title: Representation of Stimulus Speed and Direction in Vibrissal-Sensitive Regions of the Trigeminal Nuclei: A Comparison of Single Unit and Population Responses.
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.
authors.affiliation: Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, United States of America.
authors.forename: Aniket S
authors.initials: AS
authors.lastname: Kaloti
authors.affiliation: 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.
authors.forename: Erik C
authors.initials: EC
authors.lastname: Johnson
authors.affiliation: Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, United States of America.
authors.forename: Chris S
authors.initials: CS
authors.lastname: Bresee
authors.affiliation: Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America.
authors.forename: Stephanie N
authors.initials: SN
authors.lastname: Naufel
authors.affiliation: Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America.
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Perich
authors.affiliation: 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.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Jones
authors.affiliation: Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America.|Department of Mechanical Engineering, Northwestern University, Evanston, IL, United States of America.
authors.forename: Mitra J Z
authors.initials: MJ
authors.lastname: Hartmann
mesh_terms: D000200:Action Potentials; D000818:Animals; D005260:Female; D051381:Rats; D017207:Rats, Sprague-Dawley; D014278:Trigeminal Nuclei / Q000502:physiology*; D014738:Vibrissae / Q000502:physiology*