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At least 541 records · Page 30Linked to original sources
PubMed1981

Correlation analysis of neuronal interaction in the motor cortex of rats during performance of a discrete instrumental reaction.

Unit activity was recorded in 7 rats trained to reach into a narrow feeder for food. Capillary microelectrodes were inserted with a head-mounted microdrive into the motor cortex contralateral to the preferred forepaw. Recordings of pairs of identifiable units were processed with the LINC 8 computer programmed for detection and classification of spikes, compilation of perireach histograms (+/- 512 ms) and construction of auto- (64 ms) and crosscorrelation (+/- 32 ms) histograms. Perireach histograms revealed activity changes (mostly of the excitatory type) in 82% of examined neurons (n = 28). Significant crosscorrelation was found in 8 of 14 pairs of neurons recorded for about 1 h. Most crosscorrelograms showed symmetric inhibitory troughs, lasting for 6 to 15 ms and better expressed in the +/- 512 ms perireach interval than during periods of spontaneous activity. Whereas symmetric crosscorrelograms (n = 6) indicate a shared inhibitory input, asymmetric crosscorrelograms (n = 2) suggest more direct interaction between the recorded neurons. Significant crosscorrelations were found more frequently when both neurons of the pair displayed significant perireach reactions. It is concluded that reaching is accompanied not only by characteristic excitatory and inhibitory reactions of individual neurons but also by modified neural coordination probably due to shared cerebellar and basal ganglia inputs.

Action Potentials↗
PubMed1992

Exploring the hexokinase glucose binding site through correlation analysis and molecular modeling of glucosamine inhibitors.

A series of N-substituted glucosamines has been designed, synthesized, and tested as inhibitors of yeast hexokinase. All derivatives exhibited competitive inhibition kinetics with respect to glucose. Quantitative structure-activity relationships were derived from the resulting inhibition data. The most significant equation demonstrated the existence of highly specific steric effects for the seven meta-substituted benzoylglucosamines included in the relationship. Molecular modeling of potential complexes between the inhibitors and the hexokinase substrate binding site strongly suggests that the steric effects arise from potential contacts with two amino acid residues lying in the region occupied by the amide substituents.

Binding Sites↗
PubMed2002

[Correlation analysis between plasma homocysteine level and polymorphism of homocysteine metabolism related enzymes in ischemic cerebrovascular or cardiovascular diseases].

OBJECTIVE: To investigate the changes of plasma homocysteine (Hcy) level in patients with ischemic cerebrovascular or cardiovascular disease and analyze the relationship between plasma Hcy levels and the mutations in Hcy metabolism related enzymes, including methylene tetrahydrofolate reductase (MTHFR) C677T, cystathionine beta-synthetase (CBS) 844ins68 and methionine synthetase (MS) A2756G. METHODS: By using the HPLC-FLD method, the plasma total homocysteine (tHcy) concentration was determined in 86 patients with cerebral infarction, 66 with myocardial infarction and 80 healthy controls. The association of plasma tHcy levels with cardiovascular or cerebrovascular disease and mutations of MTHFR C677T, CBS 844 ins 68 and MS A2756G were evaluated by statistic methods. RESULTS: In the patient groups, the plasma tHcy concentrations increased significantly as compared with healthy controls. The individuals homozygous for MTHFR C677T mutation had significantly higher plasma Hcy levels. CONCLUSION: Hyperhomocysteinemia is an important risk factor for ischemic cerebrovascular and cardiovascular disease. The homozygosity of MTHFR C677T may contribute to the increase of plasma Hcy and vascular damage.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMedDate not supplied

[A cross correlation analysis of the electrical activity of different regions of the cerebral cortex during visual pattern recognition in children].

Characteristics of spatial-temporal organization of brain biopotentials were examined in one to 2.5 year old children during recognition of visual images. Crosscorrelation EEG analysis of frontal, motor, inferior parietal, temporal and occipital cortical zones has shown that recognition of familiar visual objects is accompanied by an increase in spatial synchronization of biopotentials, especially in the inferior parietal zones of both hemispheres and occipital centres of the left hemisphere. There is a considerable increase in the number of highly synchronous synphasic oscillations at the 4--5 per sec frequency with an intensified periodicity of processes. Recognition of unfamiliar objects does not produce a similar effect. Temporal organization of biopotentials of the associative (frontal and inferior parietal) and projection visual areas in the course of recognition of images depends on the existence of a notion of the whole object in the child's memory.

Brain Mapping↗
PubMed2002

The physiology of copper tolerance in fathead minnows: insight from an intraspecific, correlative analysis.

Exposure to a sublethal (150 microg/L) concentration of copper (Cu) can reduce the critical swimming speed (Ucrit) of some fathead minnows (Pimephales promelas). The reduction is not consistent from one individual to the next, however, as some individuals experience dramatic reductions, while others maintain performance at preexposure levels. The objective of this experiment was to determine whether fish that experienced dramatic reductions in Ucrit were physiologically different from more resistant individuals. Individual variation in gill Na+-K+ activated adenosine triphosphatase (ATPase) activity was not significantly associated with variation reduction in Ucrit. Whole-body Cu was significantly related to reduction in Ucrit, and the relationship was surprisingly negative with the greatest reductions in Ucrit occurring in the fish with the lowest whole-body Cu concentrations. Whole-body Na+ was also significantly related to reduction in Ucrit, as the fish with the greatest whole-body Na+ experienced the smallest reduction in Ucrit. Fathead minnows are differentially susceptible to sublethal concentrations of Cu; this difference appears to be related to Na+ ionoregulation as well as the capacity of the fish to accumulate Cu.

Adaptation, Physiological↗