Multisensory mental imagery of fatigue in patients with multiple Sclerosis. Preliminary evidence from a fMRI study.

Fatigue, defined as a subjective lack of physical and/or mental energy, is a clinical symptom highly characterizing multiple sclerosis (MS). The present study utilized a novel approach to the study of fatigue, examining first person-mental imagery of the symptom. Eighteen right-handed patients with MS (14F, 4 M, mean age 45.8 ± 8.15 years) were evaluated and were compared to nineteen healthy controls (10F, 9 M, mean age 43.15 ± 8.34 years) Patients were all in relapsing remitting form and no patient had presented relapses in the 6 months prior to inclusion in the study. We evaluated their behavioral performance and fMRI activations. We used an fMRI paradigm used to trigger first person-mental imagery of fatigue, through short sentences describing the principal manifestations of fatigue. Participants were asked to imagine the corresponding sensations (Sensory Imagery, SI). As a control, they had to imagine the visual scenes (Visual Imagery, VI) described in short phrases. They made a vividness rating by pressing the corresponding button. Behaviorally, we found that patients' mean scores at the Multidimensional Fatigue Symptom Inventory for the general scale, physical scale, and mental scale were significantly higher than healthy controls (p = 0.05, p = 0.002, p = 0.006 respectively), but not for the emotional scale and for vigor scale (p = 0.207, n.s., p = 0.06, n.s.). In the imagery fMRI task, patients were significantly slower (mean reaction times and standard deviation: 2.24 s ± 0.33) than controls (mean reaction times and standard deviation: 1.918 s ± 0.455) for the SI task (Z=-2.058, p = 0.040), while no significant difference was found for the VI task. Regarding brain mapping, our main result is a group by task interaction. The SI task (vs. VI task) in healthy controls (relative to patients) increased activation in the left inferior parietal lobule. These preliminary results indicate that fatigue is related to dysfunctions in higher-order aspects of motor control, given the role of the posterior parietal lobe in motor planning and multisensory integration.

Biomimetic Neuromorphic Sensory System via Electrolyte Gated Transistors.

Biomimetic neuromorphic sensing systems, inspired by the structure and function of biological neural networks, represent a major advancement in the field of sensing technology and artificial intelligence. This review paper focuses on the development and application of electrolyte gated transistors (EGTs) as the core components (synapses and neuros) of these neuromorphic systems. EGTs offer unique advantages, including low operating voltage, high transconductance, and biocompatibility, making them ideal for integrating with sensors, interfacing with biological tissues, and mimicking neural processes. Major advances in the use of EGTs for neuromorphic sensory applications such as tactile sensors, visual neuromorphic systems, chemical neuromorphic systems, and multimode neuromorphic systems are carefully discussed. Furthermore, the challenges and future directions of the field are explored, highlighting the potential of EGT-based biomimetic systems to revolutionize neuromorphic prosthetics, robotics, and human-machine interfaces. Through a comprehensive analysis of the latest research, this review is intended to provide a detailed understanding of the current status and future prospects of biomimetic neuromorphic sensory systems via EGT sensing and integrated technologies.

Intricate response dynamics enhances stimulus discrimination in the resource-limited C. elegans chemosensory system.

BACKGROUND: Sensory systems evolved intricate designs to accurately encode perplexing environments. However, this encoding task may become particularly challenging for animals harboring a small number of sensory neurons. Here, we studied how the compact resource-limited chemosensory system of Caenorhabditis elegans uniquely encodes a range of chemical stimuli. RESULTS: We find that each stimulus is encoded using a small and unique subset of neurons, where only a portion of the encoding neurons sense the stimulus directly, and the rest are recruited via inter-neuronal communication. Furthermore, while most neurons show stereotypical response dynamics, some neurons exhibit versatile dynamics that are either stimulus specific or network-activity dependent. Notably, it is the collective dynamics of all responding neurons which provides valuable information that ultimately enhances stimulus identification, particularly when required to discriminate between closely related stimuli. CONCLUSIONS: Together, these findings demonstrate how a compact and resource-limited chemosensory system can efficiently encode and discriminate a diverse range of chemical stimuli.

Form and Function in the Digenea, with an Emphasis on Host-Parasite and Parasite-Bacteria Interactions.

This review covers the general aspects of the anatomy and physiology of the major body systems in digenetic trematodes, with an emphasis on new knowledge of the area acquired since the publication of the second edition of this book in 2019. In addition to reporting on key recent advances in the morphology and physiology of tegumentary, sensory, neuromuscular, digestive, excretory, and reproductive systems, and their roles in host-parasite interactions, this edition includes a section discussing the known and putative roles of bacteria in digenean biology and physiology. Furthermore, a brief discussion of current trends in the development of novel treatment and control strategies based on a better understanding of the trematode body systems and associated bacteria is provided.

Artificial sensory system based on memristive devices.

In the biological nervous system, the integration and cooperation of parallel system of receptors, neurons, and synapses allow efficient detection and processing of intricate and disordered external information. Such systems acquire and process environmental data in real-time, efficiently handling complex tasks with minimal energy consumption. Memristors can mimic typical biological receptors, neurons, and synapses by implementing key features of neuronal signal-processing functions such as selective adaption in receptors, leaky integrate-and-fire in neurons, and synaptic plasticity in synapses. External stimuli are sensitively detected and filtered by "artificial receptors," encoded into spike signals via "artificial neurons," and integrated and stored through "artificial synapses." The high operational speed, low power consumption, and superior scalability of memristive devices make their integration with high-performance sensors a promising approach for creating integrated artificial sensory systems. These integrated systems can extract useful data from a large volume of raw data, facilitating real-time detection and processing of environmental information. This review explores the recent advances in memristor-based artificial sensory systems. The authors begin with the requirements of artificial sensory elements and then present an in-depth review of such elements demonstrated by memristive devices. Finally, the major challenges and opportunities in the development of memristor-based artificial sensory systems are discussed.

Flow sensing on dragonfly wings.

One feature of animal wings is their embedded mechanosensory system that can support flight control. Insect wings are particularly interesting as they are highly deformable yet the actuation is limited to the wing base. It is established that strain sensors on insect wings can directly mediate reflexive control; however, little is known about airflow sensing by insect wings. What information can flow sensors capture and how can flow sensing benefit flight control? Here, we use the dragonfly (Sympetrum striolatum) as a model to explore the function of wing sensory bristles in the context of flight control. Combining our detailed anatomical reconstructions of both the sensor microstructures and wing architecture, we used computational fluid dynamics simulations to ask the following questions. (1) Are there strategic locations on wings that sample flow for estimating aerodynamically relevant parameters such as the local effective angle of attack? (2) Is the sensory bristle distribution on dragonfly wings optimal for flow sensing? (3) What is the aerodynamic effect of microstructures found near the sensory bristles on dragonfly wings? We discuss the benefits of flow sensing for flexible wings and how the evolved sensor placement affects information encoding.

Adaptive Processing Enabled by Sodium Alginate Based Complementary Memristor for Neuromorphic Sensory System.

Adaptive processing allows sensory systems to autonomically adjust their sensitivity with exposure to a constant sensory stimulus and thus organisms to adapt to environmental variations. Bioinspired electronics with adaptive functions are highly desirable for the development of neuromorphic sensory systems (NSSs). Herein, the functions of desensitization and sensitivity changing with background intensity (i.e., Weber's law), as two fundamental cues of sensory adaptation, are biorealistically demonstrated in an Ag nanowire (NW)-embedded sodium alginate (SA) based complementary memristor. In particular, Weber's law is experimentally emulated in a single complementary memristor. Furthermore, three types of adaptive NSS unit are constructed to realize a multiple perceptual capability that processes the stimuli of illuminance, temperature, and pressure signals. Taking neuromorphic vision as an example, scotopic and photopic adaptation functions are well reproduced for image enhancement against dark and bright backgrounds. Importantly, an NSS system with multisensory integration function is demonstrated by combining light and pressure spikes, where the accuracy of pattern recognition is obviously enhanced relative to that of an individual sense. This work offers a new strategy for developing neuromorphic electronics with adaptive functions and paves the way toward developing a highly efficient NSS.

Motor Control of Distinct Layer 6 Corticothalamic Feedback Circuits.

Layer 6 corticothalamic (L6 CT) neurons provide massive input to the thalamus, and these feedback connections enable the cortex to influence its own sensory input by modulating thalamic excitability. However, the functional role(s) feedback serves during sensory processing is unclear. One hypothesis is that CT feedback is under the control of extrasensory signals originating from higher-order cortical areas, yet we know nothing about the mechanisms of such control. It is also unclear whether such regulation is specific to CT neurons with distinct thalamic connectivity. Using mice (either sex) combined with in vitro electrophysiology techniques, optogenetics, and retrograde labeling, we describe studies of vibrissal primary motor cortex (vM1) influences on different CT neurons in the vibrissal primary somatosensory cortex (vS1) with distinct intrathalamic axonal projections. We found that vM1 inputs are highly selective, evoking stronger postsynaptic responses in CT neurons projecting to the dual ventral posterior medial nucleus (VPm) and posterior medial nucleus (POm) located in lower L6a than VPm-only-projecting CT cells in upper L6a. A targeted analysis of the specific cells and synapses involved revealed that the greater responsiveness of Dual CT neurons was due to their distinctive intrinsic membrane properties and synaptic mechanisms. These data demonstrate that vS1 has at least two discrete L6 CT subcircuits distinguished by their thalamic projection patterns, intrinsic physiology, and functional connectivity with vM1. Our results also provide insights into how a distinct CT subcircuit may serve specialized roles specific to contextual modulation of tactile-related sensory signals in the somatosensory thalamus during active vibrissa movements.

An update and review of arthropod vector sensory systems: Potential targets for behavioural manipulation by parasites and other disease agents.

For over a century, vector ecology has been a mainstay of vector-borne disease control. Much of this research has focused on the sensory ecology of blood-feeding arthropods (black flies, mosquitoes, ticks, etc.) with terrestrial vertebrate hosts. Of particular interest are the cues and sensory systems that drive host seeking and host feeding behaviours as they are critical for a vector to locate and feed from a host. An important yet overlooked component of arthropod vector ecology are the phenotypic changes observed in infected vectors that increase disease transmission. While our fundamental understanding of sensory mechanisms in disease vectors has drastically increased due to recent advances in genome engineering, for example, the advent of CRISPR-Cas9, and high-throughput "big data" approaches (genomics, proteomics, transcriptomics, etc.), we still do not know if and how parasites manipulate vector behaviour. Here, we review the latest research on arthropod vector sensory systems and propose key mechanisms that disease agents may alter to increase transmission.

Neurobiological mechanisms underlying oxytocin-mediated parental behavior in rodents.

Parental behavior is essential for mammalian offspring to survive. Because of this significance, elucidating the neurobiological mechanisms that facilitate parental behavior has received strong interest. Decades of studies utilizing pharmacology and molecular biology have revealed that in addition to its facilitatory effects on parturition and lactation, oxytocin (OT) promotes the expression of parental behavior in rodents. Recent studies have also described the modulation of sensory processing by OT and the interaction of the OT system with other brain regions associated with parental behavior. However, the precise neurobiological mechanisms underlying the facilitation of caregiving behaviors by OT remain unclear. In this Review, I summarize the findings from rats and mice with a view toward integrating past and recent progress. I then review recent advances in the understanding of the molecular, cellular, and circuit mechanisms of OT-mediated parental behavior. Based on these observations, I propose a hypothetical model that would explain the mechanisms underlying OT-mediated parental behavior. Finally, I conclude by discussing some major remaining questions and propose potential future research directions.

Epithelial UNC-23 limits mechanical stress to maintain glia-neuron architecture in C. elegans.

For an organ to maintain correct architecture and function, its diverse cellular components must coordinate their size and shape. Although cell-intrinsic mechanisms driving homotypic cell-cell coordination are known, it is unclear how cell shape is regulated across heterotypic cells. We find that epithelial cells maintain the shape of neighboring sense-organ glia-neuron units in adult Caenorhabditis elegans (C. elegans). Hsp co-chaperone UNC-23/BAG2 prevents epithelial cell shape from deforming, and its loss causes head epithelia to stretch aberrantly during animal movement. In the sense-organ glia, amphid sheath (AMsh), this causes progressive fibroblast growth factor receptor (FGFR)-dependent disruption of the glial apical cytoskeleton. Resultant glial cell shape alteration causes concomitant shape change in glia-associated neuron endings. Epithelial UNC-23 maintenance of glia-neuron shape is specific both spatially, within a defined anatomical zone, and temporally, in a developmentally critical period. As all molecular components uncovered are broadly conserved across central and peripheral nervous systems, we posit that epithelia may similarly regulate glia-neuron architecture cross-species.

Subtle morphological changes in the visual and antennal sensory system of bees and wasps across an urbanisation gradient.

Increased temperature and fragmentation of green spaces in urban areas could drive variations in functional traits of insects. Such morphological shifts may occur for sensory systems, which were previously reported to be prone to change with habitat characteristics in non-urban contexts. Here, we measured traits related to the visual and antennal sensory systems in the bees Halictus scabiosae and Osmia cornuta and the wasp Polistes dominula along an urbanisation gradient within Milan (Italy). We hypothesised that fragmentation could filter for better visual properties, and that higher temperature could filter for fewer thermoreceptors and more olfactory hairs. While controlling for body size, results show subtle but appreciable responses to urbanisation in one or more traits in all species, though not always supporting our hypotheses. O. cornuta shows marginally higher ommatidia density and smaller ommatidia diameter (associated with better visual resolution) in more fragmented sites, as well as marginally fewer thermoreceptors in hotter sites, in agreement with our two predictions. On the other hand, H. scabiosae has marginally smaller antennae and P. dominula has smaller eyes at warmer locations, and the wasp also has smaller antennae and 9th flagellomeres in more fragmented areas. Perhaps higher temperatures accelerate development of sensory system at higher speed than the rest of body in these two species. Our results represent the first evidence of urbanisation effects on the visual and antennal sensory systems of bees and wasps and underline how such effects may involve a much broader bouquet of traits then previously observed.

Local age-dependent neuromodulation in Rhodnius prolixus antennae.

Kissing bugs do not respond to host cues when recently molted and only exhibit robust host-seeking several days after ecdysis. Behavioral plasticity has peripheral correlates in antennal gene expression changes through the week after ecdysis. The mechanisms regulating these peripheral changes are still unknown, but neuropeptide, G-protein coupled receptor, nuclear receptor, and takeout genes likely modulate peripheral sensory physiology. We evaluated their expression in antennal transcriptomes along the first week postecdysis of Rhodnius prolixus 5th instar larvae. Besides, we performed clustering and co-expression analyses to reveal relationships between neuromodulatory (NM) and sensory genes. Significant changes in transcript abundance were detected for 50 NM genes. We identified 73 sensory-related and NM genes that were assigned to nine clusters. According to their expression patterns, clusters were classified into four groups: two including genes up or downregulated immediately after ecdysis; and two with genes with expression altered at day 2. Several NM genes together with sensory genes belong to the first group, suggesting functional interactions. Co-expression network analysis revealed a set of genes that seem to connect with sensory system maturation. Significant expression changes in NM components were described in the antennae of R. prolixus after ecdysis, suggesting that a local NM system acts on antennal physiology. These changes may modify the sensitivity of kissing bugs to host cues during this maturation interval.

Corneal nerves and amyotrophic lateral sclerosis: an in vivo corneal confocal imaging study.

OBJECTIVES: Amyotrophic lateral sclerosis (ALS) is a severe motor neuron disorder. Diagnosis is challenging due to its clinical heterogeneity and the absence of definitive diagnostic tools, leading to delays averaging between 9.1 and 27 months. In vivo corneal confocal microscopy, assessing the sub-basal nerve plexus of the cornea, has been proposed as a potential biomarker for ALS. We aimed to determine whether the assessment of corneal nerves using in vivo confocal microscopy can serve as an imaging biomarker for ALS. METHODS: A single-centre prospective case-control study was conducted in France from September 2021 to March 2023 including patients with ALS according to the revised EI Escorial criteria. The corneal sub-basal nerve plexus was analysed using in vivo confocal microscopy. An automated algorithm (ACCMetrics) was used to evaluate corneal parameters: nerve fibre density, nerve branch density, nerve fibre length, nerve fibre area, nerve total branch density, nerve fibre width, and nerve fractal dimension. RESULTS: Twenty-two patients with ALS and 30 controls were included. No significant differences were found between ALS and control groups for all corneal parameters (p > 0.05). Corneal sensitivity did not differ between groups, and no correlation was identified between corneal nerve parameters and ALS disease duration, severity and rate of progression (p > 0.05). CONCLUSIONS: The present study does not support the use of in vivo corneal confocal microscopy as an early diagnostic or prognostic tool for ALS. Further research, especially longitudinal investigations, is needed to understand any potential corneal innervation changes as ALS progresses.

On the functional independence of numerical acuity and visual working memory.

Deciding where to direct our vehicle in a crowded parking area or where to line up at an airport gateway relies on our ability to appraise the numerosity of multitudes at a glimpse and react accordingly. Approximating numerosities without actually counting is an ontogenetically and phylogenetically primordial ability, given its presence in human infants shortly after birth, and in primate and non-primate animal species. Prior research in the field suggested that numerosity approximation is a ballistic automatism that has little to do with human cognition as commonly intended. Here, we measured visual working memory capacity using a state-of-the-art change detection task and numerosity approximation using a dot-comparison task, and found a null correlation between these two parametrical domains. By checking the evidential strength of the tested correlation using both classic and Bayesian analytical approaches, as well as the construct validity for working memory capacity and numerosity approximation estimates, we concluded that the present psychophysical evidence was sufficiently strong to support the view that visual working memory and numerosity approximation are likely to rely on functionally independent stages of processing of the human cognitive architecture.

Multisensory stimulation and its effect on breast milk volume production in mothers of premature infants.

Introduction: In a significant number of NICUs, mothers are unable to provide enough maternal milk to feed their premature babies, so healthcare workers rely on human milk banks. Unfortunately, this service is not available in many countries, such as Peru, where premature infants receive formula. The aim of this study was to determine the effectiveness of multisensory stimulation on mother's own milk production. Methods: Participants in this study were postpartum mothers of preterm infants 27-37 weeks gestational age. The participants were assigned to three groups: (1) audiovisual stimulation (SAV) (n = 17), (2) audiovisual and olfactory stimulation (SAVO) (n = 17), and (3) control (n = 16). A questionnaire was used to collect demographic and obstetric data, including a record of mother's own milk volume. Results: There was no significant difference between the SAV, SAVO and control groups regarding age, marital status, education level, occupation, number of children, mode of delivery, Apgar and birth weight. On the other hand, a significant difference was observed between the SAV and SAVO groups regarding the amount of milk produced, with higher production between the fourth and seventh day (Tukey p < 0.05). Similarly, milk volume was significantly greater in the SAVO group compared to the SAV and control groups (OR = 1.032, 95% CI = 1.0036-1.062, p < 0.027). Conclusion: Multisensory stimulation in postpartum mothers of preterm infants caused an increase in the volume of mother's own milk production. However, more research is needed to explain the findings presented in this study.

Distinct distribution of subplate neuron subtypes between the sensory cortices during the early postnatal period.

Subplate neurons (SpNs) are a heterogeneous neuronal population actively involved in early cortical circuit formation. In rodents, many SpNs survive and form layer 6b. The molecular heterogeneity of SpNs raises the question of whether different subpopulations of SpNs survive through the early postnatal period similarly and whether such diverse SpN populations in the auditory cortex (ACtx) share a common distribution pattern with other sensory systems. To address that, we investigated the expression pattern of multiple specific SpN markers in the ACtx, as well as in the visual (VCtx) and somatosensory (SCtx) cortices as controls, using complexin 3 (Cplx3) antibodies and different SpN-specific Cre-driver mice, such as connective tissue growth factor (CTGF), dopamine receptor D1 (Drd1a), and neurexophilin 4 (Nxph4). We focused on two early time windows in auditory development: (1) during the second postnatal week (PNW) before ear-canal opening and (2) during the third PNW after ear-canal opening. We compared the expression pattern of different SpN markers in ACtx with VCtx and SCtx. At both examined timepoints, Cplx3 and Nxph4 expressing SpNs form the largest and smallest population in the ACtx, respectively. Similar distribution patterns are observable in the VCtx and SCtx during the second PNW but not during the third PNW, for a higher proportion of Drd1a expressing SpNs is detected in the VCtx and CTGF expressing SpNs in the SCtx. This study suggests that different populations of SpNs might contribute differently to the development of individual sensory circuits.

Quantifying Human Gait Symmetry During Blindfolded Treadmill Walking.

Bilateral gait symmetry is an essential requirement for normal walking since asymmetric gait patterns increase the risk of falls and injuries. While human gait control heavily relies on the contribution of sensory inputs, the role of sensory systems in producing symmetric gait has remained unclear. This study evaluated the influence of vision as a dominant sensory system on symmetric gait production. Ten healthy adults performed treadmill walking with and without vision. Twenty-two gait parameters including ground reaction forces, joint range of motion, and other spatial-temporal gait variables were evaluated to quantify gait symmetry and compared between both visual conditions. Visual block caused increased asymmetry in most parameters of ground reaction force, however mainly in the vertical direction. When vision was blocked, symmetry of the ankle and knee joint range of motion decreased, but this change did not occur in the hip joint. Stance and swing time symmetry decreased during no-vision walking while no significant difference was found for step length symmetry between the two conditions. This study provides a comprehensive analysis to reveal how the visual system influences bilateral gait symmetry and highlights the important role of vision in gait control. This approach could be applied to investigate how vision alters gait symmetry in patients with disorders to help better understand the role of vision in pathological gaits.

Turbidity drives plasticity in the eyes and brains of an African cichlid.

Natural variation in environmental turbidity correlates with variation in the visual sensory system of many fishes, suggesting that turbidity may act as a strong selective agent on visual systems. Since many aquatic systems experience increased turbidity due to anthropogenic perturbations, it is important to understand the degree to which fish can respond to rapid shifts in their visual environment, and whether such responses can occur within the lifetime of an individual. We examined whether developmental exposure to turbidity (clear, <5 NTU; turbid, ∼9 NTU) influenced the size of morphological structures associated with vision in the African blue-lip cichlid Pseudocrenilabrus multicolor. Parental fish were collected from two sites (clear swamp, turbid river) in western Uganda. F1 broods from each population were split and reared under clear and turbid rearing treatments until maturity. We measured morphological traits associated with the visual sensory system (eye diameter, pupil diameter, axial length, brain mass, optic tectum volume) over the course of development. Age was significant in explaining variation in visual traits even when standardized for body size, suggesting an ontogenetic shift in the relative size of eyes and brains. When age groups were analyzed separately, young fish reared in turbid water grew larger eyes than fish reared in clear conditions. Population was important in the older age category, with swamp-origin fish having relatively larger eyes and optic lobes relative to river-origin fish. Plastic responses during development may be important for coping with a more variable visual environment associated with anthropogenically induced turbidity.

Remodelling the inguinal adipose sensory system to switch on the furnace: Electroacupuncture stimulation induces brown adipose thermogenesis.

Brown and white adipose tissue mediate thermogenesis through the thermogenetic centre of the brain, but safe methods for activating thermogensis and knowledge of the associated molecular mechanisms are lacking. We investigated body surface electroacupuncture stimulation (ES) at ST25 (targeted at the abdomen) induction of brown adipose thermogenesis and the neural mechanism of this process. Inguinal white adipose tissue (iWAT) and interscapular brown adipose tissue (iBAT) were collected and the thermogenic protein expression levels were measured to evaluate iBAT thermogenesis capacity. The thermogenic centre activating region and sympathetic outflow were evaluated based on neural electrical activity and c-fos expression levels. iWAT sensory axon plasticity was analysed with whole-mount adipose tissue imaging. ES activated the sympathetic nerves in iBAT and the c-fos-positive cells induced sympathetic outflow activation to the iBAT from the medial preoptic area (MPA), the dorsomedial hypothalamus (DM) and the raphe pallidus nucleus (RPA). iWAT denervation mice exhibited decreased c-fos-positive cells in the DM and RPA, and lower recombinant uncoupling orotein 1 peroxisome proliferator-activated receptor, ß3-adrenergic receptor, and tyrosine hydroxylase expression. Remodelling the iWAT sensory axons recovered the signal from the MPA to the RPA and induced iBAT thermogenesis. The sympathetic denervation attenuated sensory nerve density. ES induced sympathetic outflow from the thermogenetic centres to iBAT, which mediated thermogenesis. iWAT sensory axon remodelling induced the MPA-DM-RPA-iBAT thermogenesis pathway.