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F Peronnet

Publications and source records attributed to F Peronnet.

At least 19 recordsLinked to original sources
PubMed1989

Mental rotation: an event-related potential study with a validated mental rotation task.

Event-related potentials (ERPs) were recorded while subjects performed a validated mental rotation task, taken from the cognitive psychology literature. These ERPs show a late posterior negativity relative to a baseline condition requiring all of the same perceptual and cognitive processes except for the mental rotation itself. Our tentative identification of this posterior negativity with mental rotation is further supported by the finding that it varies systematically with the amount of mental rotation required on a trial by trial basis in the experimental task. We conclude that this late negativity is an ERP marker of the mental rotation process, and that this process engages primarily posterior brain regions.

Arousal↗
PubMed1989

Oxidation of corn starch, glucose, and fructose ingested before exercise.

The purpose of this study was to compare the metabolic and endocrine responses, and the amounts of exogenous carbohydrate oxidized, during prolonged moderate cycle ergometer exercise (120 min, 60% VO2max), preceded by ingestion of 13C enriched glucose (G), fructose (F), or pure corn starch (S) (1,592 kJ ingested with 400 ml of water, 60 min before the beginning of exercise) in six healthy young male subjects. Plasma glucose and insulin concentrations significantly increased in response to G and S feeding. The high plasma insulin values resulted in a significant transient reduction in plasma glucose concentration in the first hour of exercise and blunted the response of plasma free fatty acid and glycerol concentrations, when compared to the values observed with F ingestion, which did not modify plasma glucose or insulin concentrations. Over the 2 h exercise period, the percentages of exogenous G (67 +/- 9%) and S (73 +/- 8%) oxidized were not significantly different but were significantly higher than the percentage of exogenous F oxidized (54 +/- 6%). These results confirm that 1) exogenous F is less readily available for oxidation than G or S and 2) pure corn starch does not offer any advantage over glucose as a pre-exercise meal.

Adult↗
PubMed1988

Several attention-related wave forms in auditory areas: a topographic study.

The purpose of this study was to progress in the understanding of the electrogenesis of attention-related wave forms in order to highlight some of the underlying attentional processes. ERPs were recorded from 16 electrodes, from 12 subjects who attended selectively to either high or low pitch tones delivered at a constant inter-stimulus interval of 800 msec to either right or left ear, while ignoring a concurrent sequence of tones of the other pitch delivered to the other ear. The attention-related wave forms were obtained by subtracting ERPs to unattended tones from ERPs to the same tones when they were attended. These wave forms were topographically displayed by both potential maps and scalp current density maps and compared with the corresponding maps of the N1 component of the ERPs, to determine the similarity of their generators. It has been shown that the attention effect is expressed by at least two components in specific auditory areas, one of small amplitude, occurring during the ascending slope of the N1 component, sensitive to the pitch of the attended stimulus, and possibly originating in the supratemporal plane of the auditory cortex; another of large amplitude, peaking symmetrically over both hemispheres and having a different topography from that of the N1 component. As described by other authors, a third, later, component appears over frontal areas, but probably originates from deeper sources of the brain. Models of selective attention processes, particularly the 'attentional trace' concept, are discussed in the light of these results.

Adult↗
PubMed1988

Failure to alter sympathoadrenal response to psychosocial stress following aerobic training.

This experiment assessed the impact of aerobic training on sympathoadrenal, heart rate and subjective responses to psychosocial stress. Subjects were six previously sedentary males who demonstrated marked improvement in fitness level following 10 weeks of training. Plasma samples, heart rate and subjective arousal ratings were obtained prior to, during, and following exposure to stressful mental tasks within a laboratory session. With the exception of training-related bradycardia which was manifest throughout the session, no changes in plasma epinephrine and norepinephrine concentrations, heart rate or subjective reactivity or recovery were seen. These findings are inconsistent with the hypothesized beneficial effects of aerobic training on stress-response. Methodological factors such as self-selection inherent in previous correlation work or the duration of the training program should be considered in this context. The potential contribution of training-related bradycardia to enhanced coping with challenging situations is explored.

Adult↗
PubMed1988

Dexamethasone stimulates expression of transposable type A intracisternal retroviruslike genes in mouse (Mus musculus) cells.

Dexamethasone treatment enhances expression of transposable intracisternal type A particles (IAP) at RNA and proteins levels in a murine retrovirus-transformed cell line (Ki-BALB). This effect was ascertained by electron microscopic numeration of IAP. By sequence comparison, we located glucocorticoid-responsive elements in IAP long terminal repeats. Their regulatory potential was tested on the promoter activity of an IAP long terminal repeat construct coupled with the chloramphenicol acetyltransferase gene. Our findings suggest that the IAP activation by dexamethasone occurs at the level of transcription.

Animals↗
PubMed1987

Fluid-electrolyte shift and renin-aldosterone responses to exercise under hypoxia.

In order to describe fluid-electrolyte shift and endocrine response to exercise under moderate acute hypoxia, 8 healthy male subjects (24 +/- 3 years old) were evaluated at 40, 60, 80 and 100% VO2 max in normoxic (N) and hypoxic (H) conditions (14.5% O2). VO2 max decreased from 55.5 +/- 1.3 to 45.8 +/- 1.4 ml/kg X min in H condition. Plasma volume reductions with increasing relative workloads were similar in N (9.4%) and H (9.9%) conditions. The rise in plasma osmolality was in part related to blood lactate accumulation which occurred in both conditions. However, variations in plasma solute content and osmolality suggested that exercise under hypoxia results in a greater electrolyte loss from vascular space and in a greater K+ loss from working skeletal muscles. Increase in catecholamine concentrations were similar in normoxic and hypoxic conditions except for lower maximal norepinephrine concentration under hypoxia. Finally, although plasma renin activity increased with workload in both conditions, plasma aldosterone did not significantly change. This dissociation between renin and aldosterone suggest that aldosterone release during exercise might depend upon other factors. However, changes in plasma potassium concentration do not appear as an important stimulus for aldosterone secretion during exercise.

Adult↗
PubMed1986

1731, a new retrotransposon with hormone modulated expression.

We report here the characterisation of 1731, a new copia-like element of Drosophila melanogaster. 1731 was first isolated in a screening for ecdysterone modulated genes. This element is about 4.6 Kb long and is flanked by two long terminal repeats (LTRs) 336 base pairs in length. The whole 1731 element is transcribed into polyA+ RNAs, and these transcripts decrease rapidly upon hormonal treatment. 1731 is moderately repeated in the fly genome and slightly amplified in Kc/cells where extrachromosomal circular forms are found. The LTRs were sequenced in one cloned copy of 1731 and show a structural organisation similar to that of several other copia-like elements and retroviral proviruses. Small nucleotide stretches, similar to those found in Mouse Mammary Tumor Virus LTRs and known to be important in its regulation by a steroid hormone, occur in 1731 LTRs.

Animals↗
PubMed1986

Systemic and regional blood flows during graded treadmill exercise in dogs.

The purpose of the study was to describe hemodynamic response and regional blood flows through various organs and tissues (microsphere technique) in dogs (n = 8), at rest and during mild (4 km/h, 13% slope; heart rate = 154 bpm), moderate (4 km/h, 26% slope; heart rate = 201 bpm), and severe (4 km/h, 39% slope; heart rate = 266 bpm) exercise on treadmill. Cardiac output (rest: 3.2 +/- 0.3; 39% slope: 10.2 +/- 1.3 l/min; mean +/- SE), systolic aortic pressure (rest: 122 +/- 4; 39% slope: 158 +/- 9 mm Hg), and left atrial pressure (rest: 5 +/- 0.7; 39% slope: 11.0 +/- 0.6 mm Hg) increased linearly with workload. On the contrary stroke volume increased from rest (35 +/- 2 ml) to mild (38 +/- 2 ml) and moderate (42 +/- 3 ml) exercise but decreased in response to the severe workload (38 +/- 5 ml). Regional blood flows across the brain, femoral bone, adrenal glands and temporalis muscle were not modified during exercise. On the contrary, a marked increase in regional blood flow was observed through the flexor and extensor muscles of the limb (X 5 to X 15), the muscles of the back (X 4) and the diaphragm (X 2.5). The small inconsistent increase in nutritional tongue blood flow probably underestimated the increased perfusion through arteriovenous shunts in the mucosa for heat-loss purposes. Myocardial blood flow increased in a linear fashion with work load in both ventricles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Effects of posterior parietal lesions on visually guided movements in monkeys.

Four monkeys were trained to position, with either hand, a vertical rod in front of one of 5 target lights spaced 20 degrees apart on a semicircular screen. After the monkeys had reached the preoperative criterion (80% trials correct per session) they received a 1- or 2-stage bilateral lesion of posterior parietal cortex restricted to area 7. The lesion produced in all the monkeys considerable but temporary changes in movement latency, accuracy, velocity and duration. Latency increase appeared to be independent of changes in the other parameters. After the first lesion, movement latency increased for the contralateral arm in both left and right working spaces, from 100 ms up to 400 ms depending on the animal. A second lesion symmetrical to the first one increased movement latency of the arm contralateral or ipsilateral to the last lesion, depending on the time interval between the two lesions. In addition, unilateral lesions of area 7 induced a gross inaccuracy in movements of the arm contralateral to the lesion, more marked in the contralateral working space. These lesions also increased movement peak velocity and simultaneously decreased movement duration for the arm contralateral to the lesion. The increase in velocity appeared to be related to the decrease in duration. A second lesion of area 7 in the opposite hemisphere similarly affected accuracy, velocity and duration but for the arm contralateral to the second lesion.

Animals↗
PubMed1985

Sympathetic indices during psychological and physical stimuli before and after training.

The effects of psychological and physical stimuli on cardiovascular and catecholamine changes were studied before and after physical training. These functions were investigated in eight labile hypertensive men in response to the mild psychological stimulus of playing a video game and the mild physical stimuli of sitting and standing. The results show that plasma norepinephrine concentration rises with sitting and standing but plasma epinephrine concentration increases only with the psychological stimulus. Physical training was associated with smaller increases in blood pressure during psychological and physical stimuli and with a lower heart rate at rest. On the other hand, plasma catecholamines at rest as well as in response to the different stimuli were unchanged following moderate training. These observations suggest that the adrenal medulla is selectively activated during a period of mild psychological stress, while the activity of the sympathetic fibers is preferentially increased during mild physical stimuli. Furthermore, the results of this study show that plasma catecholamine levels at rest and their increase during various stimuli are unchanged following training.

Adult↗
PubMed1985

Sequential colour mapping system of brain potentials.

We present a colour mapping system for the visualization of both the spatial scalp distribution and the temporal evolution of brain potentials. The system is applicable to recordings of auditory, visual and somatosensory potentials. It uses a Tektronix 4113 colour terminal connected to a Solar 16 (SEMS) mini-computer. The brain potentials are recorded on up to 16 scalp electrodes. The gain and the baseline are corrected separately on each channel. At each point of the scalp the potential is reconstructed by a linear interpolation of the measured potentials of the four nearest electrodes. Simultaneously n2 (1 less than n less than 8) colour maps can be presented on the screen. This allows the study of the temporal evolution of full scalp evoked potentials. The user chooses the two extreme latencies defining the time window to be explored and the latencies of the maps are regularly time-spaced within this window. In a typical case, in which four maps are desired, the latencies of the maps can be chosen independently. The 16-colour palette is predetermined but the user has three possibilities to establish the correspondence between the electrical potential and the colours. Examples are shown in the visual and somatosensory stimulation modalities. The advantages and limitations of such a representation are discussed.

Brain↗
PubMed1979

[Original method of multivariate analysis, adapted for comparison of mean evoked potentials: E2 test].

This paper describes a multivariate statistical method of analysis for the comparison of 2 paired series. For such paired series, this test, called E2, is analogous to the generalized Hotteling T2 test, as epsilon test (pairing method) is analogous to Student's t test. Here we give an example of its application to a comparison of curves, in this particular case average auditory evoked potentials, picked up at symmetrical points on the scalp.

Acoustic Stimulation↗