Biology subjects

Takeshita, D.

Publications and source records attributed to Takeshita, D..

3 recordsLinked to original sources

bioRxiv2022

Human retina trades single-photon detection for high-fidelity contrast encoding

We lack a fundamental understanding of how the spike output of the retina enables human visual perception. Here we show that human vision at its ultimate sensitivity limit depends on the spike output of ON but not OFF parasol (magnocellular) ganglion cells. Surprisingly, nonlinear signal processing in the retinal ON pathway precludes perceptual detection of single photons in darkness, but enables quantal-resolution discrimination of differences in light intensity.

neuroscience↗

bioRxiv2022

Tactile stimulation restores inhibited stretch reflex attributable to attenuation of Ia afferents during surprise landing

PurposeArthrogenic muscle inhibition(AMI) is induced by pathological knee conditions. The present study aimed to investigate the effect of tactile stimulation on reflex changes induced by simulated AMI during unpredictable landing performances. MethodsTwenty participants performed six unilateral landing tasks: 15cm normal landing (15NL), 30cm normal landing(30NL), surprise landing(SL), 30cm normal landing following vibration (30NLV), surprise landing following vibration(SLV), and surprise landing following vibration with Kinesiology-tape(SLK). For the surprise landing tasks, the solid landing platform(15cm) was removed and replaced by a false plate platform. Since the false plate dislodged easily under load, participants unpredictably fell through the plate to the actual landing surface 15cm below. After completing 15NL, 30NL, SL, vibration stimulation was applied to participants knees to induce neurological changes similar to AMI. After vibration stimulation, participants performed 30NLV, SLV and SLK in a random order. EMG in the post-landing short latency(31-60 ms) and medium latency(61-90 ms) periods were examined. EMG signals from the vastus lateralis(VL), vastus medialis(VM), and lateral hamstrings(LH) were recorded and compared between tasks. ResultsEMG of all muscles were significantly enhanced in the medium latency period. Enhanced EMG were suppressed by vibration stimulation in the VL, but the suppressed EMG were restored after cutaneous stimulation(p<0.01). ConclusionOur findings suggest that AMI could alter motor control patterns during unpredictable landing, and that tactile stimulation could restore the altered motor control to a normal state. The use of tactile stimulation may help maintain normal motor control patterns in injured individuals.

physiology↗

bioRxiv2022

Fish environmental DNA in lake sediment overcomes the gap of reconstructing past fauna in lake ecosystems

O_LIUnderwater sediments are a natural archive of biological information. Reconstruction of past fauna has been conducted for various taxonomic groups using morphological remains and DNA derived from these remains. However, information on past occurrences of fish species, the top predator of lake ecosystems, could have been reproduced only in exceptional environments, and past quantitative information on fish, particularly in lake ecosystems, has been a knowledge gap in reconstructing past fauna. Tracking the quantitative fluctuations of fish is essential for reconstructing multiple trophic levels of organisms in lake ecosystems. C_LIO_LITo acquire past quantitative fish information from lake sediments, we collected approximately 30 cm-length of underwater sediments in Lake Biwa. We extracted sedimentary environmental DNA (eDNA) and measured temporal fluctuations in the eDNA concentration of the native and fishery target species Plecoglossus altivelis and Gymnogobius isaza. For P. altivelis, we examined the possibility of tracking quantitative fluctuations by comparing sedimentary eDNA with recorded catch per unit effort (CPUE). C_LIO_LIThe chronology of the sediments allowed us to obtain information on sediments collected in Lake Biwa over the past 100 years. The deepest depths at which sedimentary eDNA was detected were 30 and 13 cm for P. altivelis and G. isaza from the surface, corresponding to approximately 100 and 30 years ago, respectively. In the comparison of sedimentary eDNA concentrations and biomass, we found a significant correlation between the CPUE of P. altivelis and its sedimentary eDNA concentration adjusted to compensate for DNA degradation. Sedimentary eDNA fluctuations were observed in P. altivelis, possibly reflecting the abundance fluctuation due to variations in the main food resources of zooplankton. C_LIO_LIOur findings provide essential pieces for the reconstruction of past fauna of lake ecosystems. The addition of quantitative information on fish species will reach a new phase, for instance, by investigating population shifts or biological interactions in the reconstruction of past fauna in lake ecosystems. C_LI

ecology↗