Neonatal medial frontal cortex lesions disrupt circadian activity patterns.
The medial frontal cortex (MFC) is involved in the temporal organization of behaviour. It receives timing information from the master circadian clock in the suprachiasmatic nucleus (SCN), and exhibits daily oscillations in gene expression itself. In this study, we evaluate various properties of circadian rhythms of locomotor activity following neonatal or adult MFC aspiration lesions. Mice with neonatal lesions were more active during the day than mice with adult lesions and less active during the early night than both mice with adult lesions and control mice. Compared to controls, mice with neonatal lesions exhibited smaller phase delays to an early-night light pulse and marginally larger phase advances to a late-night light pulse. Mice with adult lesions did not differ from controls on either measure. The results suggest that the timing of behaviour is determined by an interaction between the MFC and the SCN and that injury early in life has a significant effect on the ability of animals to organize such behaviours.
Phillips
Catherine I
CI
Department of Psychology, University of Calgary, Calgary, Alberta, Canada.
Smith
Victoria M
VM
Antle
Michael C
MC
Dyck
Richard H
RH
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001683:Biological Clocks / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D005625:Frontal Lobe / Q000293:injuries / Q000503:physiopathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000502:physiology*