Small Set Of Neurons Research Articles

Contribution of neurons that express fruitless and Clock transcription factors to behavioral rhythms and courtship.

Animals need to integrate information across neuronal networks that direct reproductive behaviors and circadian rhythms. In Drosophila, the master regulatory transcription factors that direct courtship behaviors and circadian rhythms are co-expressed in a small set of neurons. In this study we investigate the role of these neurons in both males and females. We find sex-differences in the number of these fruitless and Clock -expressing neurons ( fru ∩ Clk neurons) that is regulated by male-specific Fru. We assign the fru ∩ Clk neurons to the electron microscopy connectome that provides high resolution structural information. We also discover sex-differences in the number of fru -expressing neurons that are post-synaptic targets of Clk -expressing neurons, with more post-synaptic targets in males. When fru ∩ Clk neurons are activated or silenced, males have a shorter period length. Activation of fru ∩ Clk neurons also changes the rate a courtship behavior is performed. We find that activation and silencing fru ∩ Clk neurons impacts the molecular clock in the sLNv master pacemaker neurons, in a cell-nonautonomous manner. These results reveal how neurons that subserve the two processes, reproduction and circadian rhythms, can impact behavioral outcomes in a sex-specific manner.

АНАЛИЗ СОВРЕМЕННЫХ СПОСОБОВ ПРИКЛАДНОГО ИСПОЛЬЗОВАНИЯ СВЕРТОЧНЫХ НЕЙРОННЫХ СЕТЕЙ В ГОРНОЙ ПРОМЫШЛЕННОСТИ

Currently there are a lot of image recognition tasks, that are being successfully solved by the use of different types of neural networks. In its turn, the leading type of neural networks architecture for mentioned tasks class is convolutional neural network (CNN). Convolutional neural networks consist of multiple layers with small sets of neurons. Each of the neurons represents a small part of the original image. Combining all sets of neurons in a layer gives us a complete representation of the image. Other layers repeat this algorithm, but work with the same image presented in a different way, allowing the system as a whole to «learn» what the picture ultimately consists of. For example, each of the convolution layers can be responsible for highlighting certain features in the image (contour lines, flat areas, sharp edges). Research results. In this article we present a classification of groups, that reflect main directions of neural networks usage in mining industry. Different examples of implemented real-world use-cases were presented. Some important CNN-algorithm alterations were mentioned and explained. Conclusion. As we can see, many major mining process stages are positively affected by the usage of convolutional neural network. Machine learning algorithms help to find illegal deposits, maintain security and stability while mining and mineral processing goes on. Neural networks are being successfully trained by researchers to work with satellite map pictures, mineral surface photos and plots of signals from various engineering equipment. It is worth mentioning, that many researchers work for solving similar industry problems, but every time they have to slightly (or drastically) change CNN algorithm details to complete the tasks for the certain material type or certain GIS object type. Resume. The high growth rate of popularity of neural networks in the mining industry was made possible due to many factors. For example, the accumulation of large amounts of digital data (satellite images, dependency graphs, photo and video materials from real-world objects) has made the process of selecting materials for CNN training and testing easier and more efficient.

Do flies dream of protein? How the gut regulates sleep depth

A recent study by Titos etal. in Cell shows that protein-rich diets are strong modulators of sleep depth in Drosophila and identifies the gut-secreted neuropeptide CCHa1 as the mediator of this effect. In the brain, CCHa1 controls dopamine release from a small set of neurons, thereby modulating arousability by integrating internal state with sensory information.

Reactivating hippocampal-mediated memories during reconsolidation to disrupt fear

Memories are stored in the brain as cellular ensembles activated during learning and reactivated during retrieval. Using the Tet-tag system in mice, we label dorsal dentate gyrus neurons activated by positive, neutral or negative experiences with channelrhodopsin-2. Following fear-conditioning, these cells are artificially reactivated during fear memory recall. Optical stimulation of a competing positive memory is sufficient to update the memory during reconsolidation, thereby reducing conditioned fear acutely and enduringly. Moreover, mice demonstrate operant responding for reactivation of a positive memory, confirming its rewarding properties. These results show that interference from a rewarding experience can counteract negative affective states. While memory-updating, induced by memory reactivation, involves a relatively small set of neurons, we also find that activating a large population of randomly labeled dorsal dentate gyrus neurons is effective in promoting reconsolidation. Importantly, memory-updating is specific to the fear memory. These findings implicate the dorsal dentate gyrus as a potential therapeutic node for modulating memories to suppress fear.

Recording from Snail Motor Nerves to Investigate Central Pattern Generation.

Feeding in pond snails has long been a model system for central pattern generation and its modulation. The pattern is generated by a small set of neurons in the buccal ganglia, which innervate the buccal mass, esophagus, and salivary glands. In this exercise, students observe feeding behavior and then record and quantify rhythmic motor activity and its response to feeding stimulants and neuromodulators. In a standard three-hour class period, students do a dissection, record from several nerves, and perform experimental manipulations such as adding feeding stimulants, serotonin, or dopamine to the preparation. Depending on the course goals, data can be presented qualitatively or cyclic measurements and spike-rate analysis can be done. This exercise leads to discussion of neural circuitry and intrinsic properties that support pattern generation for rhythmic activities such as feeding, locomotion, and respiration.

Investigation of Drosophila fruitless neurons that express Dpr/DIP cell adhesion molecules.

Drosophila reproductive behaviors are directed by fruitless neurons. A reanalysis of genomic studies shows that genes encoding dpr and DIP immunoglobulin superfamily (IgSF) members are expressed in fru P1 neurons. We find that each fru P1 and dpr/DIP (fru P1 ∩ dpr/DIP) overlapping expression pattern is similar in both sexes, but there are dimorphisms in neuronal morphology and cell number. Behavioral studies of fru P1 ∩ dpr/DIP perturbation genotypes indicate that the mushroom body functions together with the lateral protocerebral complex to direct courtship behavior. A single-cell RNA-seq analysis of fru P1 neurons shows that many DIPs have high expression in a small set of neurons, whereas the dprs are often expressed in a larger set of neurons at intermediate levels, with a myriad of dpr/DIP expression combinations. Functionally, we find that perturbations of sex hierarchy genes and of DIP-ε change the sex-specific morphologies of fru P1 ∩ DIP-α neurons.

O-GlcNAcylation regulates dopamine neuron function, survival and degeneration in Parkinson disease.

The dopamine system in the midbrain is essential for volitional movement, action selection, and reward-related learning. Despite its versatile roles, it contains only a small set of neurons in the brainstem. These dopamine neurons are especially susceptible to Parkinson's disease and prematurely degenerate in the course of disease progression, while the discovery of new therapeutic interventions has been disappointingly unsuccessful. Here, we show that O-GlcNAcylation, an essential post-translational modification in various types of cells, is critical for the physiological function and survival of dopamine neurons. Bidirectional modulation of O-GlcNAcylation importantly regulates dopamine neurons at the molecular, synaptic, cellular, and behavioural levels. Remarkably, genetic and pharmacological upregulation of O-GlcNAcylation mitigates neurodegeneration, synaptic impairments, and motor deficits in an animal model of Parkinson's disease. These findings provide insights into the functional importance of O-GlcNAcylation in the dopamine system, which may be utilized to protect dopamine neurons against Parkinson's disease pathology.

Altered expression of ionotropic L-Glutamate receptors in aged sensory neurons of Aplysia californica.

The simplified nervous system of Aplysia californica (Aplysia) allows for detailed studies of physiological and molecular changes in small sets of neurons. Sensory neurons of the biting and tail withdrawal reflexes are glutamatergic and show reduced L-Glutamate current density in aged animals, making them a good candidate to study age-related changes in glutamatergic responses. To examine if changes in ionotropic L-Glu receptor (iGluR) transcription underlie reduced physiology, mRNA expression of iGluR was quantified in two sensory neuron clusters of two cohorts of Aplysia at both sexual maturity (~8 months) and advanced age (~12 months). Sensory neuron aging resulted in a significant overall decrease in expression of iGluR subunits in both sensory neuron clusters and cohorts. Although the individual subunits differentially expressed varied between sensory neuron clusters and different cohorts of animals, all differentially expressed subunits were downregulated, with no subunits showing significantly increased expression with age. Overall declines in transcript expression suggest that age-related declines in L-Glu responsiveness in Aplysia sensory neurons could be linked to overall declines in iGluR expression, rather than dysregulation of specific subunits. In both sensory neuron clusters tested the N-methyl-D-aspartate receptor subtype was expressed at significantly greater levels than other iGluR subtypes, suggesting an in vivo role for NMDAR-like receptors in Aplysia sensory neurons.

Microstimulation in a spiking neural network model of the midbrain superior colliculus.

The midbrain superior colliculus (SC) generates a rapid saccadic eye movement to a sensory stimulus by recruiting a population of cells in its topographically organized motor map. Supra-threshold electrical microstimulation in the SC reveals that the site of stimulation produces a normometric saccade vector with little effect of the stimulation parameters. Moreover, electrically evoked saccades (E-saccades) have kinematic properties that strongly resemble natural, visual-evoked saccades (V-saccades). These findings support models in which the saccade vector is determined by a center-of-gravity computation of activated neurons, while its trajectory and kinematics arise from downstream feedback circuits in the brainstem. Recent single-unit recordings, however, have indicated that the SC population also specifies instantaneous kinematics. These results support an alternative model, in which the desired saccade trajectory, including its kinematics, follows from instantaneous summation of movement effects of all SC spike trains. But how to reconcile this model with microstimulation results? Although it is thought that microstimulation activates a large population of SC neurons, the mechanism through which it arises is unknown. We developed a spiking neural network model of the SC, in which microstimulation directly activates a relatively small set of neurons around the electrode tip, which subsequently sets up a large population response through lateral synaptic interactions. We show that through this mechanism the population drives an E-saccade with near-normal kinematics that are largely independent of the stimulation parameters. Only at very low stimulus intensities the network recruits a population with low firing rates, resulting in abnormally slow saccades.

Electrical stimulation in a spiking neural network model of monkey superior colliculus.

The superior colliculus (SC) generates saccades by recruiting a population of cells in its topographically organized motor map. Supra-threshold electrical stimulation in the SC produces a normometric saccade with little effect of the stimulation parameters. Moreover, the kinematics of electrically evoked saccades strongly resemble natural, visual-evoked saccades. These findings support models in which the saccade vector is determined by a center-of-gravity computation of activated neurons, while trajectory and kinematics arise in brainstem-cerebellar feedback circuits. Recent single-unit recordings, however, have indicated that the SC population also specifies the instantaneous saccade kinematics, supporting an alternative model, in which the saccade trajectory results from dynamic summation of movement effects of all SC spike trains. Here we reconcile the linear summation model with stimulation results, by assuming that the electric field directly activates a relatively small set of neurons around the electrode tip, which subsequently sets up a large population response through lateral synaptic interactions.

Single Neurons in the Insular Cortex of a Macaque Monkey Respond to Skin Brushing: Preliminary Data of the Possible Representation of Pleasant Touch.

Pleasant touch may serve as a foundation for affiliative behavior, providing a mechanism for the formation and maintenance of social bonds among conspecifics. In humans, this touch is usually referred to as the caress. Dynamic caressing performed on the hairy skin with a velocity of 1–10 cm/s is perceived as being pleasant and determines positive cardio-physiological effects. Furthermore, imaging human studies show that affiliative touch activates the posterior insular cortex (pIC). Recently, it was demonstrated that pleasant touch in monkeys (i.e., sweeping in a grooming-like manner) is performed with velocities similar to those characteristics of human caress (9.31 cm/s), and causes similarly positive autonomic effects, if performed with velocity of 5 cm/s and 10 cm/s, but not lower or higher. Due to similarities between the human caress and non-human primate sweeping, we investigated for the first time whether single neurons of the perisylvian regions (secondary somatosensory cortex [SII] and pIC) of a rhesus monkey can process sweeping touch differently depending on the stimulus speed. We applied stimulation with two speeds: one that optimally induces positive cardio-physiological effects in the monkey who receives it, and includes the real speed of sweep (5–15 cm/s, sweep fast), and a non-optimal speed (1–5 cm/s, sweep slow). The results show that single neurons of insular cortex differently encode the stimulus speed. In particular, even the majority of recorded somatosensory neurons (82.96%) did not discriminate the two speeds, a small set of neurons (16.59%) were modulated just during the sweep fast. These findings represent the first evidence that single neurons of the non-human primates insular cortex can code affiliative touch, highlighting the similarity between human and non-human primates’ social touch systems. This study constitutes an important starting point to carry out deeper investigation on neuronal processing of pleasant sweeping in the central nervous system.

A colourful clock.

Circadian rhythms are an essential property of life on Earth. In mammals, these rhythms are coordinated by a small set of neurons, located in the suprachiasmatic nuclei (SCN). The environmental light/dark cycle synchronizes (entrains) the SCN via a distinct pathway, originating in a subset of photosensitive retinal ganglion cells (pRGCs) that utilize the photopigment melanopsin (OPN4). The pRGCs are also innervated by rods and cones and, so, are both endogenously and exogenously light sensitive. Accumulating evidence has shown that the circadian system is sensitive to ultraviolet (UV), blue, and green wavelengths of light. However, it was unclear whether colour perception itself can help entrain the SCN. By utilizing both behavioural and electrophysiological recording techniques, Walmsley and colleagues show that multiple photic channels interact and enhance the capacity of the SCN to synchronize to the environmental cycle. Thus, entrainment of the circadian system combines both environmental irradiance and colour information to ensure that internal and external time are appropriately aligned.

Transcriptional analysis of a whole-body form of long-term habituation in Aplysia californica.

Habituation is the simplest form of learning, but we know little about the transcriptional mechanisms that encode long-term habituation memory. A key obstacle is that habituation is relatively stimulus-specific and is thus encoded in small sets of neurons, providing poor signal/noise ratios for transcriptional analysis. To overcome this obstacle, we have developed a protocol for producing whole-body long-term habituation of the siphon-withdrawal reflex (SWR) of Aplysia californica. Specifically, we constructed a computer-controlled brushing apparatus to apply low-intensity tactile stimulation over the entire dorsal surface of Aplysia at regular intervals. We found that 3 d of training (10 rounds of stimulation/day; each round = 15 min brushing at a 10-sec ISI; 15-min rest between rounds) produces habituation with several characteristics favorable for mechanistic investigation. First, habituation is widespread, with SWR durations reduced whether the reflex is evoked by tactile stimulation to the head, tail, or the siphon. Second, long-term habituation is sensitive to the pattern of training, occurring only when brushing sessions are spaced out over 3 d rather than massed into a single session. Using a custom-designed microarray and quantitative PCR, we show that long-term habituation produces long-term up-regulation of an apparent Aplysia homolog of cornichon, a protein important for glutamate receptor trafficking. Our training paradigm provides a promising starting point for characterizing the transcriptional mechanisms of long-term habituation memory.

IMMUNOLOCALIZATION OF TWO PUTATIVE PIGMENTOTROPINS AKH I AND -MSH-LIKE IMMUNOREACTIVITIES IN THE BRAIN OF ROUGH WOODLOUSE, PORCELLIO SCABER AND PILL BUGS ARMADILLIDIUM VULGARE (CRUSTACEA, ISOPODA).

Antisera against putative pigmentotropic neuropeptides, Adipokinetic hormone I (AKH I) and α-Melanocyte stimulating hormone (α-MSH) reacted with small sets of neurons in the cephalic ganglia of the isopoda Porcellio scaber and Armadillidium vulgare. The distributions of immunoreactivities resembled in the two species. AKH I-like immunoreactivity (AKH I-ir) occurs in both species. In P scaber 5 cells occurred in the optic lobe (OL) (3 small near Lamina ganglionaris, LG and 2 large dorsally) while in A.vulgare only one small cell near LG. The accessory lobe (AL) and subesophageal mass (SM) have the same pattern in both species. There are 2 cells in AL and 6 cells in SM (in the cells of mandibular ganglion,CMD). α-MSH immunoreactivity (α-MSH-ir) were located in OL, and SM in both species and in AL of A.vulgare. In P. scaber two large perikarya were located dorsally, one small ventrally, while in A.vulgare 4 large dorsally, one small ventrally and strong reactivity in pseudo-frontal organ (PFO). In AL, 3 immunopositive cells were observed. In SM 6 cells (4 in CMD, 2 in the cells of maxillulary ganglion, CML) in P scaber and 8 cells (6 in CMD, 2 in CML) were observed in A. vulgare. These results suggest the possible existence of AKH-like and α-MSH-like peptides in isopoda. No differences were detected between males and females. The projections of immunoreactive fibers were traced to several brain regions, the somatogastric nervous system and the neurohaemal organs, which suggest multiple functions of these peptides.

A pair of identified giant visual projection neurons demonstrates rhythmic activities before eclosion

A small set of neurons acting as an internal clock in the Drosophila brain is critical for regulating circadian activities behavior and pre-adult development. However, the cell basis for the circadian rhythm in correlation with light sensitivity is not fully understood. Here we identified a pair of giant visual projection neurons located laterally to the calyx of the mushroom bodies, and investigated their electrophysiological, morphological characteristics, as well as the development pathways during eclosion. The typical morphology of these giant neurons showed the size of the soma (16.0±0.6 microns in diameter) and its processes. Interestingly during development, the three major branches shrunk significantly along with gradually decreased rhythmic spikes. Furthermore, the electrical activity of the giant visual projection neurons is circadian-regulated, shown with significantly higher resting membrane potential, increase in frequency of spontaneous action potential firing, and burst firing pattern during circadian day and night time. The similarities in the morphological characteristics with other visual projection neurons highly suggest that this neuron is a type of novel visual projection neurons in this area, which has special properties in light sensitivities and rhythmic activities. Our data provided supporting evidence for the visual projection neurons with light sensitivities, and pointed to the potential correlation of visual projection neurons and circadian rhythms during the eclosion period or an adaptive development for higher sensitivity of light in adult visual systems.

Enhanced Optomotor Efficiency by Expression of the Human Gene Superoxide Dismutase Primarily in Drosophila Motorneurons

Mutation of the human gene superoxide dismutase (hSOD1) triggers the fatal neurodegenerative motorneuron disorder, familial amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease). Broad expression of this gene in Drosophila has no effect on longevity or functional senescence. We show here that restricting expression of human SOD1 primarily to motorneurons of Drosophila has significant effects on optomotor efficiency during in-flight tracking of rapidly moving visual targets. Under high-stress workloads with a recursive visual-motion stimulus cycle, young isogenic controls failed to track rapidly changing visual cues, whereas their same-aged hSOD1-activated progeny maintained coordinated in-flight tracking of the target by phase locking to the dynamic visual movement patterns. Several explanations are considered for the observed effects, including antioxidant intervention in motorneurons, changes in signal transduction pathways that regulate patterns of gene expression in other cell types, and expression of hSOD1 in a small set of neurons in the central brain. That hSOD1 overexpression improves sensorimotor coordination in young organisms may suggest possible therapeutic strategies for early-onset ALS in humans.

A Small Group of Neurosecretory Cells Expressing the Transcriptional Regulatoraponticand the NeuropeptidecorazoninMediate Ethanol Sedation in Drosophila

In the fruit fly Drosophila melanogaster, as in mammals, acute exposure to a high dose of ethanol leads to stereotypical behavioral changes beginning with increased activity, followed by incoordination, loss of postural control, and eventually, sedation. The mechanism(s) by which ethanol impacts the CNS leading to ethanol-induced sedation and the genes required for normal sedation sensitivity remain largely unknown. Here we identify the gene apontic (apt), an Myb/SANT-containing transcription factor that is required in the nervous system for normal sensitivity to ethanol sedation. Using genetic and behavioral analyses, we show that apt mediates sensitivity to ethanol sedation by acting in a small set of neurons that express Corazonin (Crz), a neuropeptide likely involved in the physiological response to stress. The activity of Crz neurons regulates the behavioral response to ethanol, as silencing and activating these neurons affects sedation sensitivity in opposite ways. Furthermore, this effect is mediated by Crz, as flies with reduced crz expression show reduced sensitivity to ethanol sedation. Finally, we find that both apt and crz are rapidly upregulated by acute ethanol exposure. Thus, we have identified two genes and a small set of peptidergic neurons that regulate sensitivity to ethanol-induced sedation. We propose that Apt regulates the activity of Crz neurons and/or release of the neuropeptide during ethanol exposure.

Brain cells for grandmother.

For decades neuroscientists have debated how memories are stored. That debate continues today, with competing theories—one of which suggests that single neurons hold the recollection, say, of your grandmother or of a famous movie star. The alternative theory asserts that each memory is distributed across many millions of neurons. A number of recent experiments during brain surgeries provide evidence that relatively small sets of neurons in specific regions are involved with the encoding of memories. At the same time, these small groupings of cells may represent many instances of one thing; a visual image of Grandma’s face or her entire body—even a front and side view or the voice of a Hollywood star such as Jennifer Aniston.

Spontaneous summation or numerosity-selective coding?

A key debate in numerical cognition concerns the neural code for number representation (e.g., Nieder and Merten, 2007; Roggeman et al., 2007; Viswanathan and Nieder, 2013). One idea is that individual neurons are tuned to individual numbers, with decreasing response to numbers with increasing distance (numerosity-selective coding or labeled-line coding). An alternative, more implicit way of representing number is by summation coding. Here, individual neurons fire either monotonically stronger or weaker to increasing number. The number can then be decoded from the pooled cell activity. The computational properties of both coding types have been studied. A summation code but not a numerosity-selective code was extracted without number-related training from a visual display in a recent modeling study (Stoianov and Zorzi, 2012). Also, the summation code serves as a precursor for a numerosity-selective code in such models (Dehaene and Changeux, 1993; Verguts and Fias, 2004). Furthermore, each coding type has distinct advantages; summation coding is more suited for smaller-larger (i.e., magnitude) processing, numerosity-selective coding is more efficient for same-different number discrimination (Verguts, 2007). In a number of papers, Nieder and colleagues demonstrated numerosity-selective coding in macaque monkeys (e.g., Nieder et al., 2002; Nieder and Miller, 2004). However, number was always relevant for the task; in other words, animals were trained on number (e.g., Nieder et al., 2002). The computational modeling work jointly predicts that summation coding is primary and foundational to numerosity-selective coding, and that in the absence of number-relevant training, only summation coding would be observed. Consistently, Roitman et al. (2007) showed that only summation coding was observed in a single-unit recording study in which number was not relevant for solving the task. However, number was relevant for computing the reward at trial offset, so it may still be that number-relevant learning took place during training. To determine the natural numerical coding system (i.e., without number learning), Viswanathan and Nieder (2013) recorded cells from ventral intraparietal area [VIP, in intraparietal sulcus (IPS)] and from prefrontal cortex (PFC) in two monkeys in a task without number relevance (and hence number learning). They found that neurons in both brain areas responded maximally to a given number (e.g., one neuron responded maximally to 1, another neuron maximally to 2, and so on). They interpret their data as suggesting numerosity-selective coding. They also found that the most frequently preferred numbers for these neurons were numbers 1 and 5, whereas a relatively small set of neurons were classified as tuned to intermediate numbers 2, 3, and 4. However, given the computational primacy of summation coding, we consider the possibility that the authors instead sampled summation coding neurons. Here, we show that the data are consistent with summation coding, and that summation coding can account for subtle and unexplained aspects of the data.

Axonal branching patterns of nucleus accumbens neurons in the rat

The patterns of axonal collateralization of nucleus accumbens (Acb) projection neurons were investigated in the rat by means of single-axon tracing techniques using the anterograde tracer biotinylated dextran amine. Seventy-three axons were fully traced, originating from either the core (AcbC) or shell (AcbSh) compartment, as assessed by differential calbindin D28k-immunoreactivity. Axons from AcbC and AcbSh showed a substantial segregation in their targets; target areas were either exclusively or preferentially innervated from AcbC or AcbSh. Axon collaterals in the subthalamic nucleus were found at higher than expected frequencies; moreover, these originated exclusively in the dorsal AcbC. Intercompartmental collaterals were observed from ventral AcbC axons into AcbSh, and likewise, interconnections at pallidal and mesencephalic levels were also observed, although mostly from AcbC axons toward AcbSh targets, possibly supporting crosstalk between the two subcircuits at several levels. Cell somata giving rise to short-range accumbal axons, projecting to the ventral pallidum (VP), were spatially intermingled with others, giving rise to long-range axons that innervated VP and more caudal targets. This anatomical organization parallels that of the dorsal striatum and provides the basis for possible dual direct and indirect actions from a single axon on either individual or small sets of neurons.