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Effects of an exhaustive exercise on motor skill learning and on the excitability of primary motor cortex and supplementary motor area
No full textWe examined, on 28 healthy adult subjects, the possible correlations of an exhaustive exercise, and the consequent high blood lactate levels, on immediate (explicit) and delayed (implicit) motor execution of sequential finger movements (cognitive task). Moreover, we determined with transcranial magnetic stimulation whether changes in motor performance are associated with variations in excitability of primary motor area (M1) and supplementary motor area (SMA). We observed that, after an acute exhaustive exercise, the large increase of blood lactate is associated with a significant worsening of both explicit and implicit sequential visuomotor task paradigms, without gender differences. We also found that, at the end of the exhaustive exercise, there is a change of excitability in both M1 and SMA. In particular, the excitability of M1 was increased whereas that of SMA decreased and, also in this case, without gender differences. These results support the idea that an increase of blood lactate after an exhaustive exercise appears to have a protective effect at level of primary cortical areas (as M1), although at the expense of efficiency of adjacent cortical regions (as SMA)
Changes in cortical excitability and blood lactate after a fatiguing hand-grip exercise
No full textExcitability of primary hand motor cortex (PHMC), evaluated with transcranial magnetic stimulation by using the "1mV resting motor threshold" method, and capillary blood lactate were measured at the end, as well as 5 and 10min after a fatiguing hand-grip exercise. The relation between blood lactate and the amplitudes of motor-evoked potentials showed a significant direct proportionality. Blood lactate seems to exert a protective role on PHMC against fatigue reduction during extremely intensive isometric exercises
The neural correlates of social communication: role of PEEF in auditory orienting.
No full textHypothesis as for auditory system hierarchical organization suggest the same organization of visual system. Anatomical and physiological data propose auditory system consisting of two streams, dorsal and ventral, which project together to the frontal lobe. The dorsal one brings auditory spatial information while the ventral one brings information as for the sound recognition. Considering both anatomical and electrophysiological evidence we propose that in dorsolateral frontal cortex there is an integration of both auditory streams. In fact, previous electrophysiological investigations support the anatomical data showing how in PEEF (area 8B) there are different kind of auditory or auditory motor neurons: neurons firing for the integration of auditory complex stimuli and eye and/or ear movements, pure auditory neurons firing for experimenters' voice, pure auditory neurons firing for sound's spatial direction. Here, we present preliminary data supporting the hypothesis that PEEF plays an important role as link between the auditory and motor system. We show a population of neurons firing for animals' and species-specific vocalizations and for head motor control. We propose PEEF as an important node for gaze and attentional shift toward auditory stimuli
Neuronal activity reflecting progression of trials in the pre-supplementary motor area of Macaque monkey: an expression of neuronal flexibility.
No full textAbstractWe studied the activity of single neurons in the pre-supplementary motor area(pre-SMA) of macaque monkeys as they performed two visuomotor tasks, called thevisual fixation task and the visual fixation-blink task. Both tasks involved asequence of three visual stimuli, red followed by yellow and green. The tasksdiffered in that the latter one had a gap within the period of the red stimulus,called a "blink". The tasks were performed in two modes, one of which includedmovements of both the arm and eye and the other of which involved only eyemovements. In the arm-eye mode, the monkeys had to press a bar and fixate the redstimulus that appeared after bar press. To receive a reward, both the bar press andvisual fixation had to be maintained until the green stimulus triggered bar release.In the eye mode, bar press and bar release were eliminated from the task. Of the 42neurons active during the visual fixation task, 15 showed task-related activity inboth arm-eye and eye modes, and our analysis focused on these cells. We found thatthe introduction of the blink in visual fixation-blink task abolished thetask-related activity of these cells over the course of 2-4 trials. This findingsuggests a role for the pre-SMA in reflecting progression of trials as an updatingof motor instruction
NEGLECT SINDROME FOR AVERSIVE AND PLEASANT STIMULI IN A MACAQUE MONKEY WITH PEEF LESION.
No full textAim: The Premotor Ear-Eye Field (PEEF), rostral to dorsal premotor cortex is involved in auditory perception and in ear-eye attentional orienting processes. In this work we describe the attentional deficits provoked by an electrolytic lesion in the PEEF.Methods: A macaque monkey was previously trained for three oculomotor tasks: Fixation task, Saccade task, Peripheral attention task. After unit activity recording, we made an electrolytic lesion using direct corrent (15 mA for 20 s), accidentally provoking an epileptic attack. During the epileptic attack, we observed rapid movements of both pinnae and a rhythmic contralateral tilting of the head, trunk and arm.Results: The animal was able to execute the oculomotor tasks as well as before the epileptic attack. Moreover we observed that the animal showed a neglect only for aversive stimuli with the head free. When the head was fixed this neglect desappered. In addition, the extinction phenomenon appeared for both aversive and pleasant stimuli and in both experimental conditions: free head and fixed head.Conclusion: These data firstly confirm that the PEEF is involved in attentional processes and secondly suggest that attentional behaviour is influenced by head condition. In addition, this last point suggests an additional role of PEEF in head movement control and also it is in favour of the double control system one for the head and one for the eye
Effects of age and sex on epigenetic modification induced by an acute physical exercise
Get PDFIt has been observed that, after 2 hours of aerobic exercise, plasma interleukin-6 (IL-6) increases whereas nuclear concentrations of enzyme DNA methyltransferase (DNMT) 3B significantly decreased in peripheral blood mononuclear cells (PBMCs), with no change observed in DNMT3A. The aim of the present study was to detect differences in these changes induced by exercise in plasma IL-6 levels as well as in PBMC nuclear concentrations of DNMT3A and DNMT3B, in relation to age and sex. Four groups were studied: 12 young men (24.8 ± 1.77 years old), 12 young women (23.8 ± 1.81 years old), 12 adult men (45.8 ± 1.82 years old), 12 adult women (mean 44.5 ± 2.07 years old). Participants had to run at 60% of maximal oxygen consumption (VO2max) for 120 minutes, interspersed with sprints at 90% of VO2max for the last 30 seconds of every 10 minutes. About 250 μL of PBMCs (1 × 10 cells) were treated with 100 μL of either pre-exercise plasma or post-exercise plasma and nuclear DNMT3A and DNMT3B concentrations were quantified. No change in nuclear concentration of DNMT3A following the exercise was observed. Conversely, nuclear concentrations of DNMT3B significantly decreased, with a reduction of about 78% in young men, 72% in young women, 61% in adult men, and 53% in adult women. Moreover, a strong positive correlation between the nuclear concentration of DNMT3B in PBMC following stimulation with post-exercise plasma and post-exercise plasma concentrations of IL-6 was observed in all the 4 studied groups. This study confirms that a single bout of endurance exercise is sufficient to decrease nuclear concentrations of DNMT3B and thus protein upregulation. Moreover, the epigenetic mechanisms induced by exercise apparently cause more intense changes in men than in women and that, in both of them, this effect seems to decrease with age
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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