BEHAVIORAL STATES IN THE FETAL BABOON

This study was designed to characterize behavioral states in the fetal baboon. Automated methods were developed and validated to recognize b ehavioral states based on relationships among three physiologic variab les (EEG patterns, eye movements, heart period variability). Data incl uded twelve 16-h records from 3 chronically instrumented fetal baboons at 0.8-0.9 of term. Randomly generated control records were used to d ifferentiate occurrences of state from chance association of the varia bles. For 41.2 +/- 4.6% (mean +/- S.E.) of the time, the physiologic v ariables were synchronous and formed cycles of state with a mean durat ion of 34.4 min. Components of these cycles had mean +/- S.E. duration s of 7.2 +/- 0.3 min for state 1FB (the analogue of quiet sleep in the human infant and state 1F in the human fetus), 20.7 +/- 1.2 min for t he state 2FB (the analogue of active sleep in the human infant and sta te 2F in the human fetus), and 3.6 +/- 0.2 min for state transitions. For 24.6 +/- 2.4% of the time, the state variables exhibited coinciden tal, state-like agreements, that were not part of state cycles, Finall y, for 34.3 +/- 2.7% of the time, there was no systematic agreement am ong the three variables. These data provide convincing evidence that o rganized behavioral states are present in the fetal baboon as early as 0.8 of term gestation.