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Biomedical subjects

S Shahidullah

Publications and source records attributed to S Shahidullah.

9 recordsLinked to original sources
PubMed1994

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.

Acoustic Stimulation↗
PubMed1993

Fetal eye movements.

Since 1981, when eye movements of the human fetus were first reported, the study of fetal eye movements has increased, mainly focusing on the ontogenesis of eye movements and as one parameter of behavioral states. Using real-time ultrasound, fetal eye movements can be clearly observed from 14 weeks of gestational age. Fetal eye movements may be described in terms of their pattern, frequency and incidence of periods containing eye movements and no eye movements. Furthermore, the relationship of eye movements to other behaviors may be used to give information on the integration of central nervous system function. A picture of normal fetal eye movements can be constructed and used to detect abnormalities in eye movements which can indicate underlying abnormalities of the central nervous system. This paper concludes that, although in its early stages, the study of fetal eye movements holds promise for a greater understanding of brain development and the assessment of the condition of the fetus.

Journal Article↗
PubMed1992

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.

Abortion, Spontaneous↗
PubMed1992

Trisomy 18: behavioral and structural abnormalities. An ultrasonographic case study.

A behavioral and structural analysis using ultrasound of a fetus suffering from Edwards syndrome is described. A number of structural anomalies were observed: the classic hand deformity, extended legs, diamond-shaped head, open mouth and a severe cardiac abnormality. A number of distinctive behavior patterns were observed: vertical eye movements, longitudinal rotation of the trunk, rotation of hands, tremor of extremities and pulsatile body movements, which are not usually seen in the normal fetus. The use of behavioral indicators in the diagnosis of abnormalities is discussed. We conclude that the analysis of behavior may make a significant contribution to the ultrasonographic diagnosis of handicap.

Journal Article↗
PubMed1992

Habituation in normal and Down's syndrome fetuses.

The ability of ten normal and two Down's 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 Down's 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.

Arousal↗
PubMed1991

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.

Female↗