Neural basis of the neurological diagnostic power of vibrotactile sensory testing

Forshey, Theresa Marie

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March 22, 2019

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Forshey, Theresa Marie
- Affiliation: School of Medicine, UNC/NCSU Joint Department of Biomedical Engineering

Abstract

As with most other injuries and disorders, the prognosis of neurological impairment is dependent upon early and accurate detection. Likewise, after an appropriate diagnosis has been made, it is important to start the patient on an effective treatment plan. Often a clinician prescribes a medication and asks the patient to come back for a follow-up appointment. It would be extremely beneficial if the clinician could instead conduct a quantitative assessment to immediately determine the effectiveness of a prescribed treatment. Our research utilizes non-invasive, non-painful tactile sensory assessments which could assist in the timely, accurate detection for neurological impairments and their corresponding treatments by quantifying minute changes in cortical functionality. Unfortunately, despite the potential to use these diagnostic assessments for a broad scope of neurological impairments (e.g. alcoholism, chronic pain, concussion, and autism), the neurological basis behind many of these diagnostic assessments are unclear. In other words, while the assessments found variations between these focus groups and healthy controls, there is not enough neurological context to fully explain the findings. To address the issue, the primary goal of this research was to establish a neurological basis for the results of these sensory assessments. Once understood, these quantitative assessments could become valuable tools in future clinical applications for the diagnosis of neurological disorders. The central goal of this study was to provide experimental evidence of a cortical mechanism that was hypothesized to be of fundamental importance in tactile perception. Based upon microelectrode recording analysis of the cortical response to various vibrotactile stimulations (cats and non-human primates), we describe two forms of cortical contrast: spatial and temporal. Those results suggest that improved cortical contrast may be important for enhancing tactile sensory perception. To test this hypothesis, we conducted a variety of tactile sensory assessments on healthy controls including frequency discrimination, amplitude discrimination, and temporal order judgment. The results of the human sensory studies are in full agreement with our basic, animal neurological studies. In conclusion, human performance on those quantitative sensory tests can be used as an indicator of the functionality of the cortical mechanisms responsible for spatial and temporal contrast enhancement.

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