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E A Vivaldi

Publications and source records attributed to E A Vivaldi.

9 recordsLinked to original sources
PubMed1994

Measures of location and dispersion of sleep state distributions within the circular frame of a 12:12 light: dark schedule in the rat.

Distributions within a 12:12 light:dark schedule of wakefulness (W), active sleep (AS), quiet sleep (QS) and of QS rich in delta (QSD) and in spindle (QSS) activities were evaluated for 52 days from 15 rats. Angular statistics were applied for each state by equating their hourly incidence to data distributed around a circle. Measures of location (mean angle, median angle, mode angle, maximum semicircle), dispersion (mean vector, standard deviation, quartile deviation), skewness and kurtosis were computed and their intra- and interindividual variabilities were compared. Mean angles (in hours and after lights-on) averaged 5.5 for QS, 8.6 for AS, 18.4 for W, 1.9 for QSD and 10.6 for QSS. Length of vectors, representing concentration around the mean angle, averaged 0.22 for QS, 0.36 for AS, 0.22 for W, 0.38 for QSD and 0.23 for QSS. Distributions of QS and W were closely related to the light-dark step function. QSD had a leptokurtic distribution, sharply rising at the beginning of the sleep-predominant phase, whereas AS and QSS had smoother distributions reaching maxima in its second half. In rodents as in humans, QSS and AS have opposite distributions to QSD. QSS may contribute to maintain sleep through the resting phase of the light-dark schedule after restorative function associated with delta activity has been fulfilled.

Animals↗
PubMed1994

Short-term homeostasis of active sleep and the architecture of sleep in the rat.

1. Sixteen rats were recorded continuously for 3 days using an automated system that detected, quantified, and stored the incidence of cortical delta waves, cortical sigma spindles, hippocampal theta rhythm, and electromyographic activity. A time series then was constructed wherein 15-s epochs were ascribed to one behavioral state: wakefulness (W), quiet sleep (QS), or active sleep (AS, a state also referred to as REM sleep). From those series, AS episodes and non-AS intervals could be determined. Episodes and intervals were defined as lasting at least two epochs and the one-epoch episodes and intervals were incorporated to the ongoing state. 2. Having established the length of each AS episode and non-AS interval, pairings were made, on the one hand between episodes and their preceding intervals, and on the other, between episodes and the intervals that followed. 3. Highly significant correlations were found between the length of AS episodes and the length of the non-AS intervals that followed. Correlations were also significant when calculated separately versus the amount of QS and of W within the following interval. Correlations improved when they were performed against the log of the interval and when only intervals with a predominance of QS were selected. 4. No significant correlation was found between the length of AS episodes and the length of the preceding non-AS intervals, except for a negative one that was present only when the statistical analysis was performed in the unsmoothed array where the one-epoch episodes and intervals were preserved. 5. These results suggest that there is a short-term homeostasis operating within the spontaneous architecture of sleep in rats. This homeostatic mechanism is not manifested by the regulation of the length of AS episodes. Instead, there is a forward regulatory mechanism that, given the duration of an AS episode, permissively controls the interval that the animal may abstain from AS, and hence the timing of the triggering of a new AS episode.

Animals↗
PubMed1991

Time course of rat sleep variables assessed by a microcomputer-generated data base.

A microcomputer-based system is described that detects, counts and stores cortical delta and sigma waves, hippocampal theta waves and electromyographic activities in the rat by building matrices with the incidence of those four variables (columns) in 15-second bins (rows). Data tables are submitted to statistical, graphics and spread-sheet software to assess internal organization of sleep episodes and 24-hour distribution of sleep variables. Within sleep episodes, cross-correlograms reveal a delta-sigma-theta sequence, while autocorrelograms quantify clustering and periodicity of variables. Sleep accumulates in the lights-on phase, with high concentration of delta at the beginning of this sleep-predominant phase and of sigma and theta in its second half. These are notable similarities with human sleep architecture. Simple procedures for data reduction into standard behavioral state diagnosis are demonstrated. The low cost of personal computers and data acquisition interfaces facilitates the automation of complex paradigms by ad hoc on-line programs that produce as output a data base that can be processed by standard software, providing a fluid pathway of automated acquisition, analysis and presentation of data.

Animals↗
PubMed1990

[Informatics in the School of Medicine of the University of Chile. I. Origin and evolution of biomedical computing in Chile].

In the sixties and seventies, the School of Medicine of the University of Chile was the first Chilean institution to incorporate computers into academic endeavors through its own Computer Center. Later, professors were marginated from policy making, which became oriented to administrative goals, but they compensated that situation with the easy access to personal computers brought about by present technology. In 1986, when School authorities were again elected by the faculty staff, professors were able to participate again in a committee designing projects in this area. Current development at the School of Medicine include a proliferation of personal computers, the implementation of a computer network with access to medical data bases, and a growing number of applications in the fields of research and teaching. In the near future, due to the accessibility of telecommunications and computers, these advancements should have an impact on the whole biomedical community, a situation that would restore, after many years, the traditional role of the University of Chile in the life of the country.

Chile↗
PubMed1990

[Informatics in the School of Medicine of the University of Chile. II. The school network and access to data bases].

Projects on informatics at the School of Medicine of the University of Chile are being brought about in accordance with both its institutional goals and present trends in technology. Prominent among the latter are the widespread distribution of autonomous processing power represented by low-cost computers and the ease of communication at local and worldwide levels. Our main project has been the design and start of a computer network that integrates the School's Departments and the geographically dispersed teaching hospitals. The principal services provided by the network are local and international electronic mail, access to data bases, and emulation of mainframe terminals (eg, to run remotely a mainframe's statistics software). Automated bibliographic search has been made available both through remote access to Medline data base and through local usage of compact disc (CD-ROM) versions. Since our network is open, it should become a forceful mean of assisting and integrating the biomedical community throughout the country.

CD-ROM↗
PubMed1988

A microcomputer-based sleep system: data acquisition and system calibration programs.

A data acquisition program is described for the Apple II series of microcomputers that allows for continuous, direct monitoring of electrographic elements from cortical, hippocampal and muscle leads from rats. The program detects cortical delta waves and sigma activity, hippocampal theta activity and electromyographic activity. The detected elements are counted and stored in memory at 15 second intervals (bins). Every three hours, the data are transferred to disks for permanent storage and off-line analysis.

Animals↗
PubMed1984

Long term stability of rat sleep quantified by microcomputer analysis.

An inexpensive microcomputer system is described for the direct recording of electrographic data from animals. Using this system, electrographic data can be recorded continuously on a polygraph and simultaneously quantitated by the computer, for days or weeks. Our system quantifies the amounts of delta waves, spindle bursts, hippocampal RSA activity and movement spikes for 15 sec epochs. These electrographic data are stored by the computer and subsequently can be used to score sleep stages. We find that the computer reliably counts waves; using these data, it can then score sleep stages off-line with about 90% accuracy. With this system, we find that the minutes/hour of both SWS and REM are remarkably stable from day to day. The absolute number of delta waves, spindle bursts, trains of RSA and movement counts/hour also remain stable from day to day. This type of system should find significant application in situations where quantitation of longterm effects of drugs, diets and other environmental inputs on sleep states or EEG wave bands are of interest.

Animals↗