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Gun control in the United States has a racist history. Nevertheless, federal courts and academics have invoked Southern gun restrictions enacted after the Civil War to suggest that history supports stringent regulation of the right to bear arms. We argue that courts’ reliance on these restrictions is illegitimate. Drawing on original research, we reveal how the post-war South restricted gun-ownership for racist reasons, deployed its new laws to disarm free blacks, yet allowed whites to bear arms with near impunity. We then show how modern reliance on these laws contravenes the Supreme Court’s decision in Ramos v. Louisiana, which deemed similarly tainted statutes unconstitutional. Since the Court will soon consider the validity of modern limits on concealed carry, placing Southern gun restrictions in their proper historical context matters today more than ever. While Southern gun control after the Civil War might tell us something about how the South sought to preserve white supremacy, it tells us almost nothing about the proper scope of the Second Amendment.

Cutaneous foot receptors are important for balance control, and their activation during quiet standing depends on the speed and the amplitude of postural oscillations. We hypothesized that the transmission of cutaneous input to the cortex is reduced during prolonged small postural sways due to receptor adaptation during continued skin compression. Central mechanisms would trigger large sways to reactivate the receptors. We compared the amplitude of positive and negative post-stimulation peaks (P50N90) somatosensory cortical potentials evoked by the electrical stimulation of the foot sole during small and large sways in 16 young adults standing still with their eyes closed. We observed greater P50N90 amplitudes during large sways compared with small sways consistent with increased cutaneous transmission during large sways. Postural oscillations computed 200 ms before large sways had smaller amplitudes than those before small sways, providing sustained compression within a small foot sole area. Cortical source analyses revealed that during this interval, the activity of the somatosensory areas decreased, whereas the activity of cortical areas engaged in motor planning (supplementary motor area, dorsolateral prefrontal cortex) increased. We concluded that large sways during quiet standing represent self-generated functional behavior aiming at releasing skin compression to reactivate mechanoreceptors. Such balance motor commands create sensory reafference that help control postural sway.

International audience; In the skin, Merkel cells connect with keratinocytes and Ab nerve fibers to form a touch receptor that functions as a slow adapting mechanoreceptor (slow adapting type 1). In human and mouse Merkel cells, we observed an increased concentration of intracellular Ca 2þ ions in response to cold temperature and transient receptor potential melastatine 8 (TRPM8) ion channel agonists. A reduction in the response to cooling and TRPM8 ag-onists occurred after the addition of TRPM8 antagonists, as well as in TRPM8 knockout mice. Cold temperature and TRPM8 agonists also induced a current that was inhibited by a TRPM8 antagonist. Our results indicate that Merkel cells sense cooling through TRPM8 channels. We hypothesized that cooling modulates the slow adapting type 1 receptor response. Cooling mouse skin to 22 C reduced the slow adapting type 1 receptor discharge frequency. Interestingly, we observed no such reduction in TRPM8 knockout mice. Similarly, in human skin, a temperature of 22 C applied to the slow adapting type 1 receptive field reduced the spiking discharge. Altogether, our results indicate that Merkel cells are polymodal sensory cells that respond to mild cold stimuli through the activation of TRPM8 channels. Thermal activation of Merkel cells, and possibly other TRPM8-expressing non-neuronal cells, such as keratinocytes, potentially adapts the discharge of slow adapting type 1 receptors during cooling.

International audience

International audience; Introduction: Tactile sensitivity is impaired in older adults, which contributes to the loss of manual dexterity and mobility function. The reliability of classical psychophysical tests, such as two-point gap discrimination, has been questioned. Here we tested a new method to determine tactile acuity during dynamic touch, which is more functional than static touch. The aim was to validate a method providing a high level of discrimination of tactile acuity in the elderly. Methods: We tested the ability of subjects to evaluate the distance between bands printed on poly-methyl-methacrylate (PMMA) sheets. Pairs of sheets were compared in two groups of participants aged from 60 to 74 years; the test group was required to apply a cosmetic foam with an active ingredient on both their hands twice a day for 1 month, the control group had an identical task but used the same cosmetic foam without any active ingredient. The tests were run in a double-blind, placebo-controlled study. Results: The tactile discrimination threshold decreased by 83 µm after 1 month of cosmetic application in the group using the active ingredient, while it was unchanged in the control group. Discussion: The test presented here provided highly accurate results and should be useful to determine tactile performance. It allows the monitoring of tactile rehabilitation and/or skin treatments used to restore tactile acuity in the elderly.

Multisensory effects are found when the input from single senses combines, and this has been well researched in the brain. Presently, we examined in humans the potential impact of visuo-proprioceptive interactions at the peripheral level, using microneurography, and compared it with a similar behavioral task. We used a paradigm where participants had either proprioceptive information only (no vision) or combined visual and proprioceptive signals (vision). We moved the foot to measure changes in the sensitivity of single muscle afferents, which can be altered by the descending fusimotor drive. Visual information interacted with proprioceptive information, where we found that for the same passive movement, the response of muscle afferents increased when the proprioceptive channel was the only source of information, as compared with when visual cues were added, regardless of the attentional level. Behaviorally, when participants looked at their foot moving, they more accurately judged differences between movement amplitudes, than in the absence of visual cues. These results impact our understanding of multisensory interactions throughout the nervous system, where the information from different senses can modify the sensitivity of peripheral receptors. This has clinical implications, where future strategies may modulate such visual signals during sensorimotor rehabilitation.

International audience; Kinesthesia, the perception of our own body movements, relies on the integration of proprioceptive information arising mostly from muscle spindles, which are sensory receptors in skeletal muscles. We recently showed that emotions alter the proprioceptive messages from such muscle afferents, making them more sensitive to muscle lengthening when participants were listening sad music. Presently, we investigated whether these changes in proprioceptive feedback relating to emotional state may affect the perception of limb movements. Kinesthetic acuity was tested in 20 healthy, young adults by imposing ramp-and-hold movements that consisted of either plantar flexion or dorsiflexion movements of the ankle at 0.04°/s, or no movement. These were imposed during four emotional conditions (listening to neutral, sad, or happy music, or no music). The participants were asked to relax and focus on music (or nothing), and then they shifted their focus to the direction of an incoming movement. Once this had finished, they were asked its direction. Muscle activity, heart rate, and electrodermal activity were recorded during each trial, and after each music condition the participants rated the emotion felt on a visual analog scale. The rating of the emotional content of the music corroborated with changes in physiological measures. Kinesthetic acuity was also affected by the emotional state and found to be larger during the sad condition, as compared to the no music or neutral conditions. We conclude that emotion can shape our perception of movements, which we show here where feeling sadness significantly increase our kinesthetic acuity, this may be functionally relevant for the preparation of appropriate behavioral responses.

Reasons for performing the study: Safety and top-level training are equally important to achieve the best athletic performance of the race horse. Along increasing daily training-load the responsiveness of the horse and improvement in fitness should be monitored. The use of new, wearable technologies - like the Equimetre® device, an innovative product of the Arioneo Company seems to be a proper way to monitor and optimize horse´s training. Hypothesis: Regularity of the stride is inversely proportional to the stride length and stride frequency. Horses exercising in the “red zone” have a longer recovery time. Methods: 12 horses were monitored twice with the Equimetre® device while doing speed work over 1700meters. Regularity, stride length, stride frequency, heart rate, speed and recovery time datas have been recorded and analyzed. Results and conclusion: The regularity of the stride increases with the stride frequency but decreases with the stride length (p

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The present study investigates whether proprioceptive training, based on kinesthetic illusions, can help in re-educating the processing of muscle proprioceptive input, which is impaired in patients with Parkinson's disease (PD). The processing of proprioceptive input before and after training was evaluated by determining the error in the amplitude of voluntary dorsiflexion ankle movement (20°), induced by applying a vibration on the tendon of the gastrocnemius-soleus muscle (a vibration-induced movement error). The training consisted of the subjects focusing their attention upon a series of illusory movements of the ankle. Eleven PD patients and eleven age-matched control subjects were tested. Before training, vibration reduced dorsiflexion amplitude in controls by 4.3° (P

Introduction Important for balance control, the activation of the cutaneous foot receptors largely depends on the speed and amplitude of the body oscillations during standing. Material and methods Here, we tested the hypothesis that the transmission of cutaneous inputs to the cortex is reduced during prolonged intervals of small body sways due to continued local skin compression and that under such circumstances, central mechanisms trigger large sways to reactivate the cutaneous receptors. We compared the amplitude of the somatosensory cortical potentials (P50-N90) evoked by electric stimulations of the foot sole during either small or large sways in 16 adults that were standing still with the eyes closed. Results We found greater P50-N90 amplitude when the stimulation occurred during large body sways, consistent with an increased sensory transmission. Importantly, body oscillations computed 200 ms prior to large sways had smaller amplitude than intervals that were not followed by large sways. Discussion The hypothesis of a depressed sensory transmission during continued skin compression was supported by our microneurographic recordings showing adaptation/suppression of tactile fibres discharge during continuous pressure applied to the mechanoreceptors. Finally, the hypothesis that large sways during standing correspond to a self-generated functional behaviour to release skin compression is supported by cortical source and EMG analyses showing respectively that large sways were preceded by activation of cortical areas known to be engaged in motor planning (supplementary motor area and dorsolateral prefrontal cortex) and by ankle muscle activations. Together, the present findings provide evidence for an important sensory function of large body sways for balance control.