The changes in fetal habituation patterns due to a decrease in inspired maternal oxygen

Abstract

Habituation is widely regarded as a basic form of learning. A fully functioning central nervous system is probably required for a normal habituation pattern. Habituation of the behavioural response to vibroacoustic stimulation was studied in 23 normal human fetuses whose gestational age was 36 or more weeks. Eighteen were tested whilst their mothers brcathcd either air or a 12% oxygen in nitrogen mixture. The test was rcpeated the tollowing day with the order of the gases reversed. In addition five fetuses were tested while their mothers breathed air on both occasions. Of the 28 fetuses 17 had a normal habituation pattern when tested in air but only two had a normal pattern when their mothers breathed 12% 0,. Four of the five fetuses tested both days in air had normal patterns on the second day. Altering the amount of inspired maternal O2 alters the fetal habituation pattern.

Maternal corticotropin-releasing hormone and habituation in the human fetus

“…There is convincing evidence that the human fetus detects and responds to a variety of ex utero stimuli, including buzzers (Leader, Baillie, Martin, & Verueulen, 1982;Shalev, Benett, Megory, Wallace, & Zuckerman, 1989;Zimmer, Chao, Guy, Marks, & Fifer, 1993), clicks, tones (Grimwade, Walker, & Bartlett, 1971), and the human voice (DeCasper & Fifer, 1980;Fifer & Moon, 1989;Lecanuet, Granier-Deferre, & Jacquet, 1992). Several studies have suggested that fetuses, by 25 weeks gestation, habituate to external stimulation (Leader & Baillie, 1988;Leader et al, 1982;Madison, Adubato, Madison, Nelson, Anderson, Erickson et al, 1986a;Madison, Madison, & Adubato, 1986b;Shalev et al, 1989;Shalev, Weiner, & Serr, 1990). Faster fetal habituation has been associated with advancing gestational age (Shalev et al, 1989), consistent with findings in general that immature nervous systems habituate more slowly than mature nervous systems (Graham, Anthony, & Zeigler, 1983).…”

Effect of Hypoxia and Catecholamines on the Habituation Rates of Chronically Catheterized Ovine Fetuses

“…Hypoxia was associated with a more rapid rate of hab ituation which may be either as a result of catecholamine release [Jones and Robinson, 1975] or the direct effect of hypoxia. In the human pregnancy, reducing the amount of oxygen inspired by the mother is associated with either more rapid habituation rates or impaired habituation by the fetus [Leader and Baillie, 1988]. Hypoxia was also associ ated with a decrease in fetal responsiveness in that 4 fetuses failed to respond to stimula tion.…”

“…Further studies are planned in fetal sheep using less severe degrees of hypoxia to see if this can reproduce the slow habituation seen in human fetuses when exposed to mild hyp oxia [Leader and Baillie, 1988],…”

“…Impairment of 'normal' habituation in the human fetus also occurs during cigarette smoking [Leader and Bennett, 1988] in which it is likely that the fetus is subjected to decreased placental perfusion, and during hypoxia [Leader and Baillie, 1988].…”

An objective assessment of fetal and neonatal auditory evoked responses

“…Also, since the proposed method is an objective measure, it can be applied reliably to more complicated scenarios such as habituation behavior (Leader and Baillie, 1988, Leader et al, 1982, Thompson and Spencer, 1966, Sheridan et al, 2008) where multiple types of stimuli limit the total number of stimuli.…”