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Nature Communications Sep 2023To localize objects during active sensing, animals must differentiate stimuli caused by volitional movement from real-world object motion. To determine a neural basis...
To localize objects during active sensing, animals must differentiate stimuli caused by volitional movement from real-world object motion. To determine a neural basis for this ability, we examined the mouse superior colliculus (SC), which contains multiple egocentric maps of sensorimotor space. By placing mice in a whisker-guided virtual reality, we discovered a rapidly adapting tactile response that transiently emerged during externally generated gains in whisker contact. Responses to self-generated touch that matched self-generated history were significantly attenuated, revealing that transient response magnitude is controlled by sensorimotor predictions. The magnitude of the transient response gradually decreased with repetitions in external motion, revealing a slow habituation based on external history. The direction of external motion was accurately encoded in the firing rates of transiently responsive neurons. These data reveal that whisker-specific adaptation and sensorimotor predictions in SC neurons enhance the localization of unexpected, externally generated changes in tactile space.
Topics: Mice; Animals; Touch; Touch Perception; Neurons; Motion; Movement; Vibrissae
PubMed: 37777516
DOI: 10.1038/s41467-023-41755-z -
Nature Communications Sep 2023Excitatory spiny stellate neurons are prominently featured in the cortical circuits of sensory modalities that provide high salience and high acuity representations of...
Excitatory spiny stellate neurons are prominently featured in the cortical circuits of sensory modalities that provide high salience and high acuity representations of the environment. These specialized neurons are considered developmentally linked to bottom-up inputs from the thalamus, however, the molecular mechanisms underlying their diversification and function are unknown. Here, we investigated this in mouse somatosensory cortex, where spiny stellate neurons and pyramidal neurons have distinct roles in processing whisker-evoked signals. Utilizing spatial transcriptomics, we identified reciprocal patterns of gene expression which correlated with these cell-types and were linked to innervation by specific thalamic inputs during development. Genetic manipulation that prevents the acquisition of spiny stellate fate highlighted an important role for these neurons in processing distinct whisker signals within functional cortical columns, and as a key driver in the formation of specific whisker-related circuits in the cortex.
Topics: Animals; Vibrissae; Neurons; Pyramidal Cells; Neurites; Somatosensory Cortex; Thalamus
PubMed: 37770450
DOI: 10.1038/s41467-023-41749-x -
Journal of Personalized Medicine Aug 2023The impact of metformin on the rat facial nerve following crush injury has only occasionally been documented to date. The purpose of the current investigation was to use...
The impact of metformin on the rat facial nerve following crush injury has only occasionally been documented to date. The purpose of the current investigation was to use functional and electrophysiological evaluations to investigate the effects of metformin administration on recovery following crush injury to the rat facial nerve. The rats were randomly divided into four groups: the nonDM/PBS group (n = 4), the nonDM/metformin group (n = 4), the DM/PBS group (n = 4), and the DM/metformin group (n = 4). Diabetes was generated by an intraperitoneal injection of streptozotocin. Facial nerve paralysis was induced by a crush injury 7 days after diabetes induction. The blood glucose levels of the DM/PBS and DM/metformin groups were maintained at over 300 mg/dL, whereas the blood glucose levels of the nonDM/PBS and nonDM/metformin groups were maintained at less than 150 mg/dL. There was no significant difference between the two nonDM groups. In comparison to the PBS group, the metformin group's recurrence of vibrissa fibrillation occurred noticeably sooner over time. The nonDM/metformin group showed the highest recovery rate in the second, third, and fourth weeks post-crush, respectively. The threshold of action potential 4 weeks after crush injury showed that the nonDM/metformin group had a significantly lower mean threshold of MAP compared to other groups. The short-term effect of metformin on the recovery of facial nerve blood flow (FNBF) was significantly increased compared to the DM/PBS group. However, there was no significant difference in FNBF between the nonDM/metformin and nonDM/PBS groups. A diabetic condition promoted a delay in FN regeneration. Metformin is able to accelerate functional recovery in diabetic or nondiabetic FN-injured rats. Further studies using a morphometric or molecular approach are planned to understand the pharmacologic mechanism of metformin.
PubMed: 37763084
DOI: 10.3390/jpm13091317 -
Current Opinion in Neurobiology Dec 2023Orofacial motor actions are movements that, in rodents, involve whisking of the vibrissa, deflection of the nose, licking and lapping with the tongue, and consumption... (Review)
Review
Orofacial motor actions are movements that, in rodents, involve whisking of the vibrissa, deflection of the nose, licking and lapping with the tongue, and consumption through chewing. These actions, along with bobbing and turning of the head, coordinate to subserve exploration while not conflicting with life-supporting actions such as breathing and swallowing. Orofacial and head movements are comprised of two additive components: a rhythm that can be entrained by the breathing oscillator and a broadband component that directs the actuator to the region of interest. We focus on coordinating the rhythmic component of actions into a behavior. We hypothesize that the precise timing of each constituent action is continually adjusted through the merging of low-level oscillator input with sensory-derived, high-level rhythmic feedback. Supporting evidence is discussed.
Topics: Animals; Nose; Movement; Rodentia; Respiration; Vibrissae
PubMed: 37757586
DOI: 10.1016/j.conb.2023.102784 -
Journal of Cerebral Blood Flow and... Feb 2024Hypoglycemia is a serious complication of insulin treatment of diabetes that can lead to coma and death. Neurovascular coupling, which mediates increased local blood...
Hypoglycemia is a serious complication of insulin treatment of diabetes that can lead to coma and death. Neurovascular coupling, which mediates increased local blood flow in response to neuronal activity, increases glucose availability to active neurons. This mechanism could be essential for neuronal health during hypoglycemia, when total glucose supplies are low. Previous studies suggest, however, that neurovascular coupling (a transient blood flow increase in response to an increase in neuronal activity) may be reduced during hypoglycemia. Such a reduction in blood flow increase would exacerbate the effects of hypoglycemia, depriving active neurons of glucose. We have reexamined the effects of hypoglycemia on neurovascular coupling by simultaneously monitoring neuronal and vascular responses to whisker stimulation in the awake mouse somatosensory cortex. We find that neurovascular coupling at both penetrating arterioles and at 2nd order capillaries did not change significantly during insulin-induced hypoglycemia compared to euglycemia. In addition, we show that the basal diameter of both arterioles and capillaries increases during hypoglycemia (10.3 and 9.7% increases, respectively). Our results demonstrate that both neurovascular coupling and basal increases in vessel diameter are active mechanisms which help to maintain an adequate supply of glucose to the brain during hypoglycemia.
Topics: Mice; Animals; Neurovascular Coupling; Arterioles; Capillaries; Cerebrovascular Circulation; Vibrissae; Hypoglycemia; Glucose; Insulins
PubMed: 37728791
DOI: 10.1177/0271678X231201241 -
Zhongguo Xiu Fu Chong Jian Wai Ke Za... Sep 2023To investigate the preparation and properties of the novel silica (SiO )/hydroxyapatite (HAP) whiskers porous ceramics scaffold.
OBJECTIVE
To investigate the preparation and properties of the novel silica (SiO )/hydroxyapatite (HAP) whiskers porous ceramics scaffold.
METHODS
The HAP whiskers were modified by the SiO microspheres using the Stöber method. Three types of SiO /HAP whiskers were fabricated under different factors (for the No.1 samples, the content of tetraethoxysilane, stirring time, calcination temperature, and soaking time were 10 mL, 12 hours, 560℃, and 0.5 hours, respectively; and in the No.2 samples, those were 15 mL, 24 hours, 650℃, and 2 hours, respectively; while those in the No.3 samples were 20 mL, 48 hours, 750℃, and 4 hours, respectively). The phase and morphology of the self-made HAP whisker and 3 types of SiO /HAP whiskers were detected by the X-ray diffraction analysis and scanning electron microscopy. Taken the self-made HAP whisker and 3 types of SiO /HAP whiskers as raw materials, various porous ceramic materials were prepared using the mechanical foaming method combined with extrusion molding method, and the low-temperature heat treatment. The pore structure of porous ceramics was observed by scanning electron microscopy. Its porosity and pore size distribution were measured. And further the axial compressive strength was measured, and the biodegradability was detected by simulated body fluid. Cell counting kit 8 method was used to conduct cytotoxicity experiments on the extract of porous ceramics.
RESULTS
The SiO microspheres modified HAP whiskers and its porous ceramic materials were prepared successfully, respectively. In the SiO /HAP whiskers, the amorphous SiO microspheres with a diameter of 200 nm, uniform distribution and good adhesion were attached to the surface of the whiskers, and the number of microspheres was controllable. The apparent porosity of the porous ceramic scaffold was about 78%, and its pore structure was composed of neatly arranged longitudinal through-holes and a large number of micro/nano through-holes. Compared with HAP whisker porous ceramic, the axial compressive strength of the SiO /HAP whisker porous ceramics could reach 1.0 MPa, which increased the strength by nearly 4 times. Among them, the axial compressive strength of the No.2 SiO /HAP whisker porous ceramic was the highest. The SiO microspheres attached to the surface of the whiskers could provide sites for the deposition of apatite. With the content of SiO microspheres increased, the deposition rate of apatite accelerated. The cytotoxicity level of the prepared porous ceramics ranged from 0 to 1, without cytotoxicity.
CONCLUSION
SiO /HAP whisker porous ceramics have good biological activity, high porosity, three-dimensional complex pore structure, good axial compressive strength, and no cytotoxicity, which make it a promising scaffold material for bone tissue engineering.
Topics: Animals; Durapatite; Porosity; Vibrissae; Apatites; Ceramics; Silicon Dioxide
PubMed: 37718429
DOI: 10.7507/1002-1892.202304073 -
Current Biology : CB Sep 2023The brainstem houses neuronal circuits that control homeostasis of vital functions. These include the depth and rate of breathing and, critically, apnea, a transient...
The brainstem houses neuronal circuits that control homeostasis of vital functions. These include the depth and rate of breathing and, critically, apnea, a transient cessation of breathing that prevents noxious vapors from entering further into the respiratory tract. Current thinking is that this reflex is mediated by two sensory pathways. One known pathway involves vagal and glossopharyngeal afferents that project to the nucleus of the solitary tract. Yet, apnea induced by electrical stimulation of the nasal epithelium or delivery of ammonia vapors to the nose persists after brainstem transection at the pontomedullary junction, indicating that the circuitry that mediates this reflex is intrinsic to the medulla. A second potential pathway, consistent with this observation, involves trigeminal afferents from the nasal cavity that project to the muralis subnucleus of the spinal trigeminal complex. Notably, the apneic reflex is not dependent on olfaction as it can be initiated even after disruption of olfactory pathways. We investigated how subnucleus muralis cells mediate apnea in rat. By means of electrophysiological recordings and lesions in anesthetized rats, we identified a pathway from chemosensors in the nostrils through the muralis subnucleus and onto both the preBötzinger and facial motor nuclei. We then monitored breathing and orofacial reactions upon ammonia delivery near the nostril of alert, head-restrained rats. The apneic reaction was associated with a grimace, characterized by vibrissa protraction, wrinkling of the nose, and squinting of the eyes. Our results show that a brainstem circuit can control facial expressions for nocifensive and potentially pain-inducing stimuli.
Topics: Rats; Animals; Apnea; Ammonia; Brain Stem; Vagus Nerve; Neurons
PubMed: 37703878
DOI: 10.1016/j.cub.2023.08.041 -
The Journal of the Acoustical Society... Sep 2023Bio-inspired geometries have many applications in engineering, including in the field of noise control. In this work, the aeroacoustic performance of a seal vibrissa...
Bio-inspired geometries have many applications in engineering, including in the field of noise control. In this work, the aeroacoustic performance of a seal vibrissa shaped cylinder (SVSC) is investigated and compared to that of a circular cylinder at Re = 37 000. Experiments conducted in an anechoic wind tunnel are compared to results from a hybrid aeroacoustic simulation with excellent agreement observed between the two. The overall sound pressure level is found to be 24.3 dB lower for the SVSC, and no prominent narrowband component is observed in the acoustic spectrum. Analysis of the flow field and surface pressure fluctuations reveals that this is because the usual large-scale alternating vortex shedding realized for bluff body flows is absent for the SVSC. Instead, smaller uncorrelated vortices are shed from the upper and lower sides of the geometry, which, when combined with a lower spanwise correlation, results in a much lower acoustic intensity spread over a broader frequency range.
PubMed: 37699104
DOI: 10.1121/10.0020912 -
Scientific Reports Sep 2023CRISPR/Cas9-based genome editing represents an unprecedented potential for plant breeding. Unlike animal cells, plant cells contain a rigid cell wall, genome editing...
CRISPR/Cas9-based genome editing represents an unprecedented potential for plant breeding. Unlike animal cells, plant cells contain a rigid cell wall, genome editing tool delivery into plant cells is thus challenging. In particular, the delivery of the Cas9-gRNA ribonucleoprotein (RNP) into plant cells is desired since the transgene insertion into the genome should be avoided for industrial applications in plants. In this study, we present a novel RNP delivery approach in rice. We applied the sonication-assisted whisker method, conventionally developed for DNA delivery in plants, for RNP delivery in rice. Combined with marker gene delivery, we successfully isolated OsLCYβ genome-edited lines generated by RNPs. The calli and regenerated shoot of the OsLCYβ mutant showed abnormal carotenoid accumulation. In addition, we also detected, although at a low frequency, genome editing events in rice calli cells by RNP delivery using the sonication-assisted whisker method without any additional. Therefore, the sonication-assisted whisker method could be an attractive way to create RNP-based genome-edited lines in plants.
Topics: Animals; Oryza; CRISPR-Cas Systems; Gene Editing; Sonication; Vibrissae; Plant Breeding; Callosities; Ribonucleoproteins
PubMed: 37679413
DOI: 10.1038/s41598-023-40433-w -
Nature Communications Sep 2023Bio-mechanoreceptors capable of micro-motion sensing have inspired mechanics-guided designs of micro-motion sensors in various fields. However, it remains a major...
Bio-mechanoreceptors capable of micro-motion sensing have inspired mechanics-guided designs of micro-motion sensors in various fields. However, it remains a major challenge for mechanics-guided designs to simultaneously achieve high sensitivity and broadband sensing due to the nature of resonance effect. By mimicking rat vibrissae, here we report a metamaterial mechanoreceptor (MMR) comprised of piezoelectric resonators with distributed zero effective masses featuring a broad range of local resonances, leading to near-infinite sensitivity for micro-motion sensing within a broad bandwidth. We developed a mechanical frequency-division multiplexing mechanism for MMR, in which the measured micro-motion signal is mechanically modulated in non-overlapping frequency bands and reconstructed by a computational multi-channel demodulation approach. The maximum sensitivity of MMR is improved by two orders of magnitude compared to conventional mechanics-guided mechanoreceptors, and its bandwidth with high sensitivity is extendable towards both low-frequency and high-frequency ranges in 0-12 kHz through tuning the local resonance of each individual sensing cell. The MMR is a promising candidate for highly sensitive and broadband micro-motion sensing that was previously inaccessible for mechanics-guided mechanoreceptors, opening pathways towards spatio-temporal sensing, remote-vibration monitoring and smart-driving assistance.
PubMed: 37673899
DOI: 10.1038/s41467-023-41222-9