Behavioural state linkage in the ovine fetus near term
- Resource Type
- Article
- Authors
- Rao, Neesha; Keen, Ashley; Czikk, Marie; Frasch, Martin; Richardson, Bryan S.
- Source
- Brain Research. Jan2009, Vol. 1250, p149-156. 8p.
- Subject
- *BEHAVIORAL assessment
*RAPID eye movement sleep
*ELECTRODES
*NEURAL development
*FETUS
*SHEEP
*REGRESSION analysis
- Language
- ISSN
- 0006-8993
Abstract: Nine fetal sheep were surgically prepared with placement of electrocortical and electro-ocular electrodes for monitoring behavioural state activity to determine the relationship of adjacent low-voltage (LV)/rapid eye movement (REM) and high-voltage (HV)/non-(N)REM epoch durations and the inter-epoch transition time. Animals were subsequently studied over an 8-hour period with behavioural state epoch duration and transition time assessed using paired t-test and regression analysis. For all animals, the duration of LV/REM epochs averaged 14.8±0.8 (SEM) minutes which was significantly greater than that for HV/NREM epochs at 10.1±0.5 min (P <0.01). The mean duration of LV/REM to HV/NREM transition periods at 93±3 s was also significantly longer than that for the HV/NREM to LV/REM transition periods at 78±6 s (P <0.05). HV/NREM epoch duration was positively correlated with the prior LV/REM epoch duration with a group mean correlation of 0.59 (P <0.01). HV/NREM epoch duration was likewise positively correlated with the subsequent LV/REM epoch duration with a group mean correlation of 0.46 (P <0.01). We conclude that the transition time into HV/NREM is longer than that into LV/REM for the ovine fetus near term which may involve differences in the rate of maturation of cycling control mechanisms for these two behavioural states and earlier development of REM-on versus REM-off pathways. The positive LV/REM–HV/NREM linkage relationships also support a homeostatic model of behavioural state control whereby LV/REM and HV/NREM timings are both controlled by accumulation of propensity for these states during the other state and favours an interactive process between these states in the brain''s growth and development. [Copyright &y& Elsevier]