Most human movements require coordinated activation of multiple muscles. Although many studies reported associations between arm, leg, and trunk muscles during functional tasks, their neural interaction mechanisms still remain unclear. Therefore, the aim of our study was to investigate arm-trunk or arm-leg neural interactions in the corticospinal tract during different arm muscle contractions. Specifically, we examined corticospinal excitability of the erector spinae (ES; trunk extensor), rectus abdominis (RA; trunk flexor), and tibialis anterior (TA; leg) muscles while participants exerted: (1) wrist flexion and (2) wrist extension isometric contraction at various contraction intensity levels ranging from rest to 50% of maximal voluntary contraction (MVC) effort. Corticospinal excitability was assessed using motor evoked potentials (MEPs) elicited through motor cortex transcranial magnetic stimulation (TMS). Results showed that ES MEPs were facilitated even at low contractions (>5% MVC) during wrist flexi...

Neuroendocrine control of reproduction is disrupted in many individuals with polycystic ovary syndrome (PCOS), who present with increased luteinizing hormone (LH), and presumably gonadotropin-releasing hormone (GnRH), release frequency, and high androgen levels. Prenatal androgenization (PNA) recapitulates these phenotypes in primates and rodents. Female offspring of mice injected with dihydrotestosterone (DHT) on gestational days 16–18 exhibit disrupted estrous cyclicity, increased LH and testosterone, and increased GnRH neuron firing rate as adults. PNA also alters the developmental trajectory of GnRH neuron firing rates, markedly blunting the prepubertal peak in firing that occurs in three-week (3wk)-old controls. GnRH neurons do not express detectable androgen receptors and are thus probably not the direct target of DHT. Rather, PNA likely alters GnRH neuronal activity by modulating upstream neurons, such as hypothalamic arcuate neurons co-expressing kisspeptin, neurokinin B (gene Tac2), and dynorphin,...

Highlighted Research Paper: [[Tracking Mitochondrial Density and Positioning along a Growing Neuronal Process in Individual C. elegans Neuron Using a Long-Term Growth and Imaging Microfluidic Device by Sudip Mondal, Jyoti Dubey, Anjali Awasthi, Guruprasad Reddy Sure, Amruta Vasudevan, and Sandhya P. Koushika.][2]][2] []: /lookup/doi/10.1523/ENEURO.0360-20.2021

Biological neural networks operate at several levels of granularity, from the individual neuron to local neural circuits to networks of thousands of cells. The daily oscillation of the brain’s master clock in the suprachiasmatic nucleus (SCN) rests on a yet to be identified network of connectivity among its ∼20,000 neurons. The SCN provides an accessible model to explore neural organization at several levels of organization. To relate cellular to local and global network behaviors, we explore network topology by examining SCN slices in three orientations using immunochemistry, light and confocal microscopy, real-time imaging, and mathematical modeling. Importantly, the results reveal small local groupings of neurons that form intermediate structures, here termed “phaseoids,” which can be identified through stable local phase differences of varying magnitude among neighboring cells. These local differences in phase are distinct from the global phase relationship, namely that between individual cells and the...

Spatial orientation memory plays a crucial role in animal navigation. Recent studies of tethered Drosophila melanogaster (fruit fly) in a virtual reality setting showed that the head direction is encoded in the form of an activity bump, i.e., localized neural activity, in the torus-shaped ellipsoid body (EB). However, how this system is involved in orientation working memory is not well understood. We investigated this question using free moving flies ( D. melanogaster ) in a spatial orientation memory task by manipulating two EB subsystems, C and P circuits, which are hypothesized for stabilizing and updating the activity bump, respectively. To this end, we suppressed or activated two types of inhibitory ring neurons (EIP and P) which innervate EB, and we discovered that manipulating the two inhibitory neuron types produced distinct behavioral deficits, suggesting specific roles of the inhibitory neurons in coordinating the stabilization and updating functions of the EB circuits. We further elucidate the ...

Social connections in gregarious species are vital for safety and survival. For these reasons, many bird species form large flocks outside the breeding season. It has been proposed that such large social groups may be maintained via reward induced by positive interactions with conspecifics and via the reduction of a negative affective state caused by social separation. Moreover, within a flock optimal social spacing between conspecifics is important, indicating that individuals may optimize spacing to be close but not too close to conspecifics. The μ-opioid receptors (MORs) in the nucleus accumbens (NAc) are well known for their role in both reward and the reduction of negative affective states, suggesting that MOR stimulation in NAc may play a critical role in flock cohesion. To begin to test this hypothesis, social and nonsocial behaviors were examined in male and female European starlings ( Sturnus vulgaris ) in nonbreeding flocks after intra-NAc infusion of saline and three doses of the selective MOR a...

The perirhinal (PER) and postrhinal (POR) cortices, structures in the medial temporal lobe, are implicated in learning and memory. The PER is understood to process object information and the POR to process spatial or contextual information. Whether the medial temporal lobe is dedicated to memory, however, is under debate. In this study, we addressed the hypothesis that the PER and POR are also involved in non-mnemonic cognitive functions. Rats with PER or POR damage and SHAM surgical controls were shaped, trained, and tested on the five-choice serial reaction time (5CSRT) task, which assesses attention and executive function. Rats with PER damage were impaired in acquiring the task and at asymptote, although processing information about objects was not relevant to the task. When confronted with attentional challenges, rats with PER damage showed a pattern consistent with decreased attentional capacity, increased response errors, and increased impulsive behavior. Rats with POR damage showed intact acquisiti...

In recent years there has been extensive research on malformations of cortical development (MCDs) that result in clinical features like developmental delay, intellectual disability, and drug-resistant epilepsy (DRE). Various studies highlighted the contribution of microtubule-associated genes (including tubulin and kinesin encoding genes) in MCD development. It has been reported that de novo mutations in KIF2A , a member of the kinesin-13 family, are linked to brain malformations and DRE. Although it is known that KIF2A functions by regulating microtubule depolymerization via an ATP-driven process, in vivo implications of KIF2A loss of function remain partly unclear. Here, we present a novel kif2a knock-out zebrafish model, showing hypoactivity, habituation deficits, pentylenetetrazole-induced seizure susceptibility and microcephaly, as well as neuronal cell proliferation defects and increased apoptosis. Interestingly, kif2a −/− larvae survived until adulthood and were fertile. Notably, our kif2a zebrafish...

Opsin 3 ( Opn3 ) is highly expressed in the adult brain, however, information for spatial and temporal expression patterns during embryogenesis is significantly lacking. Here, an Opn3 -eGFP reporter mouse line was used to monitor cell body expression and axonal projections during embryonic and early postnatal to adult stages. By applying 2D and 3D fluorescence imaging techniques, we have identified the onset of Opn3 expression, which predominantly occurred during embryonic stages, in various structures during brain/head development. In addition, this study defines over twenty Opn3 -eGFP-positive neural structures never reported before. Opn3 -eGFP was first observed at E9.5 in neural regions, including the ganglia that will ultimately form the trigeminal, facial and vestibulocochlear cranial nerves (CNs). As development proceeds, expanded Opn3 -eGFP expression coincided with the formation and maturation of critical components of the central and peripheral nervous systems (CNS, PNS), including various motor-...

The mouse vomeronasal system controls several social behaviors. Pheromones and other social cues are detected by sensory neurons in the vomeronasal organ (VNO). Stimuli activate a transduction cascade that leads to membrane potential depolarization, increase in cytosolic Ca2+ level, and increased firing. The Ca2+-activated chloride channels TMEM16A and TMEM16B are co-expressed within microvilli of vomeronasal neurons, but their physiological role remains elusive. Here, we investigate the contribution of each of these channels to vomeronasal neuron firing activity by comparing wild-type (WT) and knock-out (KO) mice. Performing loose-patch recordings from neurons in acute VNO slices, we show that spontaneous activity is modified by Tmem16a KO, indicating that TMEM16A, but not TMEM16B, is active under basal conditions. Upon exposure to diluted urine, a rich source of mouse pheromones, we observe significant changes in activity. Vomeronasal sensory neurons (VSNs) from Tmem16a cKO and Tmem16b KO mice show short...