A novel social fear conditioning procedure alters social behavior and mTOR signaling in differentially housed adolescent rats.

Vulnerabilities to fear-related disorders can be enhanced following early life adversity. This study sought to determine whether post-weaning social isolation (PSI), an animal model of early life adversity, alters the development of social fear in an innovative model of conditioned social fear. Male and female Sprague-Dawley rats underwent either social rearing (SR) or PSI for 4 weeks following weaning. Rats were then assigned to groups consisting of either Footshock only, Social conditioned stimulus (CS) only, or Paired footshock with a social CS. Social behavior was assessed the next day. We observed a novel behavioral response in PSI rats, running in circles, that was rarely observed in SR rats; moreover, this behavior was augmented after Paired treatment in PSI rats. Other social behaviors were altered by both PSI and Paired footshock and social CS. The mammalian target of rapamycin (mTOR) pathway was assessed using immunohistochemistry for phosphorylated ribosomal protein S6 (pS6) in subregions of the prefrontal cortex (PFC) and amygdala. Paired treatment produced opposite effects in the PFC and amygdala in males, but no differences were observed in females. Conditioned social fear produced alterations in social behavior and the mTOR pathway that are dependent upon rearing condition and sex.

Between-day reliability of centre of pressure measures for balance assessment in hemiplegic stroke patients.

BACKGROUND: Stroke patients have impaired postural balance that increases the risk of falls and impairs their mobility. Assessment of postural balance is commonly carried out by recording centre of pressure (CoP) displacements, but the lack of data concerning reliability of these measures compromises their interpretation. The purpose of this study was to investigate the between-day reliability of six CoP-based variables, in order to provide i) reliability data for monitoring postural sway and weight-bearing asymmetry of stroke patients in clinical practice and ii) consistent assessment method of measurement error for applications in physical medicine and rehabilitation. METHODS: Postural balance of 20 stroke patients was assessed in quiet standing on a force platform, in two sessions, 7 days apart. Six CoP-based variables were collected in eyes open and eyes closed conditions: postural sway was assessed with mean and standart deviation of CoP-velocity, CoP-velocity along the mediolateral and anteroposterior axes, and confidence ellipse area (CE(AREA)); weight-bearing asymmetry was assessed with mean CoP position along the mediolateral axis (CoP(ML)). The intraclass correlation coefficient (ICC) was used to determine the level of agreement between test-retest. Small real difference (SRD), corresponding to the smallest change that indicates a real improvement for a single individual, was used to determine the extent of measurement error. RESULTS: ICCs were satisfactory (>0.9) for all CoP-based variables, except for CE(AREA) in eyes open condition and CoP(ML) (<0.8). The SRDs (eyes open/closed conditions) were: 6.1/9.5 mm.s(-1) for mean velocity; 12.3/12.2 mm.s(-1) for standard deviation of CoP-velocity; 3.6/5.5 mm.s(-1) and 4.9/7.3 mm.s(-1) for CoP-velocity in mediolateral and anteroposterior axes, respectively; 17.4/21.4 mm for CoP(ML). Because CE(AREA) showed heteroscedasticity of measurement error distribution, SRD (eyes open/closed conditions) was expressed as a percentage (121/75%) and a ratio (3.68/2.16) obtained after log-antilog procedure. CONCLUSIONS: In clinical practice, the CoP-based velocity variables should be prefer to CE(AREA) to assess and monitor postural sway over time in hemiplegic stroke patients. The poor reliability of CoP(ML) compromises its use to assess weight-bearing asymmetry. The procedure we used could be applied in reliability studies concerning other CoP-based variables or other biological variables in the field of physical medicine and rehabilitation.

Posture analysis on young women before and after 60 days of -6 degrees head down bed rest (Wise 2005).

Twenty-four women divided into three groups: control, exercise and nutrition, have been involved in a -6 degrees head down bed rest (HDBR) experiment for 60 days. The objective was to analyse the effects of microgravity on balance function regulation. Group comparisons assessed the efficiency of countermeasures (specific exercises and in particular diet) on the deleterious effects of simulated microgravity. Measurements of orthostatic and dynamic balance were taken 9 and 2 days prior to the experiment, on the first day of getting up, the following day and 4 and 10 days after, under two visual conditions: eyes open and eyes closed. The results confirmed that, as in any other test performed with ordinary subjects, the postural balance performances are better with eyes open than with eyes closed. The static and dynamic postural performances were impaired on the first day of recovery (R0) following HDBR. This impairment lasted up to 4 days after getting up and, afterwards the volunteers recovered their initial performances. The exercise group recovered static postural performances more quickly than the other groups whereas there were no differences in the recovery of the dynamic balance performances.

Postural adaptations specific to preferred throwing techniques practiced by competition-level judoists.

The purpose of this study was to analyse the judoists' postural regulation adopted to accommodate their favorite throwing technique (tokui-waza). The tokui-waza is a technique performed in bipodal or monopodal stance. Twenty three judoists aged between 16 and 20 took part in the protocol. All had a minimum regional sportive level. They were separated into two groups: the one performed a tokui-waza in bipodal stance (BS group) and the others performed a tokui-waza in monopodal stance (MS group). The medio/lateral and antero/posterior dynamic balance was evaluated on one-leg and two-leg support with a seesaw platform laid on a force platform. On two-leg support, the BS group judoists were more efficient than the MS group judoists. On the contrary, on one-leg support, the MS group was more efficient than the BS group. The different movements practiced on one or two-leg induce specific postural adaptations in competition-level judoists. Therefore, the present study shows that the different movements practiced in a given sport can induce particular postural adaptations. This phenomenon must therefore also be taken into account in the protocols used for evaluating postural control in sportsmen.

Postural performance and strategy in the unipedal stance of soccer players at different levels of competition.

CONTEXT: Sport training enhances the ability to use somatosensory and otolithic information, which improves postural capabilities. Postural changes are different according to the sport practiced, but few authors have analyzed subjects' postural performances to discriminate the expertise level among highly skilled athletes within a specific discipline. OBJECTIVE: To compare the postural performance and the postural strategy between soccer players at different levels of competition (national and regional). DESIGN: Repeated measures with 1 between-groups factor (level of competition: national or regional) and 1 within-groups factor (vision: eyes open or eyes closed). Dependent variables were center-of-pressure surface area and velocity; total spectral energy; and percentage of low-, medium-, and high-frequency band. SETTING: Sports performance laboratory. PATIENTS OR OTHER PARTICIPANTS: Fifteen national male soccer players (age = 24 +/- 3 years, height = 179 +/- 5 cm, mass = 72 +/- 3 kg) and 15 regional male soccer players (age = 23 +/- 3 years, height = 174 +/- 4 cm, mass = 68 +/- 5 kg) participated in the study. INTERVENTION(S): The subjects performed posturographic tests with eyes open and closed. MAIN OUTCOME MEASURE(S): While subjects performed static and dynamic posturographic tests, we measured the center of foot pressure on a force platform. Spatiotemporal center-of-pressure measurements were used to evaluate the postural performance, and a frequency analysis of the center-of-pressure excursions (fast Fourier transform) was conducted to estimate the postural strategy. RESULTS: Within a laboratory task, national soccer players produced better postural performances than regional players and had a different postural strategy. The national players were more stable than the regional players and used proprioception and vision information differently. CONCLUSIONS: In the test conditions specific to playing soccer, level of playing experience influenced postural control performance measures and strategies.

Short-term effects of electrical stimulation superimposed on muscular voluntary contraction in postural control in elderly women.

Thirty-two women between 62 and 75 years old were randomized into 3 groups. Each group performed a program of 4 sessions a week over 6 weeks. Group SC (n = 11) climbed up and down stairs, group ES (n = 11) practiced electrostimulation, and group SC + ES (n = 10) superimposed the 2 activities simultaneously. Using a force platform and a seesaw platform, static and dynamic balance in eyes-open and eyes-closed conditions were analyzed before and after the programs for each group. After the programs, the results indicated that dynamic balance improved for the 3 groups, but the contribution of visual information in the control of oscillation amplitude was lower in the SC group than in the ES and SC + ES groups. In the SC + ES group, the electrical stimulation interferes with neurophysiologic afference integration in postural control in relation to voluntary movement. Voluntary exercise appears to be more efficient than electrical stimulation and the superimposed techniques to change balancing tactics in the elderly.

Influence of postural regulation in male judokas' direction of falls.

In competitions, judokas tend to have a predominant direction of fall: forwards or backwards. A relationship was hypothesized between the direction of fall and certain parameters of the judokas' postural activities. 20 judokas, 16 to 19 yr. old (17.7 +/- 0.4 yr.), had practised judo for at least seven years. They were separated into two groups. The group of forward fallers (n = 9) and the group of backward fallers (n = 11) performed posturokinetic tests to assess their static and dynamic balance. One parameter assessed through the analysis of postural activities, the average position of anteroposterior dynamic oscillations, was inversely related to the judokas' direction of fall. Postural activities might not play a direct role but perhaps an indirect one in the direction of falls by expert judokas.

A foot-pointing task and spatiotemporal gait parameters during walking in sportsmen.

Unlike many sports, karate imposes pointing to a target with the lower limb. The nature of each sport could influence gait variables of sportsmen. The aim of this study was to examine the pointing accuracy of limb swing and the spatial and temporal parameters of the walking cycle during walking in karate experts (Group K, n=6) compared to accuracy of nonkarate sportsmen (Group S, n = 11). The second aim of this study was to compare the influence of this skill on the spatial and temporal parameters of the walking cycle between the two groups. The analysis was performed with a device composed of a gait analysis system (locometer) coupled to a lighted walkway. This system provides a measurement of the motor skill and the spatial and temporal gait during walking. Analysis for the pointing task indicated no differences between the Karate and the Sportsmen Groups during walking. Moreover, neither the spatial nor temporal characteristics of walking differed between the two groups. Karate does not therefore seem to develop motor programs specific to enhanced performance on this pointing task during walking or alter the walking cycle as compared to some other competitive sports.