Sara Shahidullah

Handedness in the human fetus

The developmental origins of behavioural asymmetries, in particular handedness, have aroused considerable interest and debate. Until now such behavioural asymmetries have only been reported after birth. Here we report the existence of handedness before birth, expressed in terms of thumb-sucking by the fetus. Ultrasound observations of fetuses from 15 weeks to term revealed a marked bias for sucking the thumb of the right hand. This preference appears to be maintained throughout pregnancy, is unrelated to fetal position in utero but correlates with head position preference in the supine newborn. The findings indicate that handedness is present prior to birth and the implications of this for the development of laterality are discussed.

Frequency discrimination by the fetus

The ability to discriminate between acoustic signals of different frequencies is fundamental to the interpretation of auditory information and the development of language perception and production. The fact that the human fetus responds to sounds of different frequencies raises the question of whether the fetus is able to discriminate between them? To investigate whether the fetus has the ability to discriminate between different pure tone acoustic stimuli and different speech sounds the following study used an habituation paradigm and examined whether the fetus could discriminate between two pure tone acoustic stimuli, 250 Hz and 500 Hz, or two speech sounds, [ba] and [bi], at 27 and 35 weeks of gestational age. The results indicated that the fetus is capable of discriminating between the different sounds, i.e. 250 Hz and 500 Hz and [ba] and [bi] at 35 weeks of gestational age but less able at 27 weeks of gestational age. The implications of this for the development of the auditory system are discussed.

Habituation in normal and down's syndrome fetuses

The ability of ten normal and two Downs syndrome fetuses to habituate to a repeated auditory stimulus was assessed. The normal fetuses were assessed on two separate occasions during the final trimester of pregnancy. The number of trials to habituate and latency to respond were recorded. The results demonstrated that all normal fetuses exhibited a decrement in response to repeated presentations of the stimulus, a 250-Hz sine wave. This was the result of habituation and not fatigue since fetuses recovered responding upon presentation of a new (500 Hz) stimulus and habituated faster on re-presentation of the original stimulus. The performance of fetuses remained stable over the two testing periods. The response of the Downs syndrome fetuses was different to that of normal fetuses rarely overlapping indices of habituation exhibited by normal fetuses. The study concludes that habituation may be a powerful tool to examine the behavioural and sensory development of the fetus and may be of use in the antenatal assessment of the existence and severity of neural abnormality.

The developmental origins of fetal responsiveness to an acoustic stimulus

Abstract There is now little doubt that the fetus responds to sound during its development. Whilst many studies, based upon the observation of a response on the pan of the fetus to the presentation of a sound stimulus, have demonstrated fetal responsiveness to sound during the third trimester, few have looked in any systematic fashion at the developmental origins of this response in the fetus. To investigate the origins of fetal responsiveness to an acoustic stimulus the following study examined the response of the fetus from 15 weeks gestation to 25 weeks gestation, comparing the number of fetal movements before, during and after the presentation of an acoustic broad-band stimulus. The results of these experiments indicate that the human fetus first responds to acoustic stimulation at 20 weeks of gestation. At this age the fetus responds with a diffuse response of slow latency; however, by 25 weeks of gestation the response is an immediate auditory startle-type response. The difference in the type of res...

The beginnings of mind - evidence from the behaviour of the fetus

Abstract The developmental origins of the human mind have been the subject of much speculation. This paper reviews studies of the behaviour of the human fetus, to assess the beginnings of mind. Whilst this evidence indicates that the fetus is bchaviourally active before birch, it does not answer questions central to the existence of the mind directly, i.e. the presence of self-awareness, consciousness. However, the behaviour of the fetus may be used to explore the development of mind. Study of the prenatal ontogenesis of behaviour suggests that the mind will emerge in an immature form and that stimulation received in utero, and the behaviour emitted, will play an important role in its development.

Abnormal fetal behaviour in first trimester spontaneous abortion.

The behaviour of 5 fetuses at 10 weeks of gestational age that later underwent a spontaneous abortion during the first trimester of pregnancy was compared to similar aged normal fetuses (n = 116). Marked abnormalities of behaviour were noted in three of the pregnancies that spontaneously aborted. These behavioural abnormalities were not identified in any of the pregnancies which continued to term. We conclude that fetal behaviour, which reflects the neural integrity of the individual, and thus fetal well-being, can be used during the first trimester to give an indication as to the viability of the on-going pregnancy.