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In the present paper, we analyze local field potentials (LFPs) recorded from the secondary motor cortex (M2) and primary visual cortex (VI) of freely moving mice reared in environmental enrichment (EE) and standard condition (SC). We focus on the scaling properties of the signals by using an integrated approach combining three different techniques: the Higuchi method, detrended fluctuation analysis, and power spectrum. Each technique provides direct or indirect estimations of the Hurst exponent H and this prevents spurious identification of scaling properties in time-series analysis. It is well known that the power spectrum of an LFP signal scales as 1/fβ with ß > 0. Our results indicate the existence of a particular power spectrum scaling law 1/fβ with ß < 0 for low frequencies (f < 4 Hz) for both SC and EE rearing conditions. This type of scaling behavior is associated to the presence of anticorrelation in the corresponding LFP signals. Moreover, since EE is an experimental protocol based on the enhancement of sensorimotor stimulation, we study the possible effects of EE on the scaling properties of secondary motor cortex (M2) and primary visual cortex (VI). Notably, the difference between Hurst's exponents in EE and SC for individual cortical regions (M2) and (VI) is not statistically significant. On the other hand, using the detrended cross-correlation coefficient, we find that EE significantly reduces the functional coupling between secondary motor cortex (M2) and visual cortex (VI). [ABSTRACT FROM AUTHOR]

Epilepsy is characterized by substantial network rearrangements leading to spontaneous seizures and little is known on how an epileptogenic focus impacts on neural activity in the contralateral hemisphere. Here, we used a model of unilateral epilepsy induced by injection of the synaptic blocker tetanus neurotoxin (TeNT) in the mouse primary visual cortex (V1). Local field potential (LFP) signals were simultaneously recorded from both hemispheres of each mouse in acute phase (peak of toxin action) and chronic condition (completion of TeNT effects). To characterize the neural electrical activities the corresponding LFP signals were analyzed with several methods of time series analysis. For the epileptic mice, the spectral analysis showed that TeNT determines a power redistribution among the different neurophysiological bands in both acute and chronic phases. Using linear and nonlinear interdependence measures in both time and frequency domains, it was found in the acute phase that TeNT injection promotes a reduction of the interhemispheric coupling for high frequencies (12-30 Hz) and small time lag (<20 ms), whereas an increase of the coupling is present for low frequencies (0.5-4 Hz) and long time lag (>40 ms). On the other hand, the chronic period is characterized by a partial or complete recovery of the interhemispheric interdependence level. Granger causality test and symbolic transfer entropy indicate a greater driving influence of the TeNT-injected side on activity in the contralateral hemisphere in the chronic phase. Lastly, based on experimental observations, we built a computational model of LFPs to investigate the role of the ipsilateral inhibition and exicitatory interhemispheric connections in the dampening of the interhemispheric coupling. The time evolution of the interhemispheric coupling in such a relevant model of epilepsy has been addressed here. [ABSTRACT FROM AUTHOR]

Introduction/Background Maintaining balance depends on the integration of sensory, proprioceptive and vestibular information to appropriately adjust movements responses to different postural conditions. hunova is a new robotic device developed and validated to perform functional evaluation and sensorimotor rehabilitation of lower limbs and trunk in static and dynamic environments. Aim of this study was to evaluate balance parameters in older subjects with different risk of fall. Material and method One hundred subjects aged ≥ 65 years (mean age 77.17 ± 6.49 SD years) were enrolled. According to the number of falls in the last 12 months, participants were allocated to low, medium or high-risk of fall. Balance was evaluated by hunova in static, unstable and perturbating conditions, in both standing/seated positions and with open/closed eyes. Parameters were: sway area (SA), path length (PL), range of oscillations in anterior-posterior (OAP) and mediolateral directions (OML) in both platform and trunk oscillations. Statistical analysis was carried out by means of Kruskal–Wallis test on medians and Spearman correlation test. Results Older fallers had higher trunk PL both in unstable [fallers, median (IQR): 32.5 (23.35) vs. non-faller 43.79 (29.21) (deg), P < 0.01] and moving [fallers 35.94 (22.12) vs. non-faller 45.27 (31.29) (deg), P < 0.05] platform in standing with open eyes condition. Trunk SA and OML were significantly different in subjects with different fall risk classes in perturbating conditions when seated with closed eyes. Trunk parameters in unstable and perturbating conditions showed also a strong and significative correlation with age ( P < 0.01). Conclusion Hunova robot was able to detect physiological components involved in balance maintenance in older subjects with different fall risk. This evaluation could be crucial to prevent falls and to plan rehabilitation programs in older subjects at different risk of falls. [ABSTRACT FROM AUTHOR]