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Khasabov SG, Truong H, Rogness VM, Alloway KD, Simone DA, Giesler GJ. Responses of neurons in the primary somatosensory cortex to itch- and pain-producing stimuli in rats. J Neurophysiol 2020; 123:1944-1954. [PMID: 32292106 DOI: 10.1152/jn.00038.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Understanding of cortical encoding of itch is limited. Injection of pruritogens and algogens into the skin of the cheek produces distinct behaviors, making the rodent cheek a useful model for understanding mechanisms of itch and pain. We examined responses of neurons in the primary somatosensory cortex by application of mechanical stimuli (brush, pressure, and pinch) and stimulations with intradermal injections of pruritic and algesic chemical of receptive fields located on the skin of the cheek in urethane-anesthetized rats. Stimuli included chloroquine, serotonin, β-alanine, histamine, capsaicin, and mustard oil. All 33 neurons studied were excited by noxious mechanical stimuli applied to the cheek. Based on mechanical stimulation most neurons were functionally classified as high threshold. Of 31 neurons tested for response to chemical stimuli, 84% were activated by one or more pruritogens/partial pruritogens. No cells were activated by all five substances. Histamine activated the greatest percentage of neurons and evoked the greatest mean discharge. Importantly, no cells were excited exclusively by pruritogens or partial pruritogens. The recording sites of all neurons that responded to chemical stimuli applied to the cheek were located in the dysgranular zone (DZ) and in deep laminae of the medial border of the vibrissal barrel fields (VBF). Therefore, neurons in the DZ/VBF of rats encode mechanical and chemical pruritogens and algogens. This cortical region appears to contain primarily nociceptive neurons as defined by responses to noxious pinching of the skin. Its role in encoding itch and pain from the cheek of the face needs further study.NEW & NOTEWORTHY Processing of information related to itch sensation at the level of cerebral cortex is not well understood. In this first single-unit electrophysiological study of pruriceptive cortical neurons, we show that neurons responsive to noxious and pruritic stimulation of the cheek of the face are concentrated in a small area of the dysgranular cortex, indicating that these neurons encode information related to itch and pain.
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Affiliation(s)
- Sergey G Khasabov
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, Minnesota
| | - Hai Truong
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Victoria M Rogness
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, Minnesota
| | - Kevin D Alloway
- Center for Neural Engineering, Penn State University, University Park, Pennsylvania.,Department of Neural and Behavioral Sciences, Penn State University, University Park, Pennsylvania
| | - Donald A Simone
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, Minnesota
| | - Glenn J Giesler
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
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Kitazawa T, Rijli FM. Barrelette map formation in the prenatal mouse brainstem. Curr Opin Neurobiol 2018; 53:210-219. [PMID: 30342228 DOI: 10.1016/j.conb.2018.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/03/2018] [Accepted: 09/24/2018] [Indexed: 12/30/2022]
Abstract
The rodent whiskers are topographically mapped in brainstem sensory nuclei as neuronal modules known as barrelettes. Little is known about how the facial whisker pattern is copied into a brainstem barrelette topographic pattern, which serves as a template for the establishment of thalamic barreloid and, in turn, cortical barrel maps, and how precisely is the whisker pattern mapped in the brainstem during prenatal development. Here, we review recent insights advancing our understanding of the intrinsic and extrinsic patterning mechanisms contributing to establish topographical equivalence between the facial whisker pattern and the mouse brainstem during prenatal development and their relative importance.
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Affiliation(s)
- Taro Kitazawa
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4051 Basel, Switzerland
| | - Filippo M Rijli
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4051 Basel, Switzerland; University of Basel, 4003 Basel, Switzerland.
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Cortical modulation of sensory flow during active touch in the rat whisker system. Nat Commun 2018; 9:3907. [PMID: 30254195 PMCID: PMC6156333 DOI: 10.1038/s41467-018-06200-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 08/22/2018] [Indexed: 02/01/2023] Open
Abstract
Sensory gating, where responses to stimuli during sensor motion are reduced in amplitude, is a hallmark of active sensing systems. In the rodent whisker system, sensory gating has been described only at the thalamic and cortical stages of sensory processing. However, does sensory gating originate at an even earlier synaptic level? Most importantly, is sensory gating under top-down or bottom-up control? To address these questions, we used an active touch task in behaving rodents while recording from the trigeminal sensory nuclei. First, we show that sensory gating occurs in the brainstem at the first synaptic level. Second, we demonstrate that sensory gating is pathway-specific, present in the lemniscal but not in the extralemniscal stream. Third, using cortical lesions resulting in the complete abolition of sensory gating, we demonstrate its cortical dependence. Fourth, we show accompanying decreases in whisking-related activity, which could be the putative gating signal. During active touch, sensory responses to object touch are gated at the level of thalamus and cortex. Here, the authors report gating at the level of the brainstem and show that an intact somatosensory cortex is essential for this response modulation.
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Kaloti AS, Johnson EC, Bresee CS, Naufel SN, Perich MG, Jones DL, Hartmann MJZ. Representation of Stimulus Speed and Direction in Vibrissal-Sensitive Regions of the Trigeminal Nuclei: A Comparison of Single Unit and Population Responses. PLoS One 2016; 11:e0158399. [PMID: 27463524 PMCID: PMC4963183 DOI: 10.1371/journal.pone.0158399] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 06/15/2016] [Indexed: 11/24/2022] Open
Abstract
The rat vibrissal (whisker) system is one of the oldest and most important models for the study of active tactile sensing and sensorimotor integration. It is well established that primary sensory neurons in the trigeminal ganglion respond to deflections of one and only one whisker, and that these neurons are strongly tuned for both the speed and direction of individual whisker deflections. During active whisking behavior, however, multiple whiskers will be deflected simultaneously. Very little is known about how neurons at central levels of the trigeminal pathway integrate direction and speed information across multiple whiskers. In the present work, we investigated speed and direction coding in the trigeminal brainstem nuclei, the first stage of neural processing that exhibits multi-whisker receptive fields. Specifically, we recorded both single-unit spikes and local field potentials from fifteen sites in spinal trigeminal nucleus interpolaris and oralis while systematically varying the speed and direction of coherent whisker deflections delivered across the whisker array. For 12/15 neurons, spike rate was higher when the whisker array was stimulated from caudal to rostral rather than rostral to caudal. In addition, 10/15 neurons exhibited higher firing rates for slower stimulus speeds. Interestingly, using a simple decoding strategy for the local field potentials and spike trains, classification of speed and direction was higher for field potentials than for single unit spike trains, suggesting that the field potential is a robust reflection of population activity. Taken together, these results point to the idea that population responses in these brainstem regions in the awake animal will be strongest during behaviors that stimulate a population of whiskers with a directionally coherent motion.
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Affiliation(s)
- Aniket S. Kaloti
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, United States of America
| | - Erik C. Johnson
- Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL, United States of America
- Coordinated Science Laboratory, University of Illinois, Urbana, IL, United States of America
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, IL, United States of America
| | - Chris S. Bresee
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, United States of America
| | - Stephanie N. Naufel
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
| | - Matthew G. Perich
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
| | - Douglas L. Jones
- Department of Electrical and Computer Engineering, University of Illinois, Urbana, IL, United States of America
- Coordinated Science Laboratory, University of Illinois, Urbana, IL, United States of America
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, IL, United States of America
- Advanced Digital Sciences Center, Illinois at Singapore Pte., Singapore, Singapore
| | - Mitra J. Z. Hartmann
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
- Department of Mechanical Engineering, Northwestern University, Evanston, IL, United States of America
- * E-mail:
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On-going computation of whisking phase by mechanoreceptors. Nat Neurosci 2016; 19:487-93. [PMID: 26780508 DOI: 10.1038/nn.4221] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 12/04/2015] [Indexed: 12/25/2022]
Abstract
To attribute spatial meaning to sensory information, the state of the sensory organ must be represented in the nervous system. In the rodent's vibrissal system, the whisking-cycle phase has been identified as a key coordinate, and phase-based representation of touch has been reported in the somatosensory cortex. Where and how phase is extracted in the ascending afferent pathways remains unknown. Using a closed-loop interface in anesthetized rats, we found that whisking phase is already encoded in a frequency- and amplitude-invariant manner by primary vibrissal afferents. We found that, for naturally constrained whisking dynamics, such invariant phase coding could be obtained by tuning each receptor to a restricted kinematic subspace. Invariant phase coding was preserved in the brainstem, where paralemniscal neurons filtered out the slowly evolving offset, whereas lemniscal neurons preserved it. These results demonstrate accurate, perceptually relevant, mechanically based processing at the sensor level.
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