Biology subjects

Tamura, H.

Publications and source records attributed to Tamura, H..

24 records · Page 2Linked to original sources

bioRxiv2023

Human behavior and comfort during load carrying to autonomous mobile robot

Interactions between humans and autonomous mobile robots (AMRs) are expected to grow in smart cities to improve logistics operations, such as depositing packages on AMRs for pickup on the street. However, the way that humans walk and pass objects to an AMR when approaching each other remains largely unknown. We conducted two psychophysical experiments to clarify the behavior and comfort of humans when carrying a package and placing it on an AMR for load carrying. Participants were asked to approach a programmed AMR and pass the package in two experiments: 1) changing the stop distance and AMR speed and 2) changing the stop distance and package weight. Motion trackers quantified the participants walking speed and frequency of hesitation to walk. In addition, the subjective heaviness and comfort were recorded through a questionnaire during each trial. The results indicated that the participants speed decreased and hesitation probability increased when the stop distance of the AMR decreased. Nevertheless, the participants felt more comfortable with the close approach, whereas the package weight did not affect their behavior. By contrast, they felt uncomfortable when AMR remained still. These findings suggest that humans regard the AMR approach as load-carrying assistance and not as invading their personal space. To achieve a comfortable interaction in load carrying from humans to AMRs, we suggest that the AMR can closely approach a person without eliciting personal space invasion.

neuroscience↗

bioRxiv2022

Human collision avoidance behavior against autonomous mobile robot

Currently, the probability of pedestrians on the streets of smart cities encountering autonomous mobile robots (AMRs) is increasing. Previous studies have discussed collision avoidance between humans as they cross paths. Their avoidance behavior toward AMRs, however, remains unclear. To address this, we experimentally investigated the avoidance direction a human would choose against an AMR approaching head-on. This experiment included recording human locomotion under such a scenario. Further, an AMR was programmed to approach from various starting points, including directly through the participants (head-on collision). The participants were directed to evade it by moving rightward or leftward, and their paths were tracked. We found that the participants did not strongly prefer either direction, suggesting that the avoidance direction is not solely determined by the participants attributes, such as their adherence to the traffic rules of their region. The probability of rightward evasion when the AMR approached head-on indicated that humans use different avoidance strategies when encountering other humans and obstacles. Moreover, the participants motion analysis revealed that they involuntarily twisted their waists in the avoidance direction before they evaded the AMR. These results suggest that this twist is the most important predictor of the avoidance direction. These findings could be encoded into the programs of AMRs to adapt these vehicles to our locomotory responses more organically.

neuroscience↗

bioRxiv2022

Glossiness perception and its pupillary response

Recent studies have discovered that pupillary response changes depend on cognitive factors, such as subjective brightness caused by optical illusions and luminance. However, it remains unclear how the cognitive factor derived from the glossiness perception of object surfaces affects pupillary response. We investigated the relationship between glossiness perception and pupillary response through a gloss rating experiment that includes recording pupil diameter. For the stimuli, we prepared general object images (original) and randomized images (shuffled) that comprised of the same images with randomized small square regions. The image features were then controlled by matching the luminance histogram. The observers were asked to rate the perceived glossiness of the stimuli presented for 3,000 ms and changes in their pupil diameter were recorded. Consequently, if glossiness of the original images were rated as high, those of the shuffled were rated as low, and vice versa. High-gloss images constricted the pupil size more than the low-gloss ones near the pupillary light reflex. By contrast, the shuffled images dilated the pupil size more than the original image at a relatively later stage. These results suggest that local features comprising specular highlights involve the cognitive factor for pupil constriction, and this process is faster than pupil dilation derived from the inhibition of object recognition.

neuroscience↗

bioRxiv2021

The Temporal Pattern of Spiking Activity of a Thalamic Neuron are Related to the Amplitude of the Cortical Local Field Potential

Neuron activity in the sensory cortices mainly depends on feedforward thalamic inputs. High-frequency activity of a thalamic input can be temporally integrated by a neuron in the sensory cortex and is likely to induce larger depolarization. However, feedforward inhibition (FFI) and depression of excitatory synaptic transmission in thalamocortical pathways attenuate depolarization induced by the latter part of high-frequency spiking activity and the temporal summation may not be effective. The spiking activity of a thalamic neuron in a specific temporal pattern may circumvent FFI and depression of excitatory synapses. The present study determined the relationship between the temporal pattern of spiking activity of a single thalamic neuron and the degree of cortical activation as well as that between the firing rate of spiking activity of a single thalamic neuron and the degree of cortical activation. Spiking activity of a thalamic neuron was recorded extracellularly from the lateral geniculate nucleus (LGN) in male Long-Evans rats. Degree of cortical activation was assessed by simultaneous recording of local field potential (LFP) from the visual cortex. A specific temporal pattern appearing in three consecutive spikes of an LGN neuron induced larger cortical LFP modulation than high-frequency spiking activity during a short period. These findings indicate that spiking activity of thalamic inputs is integrated by a synaptic mechanism sensitive to an input temporal pattern. Significance StatementSensory cortical activity depends on thalamic inputs. Despite the importance of thalamocortical transmission, how spiking activity of thalamic inputs is integrated by cortical neurons remains unclear. Feedforward inhibition and synaptic depression of excitatory transmission may not allow simple temporal summation of membrane potential induced by consecutive spiking activity of a thalamic neuron. A specific temporal pattern appearing in three consecutive spikes of a thalamic neuron induced larger cortical local field potential modulation than high-frequency spiking activity during a short period. The findings indicate the importance of the temporal pattern of spiking activity of a single thalamic neuron on cortical activation.

neuroscience↗

bioRxiv2019

Role of microRNA-21 in hypertrophic cardiac remodeling

Hypertension is a major public health problem among with aging population worldwide. It causes cardiac remodeling, including hypertrophy and interstitial fibrosis, which leads to development of hypertensive heart disease (HHD). Although microRNA-21 (miR-21) is associated with fibrogenesis in multiple organs, its impact on hypertrophic cardiac remodeling in hypertension is not known. Circulating miR-21 level was higher in patients with HHD than that in the control subjects. It also positively correlated with serum myocardial fibrotic markers. MiR-21 expression levels were significantly upregulated in the mice hearts after angiotensin II (Ang II) infusion or transverse aortic constriction (TAC) compared with control mice. Expression level of programmed cell death 4 (PDCD4), a main target of miR-21, was significantly decreased in Ang II infused mice and TAC mice compared with control mice. Expression levels of transcriptional activator protein 1 (AP-1) and transforming growth factor-{beta}1 (TGF-{beta}1), which were downstream targets of PDCD4, were increased in Ang II infused mice and TAC mice compared with control mice. In vitro, mirVana-miR-21-specific inhibitor attenuated Ang II-induced PDCD4 downregulation and contributed to subsequent deactivation of AP-1/TGF-{beta}1 signaling pathway in neonatal rat cardiomyocytes. Thus, suppression of miR-21 prevents hypertrophic cardiac remodeling by regulating PDCD4, AP-1, and TGF-{beta}1 signaling pathway.

molecular biology↗

bioRxiv2016

Neurons in the inferior temporal cortex of macaque monkeys are sensitive to multiple surface features from natural objects

Object surfaces contain a variety of visual features that help us to recognize them. To understand how this information is represented and processed in the brain, we prepared a set of images from natural object surfaces that maintained surface features but lacked contours. We examined spiking responses of neurons in the inferior temporal (IT) cortex of monkeys, which is a crucial structure needed for visual object recognition. About half of IT neurons responded to surface images with sharp selectivity, indicating that a significant fraction of these neurons contribute to object surface representation in a sparse manner. Responses of IT neurons were susceptible to image manipulations, including color removal, removal of luminance contrasts, and spatial structure degradation. This shows that multiple features are required for IT responses to surface images. Comparing neuronal response properties among IT, visual area 4 (V4), and primary visual cortex (V1) revealed properties of IT neurons that differed from those in the other visual processing regions. Additionally, some neuronal response properties were similar between IT and V4, but differed from those in V1, indicating that responses of IT neurons to surface images are constructed by hierarchical processing throughout the ventral visual pathway.

neuroscience↗