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Biomedical subjects

C R Almli

Publications and source records attributed to C R Almli.

At least 37 records · Page 2Linked to original sources
PubMed1985

Postnatal development of sensory influences on neurons in the ventromedial hypothalamic nucleus of the rat.

Extracellular unitary records were obtained from neurons in the ventromedial hypothalamic nucleus (VMH) of very young (1-25 days of postnatal age) and adult rats. Spontaneous unitary activity and evoked responses to both external (somatic, gustatory, and olfactory) and internal sensory (systemic administration of hypertonic saline and glucose solutions) stimulation were determined in order to assess the functional development of VMH neurons and their afferents. The basic electrophysiological characteristics of VMH neurons were established prenatally. From the date of birth, many VMH neurons had: spontaneous action potential generation; evoked responses to external or internal sensory stimulation; and convergent sensory inputs. In contrast, the major developmental change in the neurophysiological properties of VMH neurons was the diminution with increasing age of the convergence of external and internal sensory influences. This developmental 'fine-tuning' of a complex functional feature of VMH neurons is important because the maturation of convergence coincides with a 'critical period' of VMH ontogenesis demonstrated in behavioral and experimental brain damage reports.

Animals↗
PubMed1984

Sucking behaviors of normal 3-day-old female neonates during a 24-hr period.

Feeding behaviors were measured during six feeding sessions distributed throughout a 24-hr period in 10 normal 3-day-old female infants. Infants were individually videotaped during feeding sessions at 13:00, 17:00, 21:00, 01:00, 05:00, and 09:00 hours. Total mealtime, nutritive sucking time, pause time, number of nutritive sucks, and amount of nutrient consumed were measured. None of these feeding variables were affected by the time of day an infant was fed. Maternal interactions with their infants such as auditory stimulation, caretaking touches or tender touches were unaffected by the time of a feed. These maternal behaviors did not correlate with any of the feeding variables. These findings suggest that 3-day-old infants experiencing routine nursery care do not express specific day-night feeding differences and that certain maternal behaviors do not influence the infants' feeding pattern.

Feeding Behavior↗
PubMed1984

Postnatal development of sensory influences on lateral hypothalamic neurons of the rat.

Extracellular unitary records were obtained from neurons in the lateral hypothalamic area (LHA) of very young (1-25 days of postnatal age) and adult rats. Spontaneous unitary activity and evoked responses to external sensory (somatosensory, gustatory and olfactory) and internal sensory (administration of hypertonic saline and glucose solutions) stimulation were determined in these neurons in order to assess their functional development. The basic electrophysiological characteristics of LHA neurons were established prenatally. From the day of birth, many LHA neurons had: (1) spontaneous spike generation; (2) evoked responses to external and internal sensory stimulation; and (3) convergent sensory inputs. However, each of these neurophysiological properties was modified considerably during postnatal ontogenesis: (4) spontaneous activity of LHA neurons with evoked responses to sensory stimulation increased with age; (5) internal sensory influences tended to diminish while evoked response magnitude and complexity were augmented developmentally; and (6) convergence of sensory influences decreased in older rats. This developmental 'fine tuning' of the functional features of LHA neurons is important because their maturation coincides with certain 'critical periods' of LHA ontogenesis demonstrated in behavioral, morphological, pharmacological and experimental brain damage reports.

Animals↗
PubMed1983

Parabrachial nuclei damage in infant rats produces residual deficits in gustatory preferences/aversions and sodium appetite.

Ten-day-old rats sustained bilateral electrolytic lesions of the parabrachial nuclei in the pons (PBN). Growth measures and tests of sensorimotor, feeding and drinking behaviors, sodium appetite, and gustatory capacities were made between ages 1 and 150 days. PBN rats displayed a transient period of attenuated suckling, as evidenced by body weight loss. When tested soon after weaning, PBN rats were hyperdipsic in response to cellular dehydration and during food deprivation. This effect, however, was temporary. When tested as adults, PBN rats were hypodipsic in response to extracellular fluid volume depletion, they displayed alterations in sodium appetite, showed "exaggerated" preferences and aversions to saccharin and NaCl solutions, and they displayed attenuated quinine aversions. These results are generally similar to the behaviors of rats sustaining more central gustatory pathway lesions as adults. The functional significance of the PBN in the developing rat for preference/aversion and sodium appetite behaviors are discussed.

Animals↗
PubMed1981

Cell types within the medial forebrain bundle: a Golgi study of preoptic and hypothalamic neurons in the rat.

The morphology of lateral preoptic (POL) and lateral hypothalamic (HLA) neurons was studied in 14- to 200-day-old rats with the chlorate-formaldehyde modification of the Golgi method. Drawings of 91 POL and HLA neurons revealed three distinct neuronal types within the MFB based on somatic size and shape and dendritic morphology. Class I neurons, which accounted for 75-80% of the neurons in the MFB, has fusiform or multipolar somata averaging 21 X 14 micron and 2-5 sparsely branched dendrites with a moderate number of sticklike spines. The extensive dendritic domains of Class I neurons ranged from 700 to 1,500 micron and were usually oriented perpendicular to the longitudinal fibers of the MFB. Both nonoriented and oriented Class I neurons were encountered. Nonoriented Class I neurons had expansive dendritic arbors which reached nearly all regions of the MFB in the coronal plane. Oriented Class I neurons had dendritic domains which were confined to specific regions (e.g., ventral-lateral) of the MFB. Class II neurons, which made up approximately 10% of the MFB neurons, had large multipolar somata averaging 30 X 17 micron and 2-5 stout dendrites which were densely covered with hairlike spines. Class II neurons also exhibited spines on their somata and proximal dendritic trunks and had dendritic domains of 700-1,000 micron. Class III neurons had small somata averaging 15 X 12 micron and restricted dendritic arbors of 500-700 micron in diameter. Class III neurons exhibited both spiny and spine-free dendrites and made up 10% of MFB neurons. Because of the parcellation of chemically coded fiber systems within the MFB, individual POL and HLA neurons may not be homogeneous in the type of afferents they receive from other brain areas.

Animals↗
PubMed1980

Ontogeny of chorda tympani nerve responses to gustatory stimuli in the rat.

Electrical activity (whole-nerve responses) of the chorda tympani nerve (CT) in rats at 2-110 days of age was recorded in response to chemical (0.5 M NaCl, 0.5 M LiCl, 0.5 M NH4Cl, 0.1 M citric acid) stimuli applied to the dorsal surface of the tongue. The CT of rats as young as two days of age was differentially responsive to the various chemical stimuli, and the responsiveness of the CT to 0.5 M NaCl and 0.5 M LiCl relative to 0.5 M NH4Cl increased between 20 and 34 days of age and again between 35 and 90 days of age. The responsiveness of the CT to 0.1 M citric acid relative to 0.5 M NH4Cl increased from 6--19 days of age, then decreased thereafter to adulthood. A concentration series of NH4Cl solutions (0.1 M, 0.25 M, 0.5 M and 1.0 M) revealed that the CT of rats 6--110 days of age displayed increased response magnitudes as the concentration of NH4Cl increased. The CT was responsive to mechanical and thermal stimulation of the tongue, and this responsiveness was essentially unchanged throughout development. These results show that the CT of rats as young as two days of age is differentially responsive to chemical stimuli applied to the tongue, and that CT responsiveness to chemical stimuli changes during development.

Aging↗
PubMed1976

Preweanling rats: recovery from lateral hypothalamic damage.

Preweanling male and female albino rats sustained lateral hypothalamic area (LHA) destruction at 10 days of age. Pups with bilateral LHA destruction (Bi-LHA) displayed the lateral hypothalamic recovery syndrome (LHRS) and recovered voluntary feeding and drinking between 44-75 days of age. The Bi-LHA rats of both sexes showed permanent deficits (through 200-275 days of age) in responding to hydrational challenges and did not feed in response to 2-deoxy-D-glucose treatment. Male Bi-LHA rats' body weights were permanently depressed by 20%-25%, whereas female body weight depression was only temporary. Rats sustaining LHA destruction on one side of the brain (Uni-LHA) displayed an abbreviated LHRS, recovering voluntary feeding and drinking by 25-32 days of age. The Uni-LHA rats showed some permanent deficits in responding to hydrational challenges, yet they displayed the same sex differential for body weight regulation as the Bi-LHA rats. The results of this investigation demonstrate nearly identical effects of LHA destruction whether sustained preweaning, postweaning, or during adulthood.

Age Factors↗