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Biomedical subjects

J V Brown

Publications and source records attributed to J V Brown.

At least 37 records · Page 2Linked to original sources
PubMed1986

The accuracy of aimed movements to visual targets during development: the role of visual information.

Children aged 1.5 to 8 years were required to touch accurately an illuminated target lamp located on a vertical board. Movements were made when visual information was complete (target lit for 3 s, room illuminated; partial (target lit for 3 s, room dark, and reduced (target lit for 0.7 s, room dark). Dependent variables were response accuracy, reaction time, and movement time. Accuracy decreased with decreasing availability of visual information and improved with age under all conditions. Reaction times were shorter in the dark (Conditions 2 and 3) than in the light; they decreased with age up to age 5 and did not continue to decrease thereafter. Movement time did not change with age under Conditions 1 and 3 but tended to increase with age under Condition 2. Slower movements were more accurate at all ages, provided visual feedback could be utilized. Increased reliance on the strategy "slower movements yield higher accuracy" was held to account for developmental changes under Condition 2, whereas in Conditions 1 and 3 improvement in the efficiency of motor preprogramming was implicated.

Age Factors↗
PubMed1986

Tactile recognition of laterally inverted mirror images by children: intermanual transfer and rotation of the palm.

Intermanual tactile recognition of laterally inverted mirror shapes was studied, with special reference to the role of the thumb. Children were allowed to feel the shapes either with the whole hand, with only four fingers (excluding the thumb), or with only the index finger. Intramanual recognition was also studied after rotation of the hand from the palm down/up to the palm up/down orientation. The thumb was found not to be important for intermanual mirror reversals, and only of limited importance for intramanual reversals. There was no evidence that coding with reference to the hand is of importance for either inter or intramamual reversals. The explanations for the two kinds of reversals are quite different.

Age Factors↗
PubMed1985

Confusion of laterally inverted mirror-images: a relationship to brain anatomy?

Whereas in the monkey brain the representation of spatial direction (left/ right) is the same for visual and for tactual inflow, in the human brain visual and tactual lateral directions are not aligned with respect to one another. This anatomical feature of the human brain may account in part for the particular difficulty young sighted children have with laterally inverted forms. A small group of children who were totally blind since birth distinguished mirror pairs by touch significantly more easily than did sighted children of comparable age; and monkeys succeeded at cross-modal recognition of laterally inverted mirror pairs better (relative to control pairs) than did sighted children.

Age Factors↗
PubMed1983

Visually guided reaching and tactile discrimination performance in the monkey: the effects of removals of parietal cortex soon after birth.

Unilateral removals of parietal cortex were made soon after birth in 5 monkeys. The inferior parietal lobule was removed alone or together with the superior parietal lobule; the second somatosensory area (SII) was removed alone or together with posterior parietal surface cortex. Neurological changes were observed; and the animals were assessed quantitatively for their accuracy of reaching for visual targets and for their ability to discriminate between objects by palpation in the dark. Each hand was evaluated separately. Disorders of reaching (confined to the contralateral hand) were found to persist longer than in animals with comparable removals made at a later age; whereas the ability to make tactile discriminations was not more severely impaired after an early than a late ablation.

Aging↗
PubMed1980

Gripping and moro responses: differences between small-for-gestational age and normal weight term newborns.

Small-for-gestational age and normal weight term newborns were compared on the grip and the Moro reflex. Responses were elicited by a rapid downward tilt of a board upon which the baby rested. Under the grip condition the baby held a bar with his left hand, while the baby's hands were free during the Moro condition. Two phases of the grip (finger flexion and relaxation time) and the Moro (arm extension and flexion) were measured. Small babies differed from normal weight term babies only on the second phase of each response. They took longer to relax their grips but showed weaker arm flexions during the Moro. Magnitude of Moro flexion was not related to grip amplitude, but was negatively correlated with grip relaxation time. Two explanations for these findings, related to the activity of the antagonist or of the agonist muscles involved in the two responses, were considered.

Humans↗
PubMed1980

Nursery-based intervention with prematurely born babies and their mothers: are there effects?

The effects of nursery-based intervention with healthy, prematurely born babies and their socially disadvantaged mothers were evaluated. Mother-infant dyads were randomly assigned to one of three intervention groups: In group one, the babies received special stimulation designed to make them more active contributors to the interactions with their mothers; in group two, mothers received special training to help them become more responsive to cues from their babies; in group three, infants received stimulation and mothers received training. In addition, a fourth group of preterm babies who received regular hospital care served as a comparison group to assess the short-term effects of the stimulation program. Outcome measures designed to evaluate various aspects of mother-infant interaction and infant development failed to reflect any effects of the interventions, either at the time the babies were discharged from the hospital or one year later. We attribute the lack of positive findings to the fact that the mothers faced numerous crises in their social environments. We conclude, therefore, that nothing short of massive social change is likely to result in measurable effects.

Acoustic Stimulation↗
PubMed1980

Early interaction: consequences for social and mental development at three years.

Interaction during feeding sessions between preterm infants and their mothers and that between full-term infants and their mothers were compared. (Mothers and babies were from a low-income, inner-city population.) When the children were about 3 years old, they attended a day camp for 3 weeks, during which their cognitive ability (Stanford-Binet) and social ability (both social competence and social participation) were assessed. Early interaction was quite different for preterms and full-terms, but in general it did not predict either social or cognitive ability at age 3. Birth status (preterm/full-term) did predict cognitive (but not social) ability: preterms scored lower. Finally, the children of mothers who were more emotionally and verbally responsive during a home visit at 20 months exhibited more social and cognitive ability at age 3. These results suggest that the baby, within broad normal limits, may be "buffered" against any long-term consequences of interaction during the first few months of life.

Adult↗
PubMed1977

The relationship between sucking and grasping in the human newborn: a precursor of hand-mouth coordination?

The relationship between grasping and sucking, a possible precursor of hand-mouth coordination, was examined in human newborns of varying gestational ages. Grasping was elicited by rapidly tilting the infant backwards while he rested on a padded board and held a grasp bar. Infants were tilted 4 times under each of 3 conditions: grasping, sucking, and grasping-while-sucking. The dependent variables were strength and duration of grasp and frequency and amplitude of sucks during the 15 sec following the tilt. The results indicated that grasping did not affect sucking but that sucking increased the strength and the duration of the grasp. Furthermore, either response system was more highly correlated with indices of maturity of the central nervous system when elicited in the presence rather than the absence of the other. We conclude that in human newborns sucking may be dominant over grasping but that both are part of an integrated system which may form the basis for the development of hand-mouth coordination.

Hand↗
PubMed1975

Interactions of black inner-city mothers with their newborn infants.

Interactions of 45 black inner-city mothers with their healthy full-term newborn infants were observed during a bottle-feeding on the third day after birth. An exhaustive catalog of some 100 mother and infant behaviors was used to describe objectively the interactions of mothers and infants. In addition to being observed with their mothers, infants were examined with the Rosenblith scale. The infants' birth weights, birth order, and sex and maternal medication were found to affect the infants' behaviors and/or the patterns of mother-infant interactions.

Adult↗
PubMed1975

Posture as a determinant of visual behavior in newborns.

The effects of posture on the visual behavior of 15 3-day-old healthy black newborn males and females were assessed. The amount of time each infant kept his eyes open and the quality of fixation and following a visual stimulus were measured in each of 3 positions: lying down, sitting up, and on shoulder. Although position had little effect on the amount of time the eyes were open, the on-shoulder position significantly increased the quality of the visual behavior. These findings suggest that the vestibular, proprioceptive, and contact stimulation provided by the on-shoulder position affects the newborn's ability to follow and process visual stimuli.

Black or African American↗