Sensorimotor integration is a general term to describe how task-specific motor output is generated from the selective and rapid processing of sensory and motor information. The rodent vibrissal (whisker) system is an important model for the study of sensorimotor integration and active tactile sensing. This research uses the rodent vibrissal system as a model to study sensorimotor integration at the level of the brainstem. Angular tuning is a property of whisker-sensitive neurons that describes the way a neuron responds when a single whisker is stimulated in a preferred direction. While this property can partially inform how individual whisker deflections shape the neural response to multi-whisker deflections, the study of global motion can sometimes be more ethologically relevant to the type of stimulation that a rodent experiences across the array. Specifically, my thesis investigates how neurons of the trigeminal brainstem encode stimulus speed and the extent to which they exhibit tuning for the direction of global motion. Direction of global motion tuning could aid in whisker-mediated orientating behaviors. The thesis reviews the literature on speed, angular tuning, and direction of motion tuning, and describes novel experiments to assess speed and direction of global motion tuning. Experiments on the vibrissal system often require highly repeatable stimulation of multiple whiskers and the ability to vary stimulation parameters across a wide range. The stimulator must also be easy to position and adjust, while providing real time information about whisker contact. Developing a multi-whisker stimulation system that meets these criteria remains challenging. We describe a novel multi-whisker stimulator to assess neural sensitivity to the direction of global motion. The device can generate repeatable, linear sweeps of tactile stimulation across the whisker array in any direction and with a range of speeds. A fiber optic beam break detects the interval of whisker contact as the stimulator passes through the array. We demonstrate the device’s function and utility by recording from a small number of multi-whisker-responsive neurons in the trigeminal brainstem. Neurons had higher firing rates in response to faster stimulation speeds; some also exhibited strong direction-of-motion tuning. The stimulator complements more standard piezoelectric stimulators, which offer precise control but typically stimulate only single whiskers, require whisker trimming, and travel through small angles. It also complements non-contact methods of stimulation such as air-puffs and electromagnetic-induced stimulation. Tradeoffs include stimulation speed and frequency, and the inability to stimulate whiskers individually. The stimulator could be used – in either anesthetized or awake, head-fixed preparations – as an approach to studying global motion selectivity of multi-whisker sensitive neurons at multiple levels of the vibrissal-trigeminal system.

Creator

• Dorizan, Schnaude

DOI

• https://doi.org/10.21985/n2-wkgk-9823

Subject

• Neurosciences

Language

• en

Alternate Identifier

• etdadmin_upload_879050
• http://dissertations.umi.com/northwestern:15928

Keyword

• whisker
• multi-whisker responses
• trigeminal brainstem
• vibrissa
• multivibrissal stimulation
• tactile

Date created

• 2022-01-01

Resource type

• Dissertation

Rights statement

• In Copyright