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Neuroscience Jul 2022In Robo3cKO mouse brain, rhombomere 3-derived trigeminal principal nucleus (PrV) neurons project bilaterally to the somatosensory thalamus. As a consequence,...
In Robo3cKO mouse brain, rhombomere 3-derived trigeminal principal nucleus (PrV) neurons project bilaterally to the somatosensory thalamus. As a consequence, whisker-specific neural modules (barreloids and barrels) representing whiskers on both sides of the face develop in the sensory thalamus and the primary somatosensory cortex. We examined the morphological complexity of layer 4 barrel cells, their postsynaptic partners in layer 3, and functional specificity of layer 3 pyramidal cells. Layer 4 spiny stellate cells form much smaller barrels and their dendritic fields are more focalized and less complex compared to controls, while layer 3 pyramidal cells did not show notable differences. Using in vivo 2-photon imaging of a genetically encoded fluorescent [Ca] sensor, we visualized neural activity in the normal and Robo3cKO barrel cortex in response to ipsi- and contralateral single whisker stimulation. Layer 3 neurons in control animals responded only to their contralateral whiskers, while in the mutant cortex layer 3 pyramidal neurons showed both ipsi- and contralateral whisker responses. These results indicate that bilateral whisker map inputs stimulate different but neighboring groups of layer 3 neurons which normally relay contralateral whisker-specific information to other cortical areas.
Topics: Animals; Mice; Neurons; Pyramidal Cells; Somatosensory Cortex; Thalamus; Vibrissae
PubMed: 35598701
DOI: 10.1016/j.neuroscience.2022.05.018 -
Journal of Neurophysiology May 2016Rodents use their whiskers to explore the environment, and the superior colliculus is part of the neural circuits that process this sensorimotor information. Cells in...
Rodents use their whiskers to explore the environment, and the superior colliculus is part of the neural circuits that process this sensorimotor information. Cells in the intermediate layers of the superior colliculus integrate trigeminotectal afferents from trigeminal complex and corticotectal afferents from barrel cortex. Using histological methods in mice, we found that trigeminotectal and corticotectal synapses overlap somewhat as they innervate the lower and upper portions of the intermediate granular layer, respectively. Using electrophysiological recordings and optogenetics in anesthetized mice in vivo, we showed that, similar to rats, whisker deflections produce two successive responses that are driven by trigeminotectal and corticotectal afferents. We then employed in vivo and slice experiments to characterize the response properties of these afferents. In vivo, corticotectal responses triggered by electrical stimulation of the barrel cortex evoke activity in the superior colliculus that increases with stimulus intensity and depresses with increasing frequency. In slices from adult mice, optogenetic activation of channelrhodopsin-expressing trigeminotectal and corticotectal fibers revealed that cells in the intermediate layers receive more efficacious trigeminotectal, than corticotectal, synaptic inputs. Moreover, the efficacy of trigeminotectal inputs depresses more strongly with increasing frequency than that of corticotectal inputs. The intermediate layers of superior colliculus appear to be tuned to process strong but infrequent trigeminal inputs and weak but more persistent cortical inputs, which explains features of sensory responsiveness, such as the robust rapid sensory adaptation of whisker responses in the superior colliculus.
Topics: Afferent Pathways; Animals; Evoked Potentials, Somatosensory; Mice; Neurons, Afferent; Superior Colliculi; Synapses; Vibrissae
PubMed: 26864754
DOI: 10.1152/jn.00028.2016 -
Nature Protocols Aug 2014The rodent vibrissa system is a widely used experimental model of active sensation and motor control. Vibrissa-based touch in rodents involves stereotypic, rhythmic...
The rodent vibrissa system is a widely used experimental model of active sensation and motor control. Vibrissa-based touch in rodents involves stereotypic, rhythmic sweeping of the vibrissae as the animal explores its environment. Although pharmacologically induced rhythmic movements have long been used to understand the neural circuitry that underlies a variety of rhythmic behaviors, including locomotion, digestion and ingestion, these techniques have not been available for active sensory movements such as whisking. However, recent work that delineated the location of the central pattern generator for whisking has enabled pharmacological control over this behavior. Here we specify a protocol for the pharmacological induction of rhythmic vibrissa movements that mimic exploratory whisking. The rhythmic vibrissa movements are induced by local injection of a glutamatergic agonist, kainic acid. This protocol produces coordinated rhythmic vibrissa movements that are sustained for several hours in the anesthetized mouse or rat and thus provides unprecedented experimental control in studies related to vibrissa-based neuronal circuitry.
Topics: Animals; Excitatory Amino Acid Agents; Female; Kainic Acid; Mice; Nerve Net; Rats; Rats, Long-Evans; Sensation; Stimulation, Chemical; Vibrissae
PubMed: 24992095
DOI: 10.1038/nprot.2014.119 -
The Journal of Neuroscience : the... Jun 1999The following experiments determined that the somatosensory whisker system is functional and capable of experience-dependent behavioral plasticity in the neonate before...
The following experiments determined that the somatosensory whisker system is functional and capable of experience-dependent behavioral plasticity in the neonate before functional maturation of the somatosensory whisker cortex. First, unilateral whisker stimulation caused increased behavioral activity in both postnatal day (P) 3-4 and P8 pups, whereas stimulation-evoked cortical activity (14C 2-deoxyglucose autoradiography) was detectable only in P8 pups. Second, neonatal rat pups are capable of forming associations between whisker stimulation and a reinforcer. A classical conditioning paradigm (P3-P4) showed that the learning groups (paired whisker stimulation-shock or paired whisker stimulation-warm air stream) exhibited significantly higher behavioral responsiveness to whisker stimulation than controls. Finally, stimulus-evoked somatosensory cortical activity during testing [P8; using 14C 2-deoxyglucose (2-DG) autoradiography] was assessed after somatosensory conditioning from P1-P8. No learning-associated differences in stimulus-evoked cortical activity were detected between learning and nonlearning control groups. Together, these experiments demonstrate that the whisker system is functional in neonates and capable of experience-dependent behavioral plasticity. Furthermore, in contrast to adult somatosensory classical conditioning, these data suggest that the cortex is not required for associative somatosensory learning in neonates.
Topics: Animals; Animals, Newborn; Antimetabolites; Association Learning; Behavior, Animal; Conditioning, Psychological; Deoxyglucose; Electroshock; Female; Hot Temperature; Male; Neuronal Plasticity; Physical Stimulation; Rats; Rats, Long-Evans; Somatosensory Cortex; Vibrissae
PubMed: 10366646
DOI: 10.1523/JNEUROSCI.19-12-05131.1999 -
Trends in Neurosciences Oct 2001A major portion of the primary somatosensory cortex of rodents is characterized by the discrete and patterned distribution of thalamocortical axons and layer IV granule... (Review)
Review
A major portion of the primary somatosensory cortex of rodents is characterized by the discrete and patterned distribution of thalamocortical axons and layer IV granule cells ('barrels'), which correspond to the spatial distribution of whiskers and sinus hairs on the snout. In recent years several mutant mouse models began unveiling the cellular and molecular mechanisms by which these patterns emerge presynaptically and are reflected postsynaptically. Neural activity plays a crucial role in conferring presynaptic patterns to postsynaptic cells via neurotransmitter receptor-mediated intracellular signals. Here we review recent evidence that is finally opening the doors to understanding the cellular and molecular mechanisms of pattern formation in the neocortex.
Topics: Animals; Neocortex; Somatosensory Cortex; Vibrissae
PubMed: 11576673
DOI: 10.1016/s0166-2236(00)01958-5 -
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 -
ELife Feb 2019Haptic perception synthesizes touch with proprioception, the sense of body position. Humans and mice alike experience rich active touch of the face. Because most facial...
Haptic perception synthesizes touch with proprioception, the sense of body position. Humans and mice alike experience rich active touch of the face. Because most facial muscles lack proprioceptor endings, the sensory basis of facial proprioception remains unsolved. Facial proprioception may instead rely on mechanoreceptors that encode both touch and self-motion. In rodents, whisker mechanoreceptors provide a signal that informs the brain about whisker position. Whisking involves coordinated orofacial movements, so mechanoreceptors innervating facial regions other than whiskers could also provide information about whisking. To define all sources of sensory information about whisking available to the brain, we recorded spikes from mechanoreceptors innervating diverse parts of the face. Whisker motion was encoded best by whisker mechanoreceptors, but also by those innervating whisker pad hairy skin and supraorbital vibrissae. Redundant self-motion responses may provide the brain with a stable proprioceptive signal despite mechanical perturbations during active touch.
Topics: Animals; Face; Mechanoreceptors; Mice; Motion; Proprioception; Vibrissae
PubMed: 30816844
DOI: 10.7554/eLife.41535 -
Science Advances Aug 2016Observation of terrestrial mammals suggests that they can follow the wind (anemotaxis), but the sensory cues underlying this ability have not been studied. We identify a...
Observation of terrestrial mammals suggests that they can follow the wind (anemotaxis), but the sensory cues underlying this ability have not been studied. We identify a significant contribution to anemotaxis mediated by whiskers (vibrissae), a modality previously studied only in the context of direct tactile contact. Five rats trained on a five-alternative forced-choice airflow localization task exhibited significant performance decrements after vibrissal removal. In contrast, vibrissal removal did not disrupt the performance of control animals trained to localize a light source. The performance decrement of individual rats was related to their airspeed threshold for successful localization: animals that found the task more challenging relied more on the vibrissae for localization cues. Following vibrissal removal, the rats deviated more from the straight-line path to the air source, choosing sources farther from the correct location. Our results indicate that rats can perform anemotaxis and that whiskers greatly facilitate this ability. Because air currents carry information about both odor content and location, these findings are discussed in terms of the adaptive significance of the interaction between sniffing and whisking in rodents.
Topics: Animals; Exploratory Behavior; Rats; Taxis Response; Touch; Vibrissae; Wind
PubMed: 27574705
DOI: 10.1126/sciadv.1600716 -
Scientific Reports Jul 2018Classically, texture discrimination has been thought to be based on 'global' codes, i.e. frequency (signal analysis based on Fourier analysis) or intensity (signal...
Classically, texture discrimination has been thought to be based on 'global' codes, i.e. frequency (signal analysis based on Fourier analysis) or intensity (signal analysis based on averaging), which both rely on integration of the vibrotactile signal across time and/or space. Recently, a novel 'local' coding scheme based on the waveform of frictional movements, discrete short lasting kinematic events (i.e. stick-slip movements called slips) has been formulated. We performed biomechanical measurements of relative movements of a rat vibrissa across sandpapers of different roughness. We find that the classic global codes convey some information about texture identity, but are consistently outperformed by the slip-based local code. Moreover, the slip code also surpasses the global ones in coding for active scanning parameters. This is remarkable as it suggests that the slip code would explicitly allow the whisking rat to optimize perception by selecting goal-specific scanning strategies.
Topics: Animals; Biomechanical Phenomena; Friction; Rats; Somatosensory Cortex; Touch Perception; Vibrissae
PubMed: 30042423
DOI: 10.1038/s41598-018-29225-9 -
ELife Feb 2022Vibrissa sensory inputs play a central role in driving rodent behavior. These inputs transit through the sensory trigeminal nuclei, which give rise to the ascending...
Vibrissa sensory inputs play a central role in driving rodent behavior. These inputs transit through the sensory trigeminal nuclei, which give rise to the ascending lemniscal and paralemniscal pathways. While lemniscal projections are somatotopically mapped from brainstem to cortex, those of the paralemniscal pathway are more widely distributed. Yet the extent and topography of paralemniscal projections are unknown, along with the potential role of these projections in controlling behavior. Here, we used viral tracers to map paralemniscal projections. We find that this pathway broadcasts vibrissa-based sensory signals to brainstem regions that are involved in the regulation of autonomic functions and to forebrain regions that are involved in the expression of emotional reactions. We further provide evidence that GABAergic cells of the Kölliker-Fuse nucleus gate trigeminal sensory input in the paralemniscal pathway via a mechanism of presynaptic or extrasynaptic inhibition.
Topics: Afferent Pathways; Animals; Brain Stem; Electrophysiology; Limbic System; Optogenetics; Rats; Rats, Long-Evans; Trigeminal Nuclei; Vibrissae
PubMed: 35142608
DOI: 10.7554/eLife.72096