title: Behavioural state linkage in the ovine fetus near term.
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.
authors.affiliation: Department of Obstetrics and Gynaecology, Children's Health Research Institute, The University of Western Ontario, London, Canada.
authors.forename: Neesha
authors.initials: N
authors.lastname: Rao
authors.forename: Ashley
authors.initials: A
authors.lastname: Keen
authors.forename: Marie
authors.initials: M
authors.lastname: Czikk
authors.forename: Martin
authors.initials: M
authors.lastname: Frasch
authors.forename: Bryan S
authors.initials: BS
authors.lastname: Richardson
mesh_terms: D000818:Animals; D001774:Blood Chemical Analysis; D001786:Blood Glucose / Q000032:analysis*; D001921:Brain / Q000196:embryology* / Q000502:physiology; D004567:Electrodes, Implanted; D004585:Electrooculography; D005324:Fetal Movement; D005333:Fetus / Q000502:physiology*; D019344:Lactic Acid / Q000097:blood; D012756:Sheep; D012894:Sleep Stages; D012895:Sleep, REM
chemical_list: D001786:Blood Glucose; D019344:Lactic Acid