Methods for the measurement and analysis of the temporal discrimination threshold are presented, and its application to the study of the pathogenesis of cervical dystonia are discussed.
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Method Article
Measurement & Analysis of the Temporal Discrimination Threshold Applied to Cervical Dystonia
* These authors contributed equally
In This Article
Summary
Abstract
The temporal discrimination threshold (TDT) is the shortest time interval at which an observer can discriminate two sequential stimuli as being asynchronous (typically 30-50 ms). It has been shown to be abnormal (prolonged) in neurological disorders, including cervical dystonia, a phenotype of adult onset idiopathic isolated focal dystonia. The TDT is a quantitative measure of the ability to perceive rapid changes in the environment and is considered indicative of the behavior of the visual neurons in the superior colliculus, a key node in covert attentional orienting. This article sets out methods for measuring the TDT (including two hardware options and two modes of stimuli presentation). We also explore two approaches of data analysis and TDT calculation. The application of the assessment of temporal discrimination to the understanding of the pathogenesis of cervical dystonia and adult onset idiopathic isolated focal dystonia is also discussed.
Introduction
Temporal discrimination describes a person's ability to discriminate, or perceive, rapid changes in their environment. The temporal discrimination threshold (TDT) is the shortest time interval at which an individual can perceive that two sequential sensory stimuli are asynchronous. Temporal discrimination has been shown to be abnormally prolonged in disorders affecting the basal ganglia, including dystonia1,2,3,4,5,6,7.
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Protocol
The Medical Research Ethics Committee at St. Vincent's University Hospital, Dublin gave approval for the recruitment of patients with cervical dystonia, their siblings (unaffected by dystonia), and healthy controls, to participate in the protocol described below.
1. Hardware & Software Solutions
Note: Two hardware options have been developed to display visual stimuli with precise inter-stimulus intervals. Both were designed and built in-house at the Trinity Centre for Bioengineering, Trinity College Dublin, and have been previously described5,16. Th....
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Results
Examples of filled score sheets are provided in Tables 1 and 2, where these respectively represent results following staircase and random stimulus presentation methods. The thresholds for each run (the timing of the first of three stimulus pairs deemed to be 'different'), are highlighted. In the case of Table 1, the TDT is calculated as 25 ms (i.e., the median of 40, 25, 25, 25, 45, 25, 40, 10 ms). These data are.......
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Discussion
TDT Measurement and Analysis
Two forms of apparatus (table-top and headset), two methods of stimulus presentation (staircase and random), and two approaches to data analysis (traditional and distribution) have been presented to illustrate how to measure and quantify a person's temporal discrimination ability. The portable headset provides a convenient hardware option that ensures consistency in distance and angles between the participant and the LED light sources while al.......
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Disclosures
Rebecca B Beck, Eavan M Mc Govern, John Butler, Dorina Birsanu, Brendan Quinlivan, Ines Beiser, Shruti Narasimham have no funding sources, financial disclosures or conflict of interests to declare. Michael Hutchinson receives research grants from Dystonia Ireland, the Health Research Board of Ireland (CSA-2012-5), Foundation for Dystonia Research (Belgium) and the Irish Institute of Clinical Neuroscience. Sean O'Riordan reports receiving a speaker's honorarium from Abbvie. Richard Reilly receives funding from Science Foundation Ireland, Enterprise Ireland and the Health Research Board of Ireland.
Acknowledgements
This research was supported by grants from the Health Research Board, Dystonia Ireland, Science Foundation Ireland and the Irish Institute for Clinical Neuroscience.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| TDT head set | Can be supplied by Trinity Centre for Bioengineering, Trinity College Dublin. Alternatively full instructions are available for free download from http://www.dystoniaresearch.ie/temporal-discrimination-threshold/ | 1 | A custom-built, portable device for the presentation of visual stimuli. |
| TDT table top LED box | Can be supplied by Trinity Centre for Bioengineering, Trinity College Dublin. Alternatively full instructions are available for free download from http://www.dystoniaresearch.ie/temporal-discrimination-threshold/ | 2 | A custom-built, table-top device for the presentation of visual stimuli. |
| Microcontroller | Can be supplied by Trinity Centre for Bioengineering, Trinity College Dublin. Alternatively full instructions are available for free download from http://www.dystoniaresearch.ie/temporal-discrimination-threshold/ | 3 | A custom-built microcontroller for the delivery of visual stimuli in staircase or random order, with precise inter-stimulus intervals. |
References
- Bradley, D., et al. Temporal discrimination thresholds in adult-onset primary torsion dystonia: an analysis by task type and by dystonia phenotype. J Neurol. 259 (1), 77-82 (2012).
- Hutchinson, M., et al.
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