Biomedical subjects

M D Chafetz

Publications and source records attributed to M D Chafetz.

9 recordsLinked to original sources

PubMed1996

The cerebellum and cognitive function: implications for rehabilitation.

OBJECTIVE: To characterize the cognitive effects of isolated cerebellar lesions. DESIGN: Review of two inpatient cases. SETTING: The rehabilitation unit of a tertiary general hospital. PATIENTS OR OTHER PARTICIPANTS: Two patients with acute ischemic strokes who had solitary cerebellar infarcts. INTERVENTIONS: Assessment with standard neuropsychological tests. Scores were compared with patients' premorbid levels and standardized test norms. A classical conditioning eyeblink paradigm was performed. MAIN OUTCOME MEASURES: Neuropsychological measures of intellectual and executive functions, learning and memory, visual-spatial abilities, language functioning, fine motor speed, and dexterity. RESULTS: Test findings suggested lesion-associated deficits in higher aspects of cognition (visuospatial reasoning, verbal and visual memory, and intellectual and executive functions). These functions are not usually associated with the fundamentally motoric role of the cerebellum. CONCLUSIONS: (1) Lesions in the cerebellum can be associated with impairments in higher cognitive functioning. (2) Such effects may be severe enough for a diagnosis of dementia under current diagnostic criteria. (3) These rehabilitation patients may benefit from comprehensive cognitive examination to determine if cognitive effects will detract from their participation. (4) Further research is needed to localize which cerebellar areas affect which cognitive abilities.

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PubMed1989

Effects of clonidine on self-selection of nutrients.

A Richter cafeteria was used to probe the self-selection of separate macro- and micronutrients in animals injected with the alpha 2 agonist, clonidine. The most effective dose of clonidine (25 micrograms/kg) used by previous investigators with more limited nutrient offerings elicited increases in carbohydrate (1, 12, 36 hr) and vitamin A (36 hr) consumption, and decreases in salt consumption (1, 36 hr). Casein intake was depressed at 1 hour, but increased at 12 hr. A significant negative correlation between sucrose and oil intake lent statistical support to Richter's concept of "sucrose and oil burners." Other significant correlations indicated that physiological links between nutrients may underly their cooccurrence in an animal's diet.

Animals↗

PubMed1986

Relationships between medial hypothalamic alpha 2-receptor binding, norepinephrine, and circulating glucose.

These experiments examine the dependence of medial hypothalamic alpha 2-receptor binding on the availability of circulating glucose. Food deprivation and tolbutamide-induced hypoglycemia both diminished alpha 2-binding. These binding results were highly correlated with serum glucose levels. Prevention of tolbutamide hypoglycemia by concomitant injections of dextrose blocked the effects on alpha 2-binding. Injection of norepinephrine into the medial hypothalamic sites that normally elicit feeding behavior elevated serum glucose. These results suggest a homeostasis for control of glucose in a hypothalamic feeding system.

Animals↗

PubMed1986

Timm's method modified for human tissue and compatible with adjacent section histofluorescence in the rat.

A simple dip method of Timm staining was developed. Because perfusion with sulphides and/or aldehydes is not required for adequate staining, the method can be employed with more control on human tissue taken at autopsy. Timm-stained human hippocampus reveals silver deposition in the mossy fiber region with a distribution similar to that in rats, but with some variation in the extent of penetration into stratum pyramidale. Adjacent cryostat sections of rat brain can be reacted for glyoxylic acid induced fluorescence by using the SPG dip method.

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PubMed1984

Taxonomic abstraction in psychobiology.

If a body of knowledge in a scientific discipline is to be extended beyond empirical observation and into the realm of laws and principles, one of the fundamental requirements is a taxonomy which supports the systematic integration of observations. Psychobiology benefits from taxonomies provided by biology and chemistry, which include not only object oriented taxonomies such as species or chemical elements, but also process oriented taxonomies, such as oxidation, metabolism, phototaxis, or predation. Psychobiology has yet to provide equivalent taxonomies for its behavioral observations, although the common use of terms such as fear, anger, arousal, stress, and memory might lead one to suppose that these are based on a well established taxonomy of behavioral measures. In this report the logical and quantitative requirements for treating behavioral measures in terms of taxonomic classes are reviewed. A sample of studies representing recent research in psychobiology was examined to assess interest in such a taxonomy and to identify elements of current practice which might contribute to its development. Recent practice displays some evidence of interest in behavioral classes, in choice of language, and in frequent use of multiple dependent measures. Multivariate methods, which might elicit from such data evidence contributing to the development of a taxonomy, are rarely used. Recommendations are given on some appropriate analytic methods for data resulting from current practice and for new exploratory paradigms which could aim directly at the establishment of taxonomic classes for behaviors.

Animals↗

PubMed1983

Pineal and habenula innervation altered by septal lesions.

Septal lesions result in a measurable increase in sympathetic innervation of the hippocampus. The cell bodies of origin of these sympathetic fibers reside in the superior cervical ganglion (SCG), which also projects to the pineal gland and medial habenula. If the SCG neurons which project to the pineal are the same neurons which sprout into the hippocampus after septal lesions, a common cell body reaction might mediate changes in innervation of the pineal. If cholinergic denervation is the principal trigger of hippocampal sprouting, a similar response might be observed in habenula which is also innervated cholinergically from septal area neurons. Pineal and medial habenula innervation were quantified using a new microfluorometric method at 20 post-lesion intervals following septal lesions. Changes in intensity and density of innervation were correlated with time in days after the lesions. Pineal intensity, pineal density, and habenula intensity exhibited statistically significant correlations with time in days after septal lesions. These changes occurred during the growth of sympathohippocampal fibers. The data suggest that a common cell body reaction mediated the changes in pineal and the sympathetic sprouting in the hippocampus.

Animals↗

PubMed1982

Fluorescence measurement of lesion-induced fiber growth. I. A microfluorometric technique to measure density and intensity of varicosities and fibers.

A microfluorometric (MF) technique was developed and validated as a first step in quantifying the growth of sympathohippocampal fibers. This MF technique measures independent components of areal density and fiber intensity. Areal density refers to a basic stereological measure of percentage surface or volume of fluorescent fibers. Fiber intensity refers to the amount of fluorescence (normalized for fading) emitted by varicosities or fibers at a specific wavelength. The first phase of this research was undertaken to identify the criteria yielding the best correlations with the results of classical stereological methods. The second phase then demonstrated that the MF procedure was insensitive to shifts in the use of different criteria. Five areas of the hippocampus, and the pineal and habenula, were measured in 55 animals whose survival times after septal lesions varied widely. With 309 areas finally measured, the strongest intercorrelations separated intensity from density variables. Error variance contributed little to the final solution. We concluded that this MF method was a simple and specific way to measure density and intensity of fluorescent fibers and varicosities. Slight variations in equipment characteristics or in the use of criteria across several laboratories should not affect the results obtained with this method.

Animals↗

PubMed1982

Fluorescence measurement of lesion-induced fiber growth. II. Measurement of sympathohippocampal sprouting using a new microfluorometric method.

A microfluorometric (MF) method for measuring areal density and fiber intensity of fluorescent catecholamine fibers and varicosities was described in the previous paper. This method was then used to quantify sympathetic growth observed in the hippocampus after damage to the septal area. Because this MF method does not distinguish between catecholamine fibers of central and peripheral origins, several different ways to measure sympathetic ingrowth were used. First, the ingrowth was measured in subiculum, which has a naturally sparse innervation of central catecholamine fibers. Second, multivariate analyses were used to distinguish between: (1) sham animals -- with central innervation; (2) animals with septal lesions -- with central and peripheral innervation; and (3) sympathectomized septal animals -- with peripheral innervation removed. Finally, a polynomial regression analysis was used to identify the changes in catecholamine innervation over time that suggested a decrease in central innervation with a subsequent increase in the ingrowth of sympathetic fibers. The resulting data converge in support of the objective microfluorometric measurement of sympathohippocampal ingrowth in our histofluorescence preparations.

Animals↗

PubMed1981

Biochemical specificity of septal hyperreactivity: a behavioral discrimination.

Intra-septal injections of specific monoamine and cell body neurotoxins were used to determine the anatomical and biochemical elements critical to both short and longer term changes in reactivity normally seen after septal lesions. A multivariate discrimination performed on the basis of tactile, foot-shock and heat responsiveness revealed that septal lesions have a unique effect not accounted for by specific monoamine induced degeneration. Injections of 6-hydroxydopa and monosodium glutamate had slight effects on heat and shock responsiveness not at all comparable in degree or kind to septal lesion effects. Decreased hippocampal, but not hypothalamic, levels of norepinephrine may be associated with the longer term increased responsiveness to shock and heat in animals with septal lesions.

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