Highlights d Targeted training prevents mirror confusion for letters (b = d) in first graders d Sleep boosts the magnitude, automaticity, and duration of this learning d Training followed by sleep doubles reading fluency in first graders

a b s t r a c tThe efficiency of most of the new antiepileptic drugs (AEDs) on clinical trials still falls short the success reported in pre-clinical studies, possibly because the validity of the animal models is insufficient to fully represent the human pathology. To improve the translational value for testing AEDs, we propose the use of non-human primates. Here, we suggest that triggering limbic seizures with low doses of PTZ in pilocarpine-treated marmosets might provide a more effective basis for the development of AED. Marmosets with epileptic background were more susceptible to seizures induced by PTZ, which were at least 3 times longer and more severe (about 6 times greater frequency of generalized seizures) in comparison to naïve peers. Accordingly, PTZ-induced seizures were remarkably less attenuated by AEDs in epileptic than naïve marmosets. While phenobarbital (40 mg/kg) virtually abolished seizures regardless of the animal's background, carbamazepine (120 mg/kg) and valproic acid (400 mg/kg) could not prevent PTZinduced seizures in epileptic animals with the same efficiency as observed in naïve peers. VPA was less effective regarding the duration of individual seizures in epileptic animals, as assessed in ECoG (p = 0.05). Similarly following CBZ treatment, the behavioral manifestation of generalized seizures lasted longer in epileptic (p < 0.05), which were also more frequent than in the naïve group (p < 0.05). As expected, epileptic marmosets experiencing stronger seizures showed more NPY-and FosB-immunostained neurons in a number of brain areas associated with the generation and spread of limbic seizures. Our results suggest that PTZ induced seizures over an already existing epileptic background constitutes a reliable and controllable mean for the screening of new AEDs.

Aims/Hypothesis: Tinnitus is a phantom sound perception affecting both auditory and limbic structures. The mechanisms of tinnitus remain unclear and it is debatable whether tinnitus alters attention to sound and the ability to inhibit repetitive sounds, a phenomenon also known as auditory gating. Methods: 22 male C57BL/6J mice were used in this study. Anesthetized mice were exposed to a 9-11 kHz narrow band noise (90 dBSPL for 1 hr) and sham exposed mice were used as controls. Hearing thresholds were measured using auditory brainstem responses (ABRs) and tinnitus was assessed using Gap prepulse inhibition of acoustic startle (GPIAS). After the induction of tinnitus, mice were implanted multi-electrodes to assess auditory event-related potentials (aERPs) in the dorsal hippocampus in response to paired clicks. Alterations of aERPs under nicotine (1.0 mg/kg, intraperitoneal (i.p.) or cannabis extract (100 mg/Kg, i.p.) were evaluated (in isolation or in combination), the latter containing 47.25 mg/kg of tetrahydrocannabinol (THC); 0.43 mg/kg of cannabidiol (CBD) and 1.17 mg/kg of cannabinol (CBN), as analyzed by high-performance liquid chromatography (HPLC). Saline-treated animals were used as controls. Results: Our results show that mice with behavioral evidence of tinnitus display auditory gating of repetitive click, but with larger amplitudes and longer latencies of the N40 component. In contrast, no difference was observed in the P80 amplitude and latency between groups or treatments. The combination of cannabis extract and nicotine also improved auditory gating ratio in mice with noise-induced tinnitus without permanent hearing threshold shifts by strongly increasing the first N40 click amplitude but without altering the second click response amplitude. Furthermore, the increased latency of the N40 component suggests altered temporal processing of triggered attention in mice with tinnitus due to an increased sensitivity to the exposure to cannabis extract. Conclusion/Interpretation: In summary, we show that nicotine and cannabis extract alter sensory gating in mice with behavioral evidence of tinnitus and propose that the altered central plasticity in tinnitus is more sensitive to the combined actions on the cholinergic and the endocannabinoid systems. We conclude that the limbic system may play a role in the altered sensory gating responses on tinnitus since the hippocampus responses to auditory inputs are altered. These findings could enable a new understanding of which neuronal pathways could be involved in sensory gating in tinnitus.

No abstract

The COVID-19 pandemic changed people’s lives all over the world. While anxiety and stress decreased sleep quality for most people, an increase in total sleep time was also observed in certain cohorts. Dream recall frequency also increased, especially for nightmares. However, to date, there are no consistent reports focusing on pandemic-related changes in lucid dreaming, a state during which dreamers become conscious of being in a dream as it unfolds. Here we investigated lucid dreaming recall frequency and other sleep variables in 1,857 Brazilian subjects, using an online questionnaire. Firstly, we found that most participants (64.78%) maintained their lucid dream recall frequency during the pandemic, but a considerable fraction (22.62%) informed that lucid dreams became more frequent, whereas a smaller subset (12.60%) reported a decrease in these events during the pandemic. Secondly, the number of participants reporting lucid dreams at least once per week increased during the pandemic. Using a mixed logistic regression model, we confirmed that the pandemic significantly enhanced the recall frequency of lucid dreams (p = 0.002). Such increase in lucid dreaming during the pandemic was significantly associated with an enhancement in both dream and nightmare recall frequencies, as well as with sleep quality and symptoms of REM sleep behavior disorder. Pandemic-related increases in stress, anxiety, sleep fragmentation, and sleep extension, which enhance REM sleep awakening, may be associated with the increase in the occurrence of lucid dreams, dreams in general, and nightmares.

Loud noise-exposure generates tinnitus in both humans and animals. Macroscopic studies show that noise exposure affects the auditory cortex; however, cellular mechanisms of tinnitus generation are unclear. Here we compare membrane properties of layer 5 (L5) pyramidal cells (PCs) of the primary auditory cortex (A1) from control and noise-exposed mice. PCs were previously classified in type A or type B based on connectivity and firing properties. Our analysis based on a logistic regression model predicted that afterhyperpolatization and afterdepolarization following the injection of inward and outward current are enough to predict cell type and these features are preserved after noise trauma. One week after a noise-exposure (4-18kHz, 90dB, 1.5 hr, followed by 1.5hr silence) no passive membrane properties of type A or B PCs were altered but principal component analysis showed greater separation between control/noise-exposure recordings for type A neurons. When comparing individual firing properties, noise exposure differentially affected type A and B PC firing frequency in response to depolarizing current steps. Specifically, type A PCs decreased both initial and steady state firing frequency and type B PCs significantly increased steady state firing frequency following noise exposure. These results show that loud noise can cause distinct effects on type A and B L5 auditory cortex PCs one week following noise exposure. As the type A PC electrophysiological profile is correlated to corticofugal L5 neurons, and type B PCs correlate to contralateral projecting PCs these alterations could partially explain the reorganization of the auditory cortex observed in tinnitus patients.

IntroductionLoud noise-exposure can generate noise-induced tinnitus in both humans and animals. Imaging and in vivo studies show that noise exposure affects the auditory cortex; however, cellular mechanisms of tinnitus generation are unclear.MethodsHere we compare membrane properties of layer 5 (L5) pyramidal cells (PCs) and Martinotti cells expressing the cholinergic receptor nicotinic alpha 2 subunit gene (Chrna2) of the primary auditory cortex (A1) from control and noise-exposed (4–18 kHz, 90 dB, 1.5 h, followed by 1.5 h silence) 5–8 week old mice. PCs were furthermore classified in type A or type B based on electrophysiological membrane properties, and a logistic regression model predicting that afterhyperpolarization (AHP) and afterdepolarization (ADP) are sufficient to predict cell type, and these features are preserved after noise trauma.ResultsOne week after a loud noise-exposure no passive membrane properties of type A or B PCs were altered but principal component analysis showed greater separation between type A PCs from control and noise-exposed mice. When comparing individual firing properties, noise exposure differentially affected type A and B PC firing frequency in response to depolarizing current steps. Specifically, type A PCs decreased initial firing frequency in response to +200 pA steps (p = 0.020) as well as decreased steady state firing frequency (p = 0.050) while type B PCs, on the contrary, significantly increased steady state firing frequency (p = 0.048) in response to a + 150 pA step 1 week after noise exposure. In addition, L5 Martinotti cells showed a more hyperpolarized resting membrane potential (p = 0.04), higher rheobase (p = 0.008) and an increased initial (p = 8.5 × 10–5) and steady state firing frequency (p = 6.3 × 10–5) in slices from noise-exposed mice compared to control.DiscussionThese results show that loud noise can cause distinct effects on type A and B L5 PCs and inhibitory Martinotti cells of the primary auditory cortex 1 week following noise exposure. As the L5 comprises PCs that send feedback to other areas, loud noise exposure appears to alter levels of activity of the descending and contralateral auditory system.