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ELife Sep 2020Brain development relies on an interplay between genetic specification and self-organization. Striking examples of this relationship can be found in the somatosensory...
Brain development relies on an interplay between genetic specification and self-organization. Striking examples of this relationship can be found in the somatosensory brainstem, thalamus, and cortex of rats and mice, where the arrangement of the facial whiskers is preserved in the arrangement of cell aggregates to form precise somatotopic maps. We show in simulation how realistic whisker maps can self-organize, by assuming that information is exchanged between adjacent cells only, under the guidance of gene expression gradients. The resulting model provides a simple account of how patterns of gene expression can constrain spontaneous pattern formation to faithfully reproduce functional maps in subsequent brain structures.
Topics: Animals; Mice; Models, Neurological; Rats; Somatosensory Cortex; Thalamus; Vibrissae
PubMed: 32988453
DOI: 10.7554/eLife.55588 -
Anatomical Record (Hoboken, N.J. : 2007) Mar 2022The sense of touch in the largest marine mammals is poorly understood. While mysticetes possess specialized sensory hairs that are present through adulthood,...
The sense of touch in the largest marine mammals is poorly understood. While mysticetes possess specialized sensory hairs that are present through adulthood, descriptions of these structures are based almost entirely on examination of tissues in post-mortem individuals. Sensory hairs have rarely been observed and described in living whales. We photographed Antarctic minke whales Balaenoptera bonaerensis in the Western Antarctic Peninsula and used high-resolution images to describe the number, distribution, orientation, and relative size of sensory hairs in freely swimming individuals. Sensory hairs were well developed. They were distributed on the tip of the lower jaw, the margins of the upper and lower jaw, and near the blowhole. Far fewer hairs were observed than reported for other mysticete species, including the related species Balaenoptera acutorostrata. Placement and apparent stiffness of sensory hairs within living tissue combined with observations and images of moving whales suggest these structures aid in detecting air and ice interfaces, and possibly, the boundaries of submerged prey fields.
Topics: Animals; Antarctic Regions; Hair; Minke Whale
PubMed: 34288524
DOI: 10.1002/ar.24720 -
Neurobiology of Disease Jul 2022Sensory abnormalities are a common feature in autism spectrum disorders (ASDs). Tactile responsiveness is altered in autistic individuals, with hypo-responsiveness being...
Sensory abnormalities are a common feature in autism spectrum disorders (ASDs). Tactile responsiveness is altered in autistic individuals, with hypo-responsiveness being associated with the severity of ASD core symptoms. Similarly, sensory abnormalities have been described in mice lacking ASD-associated genes. Loss-of-function mutations in CNTNAP2 result in cortical dysplasia-focal epilepsy syndrome (CDFE) and autism. Likewise, Cntnap2 mice show epilepsy and deficits relevant with core symptoms of human ASDs, and are considered a reliable model to study ASDs. Altered synaptic transmission and synchronicity found in the cerebral cortex of Cntnap2 mice would suggest a network dysfunction. Here, we investigated the neural substrates of whisker-dependent responses in Cntnap2 and Cntnap2 adult mice. When compared to controls, Cntnap2 mice showed focal hyper-connectivity within the primary somatosensory cortex (S1), in the absence of altered connectivity between S1 and other somatosensory areas. This data suggests the presence of impaired somatosensory processing in these mutants. Accordingly, Cntnap2 mice displayed impaired whisker-dependent discrimination in the textured novel object recognition test (tNORT) and increased c-fos mRNA induction within S1 following whisker stimulation. S1 functional hyperconnectivity might underlie the aberrant whisker-dependent responses observed in Cntnap2 mice, indicating that Cntnap2 mice are a reliable model to investigate sensory abnormalities that characterize ASDs.
Topics: Animals; Autism Spectrum Disorder; Autistic Disorder; Cerebral Cortex; Membrane Proteins; Mice; Nerve Tissue Proteins; Somatosensory Cortex; Vibrissae
PubMed: 35483565
DOI: 10.1016/j.nbd.2022.105742 -
International Journal of Molecular... Aug 2022The fibroblast growth factor (FGF) family has various biological functions, including cell growth, tissue regeneration, embryonic development, metabolism, and...
The fibroblast growth factor (FGF) family has various biological functions, including cell growth, tissue regeneration, embryonic development, metabolism, and angiogenesis. In the case of hair growth, several members of the FGF family, such as FGF1 and FGF2, are involved in hair growth, while FGF5 has the opposite effect. In this study, the regulation of the hair growth cycle by FGF12 was investigated. To observe its effect, the expression of FGF12 was downregulated in mice and outer root sheath (ORS) by siRNA transfection, while FGF12 overexpression was carried out using FGF12 adenovirus. For the results, FGF12 was primarily expressed in ORS cells with a high expression during the anagen phase of hair follicles. Knockdown of FGF12 delayed telogen-to-anagen transition in mice and decreased the hair length in vibrissae hair follicles. It also inhibited the proliferation and migration of ORS cells. On the contrary, FGF12 overexpression increased the migration of ORS cells. FGF12-overexpressed ORS cells induced the telogen-to-anagen transition in the animal model. In addition, FGF12 overexpression regulated the expression of PDGF-CC, MDK, and HB-EGF, and treatment of these factors exhibited hair growth promotion. Altogether, FGF12 promoted hair growth by inducing the anagen phase of hair follicles, suggesting the potential for hair loss therapy.
Topics: Animals; Cell Cycle; Fibroblast Growth Factors; Hair; Hair Follicle; Mice; Vibrissae
PubMed: 36012732
DOI: 10.3390/ijms23169467 -
Anatomical Record (Hoboken, N.J. : 2007) Oct 2019Our understanding of vibrissal function in pinnipeds is poor due to the lack of comparative morphological, neurobiological, and psychophysical performance data. In...
Our understanding of vibrissal function in pinnipeds is poor due to the lack of comparative morphological, neurobiological, and psychophysical performance data. In contrast, the function of terrestrial mammalian vibrissae is better studied. Pinnipeds have the largest vibrissae of all mammals, and phocids may have the most modified vibrissae. The tactile performance for pinniped vibrissae is well known for harbor seals (Phoca vitulina). Harbor seals display at least two types of tactile behavior involving their mystacial vibrissae: a fine discriminatory capability using active touch and hydrodynamic trail following (the ability to detect and follow turbulent trails). This study investigated innervation patterns of harbor seal follicle-sinus complexes (F-SCs) to test the hypothesis that the whiskers used in hydrodynamic trail following possess increased innervation investment compared to other phocids. Therefore, the most lateral vibrissae from five harbor seals were histologically processed so that morphometric measurements and axon counts could be collected. Vibrissae from one harbor seal were immunolabeled with anti-protein gene product (PGP 9.5) to document the pattern of deep vibrissal nerve innervation of the F-SCs. Overall, harbor seals showed an innervation pattern (axons/F-SC and axons/muzzle) similar to other phocids. The ventrolateral vibrissae, involved in hydrodynamic trail following, have greater axon density in harbor seals than harp seals, suggesting harbor seal F-SC innervation patterns could explain their performance at trail following. The combination of microstructural, innervation investment, and behavioral data provides a foundation for functional inference regarding this tactile behavior in harbor seals and also facilitates future comparative work for other pinniped species. Anat Rec, 302:1837-1845, 2019. © 2019 American Association for Anatomy.
Topics: Animals; Behavior, Animal; Hydrodynamics; Phoca; Swimming; Touch Perception; Vibrissae
PubMed: 30980470
DOI: 10.1002/ar.24134 -
The Journal of Physiology Jan 2021The neuronal and network properties that persist during an isoelectric coma remain largely unknown. We developed a new in vivo rat model to assess cell excitability...
KEY POINTS
The neuronal and network properties that persist during an isoelectric coma remain largely unknown. We developed a new in vivo rat model to assess cell excitability and sensory responsiveness in the thalamo-cortical pathway during an isoflurane-induced isoelectric brain state. The isoelectric electrocorticogram reflected a complete interruption of spontaneous synaptic and firing activities in cortical and thalamic neurons. Cell excitability and sensory responses in the thalamo-cortical network persisted at a reduced level in the isoelectric condition and returned to control values after resumption of background brain activity. These findings could lead to a reassessment of the functional status of the drug-induced isoelectric state: a latent state in which individual neurons and networks retain to some extent the ability of being activated by external inputs.
ABSTRACT
The neuronal and network properties that persist in an isoelectric brain completely deprived of spontaneous electrical activity remain largely unexplored. Here, we developed a new in vivo rat model to examine cell excitability and sensory responsiveness in somatosensory thalamo-cortical networks during the interruption of endogenous brain activity induced by high doses of isoflurane. Electrocorticograms (ECoGs) from the barrel cortex were captured simultaneously with either intracellular recordings of subjacent cortical pyramidal neurons or extracellular records of the related thalamo-cortical neurons. Isoelectric ECoG periods reflected the disappearance of spontaneous synaptic and firing activities in cortical and thalamic neurons. This was associated with a sustained membrane hyperpolarization and a reduced intrinsic excitability in deep-layer cortical neurons, without significant changes in their membrane input resistance. Concomitantly, we found that whisker-evoked potentials in the ECoG and synaptic responses in cortical neurons were attenuated in amplitude and increased in latency. Impaired responsiveness in the barrel cortex paralleled with a lowering of the sensory-induced firing in thalamic cells. The return of endogenous brain electrical activities, after reinstatement of a control isoflurane concentration, led to the recovery of cortical neurons excitability and sensory responsiveness. These findings demonstrate the persistence of a certain level of cell excitability and sensory integration in the isoelectric state and the full recovery of cortico-thalamic functions after restoration of internal cerebral activities.
Topics: Animals; Brain; Neurons; Pyramidal Cells; Rats; Somatosensory Cortex; Thalamus; Vibrissae
PubMed: 33095909
DOI: 10.1113/JP280266 -
Neuron Jun 2024Whisker stimulation in awake mice evokes transient suppression of simple spike probability in crus I/II Purkinje cells. Here, we investigated how simple spike...
Whisker stimulation in awake mice evokes transient suppression of simple spike probability in crus I/II Purkinje cells. Here, we investigated how simple spike suppression arises synaptically, what it encodes, and how it affects cerebellar output. In vitro, monosynaptic parallel fiber (PF)-excitatory postsynaptic currents (EPSCs) facilitated strongly, whereas disynaptic inhibitory postsynaptic currents (IPSCs) remained stable, maximizing relative inhibitory strength at the onset of PF activity. Short-term plasticity thus favors the inhibition of Purkinje spikes before PFs facilitate. In vivo, whisker stimulation evoked a 2-6 ms synchronous spike suppression, just 6-8 ms (∼4 synaptic delays) after sensory onset, whereas active whisker movements elicited broadly timed spike rate increases that did not modulate sensory-evoked suppression. Firing in the cerebellar nuclei (CbN) inversely correlated with disinhibition from sensory-evoked simple spike suppressions but was decoupled from slow, non-synchronous movement-associated elevations of Purkinje firing rates. Synchrony thus allows the CbN to high-pass filter Purkinje inputs, facilitating sensory-evoked cerebellar outputs that can drive movements.
Topics: Animals; Purkinje Cells; Cerebellar Nuclei; Mice; Action Potentials; Synapses; Vibrissae; Excitatory Postsynaptic Potentials; Mice, Inbred C57BL; Inhibitory Postsynaptic Potentials; Male
PubMed: 38492575
DOI: 10.1016/j.neuron.2024.02.014 -
Proceedings. Biological Sciences Feb 2023Whiskers are important tactile structures widely used across mammals for a variety of sensory functions, but it is not known how bats-representing about a fifth of all...
Whiskers are important tactile structures widely used across mammals for a variety of sensory functions, but it is not known how bats-representing about a fifth of all extant mammal species-use them. Nectar-eating bats typically have long vibrissae (long, stiff hairs) arranged in a forward-facing brush-like formation that is not present in most non-nectarivorous bats. They also commonly use a unique flight strategy to access their food-hovering flight. Here we investigated whether these species use their vibrissae to optimize their feeding by assisting fine flight control. We used behavioural experiments to test if bats' flight trajectory into the flower changed after vibrissa removal, and phylogenetic comparative methods to test whether vibrissa length is related to nectarivory. We found that bat flight trajectory was altered after vibrissae removal and that nectarivorous bats possess longer vibrissae than non-nectivorous species, providing evidence of an additional source of information in bats' diverse sensory toolkit.
Topics: Animals; Chiroptera; Vibrissae; Phylogeny; Flowers; Food
PubMed: 36722088
DOI: 10.1098/rspb.2022.2085 -
International Journal of Biological... Sep 2022Nanochitin whisker (NC) is an advanced nanobiomaterial with novel physicochemical and biological properties. Fusarium pseudograminearum (Fpg) is an important pathogenic...
Nanochitin whisker (NC) is an advanced nanobiomaterial with novel physicochemical and biological properties. Fusarium pseudograminearum (Fpg) is an important pathogenic fungus causing wheat crown rot disease. This study explored the mode of action of NC against Fpg as a target microorganism. The effects of different treatments and concentrations of NC on the fungal growth and conidial germination were investigated by in vitro bioassay. The impacts of NC on cell structure integrity, membrane permeability, pathogenesis related key enzymes activity, and the mycotoxin production were examined by electron microscopy, fluorescence spectroscopy, IR spectroscopy, conductometry, and spectrophotometry, respectively. The results showed that NC significantly reduced hyphal growth, and the spore germination rate of Fpg declined by 33.0 % and 23.2 % when Fpg was treated with 30 and 300 μg/mL of NC, respectively. NC vigorously influenced structural stability of cell wall by destroying dextran structure, and strongly stimulated ergosterol production altering membrane integrity of the fungus. It reduced the activities of enzymes related to energy-supply like nicotinamide adenine dinucleotide oxidase and succinate dehydrogenase remarkably. The production of fungal mycotoxin deoxynivalenol was also decreased by NC. These findings provide an important basis for fully understanding the mechanism of nanobiomaterial in plant fungal disease control.
Topics: Animals; Fusarium; Mycotoxins; Plant Diseases; Vibrissae
PubMed: 35839953
DOI: 10.1016/j.ijbiomac.2022.07.056 -
International Journal of Molecular... Nov 2020Methamphetamine (MA) use disorder is a chronic neuropsychiatric disease characterized by recurrent binge episodes, intervals of abstinence, and relapses to MA use....
Methamphetamine (MA) use disorder is a chronic neuropsychiatric disease characterized by recurrent binge episodes, intervals of abstinence, and relapses to MA use. Therefore, identification of the key genes and pathways involved is important for improving the diagnosis and treatment of this disorder. In this study, high-throughput RNA sequencing was performed to find the key genes and examine the comparability of gene expression between whisker follicles and the striatum of rats following MA self-administration. A total of 253 and 87 differentially expressed genes (DEGs) were identified in whisker follicles and the striatum, respectively. Multivariate and network analyses were performed on these DEGs to find hub genes and key pathways within the constructed network. A total of 129 and 49 genes were finally selected from the DEG sets of whisker follicles and of the striatum. Statistically significant DEGs were found to belong to the classes of genes involved in nicotine addiction, cocaine addiction, and amphetamine addiction in the striatum as well as in Parkinson's, Huntington's, and Alzheimer's diseases in whisker follicles. Of note, several genes and pathways including retrograde endocannabinoid signaling and the synaptic vesicle cycle pathway were common between the two tissues. Therefore, this study provides the first data on gene expression levels in whisker follicles and in the striatum in relation to MA reward and thereby may accelerate the research on the whisker follicle as an alternative source of biomarkers for the diagnosis of MA use disorder.
Topics: Alzheimer Disease; Amphetamine-Related Disorders; Animals; Corpus Striatum; Disease Models, Animal; Gene Expression Regulation; Hair Follicle; High-Throughput Nucleotide Sequencing; Humans; Huntington Disease; Methamphetamine; Neostriatum; Parkinson Disease; Rats; Self Administration; Signal Transduction; Transcriptome; Vibrissae
PubMed: 33238484
DOI: 10.3390/ijms21228856