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Biomedical subjects

P G Hepper

Publications and source records attributed to P G Hepper.

At least 19 recordsLinked to original sources
PubMed1999

Prevalence of disease in dogs purchased from an animal rescue shelter.

The prevalence of diseases suffered by dogs within two weeks of their acquisition from a rescue shelter in Northern Ireland was investigated. A postal questionnaire was completed by 556 people who had purchased a dog from the Ulster Society for the Prevention of Cruelty to Animals (USPCA) to provide information on the diseases suffered by their dog. The majority of the dogs (53.7 per cent) had an ailment the most common being coughing and diarrhoea. Of the respondents who returned their dog to the USPCA, 92 per cent did so because the animal was unhealthy. Stray dogs were more likely to have an ailment than unwanted dogs, specifically coughing, and/or skin problems. More puppies suffered from parvovirus, vomiting, and/or diarrhoea than did juveniles or adults. Adult dogs were more likely to have a cough than juveniles or puppies. There was no association between the sex of the dogs and their ailments.

Animal Welfare↗
PubMed1999

A simple method for testing odor detection and discrimination in chicks.

A simple procedure for testing newly hatched chicks' responses to olfactory stimuli is described. Chicks that were hand held under a heatlamp became inactive and closed their eyes (as if asleep) within 2 min. Sleeping chicks displayed overt behavioral responses to an odorized q-tip (head shaking, beak clapping) that were not observed in awake chicks. Sleeping latencies were shorter for 1-day-old chicks that had been food deprived prior to testing than for chicks that had ad lib access to food and water. When airborne odors were presented by squeezing a soft plastic odor bottle near the beak, sleeping chicks' reactions to mint were of a greater magnitude than their responses to lavender or orange scents. Nonetheless, all three odors elicited more pronounced behavioral responses than did the water control stimulus. This method allows rapid testing of individual chicks for odor detection and discrimination.

Analysis of Variance↗
PubMed1998

Lateralised behaviour in first trimester human foetuses.

Behavioural lateralisation is a common feature of everyday behaviour, most familiar in the exhibition of handedness. Despite differing theories about the origins of laterality, little is known about their ontogenesis. This study observed the left and right arm movements of 72 foetuses at 10 weeks of gestational age, the first age at which lateralised behaviour may be observed. There was a highly significant preference for foetuses to move their right arm more than their left arm, 85% exhibiting more right arm than left arm movements. There was no difference in the amount of movements exhibited with the preferred arm, whether it be right or left. Laterality of behaviour at such an early gestational age (probably as early as it is possible for it to be observed) is unlikely to be under brain control but is probably of more muscular or spinal determination. The possibility that early differential motor behaviour may contribute to subsequent laterality of behaviour and asymmetrical brain growth, must be considered.

Arm↗
PubMed1998

Chemosensory learning in the chicken embryo.

Prenatal chemosensory learning has been demonstrated in mammals, fish, amphibians, and insects, but not birds, although there is evidence of the avian's ability to learn auditory stimuli before hatching. This paper examines how exposure to a chemosensory stimulus (strawberry) prior to hatching affects subsequent chemosensory preferences of newly hatched chicks. The chicks' preferences were assessed at 2 days after hatching using an "olfactory" preference test (strawberry-smelling shavings versus water-coated shavings) and at 4 days after hatching using a "gustatory" preference test (strawberry-flavoured water versus unflavoured water). Chicken embryos were exposed to strawberry from Day 15 to Day 20 of incubation by either presenting the odour in the air around the egg, rubbing it onto the shell, or injecting it into the air space. With no exposure to strawberry before hatching, strawberry was highly aversive to chicks after hatching. However, following exposure to strawberry before hatching, chicks expressed a greater preference for (or weaker aversion to) the strawberry stimulus. Chicks exposed to strawberry before hatching drank more strawberry-flavoured water and spent more time in a strawberry-scented area than chicks having no exposure before hatching. This change in preference was specific to the stimulus experienced before hatching and was present in the absence of any posthatching exposure to the stimulus. The results demonstrate that a chick's chemosensory preferences are changed as a result of experience with a stimulus before hatching and are suggestive of learning. The results, similar to those obtained in other animal groups, indicate the universality of "prenatal" chemosensory learning in the animal kingdom. A possible role of embryonic chemosensory learning for recognition is discussed.

Animals↗
PubMed1997

Memory in utero?

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Conditioning, Classical↗
PubMed1996

Fetal memory: does it exist? What does it do?

Whether fetal memory exists has attracted interest for many thousands of years. The following review draws on recent experimental evidence to consider two questions: does the fetus have a memory? And, if so, what function(s) does it serve? Evidence from fetal learning paradigms of classical conditioning, habituation and exposure learning reveal that the fetus does have a memory. By comparison little attention has been paid to the possible function of memory. Possible functions discussed are: practice, recognition of and attachment to the mother, promotion of breastfeeding, and language acquisition. It is concluded that the fetus does possess a memory but that more attention to the functions of fetal memory will guide future studies of fetal memory abilities.

Breast Feeding↗
PubMed1995

Human fetal behaviour and maternal cocaine use: a longitudinal study.

This paper reports a series of ultrasound observations on a human fetus from 21 weeks of gestational age at two weekly intervals to term. The mother, until 18 weeks of gestational age, was a user of cocaine but after this age used cocaine only once at 31 weeks gestation. The behaviour of this fetus was compared to a group of 10 similar aged fetuses who were not exposed to cocaine. Exposure to cocaine resulted in prolonged periods of inactivity interspersed with periods of increased general activity and an increased number of startles. This was particularly evident immediately following exposure to cocaine but behaviour appeared to become more normal with time as the mother stopped using cocaine. The behavioural states of the cocaine exposed fetus were different from unexposed fetuses. Longer periods were spent in States 1F and 4F and less time in State 2F. Furthermore the incidence of periods where no states were observed was considerably higher. These observations demonstrate that maternal cocaine use disrupts the behaviour of the fetus indicating a direct effect on the CNS. The value of prenatal behavioural observations to assess the effects of neurotoxic agents is demonstrated.

Age Distribution↗
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↗
PubMed1994

Development of fetal hearing.

Previous research has revealed that the human fetus responds to sound, but to date there has been little systematic investigation of the development of fetal hearing. The development of fetal behavioural responsiveness to pure tone auditory stimuli (100 Hz, 250 Hz, 500 Hz, 1000 Hz, and 3000 Hz) was examined from 19 to 35 weeks of gestational age. Stimuli were presented by a loudspeaker placed on the maternal abdomen and the fetus's response, a movement, recorded by ultrasound. The fetus responded first to the 500 Hz tone, where the first response was observed at 19 weeks of gestational age. The range of frequencies responded to expanded first downwards to lower frequencies, 100 Hz and 250 Hz, and then upwards to higher frequencies, 1000 Hz and 3000 Hz. At 27 weeks of gestational age, 96% of fetuses responded to the 250 Hz and 500 Hz tones but none responded to the 1000 Hz and 3000 Hz tones. Responsiveness to 1000 Hz and 3000 Hz tones was observed in all fetuses at 33 and 35 weeks of gestational age, respectively. For all frequencies there was a large decrease (20-30 dB) in the intensity level required to elicit a response as the fetus matured. The observed pattern of behavioural responsiveness reflects underlying maturation of the auditory system. The sensitivity of the fetus to sounds in the low frequency range may promote language acquisition and result in increased susceptibility to auditory system damage arising from exposure to intense low frequency sounds.

Audiometry, Pure-Tone↗
PubMed1993

In utero release from a single transient hypoxic episode: a positive reinforcer?

In this experiment, fetal rats, Rattus norvegicus, were subjected to a single transient hypoxic episode before an injection of orange essence or isotonic saline through the uterine and amniotic membranes into the amniotic fluid within 5 s of the release from hypoxia. Other animals experienced either orange essence or isotonic saline alone following no hypoxic episode. At 120 days after birth, adult rats were given a two-choice preference test between orange and water. Only those animals who experienced the orange following release from hypoxia showed a preference for the orange. These results suggest that the acquired preference is not a result of simple exposure but is suggestive of a role for reoxygenation as a positive reinforcer.

Animals↗
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

Embryonic olfactory learning in frogs.

We examined the effect of embryonic olfactory experiences on behaviour after hatching in two species of anuran amphibians, Rana temporaria and Rana sylvatica. Odorants (orange and citral) injected into the egg were "learned" by the embryo and subsequently preferred by tadpoles after hatching. The observed preferences were specific to the odours experienced prior to hatching, and tadpoles discriminated between the odour experienced as embryos and a novel odour. The acquired preference was maintained after metamorphosis for those individuals that exhibited a preference as tadpoles. Preferences of tadpoles were also influenced "naturally" by odours present in the water surrounding the developing embryos. The experimentally induced olfactory preferences did not appear to influence the exhibition of sibling recognition abilities. The study represents the first demonstration of "embryonic" learning in amphibians, and the functions and importance of early olfactory learning for amphibians are discussed.

Animals↗
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↗
PubMed1991

Heart rate response of the rat fetus and neonate to a chemosensory stimulus.

Resting heart rate (HR) and HR responses of fetal and neonatal rats are described before and after intraoral infusion of isotonic saline or lemon solution. Stable measurements of resting HR were obtained for fetuses over the last three days of gestation (E19, E20, E21) and pups on the day of birth (P0) and four subsequent postnatal ages (P1, P3, P5, P7). Resting HR decreased significantly on P0 relative to the three prenatal ages and exhibited a linear increase thereafter. Variability in resting HR was pronounced on E21, decreased sharply after birth, and gradually increased through P7. Developmental changes in the HR response of fetuses and pups were evident following infusion of lemon. Fetal HR responses to lemon were characterized by bradycardia, which increased in magnitude through P1, diminished after P1, and eventually changed to tachycardia by P7. Both resting HR and HR responses to chemosensory stimulation point to the immediate perinatal period as a time of quantitative and qualitative change during sensory development.

Aging↗