Relating ion channel expression, bifurcation structure, and diverse firing patterns in a model of an identified motor neuron

Neurons show diverse firing patterns. Even neurons belonging to a single chemical or morphological class, or the same identified neuron, can display different types of electrical activity. For example, motor neuron MN5, which innervates a flight muscle of adult Drosophila, can show distinct firing patterns under the same recording conditions. We developed a two-dimensional biophysical model and show that a core complement of just two voltage-gated channels is sufficient to generate firing pattern diversity. We propose Shab and DmNa _v to be two candidate genes that could encode these core currents, and find that changes in Shab channel expression in the model can reproduce activity resembling the main firing patterns observed in MN5 recordings. We use bifurcation analysis to describe the different transitions between rest and spiking states that result from variations in Shab channel expression, exposing a connection between ion channel expression, bifurcation structure, and firing patterns in models of membrane potential dynamics.     

The difference between the heterogeneity of the centromeric index and intrachromosomal asymmetry

Intrachromosomal asymmetry, one of the two aspects of karyotype asymmetry, increases because of shifts of the centromere position from the median/submedian to terminal or subterminal. Conventional measures of asymmetry use comparisons with the most symmetrical karyotype and thus are an absolute measure of variation in the centromeric index. Conversely, the CV_CI index, the coefficient of variation for the centromeric index, only evaluates the relative variation in the centromeric index. We performed a detailed analysis of the capability of the CV_CI index and conventional measures of karyotype asymmetry to accurately characterize differences in intrachromosomal asymmetry. Our results show that the CV_CI index is unable to accurately evaluate intrachromosomal asymmetry. In fact, the CV_CI index evaluates a different measure than other conventional measures of karyotype asymmetry. Therefore, to avoid confusion, we propose that the variation evaluated by the CV_CI index should be named heterogeneity of the centromeric index.     

Sperm length variation as a predictor of extrapair paternity in passerine birds

Background

The rate of extrapair paternity is a commonly used index for the risk of sperm competition in birds, but paternity data exist for only a few percent of the approximately 10400 extant species. As paternity analyses require extensive field sampling and costly lab work, species coverage in this field will probably not improve much in the foreseeable future. Recent findings from passerine birds, which constitute the largest avian order (∼5 900 species), suggest that sperm phenotypes carry a signature of sperm competition. Here we examine how well standardized measures of sperm length variation can predict the rate of extrapair paternity in passerine birds.

Methodology/Principal Findings

We collected sperm samples from 55 passerine species in Canada and Europe for which extrapair paternity rates were already available from either the same (n = 24) or a different (n = 31) study population. We measured the total length of individual spermatozoa and found that both the coefficient of between-male variation (CV_bm) and within-male variation (CV_wm) in sperm length were strong predictors of the rate of extrapair paternity, explaining as much as 65% and 58%, respectively, of the variation in extrapair paternity among species. However, only the CV_bm predictor was independent of phylogeny, which implies that it can readily be converted into a currency of extrapair paternity without the need for phylogenetic correction.

Conclusion/Significance

We propose the CV_bm index as an alternative measure to extrapair paternity for passerine birds. Given the ease of sperm extraction from male birds in breeding condition, and a modest number of sampled males required for a robust estimate, this new index holds a great potential for mapping the risk of sperm competition across a wide range of passerine birds.     

Inter-session reliability and sex-related differences in hamstrings total reaction time,pre-motor time and motor time during eccentric isokinetic contractions in recreational athlete

The purposes were twofold: (a) to ascertain the inter-session reliability of hamstrings total reaction time, pre-motor time and motor time; and (b) to examine sex-related differences in the hamstrings reaction times profile. Twenty-four men and 24 women completed the study. Biceps femoris and semitendinosus total reaction time, pre-motor time and motor time measured during eccentric isokinetic contractions were recorded on three different occasions. Inter-session reliability was examined through typical percentage error (CV_TE), percentage change in the mean (CM) and intraclass correlations (ICC). For both biceps femoris and semitendinosus, total reaction time, pre-motor time and motor time measures demonstrated moderate inter-session reliability (CV_TE < 10%; CM < 3%; ICC > 0.7). The results also indicated that, although not statistically significant, women reported consistently longer hamstrings total reaction time (23.5 ms), pre-motor time (12.7 ms) and motor time (7.5 ms) values than men. Therefore, an observed change larger than 5%, 9% and 8% for total reaction time, pre-motor time and motor time respectively from baseline scores after performing a training program would indicate that a real change was likely. Furthermore, while not statistically significant, sex differences were noted in the hamstrings reaction time profile which may play a role in the greater incidence of ACL injuries in women.     

Multicellular recordings of cultured brainstem neurons in microelectrode arrays

Several vital systemic functions are controlled by the brainstem, which has been studied in a variety of experimental preparations and by various techniques, including in-vitro electrophysiological preparations. Although these in-vitro approaches have greatly advanced the understanding of brainstem neurons, most recording methods with microelectrodes and patch pipettes are invasive. To take advantage of in-vitro approaches but avoid their potential problems, we have studied brainstem neurons in microelectrode arrays (MEA). Neurons were isolated from the medulla oblongata and cultured in DMEM. Extracellular recordings were performed with no evident perturbations to the cellular environment. Neurons started firing after 24–48 h in culture, reached stable activity in 3–4 weeks, and retained this activity for at least 3 months. From their firing patterns, these neurons could be divided into tonic and bursting units. The latter could be further divided into regular and irregular bursters based on their burst intervals. Cells were stimulated or inhibited by exposure to 10% CO₂. The stimulatory effect of CO₂, though smaller, was still seen after selective ablation of serotonergic neurons or with low Ca⁺⁺ and high Mg⁺⁺ in the extracellular medium. Similar treatments had no significant effect on CO₂-inhibited units. The abundance of units with respect to their firing patterns and CO₂ responses, together with the long-term stable non-invasive recordings with no evident perturbation to cellular environments, suggests that MEA represent another promising in-vitro approach for studying brainstem neurons.This work was supported by NIH grant (HL058410, HL067890).     

Modeling weight variability in a pan coating process using Monte Carlo simulations

The primary objective of the current study was to investigate process variables affecting weight gain mass coating variability (CV _m) in pan coating devices using novel video-imaging techniques and Monte Carlo simulations. Experimental information such as the tablet location, circulation time distribution, velocity distribution, projected surface area, and spray dynamics was the main input to the simulations. The data on the dynamics of tablet movement were obtained using novel video-imaging methods. The effects of pan speed, pan loading, tablet size, coating time, spray flux distribution, and spray area and shape were investigated. CV _m was found to be inversely proportional to the square root of coating time. The spray shape was not found to affect the CV _m of the process significantly, but an increase in the spray area led to lower CV _ms. Coating experiments were conducted to verify the predictions from the Monte Carlo simulations, and the trends predicted from the model were in good agreement. It was observed that the Monte Carlo simulations underpredicted CV _ms in comparison to the experiments. The model developed can provide a basis for adjustments in process parameters required during scale-up operations and can be useful in predicting the process changes that are needed to achieve the same CV _m when a variable is altered.     

Selection,structure and the heritability of behaviour

Characters which are closely linked to fitness often have low heritabilities (V_A/V_P). Low heritabilities could be because of low additive genetic variation (V_A), that had been depleted by directional selection. Alternatively, low heritabilities may be caused by large residual variation (V_R=V_P – V_A) compounded at a disproportionately higher rate than V_A across integrated characters. Both hypotheses assume that each component of quantitative variation has an independent effect on heritability. However, V_A and V_R may also covary, in which case differences in heritability cannot be fully explained by the independent effects of elimination‐selection or compounded residual variation. We compared the central tendency of published behavioural heritabilities (mean=0.31, median=0.23) with morphological and life history data collected by 26 ). Average behavioural heritability was not significantly different from average life history heritability, but both were smaller than average morphological heritability. We cross‐classified behavioural traits to test whether variation in heritability was related to selection (dominance, domestic/wild) or variance compounding (integration level). There was a significant three‐way interaction between indices of selection and variance compounding, related to the absence of either effect at the highest integration level. At lower integration levels, high dominance variance indicated effects of selection. It was also indicated by the low CV_A of domestic species. At the same time CV_R increased disproportionately faster than CV_A across integration levels, demonstrating variance compounding. However, neither CV_R nor CV_A had a predominant effect on heritability. The partial regression coefficients of CV_R and CV_A on heritability were similar and a path analysis indicated that their (positive) correlation was also necessary to explain variation in heritability. These results suggest that relationships between additive genetic and residual components of quantitative genetic variation can constrain their independent direct effects on behavioural heritability.     

Estimation of Noise-Free Variance to Measure Heterogeneity

Variance is a statistical parameter used to characterize heterogeneity or variability in data sets. However, measurements commonly include noise, as random errors superimposed to the actual value, which may substantially increase the variance compared to a noise-free data set. Our aim was to develop and validate a method to estimate noise-free spatial heterogeneity of pulmonary perfusion using dynamic positron emission tomography (PET) scans. On theoretical grounds, we demonstrate a linear relationship between the total variance of a data set derived from averages of n multiple measurements, and the reciprocal of n. Using multiple measurements with varying n yields estimates of the linear relationship including the noise-free variance as the constant parameter. In PET images, n is proportional to the number of registered decay events, and the variance of the image is typically normalized by the square of its mean value yielding a coefficient of variation squared (CV ²). The method was evaluated with a Jaszczak phantom as reference spatial heterogeneity (CV_r ²) for comparison with our estimate of noise-free or ‘true’ heterogeneity (CV _t ²). We found that CV _t ² was only 5.4% higher than CV _r ². Additional evaluations were conducted on 38 PET scans of pulmonary perfusion using ¹³NN-saline injection. The mean CV _t ² was 0.10 (range: 0.03–0.30), while the mean CV ² including noise was 0.24 (range: 0.10–0.59). CV _t ² was in average 41.5% of the CV ² measured including noise (range: 17.8–71.2%). The reproducibility of CV _t ² was evaluated using three repeated PET scans from five subjects. Individual CV _t ² were within 16% of each subject''s mean and paired t-tests revealed no difference among the results from the three consecutive PET scans. In conclusion, our method provides reliable noise-free estimates of CV _t ² in PET scans, and may be useful for similar statistical problems in experimental data.     

Alterations in the Intrinsic Burst Activity of Purkinje Neurons in Offspring Maternally Exposed to the CB1 Cannabinoid Agonist WIN 55212-2

Burst firing plays an important role in normal neuronal function and dysfunction. In Purkinje neurons, where the firing rate and discharge pattern encode the timing signals necessary for motor function, any alteration in firing properties, including burst activity, may affect the motor output. Therefore, we examined whether maternal exposure to the cannabinoid receptor agonist WIN 55212-2 (WIN) may affect the burst firing properties of cerebellar Purkinje cells in offspring. Whole-cell somatic patch-clamp recordings were made from cerebellar slices of adult male rats that were exposed to WIN prenatally. WIN exposure during pregnancy induced long-term alterations in the burst firing behavior of Purkinje neurons in rat offspring as evidenced by a significant increase in the mean number of spikes per burst (p < 0.05) and the prolongation of burst firing activity (p < 0.01). The postburst afterhyperpolarization potential (p < 0.001), the mean intraburst interspike intervals (p < 0.001) and the mean intraburst firing frequency (p < 0.001) were also significantly increased in the WIN-treated group. Prenatal exposure to WIN enhanced the firing irregularity as reflected by a significant decrease in the coefficient of variation of the intraburst interspike interval (p < 0.05). Furthermore, whole-cell voltage-clamp recordings revealed that prenatal WIN exposure significantly enhanced Ca²⁺ channel current amplitude in offspring Purkinje neurons compared to control cells. Overall, the data presented here strongly suggest that maternal exposure to cannabinoids can induce long-term changes in complex spike burst activity, which in turn may lead to alterations in neuronal output.     

Biomass estimation on the basis of yeast cultivation model with morphophysiological parameters

An approach of biomass estimation of yeast fed-batch cultivation is proposed. It is based on the model that takes into account the information about the morphophysiological parameters: size, coefficients of shape and skewness of optical density of yeast cells. Procedure for parameter identification of the model, r ₁-rate of transformation of active cells into weakened cells, r ₂-rate of transformation of weakened cells into dead cells, r ₃-rate of transformation of weakened cells into active cells, r ₄-rate by which the buds of the budding cells grow and transform after their separation into active cells and r ₅-rate of transformation of active cells into budding cells, is described. The procedure is performed in MATLAB environment.     

Plant intraspecific functional trait variation is related to within‐habitat heterogeneity and genetic diversity in Trifolium montanum L.

Intraspecific trait variation (ITV), based on available genetic diversity, is one of the major means plant populations can respond to environmental variability. The study of functional trait variation and diversity has become popular in ecological research, for example, as a proxy for plant performance influencing fitness. Up to now, it is unclear which aspects of intraspecific functional trait variation (iFD_CV) can be attributed to the environment or genetics under natural conditions. Here, we examined 260 individuals from 13 locations of the rare (semi‐)dry calcareous grassland species Trifolium montanum L. in terms of iFD_CV, within‐habitat heterogeneity, and genetic diversity. The iFD_CV was assessed by measuring functional traits (releasing height, biomass, leaf area, specific leaf area, leaf dry matter content, F_v/F_m, performance index, stomatal pore surface, and stomatal pore area index). Abiotic within‐habitat heterogeneity was derived from altitude, slope exposure, slope, leaf area index, soil depth, and further soil factors. Based on microsatellites, we calculated expected heterozygosity (H_e) because it best‐explained, among other indices, iFD_CV. We performed multiple linear regression models quantifying relationships among iFD_CV, abiotic within‐habitat heterogeneity and genetic diversity, and also between separate functional traits and abiotic within‐habitat heterogeneity or genetic diversity. We found that abiotic within‐habitat heterogeneity influenced iFD_CV twice as strong compared to genetic diversity. Both aspects together explained 77% of variation in iFD_CV ( = .77, F_{2, 10} = 21.66, p < .001). The majority of functional traits (releasing height, biomass, specific leaf area, leaf dry matter content, F_v/F_m, and performance index) were related to abiotic habitat conditions indicating responses to environmental heterogeneity. In contrast, only morphology‐related functional traits (releasing height, biomass, and leaf area) were related to genetics. Our results suggest that both within‐habitat heterogeneity and genetic diversity affect iFD_CV and are thus crucial to consider when aiming to understand or predict changes of plant species performance under changing environmental conditions.     

Activity of single motor units in attention-demanding tasks: firing pattern in the human trapezius muscle

Activity of single motor units in relation to surface electromyography (EMG) was studied in 11 subjects in attention-demanding work tasks with minimal requirement of movement. In 53 verified firing periods, single motor units fired continuously from 30 s to 10 min (duration of the experiment work task) with a stable median firing rate in the range of 8–13 Hz. When the integrated surface EMG were stable, the motor units identified as a rule were continuously active with only small modulations of firing rate corresponding to low-amplitude fluctuations in surface EMG. Marked changes in the surface EMG, either sudden or gradual, were caused by recruitment or derecruitment of motor units, and not by modulations of the motor unit firing rate. Motor unit firing periods (duration 10 s-35 s) in low-level voluntary contractions (approximately 1%–5% EMG_max) performed by the same subjects showed median firing rates (7–12 Hz) similar to the observations in attention-related activation.     

High-density surface EMG study on the time course of central nervous and peripheral neuromuscular changes during 8 weeks of bed rest with or without resistive vibration exercise

The aim of the present study was to assess the time course and the origin of adaptations in neuromuscular function as a consequence of prolonged bed rest with or without countermeasure. Twenty healthy males volunteered to participate in the present study and were randomly assigned to either an inactive control group (Ctrl) or to a resistive vibration exercise (RVE) group. Prior to, and seven times during bed rest, we recorded high-density surface electromyogram (sEMG) signals from the vastus lateralis muscle during isometric knee extension exercise at a range of contraction intensities (5–100% of maximal voluntary isometric torque). The high-density sEMG signals were analyzed for amplitude (root mean square, RMS), frequency content (median frequency, F_med) and muscle fiber conduction velocity (MFCV) in an attempt to describe bed rest-induced changes in neural activation properties at the levels of the motor control and muscle fibers. Without countermeasures, bed rest resulted in a significant progressive decline in maximal isometric knee extension strength, whereas RMS remained unaltered throughout the bed rest period. In line with observed muscle atrophy, both F_med and MFCV declined during bed rest. RVE training during bed rest resulted in maintained maximal isometric knee extension strength, and a strong increase (～30%) in maximal EMG amplitude, from 10 days of bed rest on. Exclusion of other factors led to the conclusion that the RVE training increased motor unit firing rates as a consequence of an increased excitability of motor neurons. An increased firing rate might have been essential under training sessions, but it did not affect isometric voluntary torque capacity.     

Phase-resetting curve determines how BK currents affect neuronal firing

BK channels are large conductance potassium channels gated by calcium and voltage. Paradoxically, blocking these channels has been shown experimentally to increase or decrease the firing rate of neurons, depending on the neural subtype and brain region. The mechanism for how this current can alter the firing rates of different neurons remains poorly understood. Using phase-resetting curve (PRC) theory, we determine when BK channels increase or decrease the firing rates in neural models. The addition of BK currents always decreases the firing rate when the PRC has only a positive region. When the PRC has a negative region (type II), BK currents can increase the firing rate. The influence of BK channels on firing rate in the presence of other conductances, such as I _m and I _h , as well as with different amplitudes of depolarizing input, were also investigated. These results provide a formal explanation for the apparently contradictory effects of BK channel antagonists on firing rates.     

Singlet Oxygen-Mediated Oxidation during UVA Radiation Alters the Dynamic of Genomic DNA Replication

UVA radiation (320–400 nm) is a major environmental agent that can exert its deleterious action on living organisms through absorption of the UVA photons by endogenous or exogenous photosensitizers. This leads to the production of reactive oxygen species (ROS), such as singlet oxygen (¹O₂) and hydrogen peroxide (H₂O₂), which in turn can modify reversibly or irreversibly biomolecules, such as lipids, proteins and nucleic acids. We have previously reported that UVA-induced ROS strongly inhibit DNA replication in a dose-dependent manner, but independently of the cell cycle checkpoints activation. Here, we report that the production of ¹O₂ by UVA radiation leads to a transient inhibition of replication fork velocity, a transient decrease in the dNTP pool, a quickly reversible GSH-dependent oxidation of the RRM1 subunit of ribonucleotide reductase and sustained inhibition of origin firing. The time of recovery post irradiation for each of these events can last from few minutes (reduction of oxidized RRM1) to several hours (replication fork velocity and origin firing). The quenching of ¹O₂ by sodium azide prevents the delay of DNA replication, the decrease in the dNTP pool and the oxidation of RRM1, while inhibition of Chk1 does not prevent the inhibition of origin firing. Although the molecular mechanism remains elusive, our data demonstrate that the dynamic of replication is altered by UVA photosensitization of vitamins via the production of singlet oxygen.     

Modeling the Cellular Mechanisms and Olfactory Input Underlying the Triphasic Response of Moth Pheromone-Sensitive Projection Neurons

In the antennal lobe of the noctuid moth Agrotis ipsilon, most pheromone-sensitive projection neurons (PNs) exhibit a triphasic firing pattern of excitation (E₁)-inhibition (I)-excitation (E₂) in response to a pulse of the sex pheromone. To understand the mechanisms underlying this stereotypical discharge, we developed a biophysical model of a PN receiving inputs from olfactory receptor neurons (ORNs) via nicotinic cholinergic synapses. The ORN is modeled as an inhomogeneous Poisson process whose firing rate is a function of time and is fitted to extracellular data recorded in response to pheromone stimulations at various concentrations and durations. The PN model is based on the Hodgkin-Huxley formalism with realistic ionic currents whose parameters were derived from previous studies. Simulations revealed that the inhibitory phase I can be produced by a SK current (Ca²⁺-gated small conductance K⁺ current) and that the excitatory phase E₂ can result from the long-lasting response of the ORNs. Parameter analysis further revealed that the ending time of E₁ depends on some parameters of SK, Ca²⁺, nACh and Na⁺ currents; I duration mainly depends on the time constant of intracellular Ca²⁺ dynamics, conductance of Ca²⁺ currents and some parameters of nACh currents; The mean firing frequency of E₁ and E₂ depends differentially on the interaction of various currents. Thus it is likely that the interplay between PN intrinsic currents and feedforward synaptic currents are sufficient to generate the triphasic firing patterns observed in the noctuid moth A. ipsilon.     

Photoinhibition and Active Oxygen Species Production in Detached Apple Leaves During Dehydration

In the course of dehydration, the gas exchange and chlorophyll (Chl) fluorescence were measured under irradiance of 800 mol m^–2 s^–1 in detached apple leaves, and the production of active oxygen species (AOS), hydrogen peroxide (H₂O₂), superoxide (O₂ ^–), hydroxyl radical (–OH), and singlet oxygen (¹O₂), were determined. Leaf net photosynthetic rate (P _N) was limited by stomatal and non-stomatal factors at slight (2–3 h dehydration) and moderate (4–5 h dehydration) water deficiency, respectively. Photoinhibition occurred after 3-h dehydration, which was defined by the decrease of photosystem 2 (PS2) non-cyclic electron transport (P-rate). After 2-h dehydration, an obvious rise in H₂O₂ production was found as a result of photorespiration rise. If photorespiration was inhibited by sodium bisulfite (NaHSO₃), the rate of post-irradiation transient increase in Chl fluorescence (Rfp) was enhanced in parallel with a slight decline in P-rate and with an increase in Mehler reaction. At 3-h dehydration, leaf P-rate decrease could be blocked by glycine (Gly) or methyl viologen (MV) pre-treatment, and MV was more effective than Gly at moderate drought time. AOS (H₂O₂ and O₂ ^–), prior to photoinhibition produced from photorespiration and Mehler reaction in detached apple leaves at slight water deficiency, were important in dissipating photon energy which was excess to the demand of CO₂ assimilation. So photoinhibition could be effectively prevented by the way of AOS production.     

Periodicity,persistence, and collapse in host–parasitoid systems with egg limitation

There is an emerging consensus that parasitoids are limited by the number of eggs which they can lay as well as the amount of time they can search for their hosts. Since egg limitation tends to destabilize host–parasitoid dynamics, successful control of insect pests by parasitoids requires additional stabilizing mechanisms such as heterogeneity in the distribution of parasitoid attacks and host density-dependence. To better understand how egg limitation, search limitation, heterogeneity in parasitoid attacks, and host density-dependence influence host–parasitoid dynamics, discrete time models accounting for these factors are analyzed. When parasitoids are purely egg-limited, a complete anaylsis of the host–parasitoid dynamics are possible. The analysis implies that the parasitoid can invade the host system only if the parasitoid’s intrinsic fitness exceeds the host’s intrinsic fitness. When the parasitoid can invade, there is a critical threshold, CV ^*>1, of the coefficient of variation (CV) of the distribution of parasitoid attacks that determines that outcome of the invasion. If parasitoid attacks sufficiently aggregated (i.e., CV>CV ^*), then the host and parasitoid coexist. Typically (in a topological sense), this coexistence is shown to occur about a periodic attractor or a stable equilibrium. If the parasitoid attacks are sufficiently random (i.e. CV<CV ^*), then the parasitoid drives the host to extinction. When parasitoids are weakly search-limited as well as egg-limited, coexistence about a global attractor occurs even if CV<CV ^*. However, numerical simulations suggest that the nature of this attractor depends critically on whether CV<1 or CV>1. When CV<1, the parasitoid exhibits highly oscillatory dynamics. Alternatively, when parasitoid attacks are sufficiently aggregated but not overly aggregated (i.e. CV>1 but close to 1), the host and parasitoid coexist about a stable equilibrium with low host densities. The implications of these results for classical biological control are discussed.     

Method of analysis influences interpretations of sex-related differences in firing rates during prolonged submaximal isometric contractions

Objective:This study examined motor unit (MU) firing rates during a prolonged isometric contraction of the vastus lateralis (VL) for females and males.Methods:Surface electromyographic (sEMG) signals were recorded from the VL for eleven females and twelve males during a 45-second isometric trapezoid muscle actions at 40% of maximal voluntary contraction (MVC). For each MU, mean firing rate (MFR) was calculated for the initial and final 10-second epochs of the steady torque segment and regressed against recruitment threshold (RT, expressed as %MVC), as well as time at recruitment (T_REC, seconds). MFR was also averaged for each subject.Results:Significant differences existed across epochs for the y-intercepts (P=0.009) of the MFR vs. T_REC relationship, as well as the grouped MFR analysis (P<0.001); no differences were observed between epochs for the MFR vs. RT relationship. Significant differences existed between sexes for the grouped MFR analysis (P=0.049), but no differences were observed for the MFR vs. T_REC or MFR vs. RT relationships.Conclusion:Analysis method may impact interpretation of firing rate behavior; increases in MU firing rates across a prolonged isometric contraction were observed in the MFR vs. T_REC relationship and the grouped MFR analysis.     

Spatiotemporal firing patterns in the cerebellum

Neurons are generally considered to communicate information by increasing or decreasing their firing rate. However, in principle, they could in addition convey messages by using specific spatiotemporal patterns of spiking activities and silent intervals. Here, we review expanding lines of evidence that such spatiotemporal coding occurs in the cerebellum, and that the olivocerebellar system is optimally designed to generate and employ precise patterns of complex spikes and simple spikes during the acquisition and consolidation of motor skills. These spatiotemporal patterns may complement rate coding, thus enabling precise control of motor and cognitive processing at a high spatiotemporal resolution by fine-tuning sensorimotor integration and coordination.