Troubles du spectre autistique et réalité virtuelle. Risque de pratique excessive des jeux vidéo chez les adolescents avec TSA ?

OBJECTIVES : To compare excessive video gaming (EVG) between a group of adolescents with Autistic Spectrum Disorders (ASD) and an adolescents control group. METHODS : 40 subjects aged 11-18 years, diagnosed with ASD (DSM-5 and ICD-10 criteria) and 40 control subjects matched for age and sex were included. The subjects were evaluated using the Quotient of Autism (AQ) that assesses the severity of ASD, the Empathy Quotient (EQ), which evaluates the capacity for empathy and GRIFFITHS EVG questionnaire. The questionnaires were completed by parents of adolescents with ASD and controls. RESULTS : the frequency of EVG (scores greater than 4 in the GRIFFITHS questionnaire) was higher (40 %, n=16) in the ASD group subjects than in the control group subjects (12.5 %, n=5, p=0.005), in particular for the video game “action” type (p=0.014). The average scores of the EVG GRIFFITHS questionnaire were higher in the ASD group subjects than in the control group subjects (p=0.008). The ASD subgroup subjects with EVG had higher average scores in AQ questionnaire autistic symptomatology (p=0.009), higher alterations in social skills AQ sub-score (p=0.02) and higher attention to detail AQ sub-score (p=0.02) compared to the ASD subgroup subjects without EVG. CONCLUSIONS : The PEJV are more frequent in adolescents with ASD than control adolescents. Adolescents with ASD and associated EVG have lower social skills and greater attention to detail than subjects with ASD without EVG.OBJECTIFS : comparer la pratique excessive des jeux vidéo (PEJV) entre un groupe d’adolescents présentant des Troubles du Spectre Autistique (TSA) et un groupe d’adolescents témoins. MÉTHODES : 40 sujets âgés de 11 à 18 ans, diagnostiqués TSA (critères DSM-5 et de la CIM-10) et 40 sujets témoins appariés sur l’âge et le sexe ont été inclus. Les sujets ont été évalués à l’aide du Quotient du Spectre de l’Autisme (AQ) qui évalue la sévérité des TSA, du Quotient d’Empathie (EQ) qui évalue la capacité d’empathie et du questionnaire de PEJV de GRIFFITHS. Les questionnaires ont été remplis par les parents d'adolescents avec TSA et des témoins. RÉSULTATS : la fréquence des PEJV (scores supérieurs à 4 au questionnaire de GRIFFITHS) était plus élevée (40%, n=16) dans le groupe de sujets diagnostiqués TSA que dans le groupe de sujets témoins (12,5%, n=5, p=0,005), notamment pour le type de jeu vidéo action (p=0,014). Les scores moyens au questionnaire de PEJV de GRIFFITHS étaient plus élevés dans le groupe de sujets avec TSA que dans le groupe de sujets témoins (p=0,008). Le sous-groupe de sujets avec PEJV du groupe TSA présentaient des scores moyens plus élevés au questionnaire AQ de symptomatologie autistique (p=0,009), au sous-score AQ d’altérations des habilités sociales (p=0,02) et au sous-score AQ d'attention aux détails (p=0,02) par rapport au sous-groupe de sujets sans PEJV du groupe TSA. CONCLUSIONS : les PEJV sont plus fréquents chez les adolescents avec TSA que chez les adolescents témoins. Les adolescents avec TSA et PEJV associée présentent des habilités sociales moindres et une plus grande attention aux détails que les sujets avec TSA sans PEJV

Nonlinear electron acoustic structures generated on the high-potential side of a double layer

High-time resolution measurements of the electron distribution function performed in the auroral upward current region reveals a large asymmetry between the low- and high-potential sides of a double-layer. The latter side is characterized by a large enhancement of a locally trapped electron population which corresponds to a significant part (~up to 30%) of the total electron density. As compared to the background hot electron population, this trapped component has a very cold temperature in the direction parallel to the static magnetic field. Accordingly, the differential drift between the trapped and background hot electron populations generates high frequency electron acoustic waves in a direction quasi-parallel to the magnetic field. The density of the trapped electron population can be deduced from the frequency where the electron acoustic spectrum maximizes. In the auroral midcavity region, the electron acoustic waves may be modulated by an additional turbulence generated in the ion acoustic range thanks to the presence of a pre-accelerated ion beam located on the high-potential side of the double layer. Electron holes characterized by bipolar pulses in the electric field are sometimes detected in correlation with these electron acoustic wave packets

Electron-cylotron maser radiation from electron holes: downward current region

The electron-cyclotron maser emission theory from electron holes is applied to holes generated in the down- ward current region of the aurora. It is argued that the main background auroral kilometric radiation source may still be located in the upward current region electron-ring (horseshoe) distribution while the fine structure is caused by electron holes predominantly in the downward current re- gion. There the existence of electron holes is well established and electron densities are high enough for substantial maser growth rates. Trapping of radiation by the holes provides strong amplification. Upward motion of holes favours the escape of radiation both, from the holes and from the down- ward current region, into the upward current region. Since upward and downward current regions always exist simulta- neously, they are acting in tandem in generating auroral kilo- metric radiation and its fine structure by the same mechanism though in different ways. This mechanism solves the long- standing problem of auroral kilometric radiation fine struc- ture

Crossing a Narrow-In-Altitude Turbulent Auroral Acceleration Region

We report on the in situ identification of a narrow electrostatic acceleration layer (electrostatic shock) containing intense plasma turbulence in the upward current region, and its effect on auroral particles. Wave turbulence recorded in the center of the layer differs in character from that recorded above and beneath. It is concluded that the shock is sustained by different nonlinear waves which, at each level, act on the particles in such a way to produce a net upward directed electric field. The main power is in the ion acoustic range. We point out that anomalous resistivities are incapable of locally generating the observed parallel potential drop

On deformation of electron holes in phase space

This Letter shows that for particularly shaped background particle distributions momentum exchange between phase space holes and the distribution causes acceleration of the holes along the magnetic field. In the particular case of a non-symmetric ring distribution (ring with loss cone) this acceleration is nonuniform in phase space being weaker at larger perpendicular velocities thus causing deformation of the hole in phase space.Comment: Original MS in EPL style, 1 Figur

Auroral Evidence for Multiple Reconnection in the Magnetospheric Tail Plasma Sheet

We present auroral evidence for multiple and, most probably, small-scale reconnection in the near-Earth magnetospheric plasma sheet current layer during auroral activity. Hall currents as the source of upward and downward field-aligned currents require the generation of the corresponding electron fluxes. The auroral spatial ordering in a multiple sequence of these fluxes requires the assumption of the existence of several —and possibly— even many tailward reconnection sites

Electron-cylotron maser radiation from electron holes: Upward current region

Electron holes are suggested to be an important source for generation of electron-cyclotron maser radiation. We demonstrate that electron holes generated in a ring-horseshoe distribution in the auroral-kilometric radiation source region have the capacity to emit band-limited radiation. The radiation is calculated in the proper frame of a circular model hole and shown to be strictly perpendicular in this frame. Its bandwidth under auroral conditions is of the order of $\sim1$ kHz, which is a reasonable value. {It is also shown that much of the drift of fine structure in the radiation can be interpreted as Doppler shift. Estimates based on data are in good agreement with theory. Growth and absorption rates have been obtained for the emitted radiation. However, the growth rate of a single hole obtained under conservative conditions is small, too small for reproducing the observed fine structure flux. Trapping of radiation inside the hole for the hole's lifetime helps amplifying the radiation additionally but introduces other problems. This entire set of questions is discussed at length and compared to radiation from the global horseshoe distribution.} The interior of the hole produces a weak absorption at slightly higher frequency than emission. The absorptivity is roughly two orders of magnitude below the growth rate of the radiation thus being weak even when the emission and absorption bands overlap. Transforming to the stationary observer's frame it is found that the radiation becomes oblique against the magnetic field. For approaching holes the radiated frequencies may even exceed the local electron cyclotron frequency.Comment: 19 pages, 9 figures, revised version to appear in Ann. Geophys. vol 29, 201

Dependence of CMI Growth Rates on Electron Velocity Distributions and Perturbation by Solitary Waves

We calculate growth rates and corresponding gains for RX and LO mode radiation associated with the cyclotron maser instability for parameterized horseshoe electron velocity distributions. The velocity distribution function was modeled to closely fit the electron distribution functions observed in the auroral cavity. We systematically varied the model parameters as well as the propagation direction to study the dependence of growth rates on model parameters. The growth rate depends strongly on loss cone opening angle, which must be less than $90^{o}$ for significant CMI growth. The growth rate is sharply peaked for perpendicular radiation ($k_{\parallel} = 0$), with a full-width at half-maximum $1.7^{o}$, in good agreement with observed k-vector orientations and numerical simulations. The fractional bandwidth varied between 10$^{-4}$ and 10$^{-2}$, depending most strongly on propagation direction. This range encompasses nearly all observed fractional AKR burst bandwidths. We find excellent agreement between the computed RX mode emergent intensities and observed AKR intensities assuming convective growth length $L_c\approx$20-40 km and group speed 0.15$c$. The only computed LO mode growth rates compatible observed LO mode radiation levels occurred for number densities more than 100 times the average energetic electron densities measured in auroral cavities. This implies that LO mode radiation is not produced directly by the CMI mechanism but more likely results from mode conversion of RX mode radiation. We find that perturbation of the model velocity distribution by large ion solitary waves (ion holes) can enhance the growth rate by a factor of 2-4. This will result in a gain enhancement more than 40 dB depending on the convective growth length within the structure. Similar enhancements may be caused by EMIC waves.Comment: 21 pages, 11 figures. J. Geophys. Res. 2007 (accepted