Groups Of Neurons Research Articles

Огляд досліджень в напрямку міоелектричного методу керування біонічним протезом

Myoelectric control of bionic prostheses is an important field of research in the field of rehabilitation. Intuitive and intelligent myoelectric control can restore upper limb function. However, much research now focuses on the development of various myoelectrical and biotechnical control methods, limiting research to the complex daily tasks of prosthetic manipulation, such as grasping and releasing. The article examines the latest advances in the research areas of bionic prosthesis management. In particular, attention is paid to the methods of determining movement intentions, classification of discrete movements, estimation of continuous movements, single-channel control, feedback control and combined control. Motor neurons group input signals from the central nervous system that affect muscles and form motor units. The electromyography (EMG) signal, which is obtained by recording motor neuron action potentials, reflects muscle activity. This signal, oscillating within ±5000 μV with a frequency of 6 to 500 Hz, reflects the characteristics of muscle contraction. Depending on the location of the sensors, EMG signals are divided into intramuscular and surface electromyography. Intramuscular electromyography provides an accurate study of muscle activation, but requires the implantation of sensors, which can lead to physical problems. EMG, which captures a signal from the surface of the skin, is easier to use and is widely used in experiments with myoelectric prostheses.

Multiple NTS neuron populations cumulatively suppress food intake.

Several discrete groups of feeding-regulated neurons in the nucleus of the solitary tract (nucleus tractus solitarius; NTS) suppress food intake, including avoidance-promoting neurons that express Cck (NTSCck cells) and distinct Lepr- and Calcr-expressing neurons (NTSLepr and NTSCalcr cells, respectively) that suppress food intake without promoting avoidance. To test potential synergies among these cell groups, we manipulated multiple NTS cell populations simultaneously. We found that activating multiple sets of NTS neurons (e.g. NTSLepr plus NTSCalcr [NTSLC], or NTSLC plus NTSCck [NTSLCK]) suppressed feeding more robustly than activating single populations. While activating groups of cells that include NTSCck neurons promoted conditioned taste avoidance (CTA), NTSLC activation produced no CTA despite abrogating feeding. Thus, the ability to promote CTA formation represents a dominant effect but activating multiple non-aversive populations augments the suppression of food intake without provoking avoidance. Furthermore, silencing multiple NTS neuron groups augmented food intake and body weight to a greater extent than silencing single populations, consistent with the notion that each of these NTS neuron populations plays crucial and cumulative roles in the control of energy balance. We found that silencing NTSLCK neurons failed to blunt the weight-loss response to vertical sleeve gastrectomy (VSG) and that feeding activated many non-NTSLCK neurons, however, suggesting that as-yet undefined NTS cell types must make additional contributions to the restraint of feeding.

Associative memory neurons of encoding multi-modal signals are recruited by neuroligin-3-mediated new synapse formation

The joint storage and reciprocal retrieval of learnt associated signals are presumably encoded by associative memory cells. In the accumulation and enrichment of memory contents in lifespan, a signal often becomes a core signal associatively shared for other signals. One specific group of associative memory neurons that encode this core signal likely interconnects multiple groups of associative memory neurons that encode these other signals for their joint storage and reciprocal retrieval. We have examined this hypothesis in a mouse model of associative learning by pairing the whisker tactile signal sequentially with the olfactory signal, the gustatory signal, and the tail-heating signal. Mice experienced this associative learning show the whisker fluctuation induced by olfactory, gustatory, and tail-heating signals, or the other way around, that is, memories to multi-modal associated signals featured by their reciprocal retrievals. Barrel cortical neurons in these mice become able to encode olfactory, gustatory, and tail-heating signals alongside the whisker signal. Barrel cortical neurons interconnect piriform, S1-Tr, and gustatory cortical neurons. With the barrel cortex as the hub, the indirect activation occurs among piriform, gustatory, and S1-Tr cortices for the second-order associative memory. These associative memory neurons recruited to encode multi-modal signals in the barrel cortex for associative memory are downregulated by neuroligin-3 knockdown. Thus, associative memory neurons can be recruited as the core cellular substrate to memorize multiple associated signals for the first-order and the second-order of associative memories by neuroligin-3-mediated synapse formation, which constitutes neuronal substrates of cognitive activities in the field of memoriology.

Associative memory neurons of encoding multi-modal signals are recruited by neuroligin-3-mediated new synapse formation.

The joint storage and reciprocal retrieval of learnt associated signals are presumably encoded by associative memory cells. In the accumulation and enrichment of memory contents in lifespan, a signal often becomes a core signal associatively shared for other signals. One specific group of associative memory neurons that encode this core signal likely interconnects multiple groups of associative memory neurons that encode these other signals for their joint storage and reciprocal retrieval. We have examined this hypothesis in a mouse model of associative learning by pairing the whisker tactile signal sequentially with the olfactory signal, the gustatory signal, and the tail-heating signal. Mice experienced this associative learning show the whisker fluctuation induced by olfactory, gustatory, and tail-heating signals, or the other way around, that is, memories to multi-modal associated signals featured by their reciprocal retrievals. Barrel cortical neurons in these mice become able to encode olfactory, gustatory, and tail-heating signals alongside the whisker signal. Barrel cortical neurons interconnect piriform, S1-Tr, and gustatory cortical neurons. With the barrel cortex as the hub, the indirect activation occurs among piriform, gustatory, and S1-Tr cortices for the second-order associative memory. These associative memory neurons recruited to encode multi-modal signals in the barrel cortex for associative memory are downregulated by neuroligin-3 knockdown. Thus, associative memory neurons can be recruited as the core cellular substrate to memorize multiple associated signals for the first-order and the second-order of associative memories by neuroligin-3-mediated synapse formation, which constitutes neuronal substrates of cognitive activities in the field of memoriology.

Zona incerta distributes a broad movement signal that modulates behavior

The zona incerta is a subthalamic nucleus made up mostly of GABAergic neurons. It has wide-ranging inputs and outputs and is believed to have many integrative functions that link sensory stimuli with motor responses to guide behavior. However, its role is not well established perhaps because few studies have measured the activity of zona incerta neurons in behaving animals under different conditions. To record the activity of zona incerta neurons during exploratory and cue-driven goal-directed behaviors, we used electrophysiology in head-fixed mice moving on a spherical treadmill and fiber photometry in freely moving mice. We found two groups of neurons based on their sensitivity to movement, with a minority of neurons responding to whisker stimuli. Furthermore, zona incerta GABAergic neurons robustly code the occurrence of exploratory and goal-directed movements, but not their direction. To understand the function of these activations, we performed genetically targeted lesions and optogenetic manipulations of zona incerta GABAergic neurons during exploratory and goal-directed behaviors. The results showed that the zona incerta has a role in modulating the movement associated with these behaviors, but this has little impact on overall performance. Zona incerta neurons distribute a broad corollary signal of movement occurrence to their diverse projection sites, which regulates behavior.

Zona incerta distributes a broad movement signal that modulates behavior.

The zona incerta is a subthalamic nucleus made up mostly of GABAergic neurons. It has wide-ranging inputs and outputs and is believed to have many integrative functions that link sensory stimuli with motor responses to guide behavior. However, its role is not well established perhaps because few studies have measured the activity of zona incerta neurons in behaving animals under different conditions. To record the activity of zona incerta neurons during exploratory and cue-driven goal-directed behaviors, we used electrophysiology in head-fixed mice moving on a spherical treadmill and fiber photometry in freely moving mice. We found two groups of neurons based on their sensitivity to movement, with a minority of neurons responding to whisker stimuli. Furthermore, zona incerta GABAergic neurons robustly code the occurrence of exploratory and goal-directed movements, but not their direction. To understand the function of these activations, we performed genetically targeted lesions and optogenetic manipulations of zona incerta GABAergic neurons during exploratory and goal-directed behaviors. The results showed that the zona incerta has a role in modulating the movement associated with these behaviors, but this has little impact on overall performance. Zona incerta neurons distribute a broad corollary signal of movement occurrence to their diverse projection sites, which regulates behavior.

Prelimbic and infralimbic responsivity to amygdala input is modified by gonadal hormones in parallel to low anxiety-like behavior in ovariectomized rats

Gonadal hormones may influence sexual activity by reducing anxiety. The basolateral amygdala (BLA) and prelimbic (PL) and infralimbic (IL) cortical regions comprise a loop that is related to fear, anxiety, and social behavior. In female ovariectomized rats, actions of estradiol, progesterone, and sequential estradiol and progesterone administration were explored in the open field test (OFT) and plus maze test (PMT) to evaluate signs of anxiety-like behavior. The three hormonal treatments reduced indicators of anxiety in the PMT but did not influence behavior in the OFT. In the same behaviorally tested rats under urethane anesthesia, single-unit extracellular recordings were obtained from the PL and IL during electrical stimulation of the BLA. The analysis of 250 ms peristimulus histograms showed that BLA stimulation produced two kinds of response. A small group of neurons increased their firing rate after BLA stimulation. Most neurons exhibited a reduction of spiking. Neurons that increased their firing rate after BLA stimulation did not show any difference with the hormonal treatments. In neurons that were inhibited by BLA stimulation, estradiol reduced the neuronal firing rate in the PL and IL, and progesterone alone and the sequential administration of estradiol followed by progesterone administration 24 h later (priming) increased the firing rate during the 240 ms before BLA stimulation. Analyses of responsivity of the PL and IL during electrical stimulation of the BLA indicated that estradiol, progesterone, and estradiol followed by progesterone administration 24 h later (priming) reduced inhibitory actions of the BLA on the PL but not IL. In the BLA-IL connection, progesterone exacerbated the inhibitory response. These findings indicate that anxiolytic actions of estradiol, progesterone, and estradiol followed by progesterone administration 24 h later (priming) correspond to lower BLA-PL responsivity. Actions of progesterone on BLA-IL responsivity appear to contribute to sexual activity by interacting with other forebrain structures that are also related to sexual receptivity.

A group of pancreatic islet β cell‐like neurons are vulnerable to energy deficiency

AbstractBackgroundAlzheimer’s disease (AD) bear resemblance to the diabetes mellitus for that both of them exhibit beta‐amyloid (Aβ) deposition, insulin resistance and glycometabolic disorder. Peripheral islet β cells produce insulin and islet amyloid peptides, but whether there is a group of neurons in the brain like islet β cells is not clear.MethodHybridize APP/PS1 transgenic mice and CaMKII‐CreERT2/+ ;Tpkfl/fl strain, with tamoxifen induced Tpk knockout at 6 months of age, to form a model of energy deficiency. Labeling neuron and microglia with NeuN and Iba1 antibody, and immunofluorescence was used to observe Aβ, insulin‐like growth factor expression. TUNEL staining was applied to test cell apoptosis.ResultWe found that layer 5 cortical pyramidal neurons are strongly marked by Aβ antibody, 4G8, in APP/PS1 transgenic mice. Immunofluorescence showed that these 4G8‐positive neurons colocalized with insulin‐like growth factor 1/2 and highly expressed prohormone convertase 2. Further, we conditionally knocked out Tpk gene, a key gene involved in glucose metabolism, in excitatory neurons of APP/PS1 mice. Over time, NeuN and Iba1 labeling showed that the significant loss of neuron and activation of microglia happened in layer 5 cerebral cortex at the earliest. Additionally, the 4G8‐positive neurons in this layer were stained by TUNEL and markedly reduced in the early stage.ConclusionWe found a group of islet β cell‐like neurons that are vulnerable to glucose energy impairment, suggesting a group of vulnerable neurons in sporadic AD, and implicating the cytological mechanism of association between AD and diabetes.

OFC neurons do not represent the negative value of a conditioned inhibitor

The orbitofrontal cortex (OFC) is often proposed to function as a value integrator; however, alternative accounts focus on its role in representing associative structures that specify the probability and sensory identity of future outcomes. These two accounts make different predictions about how this area should respond to conditioned inhibitors of reward, since in the former, neural activity should reflect the negative value of the inhibitor, whereas in the latter, it should track the estimated probability of a future reward based on all cues present. Here, we assessed these predictions by recording from small groups of neurons in the lateral OFC of rats during training in a conditioned inhibition design. Rats showed negative summation when the inhibitor was compounded with a novel excitor, suggesting that they learned to respond to the conditioned inhibitor appropriately. Against this backdrop, we found unit and population responses that scaled with expected reward value on excitor + inhibitor compound trials. However, the responses of these neurons did not differentiate between the conditioned inhibitor and a neutral cue when both were presented in isolation. Further, when the ensemble patterns were analyzed, activity to the conditioned inhibitor did not classify according to putative negative value. Instead, it classified with a same-modality neutral cue when presented alone and as a unique item when presented in compound with a novel excitor. This pattern of results supports the notion that OFC encodes a model of the causal structure of the environment rather than either the modality or the value of cues.

Selective vulnerability of motor neuron types and functional groups to degeneration in amyotrophic lateral sclerosis: review of the neurobiological mechanisms and functional correlates.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition characterised by a progressive loss of motor neurons controlling voluntary muscle activity. The disease manifests through a variety of motor dysfunctions related to the extent of damage and loss of neurons at different anatomical locations. Despite extensive research, it remains unclear why some motor neurons are especially susceptible to the disease, while others are affected less or even spared. In this article, we review the neurobiological mechanisms, neurochemical profiles, and morpho-functional characteristics of various motor neuron groups and types of motor units implicated in their differential exposure to degeneration. We discuss specific cell-autonomous (intrinsic) and extrinsic factors influencing the vulnerability gradient of motor units and motor neuron types to ALS, with their impact on disease manifestation, course, and prognosis, as revealed in preclinical and clinical studies. We consider the outstanding challenges and emerging opportunities for interpreting the phenotypic and mechanistic variability of the disease to identify targets for clinical interventions.

Mixed Selectivity Coding of Content-Temporal Detail by Dorsomedial Posterior Parietal Neurons.

The dorsomedial posterior parietal cortex (dmPPC) is part of a higher-cognition network implicated in elaborate processes underpinning memory formation, recollection, episode reconstruction, and temporal information processing. Neural coding for complex episodic processing is however under-documented. Here, we recorded extracellular neural activities from three male rhesus macaques (Macaca mulatta) and revealed a set of neural codes of "neuroethogram" in the primate parietal cortex. Analyzing neural responses in macaque dmPPC to naturalistic videos, we discovered several groups of neurons that are sensitive to different categories of ethogram items, low-level sensory features, and saccadic eye movement. We also discovered that the processing of category and feature information by these neurons is sustained by the accumulation of temporal information over a long timescale of up to 30 s, corroborating its reported long temporal receptive windows. We performed an additional behavioral experiment with additional two male rhesus macaques and found that saccade-related activities could not account for the mixed neuronal responses elicited by the video stimuli. We further observed monkeys' scan paths and gaze consistency are modulated by video content. Taken altogether, these neural findings explain how dmPPC weaves fabrics of ongoing experiences together in real time. The high dimensionality of neural representations should motivate us to shift the focus of attention from pure selectivity neurons to mixed selectivity neurons, especially in increasingly complex naturalistic task designs.

Design a New Neural Network Architecture Using a Layer of Neurons

Nowadays there are many different models of artificial neural networks. The difference between these models lies in the learning methods only, that is, in the rules for changing the parameters of the algorithm tuning, with or without links and side comments. While studying the general framework of network models, we see that the rules for obtaining the result and the mechanism for calculating the error can differ. For example, a multilayer realization might produce a threshold function when used as a classifier, or a linear function if used as an internal typeface.
 Where this research came to discuss the possibilities of the standard representation of some models of artificial neural networks, which clarify and treat some of the characteristics of that representation. Which can be considered an essential element in the process of typical representation of these networks, where a new proposal is made during this representation by using a “layer” of neurons, in other words, using a group of neurons that work in parallel and perform the same functions for which they were set .

The proneural factors Ascl1a and Ascl1b contribute to the terminal differentiation of dopaminergic GABAergic dual transmitter neurons in zebrafish

The proneural factor Ascl1 is involved in several steps of neurogenesis, from neural progenitor maintenance to initiation of terminal differentiation and neuronal subtype specification. In neural progenitor cells, Ascl1 initiates the cell-cycle exit of progenitors, and contributes to their differentiation into mainly GABAergic neurons. Several catecholaminergic neuron groups in the forebrain of zebrafish use GABA as co-transmitter, but a potential role of the two paralogues Ascl1a and Ascl1b in their neurogenesis is not understood. Here, we show that ascl1a, ascl1b double mutant embryos develop a significantly reduced number of neurons in all GABAergic and catecholaminergic dual transmitter neuron anatomical clusters in the fore- and hindbrain, while glutamatergic catecholaminergic clusters develop normally. However, none of the affected catecholaminergic cell clusters are lost completely, suggesting an impairment in progenitor pools, or a requirement of Ascl1a/b for differentiation of a subset of neurons in each cluster. Early progenitors which are dlx2a+, fezf2 + or emx2 + are not reduced whereas late progenitors and differentiating neurons marked by the expression of dlx5a, isl1 and arxa are severely reduced in ascl1a, ascl1b double mutant embryos. This suggests that Ascl1a and Ascl1b play only a minor or no role in the maintenance of their progenitor pools, but rather contribute to the initiation of terminal differentiation of GABAergic catecholaminergic neurons.

Caenorhabditis elegans: A transgenic model for studying age-associated neurodegenerative diseases.

Neurodegenerative diseases (NDs) are a heterogeneous group of aging-associated ailments characterized by interrupting cellular proteostasic machinery and the misfolding of distinct proteins to form toxic aggregates in neurons. Neurodegenerative diseases, which include Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and others, are becoming an increasing threat to human health worldwide. The degeneration and death of certain specific groups of neurons are the hallmarks of these diseases. Over the past decades, Caenorhabditis eleganshas beenwidely used as a transgenic model to investigate biological processes related to health and disease. The nematode Caenorhabditis elegans (C. elegans) has developed as a powerful tool for studying disease mechanisms due to its ease of genetic handling and instant cultivation while providing a whole-animal system amendable to several molecular and biochemical techniques. In this review, we elucidate the potential of C. elegans as a versatile platform for systematic dissection of the molecular basis of human disease, focusing on neurodegenerative disorders, and may help better our understanding of the disease mechanisms and search for new therapeutics for these devastating diseases.

Receptive field surround influences on the neuron’s activity in extrastriate area 21a.

The formation of the neuron response to the specific visual stimulus is attributed to the involvement of many interconnected neuron groups, various both qualitatively and quantitatively. The main aim of the present study was to identify patterns of modulating influences exerted on the neuron response patterns when the space surrounding their receptive fields (RF) was stimulated. The presented results demonstrated that the parallel and synchronous activation of the surrounding RF space significantly modulates the response patterns of neurons in area 21a to the moving visual stimuli. This modulation can have both facilitating and inhibitory effects. In most cases (68%), activation of the near environment of the RF had a facilitating effect, while stimulation of more distant areas of the visual field led to inhibition of responses. These data suggest that the coordinated interaction among a multitude of simultaneously activated neurons with overlapping RFs may play a crucial role in the integration and diversification of incoming visual information.

Effect of non-selective NO-synthase inhibitor administered during pregnancy on the development of the cerebral cortex in 20-day-old rat pups

Aim. To study the morphology of neurons in the cerebral cortex of rat pups on day 20 under conditions of administration of a nitric oxide synthase inhibitor (NOS) during placentation.Materials and methods. Outbred white female rats (n = 12) were randomly divided into 2 groups of 6 rats each. On the 11th day of pregnancy, the experimental group received a single intramuscular injection of N(omega)-nitro-L-arginine methyl ester (L NAME) at a dose of 25 mg/kg, in the control group – once intramuscularly 0.9% NaCl solution. Born rat pups were randomly selected one from the mother. On the 20th day, after medical euthanasia, the brain was collected. In the anterior part of the frontal cortex, we studied the density and area of neurons, the size and shape of perikarya and the severity of their staining with toluidine blue. Results. In the experimental group of 20-day-old rat pups, compared to the control group, the density and area of neurons were less by 10% (p > 0.05) and 22% (p > 0.05), respectively, the shape of the perikarya also changed to elongated, the elongation factor increased by 0.3 units. (p < 0.05) and there was a sixfold increase in the proportion of hyperchromic neurons (p < 0.05), hyperchromic wrinkled (p < 0.001) neurons appeared, which were absent in control animals. Conclusion. Morphological changes in neurons of the cerebral cortex in rat pups born from females who received a NOS inhibitor during placentation may be a consequence of a decrease in the formation of nitric oxide in the neurons themselves and in the endothelium of the vessels supplying the brain

Light and dark cycles modify the expression of clock genes in the ovaries of Aedes aegypti in a noncircadian manner.

Circadian oscillators (i.e., circadian clocks) are essential to producing the circadian rhythms observed in virtually all multicellular organisms. In arthropods, many rhythmic behaviors are generated by oscillations of the central pacemaker, specific groups of neurons of the protocerebrum in which the circadian oscillator molecular machinery is expressed and works; however, oscillators located in other tissues (i.e., peripheral clocks) could also contribute to certain rhythms, but are not well known in non-model organisms. Here, we investigated whether eight clock genes that likely constitute the Aedes aegypti clock are expressed in a circadian manner in the previtellogenic ovaries of this mosquito. Also, we asked if insemination by conspecific males would alter the expression profiles of these clock genes. We observed that the clock genes do not have a rhythmic expression profile in the ovaries of virgin (VF) or inseminated (IF) females, except for period, which showed a rhythmic expression profile in ovaries of IF kept in light and dark (LD) cycles, but not in constant darkness (DD). The mean expression of seven clock genes was affected by the insemination status (VF or IF) or the light condition (LD 12:12 or DD), among which five were affected solely by the light condition, one solely by the insemination status, and one by both factors. Our results suggest that a functional circadian clock is absent in the ovaries of A. aegypti. Still, their differential mean expression promoted by light conditions or insemination suggests roles other than circadian rhythms in this mosquito's ovaries.

FRI419 Progesterone Regulation Of The GnRH Pulse Generator

Abstract Disclosure: E.G. Wall: None. A group of kisspeptin neurons located in the arcuate nucleus (ARN) of the hypothalamus represent the GnRH pulse generator and their activity is thought to be controlled primarily by the feedback actions of estradiol and progesterone (P4). In a healthy menstruating woman, following the mid-cycle ovulation, P4 levels dramatically increase and exert a negative feedback action onto the hypothalamus to slow pulsatile LH secretion. However, the exact mechanism by which P4 negatively feeds back to the hypothalamus remains unknown. The ARN kisspeptin neurons display synchronized episodes (SEs) of activity approximately every hour for most of the cycle but these dramatically reduce in number following the LH surge. As these ARN kisspeptin neurons express the progesterone receptor (PR) it is hypothesized that they may be the site at which P4 negative feedback occurs. Given the lack of detailed information in the mouse, we first assessed the profile of circulating P4 levels in mice at 8-hr intervals throughout the estrous cycle. Terminal blood samples were taken from individual mice along the 4 stages of the estrous cycle at 3-time points 8 hrs apart and the gonadal hormones were analyzed using LC-MS. The concentration of P4 was found to peak around the time of the LH surge at 6 pm on proestrus (21.94 ± 3.78 ng/ml) and was at its lowest at diestrus 10 am (0.42 ± 0.11 ng/ml). We next assessed the impact of circulating P4 on the activity of the ARN kisspeptin pulse generator using GCaMP fibre photometry in freely behaving mice. A prior study found that IP administration of 8 mg/kg P4 resulted in circulating P4 concentrations reaching 34 ng/ml (Wong et al., J Pharm Pharmacol 64, 2012). Hence, in this study, diestrus mice equipped for monitoring the activity of the kisspeptin pulse generator were injected with either 8 or 4 mg/kg P4 at 10 am and SEs monitored for 24 hrs. Both doses resulted in a significantly decreased frequency of SEs compared to the vehicle (p<0.05), which persisted for 6 hrs. To next examine whether P4 may be acting directly on the ARN kisspeptin neurons to slow pulse generation, P4 (25 ng/ml) was infused directly into the ARN while the activity of the pulse generator was monitored. Again, this resulted in a decreased frequency of SEs compared to the vehicle with the effects lasting approximately 5 hrs (p<0.05).These results indicate that P4 exerts powerful inhibitory control over the activity of the kisspeptin pulse generator and that these effects may be direct. Elucidating the mechanisms of P4 negative feedback may provide a platform for the development of new therapeutic strategies in the infertility clinic. Presentation: Friday, June 16, 2023

Inferring population dynamics in macaque cortex

Objective. The proliferation of multi-unit cortical recordings over the last two decades, especially in macaques and during motor-control tasks, has generated interest in neural ‘population dynamics’: the time evolution of neural activity across a group of neurons working together. A good model of these dynamics should be able to infer the activity of unobserved neurons within the same population and of the observed neurons at future times. Accordingly, Pandarinath and colleagues have introduced a benchmark to evaluate models on these two (and related) criteria: four data sets, each consisting of firing rates from a population of neurons, recorded from macaque cortex during movement-related tasks. Approach. Since this is a discriminative-learning task, we hypothesize that general-purpose architectures based on recurrent neural networks (RNNs) trained with masking can outperform more ‘bespoke’ models. To capture long-distance dependencies without sacrificing the autoregressive bias of recurrent networks, we also propose a novel, hybrid architecture (‘TERN’) that augments the RNN with self-attention, as in transformer networks. Main results. Our RNNs outperform all published models on all four data sets in the benchmark. The hybrid architecture improves performance further still. Pure transformer models fail to achieve this level of performance, either in our work or that of other groups. Significance. We argue that the autoregressive bias imposed by RNNs is critical for achieving the highest levels of performance, and establish the state of the art on the neural latents benchmark. We conclude, however, by proposing that the benchmark be augmented with an alternative evaluation of latent dynamics that favors generative over discriminative models like the ones we propose in this report.

MORPHOMETRIC PARAMETERS OF THE HUMAN FETUS PONS 17-18 WEEKS OF INTRAUTERINE DEVELOPMENT

Relevance. Currently, increased interest is observed in the early stages of postnatal ontogenesis in research of age-related changes in the systems of the human body.
 Aim: To define the macrometric parameters of the pons of human fetuses of 17-18 weeks of fetal development, the sizes and area of the cranial nerve nuclei contained in pons, as well as the size and area of the nerve cells that form these nuclei.
 Materials and methods: We performed an anatomical and histological examination of 10 human fetuses at the stage of 17-18 weeks of intrauterine development.
 Results: The boundaries of the nucleus of the abductor nerve are unclear, the neurons of the nucleus are spherical or rounded in shape. The vestibular nucleus of the vestibulocochlear nerve has an indeterminate shape, the boundaries of the nucleus are not clear, neurons with different areas of the nucleus are noted, from large to small. The motor nucleus of the facial nerve has an elongated shape, with not clear outer edges, the nerve cells are dome-shaped. The principal nucleus of the trigeminal nerve has a rounded shape.
 Conclusions: We established that at 17-18 weeks of intrauterine development of human fetuses, the nucleus of the abductor nerve, the motor nucleus of the facial nerve, the principal nucleus of the trigeminal nerve, and the vestibular nucleus of the vestibulocochlear nerve were visualized. Nucleus of the abductor nerve has the largest area, the smallest -has the vestibular nucleus of the vestibulocochlear nerve. The largest area of neurons of the vestibular nucleus was established in comparison with the area of the nucleus of the facial, trigeminal and abductor nerves. The diameter and area of the nuclei of the cells of the abductor nerve, the motor nucleus of the facial nerve, and the principal nucleus of the trigeminal nerve have almost the same size, while the area of the neurons of the vestibulocochlear nerve is different, there is a group of neurons with a large area, and there is a group with a much smaller area of neurons.