43.6 Thursday, Jan. 5 Phase Inversion in Neural Activity of the Sensory Systems but not the Putative Biological Clock Parallels Behavioral Shift during Migration in a Night-Migratory Songbird RASTOGI, A.; RANI, S.; KUMAR, V.*; University of Lucknow; University of Lucknow; University of Delhi firstname.lastname@example.org
The present study investigated neural activity in relation to photoperiodic induction of migration in the Palaearctic-Indian, migratory blackheaded buntings, Emberiza melanocephala, using c-fos as neuronal activation marker, and vasoactive intestine peptide (VIP) and neuropeptide Y (NPY) as functional correlates. Activity of individual birds exposed to inductive long days was continuously monitored, and data on body mass and testis size were recorded at intervals. The daily activity pattern defined the non-migratory phase (no nocturnal activity) and migratory phase (intense nocturnal activity, Zugunruhe - a behavioral phenotype that characterizes migration in caged birds). The c-fos, VIP and NPY immunoreactivity (lir) was measured during the day and night in the suprachiasmatic nuclei (SCN) and mediobasal hypothalamus (MBH) regions, which are putative daily and seasonal clock sites, respectively, and in the olfactory and visual subsystems, which contain sensory circuits linked with migration. The MBH, but not the SCN, showed a significant temporal difference in the fos, VIP and NPY immunoreactive cells. This indicated that MBH, and not the SCN, contained photoperiodic clock and VIP and NPY are probably part of neuroendocrine mechanism involved in regulation of avian seasonality. Importantly, there was also phase inversion in the neural activity of the olfactory and visual sensory systems in parallel with the behavioral (activity) shift that occurred during the migratory phase. This suggested the migration linked changes in the activity of olfactory and visual sensory systems that were involved in the migratory orientation and navigation.