persists in large LNv recorded from pdfGAL4/UAS-Q128-Htt flies up to 20 days of age. doi:10.1371/journal.pone.0011628.g004 PLoS ONE | www.plosone.org 6 July 2010 | Volume 5 | Issue 7 | e11628