Stress-induced Fos-like Immunoreactivity in the Pons and the Medulla Oblongata of Rats

Immunoreactivity of the immediate early gene c-fos was used to investigate changes in the activity of brainstem neurons in response to acute stressors like immobilization, formalin-induced pain, cold exposure, hemorrhage and insulin-induced hypoglycemia. Different stressors induced Fos-like immunoreactivity in different pontine and medullary neurons. A single, 3 hour immobilization was found to be a very strong stimulus that activated brainstem catecholaminergic (tyrosine hydroxylase-immunopositive) neurons and cells in the raphe and certain pontine tegmental nuclei, as well as in the reticular formation. Pain, induced by a subcutaneous injection of formalin was also effective on catecholamine-synthesizing neurons and on others cells in the nucleus of the solitary tract. Cold exposure activated cells mainly in the sensory spinal trigeminal and parabrachial nuclei and in the so-called "pontine thermoregulatory area". Moderate Fos-like immunoreactivity was induced by a hypotonic (25%) hemorrhage in medullary catecholaminergic neurons, the nucleus of the solitary tract and the Barrington nucleus. Among stressful stimuli used, insulin-induced hypoglycemia elicited the smallest Fos activation in the lower brainstem. The present observations indicate that different stressors may use different neuronal pathways in the central organization of the stress response.     

Piagetian cognitive development and primary process thinking in children

On the hypothesis that, as children develop from the preoperational to the concrete level of operations, there would be a corresponding increase in the effective control of primary process ideation, 37 white, middle-class children, from 5 to 8 years old, were individually tested on eight Piagetian tasks and the Rorschach test. Piagetian Development was significantly correlated with Holt's Primary Process Manual measures of (a) Form Level, (b) Defense Effectiveness, (c) Adaptive Regression, (d) Primary Process Level 2, (e) Content Level 2, (f) Control/Defense Plus, and (g) Control/Defense Total. An analysis of variance demonstrated significant primary process differences between preoperational, transitional and concrete operational groups. Correlations between the eight Piaget tasks and the constructed mean Piaget score ranged from .65 to .91. The negative findings of other researchers, which contrast with the positive results in this study, may be explained by the narrower age ranges of their samples.