J. Wesley Burgess

Recovery of function after neonatal or adult hemispherectomy in cats: I. Time course, movement, posture and sensorimotor tests

Cats with removal of the left hemitelencephalon (hemispherectomy) as neonates (n = 12) or in adulthood (n = 14), were compared using a battery of 16 neurological and behavioral tests given when they were young adults (kittens) or at least 5 months after the lesion (adults). The neonatal-lesioned subjects grew normally and performed markedly and significantly better than adult-lesioned cats in 13 tests covering the wide range of movement, posture and sensory functions which were assessed. None of the animals recovered tactile placing of the right forelimb or a normal vision in the right visual field. However, the overall recovery was outstanding for all cats such that the neonatal-lesioned were hard to differentiate from intact controls in their spontaneous, daily activities. Because the lesions were similar in the two age-at-lesion groups, and since numerous functions were followed for prolonged, comparable postlesion time, we conclude that, after hemispherectomy in the cat, there definitely is greater functional recovery if the lesion is sustained early in life. We propose that the enhanced recovery of function in neonatal-lesioned cats is largely due to the extensive anatomical reorganization which we have demonstrated in ongoing studies, and which contrasts with a lesser remodeling in adult-lesioned cats.

There is less thalamic degeneration in neonatal-lesioned than in adult-lesioned cats after cerebral hemispherectomy.

In order to study age-related processes of degeneration and recovery, the left hemitelencephalon was surgically removed in 5 adult cats and 5 neonatal kittens which were compared to 5 intact controls. After long survival, brains were sectioned in the coronal plane and thionine-stained. Drawings of gross and microscopic thalamic structures were made at 4 planes and computer-digitized to provide 7 measures: total thalamic area at planes A 7.5 and A 8.5; counts of neuroglia, small neurons (31-100 microns2) and large neurons (101-1000 microns2); area of neuroglia, small neurons and large neurons. All cellular measurements were in the ventrobasal complex at planes A 8.0 and A 10.0. Morphological changes were found bilaterally in all lesioned cats. Ipsilateral to the ablation in adult-lesioned cats, thalamic area, large neuron count and glia cells size were markedly and significantly decreased (P less than 0.01), while in neonatal-lesioned cats these changes were present but significantly reduced in magnitude compared to adult-lesioned animals. In addition, adult-lesioned cats showed a marked increase in glial cell numbers (P less than 0.01) and a decrease in small neuron size (P less than 0.01), while kitten-lesioned animals did not show changes in these measures. In the intact side of the brain, the thalamus of adult-lesioned cats was decreased in size (P less than 0.01), and glial cells were decreased in number and size (P less than 0.05), while in kitten-lesioned brains there were few changes. In both lesioned groups large neurons showed a significant increase in size (P less than 0.01). We conclude that neonatal hemispherectomy results in markedly less thalamic atrophy, retrograde neuronal degeneration and gliosis than the equivalent lesion in adults. The changes are discussed in the context of the increased neuroanatomical reorganization and functional recovery which were reported in neonatal- vs adult-lesioned animals.

Interpersonal spacing behavior between surrounding nearest neighbors reflects both familiarity and environmental density

Abstract Patterns of proxemic behavior were studied in casual groups within public environments. Observations were made in the corridors of large shopping malls and on sidewalks in small towns. In walking and sitting groups, social distances between surrounding neighbors and the sizes of casual groups were measured from photographs or maps. A similar group spatial pattern was found during both walking and sitting: individuals aggregated significantly with their 1st, 2nd, and 3rd nearest companions, while avoiding proximity to or maintaining random distances toward 1st, 2nd, or 3rd nearest strangers. Companions in these groups always maintained closer social distances toward each other than toward strangers. Distances between walking companions were inversely correlated with density, but distances to strangers were independent of density. The resulting subgroups were larger in size than some groups previously observed in comparable environments. The results are contrasted with naturally-occurring proxemic behavior observed in the groups of nonhuman primates and other social animals, and are discussed in the context of ecological pressures favoring social spacing responses.

Recovery of functions after neonatal or adult hemispherectomy in cats. III. Complex functions: Open field exploration, social interactions, maze and holeboard performances

Complex behavioral patterns were studied in cats with removal of the entire left cerebral hemisphere either as neonates (n = 10) or adults (n = 11), and in intact control cats (n = 24). Adult-lesioned cats showed decreased open field activity in locomotion, rearing and sniffing. Lesioned kittens showed similar deficits at 100 days of age, but by 150 days of age they resembled normal littermates in all 3 measures. In the presence of another cat, adult-hemispherectomized cats violated species-typical body-buffer space, approaching and attacking other cats. By comparison, normal cats never attacked and seldom approached in the open field. Neonatal-lesioned adults showed only occasional approach and a tendency to sit or stiff-walk in the presence of other cats; attacks were rare. Adult-lesioned cats responded poorly to reversal training for preferred arm of a T-maze, whereas neonatal-lesioned adults were significantly more trainable. Similarly, adult-lesioned cats exhibited a search deficit in a baited holeboard, while neonatal-lesioned adults searched normally. Overall, these results demonstrate that in this animal model, enhanced recovery following early vs adult lesions can also be found in relatively complex, spontaneous behavioral responses not previously studied in this regard.

Reassessing morphine effects in cats: II. Protracted effects on sleep-wakefulness and the EEG

Adult cats were implanted with standard electrodes to record EEG, EOG, and EMG. After 15 days, morphine sulphate or saline placebo was given IP at 0.5, 1.0, 2.0, 3.0 mg/kg, at least 15 days apart. Cats were continuously recorded for 72 hr postinjection. Wakefulness, drowsiness, NREM and REM sleep percentages were scored from polygraphic features and statistically analysed. There was a dose-dependent suppression of NREM and REM sleep for at least 6 hours postmorphine, with a progressive sleep recovery thereafter. During the insomnia period there was an EEG/behavioral dissociation where bursts of high-voltage waves were seen over a background of desynchrony; meanwhile the animal was first aroused although quiet and later showed stereotypic behavior. There was a prolonged NREM sleep rebound which started later at the higher doses. A significant, relatively brief REM sleep rebound was seen only at the lowest dose. The latency for NREM and REM sleep onset was also dose-dependent. Possible brain sites of morphine actions and similarities with effects in other species are discussed.

Development of social spacing in normal and mentally retarded children

Distances between closest playmates were measured during free play in mentally retarded and normal grade school children. Unobtrusive observation techniques minimized interference and a spacious playground environment was chosen to avoid effects of confining walls on spatial behavior. Younger children (grades 1–3) kept closer distances than older children (grades 4–6), independent of clinical history or sex (p<.0001). Parallels are drawn with findings of previous observational studies in adults and non-human primates; two hypotheses, based on cognitive development and social disturbance, are proposed to explain the findings.

Developmental trends in proxemic spacing behavior between surrounding companions and strangers in casual groups

This study examined age differences in the pattern of proxemic behavior observed in casual groups frequenting public environments. Observations were made in the corridors of large shopping malls and along sidewalks of small towns. The relative positions of all walking subjects were inconspicuously recorded in photographs, and interpersonal distances were measured by projecting slides on a calibrated grid. Distances to first, second, and third nearest companions and first, second, and third nearest strangers were computed for subjects in six age classes: preschool children, grade school children, teenagers, young adults, middle adults, and senior adults. All classes showed significant age differences in the distances maintained to companions (p = .00001), but only senior adults differed in their spacing toward strangers, by maintaining significantly closer distances than the other age groups (p < .01). Tests of spatial patterns showed significant aggregations between first, second, and third nearest companions, and essentially random spacing toward first nearest strangers in all age groups. Senior adults showed a significant tendency to aggregate with their second and third nearest surrounding strangers. These results are discussed in the light of oer research and in the context of the ecology and development of proxemic behavior.

The spacing of rhesus monkey troops changes when a few group members receive Δ9THC or D-amphetamine

Free ranging troops of 18--25 rhesus macaques were housed in large enclosures where a few higher-ranking monkeys were given psychotropic agents (delta 9THC: 4 mg/kg or d-amphetamine: 2 mg/kg). Measures of group spacing were (1) mean distance between all animals. (2) daily variance in mean distance, (3) nearest neighbor distance, (4) daily variance in nearest neighbor distance, (5) index of clumping (S2/mean ratio), (6) % touching, and (7) % movement/2 sec. When 3--4 animals were drugged, the entire group moved closer together and distances were more variable. Acute changes after the first week of delta 9THC and effects after delta 9THC withdrawal were seen in two experiments. Chronic behavioral changes were found for d-amphetamine and in one delta 9THC experiment.

Do humans show a “species-typical” group size?: Age, sex, and environmental differences in the size and composition of naturally-occurring casual groups

Abstract The size, age,and sex composition of 2277 casual groups from eight shopping malls and two sidewalk shopping areas, and 1086 groups from other public environments, were recorded and analyzed to reveal age, sex, and environmental components of human grouping tendencies. Groups containing grade school or teenage children were significantly larger than groups of other ages. Adult females were found in larger groups than males; although females readily formed groups with either sex, adult males formed few groups containing one or two other males. Group size showed a significant, inverse correlation with social distances between first, second, and third nearest neighboring group members in a photo sample, but group size showed no correlation with social distances between strangers. These results are interpreted in the light of an ethological hypothesis that contemporary grouping patterns had their origins in adaptive, inborn aggregative tendencies that were later incorporated into the repertoire of nonverbal human behaviors.

Chronic exposure to caffeine during early development modifies spatial behavior in juvenile jewel fish schools

Thirty sibling African jewel fish (Hemichromis bimaculatus) were either chronically exposed to caffeine between 50 to 100 days of age (at a concentration of 14 mg/l) or reared without drug in a control environment. After caffeine was withdrawn, fish in each group were videotaped for 30 minutes while schooling in a large tank. From the video record, mean distances and coefficients of variation of spacing were computed for each fish and its 1st to 9th nearest neighbors in all observations. Spacing distances were nearly identical for the two groups, but the caffeine fish exhibited much more variability in their spacing behavior (p less than 0.00001). This study demonstrates an effect on behavior of moderate caffeine levels present throughout the early developmental period, and illustrates a quantitative method to test for such effects.