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Brain rhythms are widely believed to reflect numerous cognitive processes. Changes in rhythmicity have been associated with pathological states. However, the mechanism underlying these rhythms remains unknown. Here, we present a theoretical analysis of the evolvement of rhythm generating capabilities in neuronal circuits. We tested the hypothesis that brain rhythms can be acquired via an intrinsic unsupervised learning process of activity dependent plasticity. Specifically, we focused on spike timing dependent plasticity (STDP) of inhibitory synapses. We detail how rhythmicity can develop via STDP under certain conditions that serve as a natural prediction of the hypothesis. We show how global features of the STDP rule govern and stabilize the resultant rhythmic activity. Finally, we demonstrate how rhythmicity is retained even in the face of synaptic variability. This study suggests a role for inhibitory plasticity that is beyond homeostatic processes. [ABSTRACT FROM AUTHOR]

Auditory and vestibular hair cell bundles exhibit active mechanical oscillations at natural frequencies that are typically lower than the detection range of the corresponding end organs. We explore how these noisy nonlinear oscillators mode-lock to frequencies higher than their internal clocks. A nanomagnetic technique is used to stimulate the bundles without an imposed mechanical load. The evoked response shows regimes of high-order mode-locking. Exploring a broad range of stimulus frequencies and intensities, we observe regions of high-order synchronization, analogous to Arnold Tongues in dynamical systems literature. Significant areas of overlap occur between synchronization regimes, with the bundle intermittently flickering between different winding numbers. We demonstrate how an ensemble of these noisy spontaneous oscillators could be entrained to efficiently detect signals significantly above the characteristic frequencies of the individual cells. [ABSTRACT FROM AUTHOR]

The nuclear pore complex (NPC) is the portal for bidirectional transportation of cargos between the nucleus and the cytoplasm. While most of the structural elements of the NPC, i.e. nucleoporins (Nups), are well characterized, the exact transport mechanism is still under much debate. Many of the functional Nups are rich in phenylalanine-glycine (FG) repeats and are believed to play the key role in nucleocytoplasmic transport. We present a bioinformatics study conducted on more than a thousand FG Nups across 252 species. Our results reveal the regulatory role of polar residues and specific sequences of charged residues, named 'like charge regions' (LCRs), in the formation of the FG network at the center of the NPC. Positively charged LCRs prepare the environment for negatively charged cargo complexes and regulate the size of the FG network. The low number density of charged residues in these regions prevents FG domains from forming a relaxed coil structure. Our results highlight the significant role of polar interactions in FG network formation at the center of the NPC and demonstrate that the specific localization of LCRs, FG motifs, charged, and polar residues regulate the formation of the FG network at the center of the NPC. [ABSTRACT FROM AUTHOR]

We here illustrate how a well-founded study of the brain may originate in assuming analogies with phase-transition phenomena. Analyzing to what extent a weak signal endures in noisy environments, we identify the underlying mechanisms, and it results a description of how the excitability associated to (non-equilibrium) phase changes and criticality optimizes the processing of the signal. Our setting is a network of integrate-and-fire nodes in which connections are heterogeneous with rapid time-varying intensities mimicking fatigue and potentiation. Emergence then becomes quite robust against wiring topology modification-in fact, we considered from a fully connected network to the Homo sapiens connectome-showing the essential role of synaptic flickering on computations. We also suggest how to experimentally disclose significant changes during actual brain operation. [ABSTRACT FROM AUTHOR]

Inspired by auditory hair cells of lower vertebrates, we design and fabricate an opto-electro-mechanical sensor at the border of its spontaneous activity, called Hopf bifurcation critical point. As proposed for biological hair cells, we observe that, as the system approaches the critical point, the frequency selectivity and the force sensitivity are enhanced. However, we find that the enhancement has limits because of its intrinsic nonlinearity, even at the critical point. We also find that the minimally detectable force is not influenced by the active feedback force despite its enhanced sensitivity. This is due to the inevitable heating of the hair bundle, which implies that the active amplification of the hair cell bundle might not lower the threshold level of detectable sound. [ABSTRACT FROM AUTHOR]

Executive functions are crucial for performance of everyday activities. In Multiple Sclerosis (MS), executive dysfunctions can be apparent from the early onset of the disease. Technology-based time-efficient and resource-saving tools for early evaluation of executive functions using an ecological approach are needed to assess functional performance in real-life. The aim was to compare the efficiency of the Picture Interpretation Test 360° (PIT 360°) with traditional measures on executive dysfunction in Persons with Multiple Sclerosis (PwMS) and Healthy Controls (HC). Participants were 31 patients with Relapsing-Remitting MS (mean age = 44.323 ± 13.149; mean Expanded Disability Status Scale = 2) and 39 HC (mean age = 39.538 ± 15.728). All were tested with standard neuropsychological tests of executive functions, PIT 360°, and measures of user experience. While standard neuropsychological tests failed to differentiate between PwMS and HC group, the PIT 360° was successful in detecting executive dysfunction in PwMS. All participants reported the PIT 360° to be an engaging tool and endorsed positive reactions to their experience. Overall, the PIT 360° is a quick, sensitive, and ecological tool that captures real-world executive dysfunction in PwMS. This engaging measure is sensitive for the detection of executive deficits since the early phases of the disease. [ABSTRACT FROM AUTHOR]