Biomedical subjects
D R Moore
Publications and source records attributed to D R Moore.
Aggressive behavior in the home as a function of the age and sex of control-problem and normal children.
This cross-sectional study investigated the ability of age, sex, and clinic-referred or nonreferred status of children to account for variance in the performance of aggressive behavior. Two clinic-referred groups and one normative group of children, composed of 137 males and 86 females between the ages of 3 and 13, were observed during unstructured family interactions in the home setting. Measures of aggressive/aversive child behavior included a composite total aversive behavior (TAB) score, a physical aggression (PAB) score, a verbal aggression (VAB) score, a passive-dependent behavior (PDB) score, and a disobedience (DSB) score. The total regression model and referral status were significant for each of these dependent variables. Age was significant for each variable except VAB, and sex was significant only for PAB. Significant age X group interactions were obtained for TAB, PDB, and DSB. Rates of behavior clearly differentiated groups, but the relationship of age and sex of child to behavior rates was the same across groups. Decreases in all behaviors with increasing age, except for VAB, replicate findings from previous studies in preschool settings. However, the meager sex differences failed to replicate more robust findings generally reported in previous research.
Management of primary hyperparathyroidism: report on a workshop.
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Late onset of hearing in the ferret.
Onset of hearing in the ferret was judged by simple behavioral, physiological and anatomical indices. The ear canals do not open until the end of the first postnatal month. This coincides with the appearance of a startle response to loud hand claps and the recording of acoustically activated neurons in the midbrain. The late onset of hearing in the ferret (around 32 days postnatal) contrasts with the cat (6 days) and the mouse (12 days).
Gangrene of a fingertip from a mitten thread.
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Development of the cat peripheral auditory system: input-output functions of cochlear potentials.
Compound auditory nerve action potentials (APs) and cochlear microphonics (CMs) were recorded from the round-window of kittens aged 3-9 weeks and of adult cats. Animals were anaesthetized and pure tone stimuli were delivered via calibrated, sealed, transducer systems. AP and CM amplitude and AP latency were measured over a wide range of stimulus intensities (up to 80 dB SPL) and at 5 octave-interval stimulus frequencies (1-16 kHZ). At low stimulus intensity levels, AP amplitude had attained adult levels to low and high frequency stimuli by 6 1/2 weeks of age and to mid-frequency stimuli by 9 weeks. As stimulus intensity levels were increased, the kitten input-output functions diverged progressively from those of the adults. At these higher intensity levels, AP amplitude maturation in even the 9 week animals was incomplete. AP latencies to stimuli of all frequencies shortened between the third and fourth weeks but remained stable thereafter. CM amplitude also reached maturity by the fourth week. These findings suggest that the development of AP after the fourth week consists of an increase in the synchrony of auditory nerve fibre responses, since both the fine structure of the cochlea and the responses of single nerve fibres are known to be mature by the end of the first postnatal month.
Plasticity of binaural interaction in the cat inferior colliculus.
Responses of single neurones in the inferior colliculus (IC) to acoustic interaural intensity difference (IID) were examined in normal, adult cats and in cats that had been reared for 3--4 months, either from birth or as adults, with unilateral ligation of the external meatus. There were significantly fewer units displaying IID sensitivity in either of the ligated groups than there were in the normal group. The loss of IID sensitivity in the ligated animals reflected a diminished inhibitory input from the non-ligated ear.
Development of responses to acoustic interaural intensity differences in the car inferior colliculus.
Responses of single neurones in the inferior colliculus of anesthetized adult cats and kittens were studied using best-frequency stimuli of varying interaural intensity differences (IID). Two broad classes of neurone, distinguished by the predominant type of input from each ear, were examined. One class of cells received predominantly excitatory input from each er (EE cells). The other class were excited by monaural stimulation of the contralateral ear and showed no response to monaural stimulation of the ipsilateral ear, but inhibition of the excitatory response by simultaneous ipsilateral stimulation (EI cells). Fourteen of the 18 adult EI cells showed marked changes in discharge rate with variation in IID. Adult EI cells showed low response variability and were insensitive to changes in average binaural intensity. In all cases of IID sensitivity, the onset component of the response was less sensitive to IID than the sustained component. Eight out of ten EE cells were insensitive to IID over the range tested. Cells of high best-frequency in kittens younger than 28 days showed irregular changes in discharge rate with variation in IID and wide response variability. Some low-frequency EI cells in young kittens showed sensitivity to IID, but it is unlikely that these could be involved in sound localization as their frequency response was inappropriate. Many cells in kittens aged 31-40 days showed monotonic, adult-like IID functions, but the response variability of these cells remained higher than that of adult cat neurones. These data provide evidence for a developmental change of binaural interaction in the cat.
Development of binaural input, response patterns, and discharge rate in single units of the cat inferior colliculus.
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Role of interproblem learning in interocular transfer.
The learning of a pattern discrimination may be divided into two components, one specific to the pattern task and another general to it and other tasks. The purpose of these experiments was to assess the degree to which these different components transfer interocularly, as well as to determine the effects of variations in prior acquisition on interocular transfer. In the first experiment, 28 albino rats were assigned to four equal groups that permitted assessment of the influences, on acquisition or interocular transfer of a pattern discrimination, of prior ipsi-ocular, contra-ocular, or sequential binocular training on a black-white task. Interocular savings were reduced by a factor of three when the black-white task (the general component) was acquired priorly, but there was no difference between the effects of prior contra-ocular training on black-white or pattern on subsequent monocular acquisition of the pattern task. Thus, all interocular transfer might be due to the general component. The second experiment, a partial replication, was performed to clarify whether information specific to the pattern task transferred interocularly. Again, interocular savings were reduced by a factor of three after prior black-white training. However, monocular acquisition of the pattern task facilitated subsequent contra-ocular learning of that same task more so than did prior monocular acquisition of a black-white task, indicating that some contribution is made to interocular savings by the information specific to the pattern task.
The development of some peripheral and central auditory responses in the neonatal cat.
The development of cochlear nerve action potential thresholds at different frequencies (AP audiograms) and inferior colliculus (IC) single unit thresholds and tuning was examined in barbiturate-anaesthetized kittens. AP thresholds decreased over the whole frequency spectrum during the first 5 weeks of life. Thresholds to high-frequency stimulation remained higher in 7-week-old animals than in adults. These results are in contrast to previous reports which have suggested that the AP response and gross cochlear anatomy are mature by the end of the second week. These differences may be due to the fact that the AP audiogram technique provides a measure of the activity of discrete regions along the cochlear partition. IC units in animals younger than 3.5 weeks had significantly elevated thresholds and broader tuning than those of the adult cat. Comparison of AP audiogram and IC unit thresholds in the adult revealed that these indices show similar frequency-dependent sensitivity. The slower maturation revealed by the AP audiogram may be due to the greater number and/or synchrony of cochlear nerve discharges needed to produce the gross AP. If this were the case, perception of suprathreshold sounds might not develop as quickly as thresholds for sound detection.
Children at risk for delinquency: a follow-up comparison of aggressive children and children who steal.
This study compared the follow-up incidence of court-recorded nonstatus offenses for three groups of adolescent children. These children had been seen 2 to 9 years earlier for problems with aggression in the home (N = 21), for stealing problems (N = 25), or for normative comparisons (N = 14). The results showed that 77% of the children with stealing problems had court-recorded offenses. This was significantly higher than the aggressive children, whose rate did not differ from the normative sample. These findings suggested that young aggressive children were not at risk for adolescent court contact. Instead, it was the young child with identified stealing problems who was highly likely to become an official delinquent. It also appeared that parental reports of stealing events constituted a predictive measure of later criminal acts.
A barrier cabinet for mice based on the Houghton chicken isolator.
Nuclei of a disease-free foundation stock of mice housed in a barrier unit and a barrier cabinet constructed from resin-bonded glass-fibre were compared over a period of 7 years. The cabinet was found to be a satisfactory alternative to a flexible-film isolator and was thought to be preferable. A description is given of the cabinet, the method of sterilization and the breeding schedules for 2 generations adopted to make the maximum use of the 10-month life of the high-efficiency filter employed. Throughout many cycles of this duration the degree of cleanliness was of a high order. A major contribution towards this was the collection of excreta on a tray lined with both absorbent and grease-proof paper, and the removal from the cabinet of dirt boxes when weaners were issued in them at the age of 5 weeks. These boxes were replaced in the cabinet by clean, sterile ones.
Inferior colliculus. II. Development of tuning characteristics and tonotopic organization in central nucleus of the neonatal cat.
Tuning curves were measured for 65 units in the inferior colliculus of seven anesthetized kittens aged from 6 to 28 days. At 2 days of age the inferior colliculus was divisible into central, pericentral, and external nuclei. Evidence was found for broader tuning curves to occur in the pericentral nucleus compared with the central nucleus, as has been observed in the adult. The middle ear was filled with serous fluid to 6 days, while the external auditory meatus remained collapsed until 10 days. Central nucleus tuning curves in kittens were relatively flat with high thresholds. Best-frequency thresholds diminished from a mean of near 100 dB SPL at 6-11 days to near 50 dB in the adult. The marked drop in thresholds between days 22 and 21 led to the adoption of the sharp form of tuning curve common for adults. Tonotopic organization of the central nucleus was clear at day 11. Speculations were advanced about the dependence of central auditory maturations on cochlear development, axon myelination in the auditory pathway, and changes in synaptic density as a function of age.
Effect of septal and frontal ablations on species-typical behavior in the rat.
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Influence of aging on rat liver enzymes involved in glutathione synthesis and degradation.
The purpose of this study was to determine the effects of aging on the activities of rat liver enzymes involved in the synthesis and degradation of glutathione, as well as those important for maintaining glutathione in its reduced form. gamma-Glutamylcysteine synthetase, gamma-glutamyltransferase, glutathione reductase, and glucose-6-phosphate dehydrogenase activities were measured in liver fractions prepared from male and female Fischer-344 rats at the ages 4, 14, and 29 months. The activity of gamma-glutamylcysteine synthetase, the rate-limiting enzyme in GSH synthesis, and overall rates of glutathione synthesis were unaffected by aging. In contrast, the activity of gamma-glutamyltransferase, the key enzyme in glutathione degradation, was markedly influenced by animal age; activity increased with age in male rats and decreased with age in female rats. Age-associated alterations also were observed in activities of hepatic enzymes needed to maintain glutathione in its reduced form. Glutathione reductase activity was greater in old female rats and glucose-6-phosphate dehydrogenase activity was greater in old male rats than in young and middle-aged rats of the same sex. Age-dependent changes in glutathione metabolizing enzymes could have important toxicological implications.
How plastic is spatial hearing?
The location of a sound source is derived by the auditory system from spatial cues present in the signals at the two ears. These cues include interaural timing and level differences, as well as monaural spectral cues generated by the external ear. The values of these cues vary with individual differences in the shape and dimensions of the head and external ears. We have examined the neurophysiological consequences of these intersubject variations by recording the responses of neurons in ferret primary auditory cortex to virtual sound sources mimicking the animal's own ears or those of other ferrets. For most neurons, the structure of the spatial response fields changed significantly when acoustic cues measured from another animal were presented. This is consistent with the finding that humans localize less accurately when listening to virtual sounds from other subjects. To examine the role of experience in shaping the ability to localize sound, we have studied the behavioural consequences of altering binaural cues by chronically plugging one ear. Ferrets raised and tested with one ear plugged learned to localize as accurately as control animals, which is consistent with previous findings that the representation of auditory space in the midbrain can accommodate abnormal sensory cues during development. Adaptive changes in behaviour were also observed in adults, particularly if they were provided with regular practice in the localization task. Together, these findings suggest that the neural circuits responsible for sound localization can be recalibrated throughout life.
Auditory learning as a cause and treatment of central dysfunction.
Conductive hearing loss produced by middle ear disease (MED) is very prevalent in the first 5 years of childhood. Both MED in children and prolonged ear plugging in animals lead to a binaural hearing impairment that persists beyond the duration of the peripheral impairment. However, after cessation of the MED, or removal of the ear plug, binaural hearing gradually improves. We suggest here that this improvement is a passive form of auditory learning. We also show that active auditory learning, through repetition of discrimination tasks, can accelerate performance increments, both after hearing loss and in unimpaired individuals. A more detailed understanding of auditory learning holds out the prospect of improving rehabilitation strategies for the language- and hearing-impaired.