Search

Functional cortical organization is not dependent on cognition only, but also reflects basic intrinsic individual characteristics stable over time and across physiological conditions that suggest the existence of self-organization patterns operating even during rest. The aim of the present study was to investigate the pattern of functional organization of EEG broad bands and coherent activity during rest by means of Principal Component Analysis (PCA) with closed and open eyes of 28 men and women. PCA revealed patterns of covariant oscillatory activity and functionally related regions with covariant coherent activity present during resting conditions, different for open and closed eyes. Different patterns of covariant oscillations within alpha frequencies were identified consistent with current notions on overlapping frequencies with different origin and behavioral context. Covariant coherent cortical networks were revealed congruent with functional systems described during cognitive processes; one, linking regions involved in visuo-motor coordination, another in language, and a third one in visuo-spatial processes suggesting that strong functional links are present during rest. [ABSTRACT FROM AUTHOR]

The aim of this study was to characterize the circadian motor rhythm in the spider monkey, A. goeffroyi, in both entrained and free-running conditions. Four monkeys, 2 males and 2 females, were maintained for 32 days in constant light (LL) and 32 days in 13.25:10.75 LD. Before each experimental cycle, and between the LL and LD recordings, animals were maintained on 12:12 LD in their natural outdoor housing with the rest of their group. Each animal had its own Actiwatch collar for recording motor activity. The duration of the activity and rest periods and onset and offset of activity were averaged for each animal and in each condition. Recordings were analyzed with the ACTIWATCH program, and time series were analyzed with PGRAPH periodogram analyses. Actograms, histogram plots and periodograms were created for every subject. The data were also submitted to Fourier analysis using POTENCOR to determine circadian time and peaks under each experimental condition. Finally, Student's t-tests for paired samples were used to determine the differences between the artificial LL and natural LD conditions of every subject. A clear biphasic circadian pattern in the activity?–?rest cycle was observed in both conditions, confirmed by Fourier analysis with a periodicity of 24?h 01?min in LL. In LL the activity showed a dispersed temporal pattern with several small intermingled peaks, while the bimodal pattern of activity was more pronounced in LD with peaks at 08:11?h and 14:45?h. This data demonstrate the presence of a pacemaker with intrinsic ability to oscillate when the organism is under constant external conditions LL, that becomes entrained by the solar day when the animal is exposed to natural LD conditions. [ABSTRACT FROM AUTHOR]

On June 19 2009, everyone who knew Leon Cintra was shocked by the terrible news of the automobile accident that took his life. The feeling within the scientific community was that his passing was not only a great loss for Mexican science but also the loss of a beloved friend. He will be missed and forever remembered for his brilliant mind and noble heart. His scientific career was focused, since the beginning, on the study of protein malnutrition effects on brain morphometry, somato-sensory transmission, sleep, circadian rhythms and behavior. His findings showed that malnutrition has long lasting adverse effects on morphometry of systems involved in sleep regulation such as locus coeruleus, nucleus raphe dorsalis and susprachiasmatic nucleus, and on hippocampal circuit implicated in theta activity generation. His results on spectral analysis of electrical field potential at every 4 sec from 24-h baseline recording and 72-h of recovery sleep after total sleep deprivation or selective REM sleep deprivation demonstrated that protein malnutrition induced alterations on homeostatic as well as on circadian sleep regulation; brain oscillations and theta coherent activity between left and right hemisphere and between hippocampus and cerebral cortex are also affected by malnutrition. [ABSTRACT FROM AUTHOR]