Sadnicka A, Daum C, Cordivari C, Bhatia K P, Rothwell J C, Manohar S, Edwards M J
Sobell Department for Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, UK.
Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK.
Eur J Neurol. 2017 Jun;24(6):796-806. doi: 10.1111/ene.13293.
One of the most widely studied perceptual measures of sensory dysfunction in dystonia is the temporal discrimination threshold (TDT) (the shortest interval at which subjects can perceive that there are two stimuli rather than one). However the elevated thresholds described may be due to a number of potential mechanisms as current paradigms test not only temporal discrimination but also extraneous sensory and decision-making parameters. In this study two paradigms designed to better quantify temporal processing are presented and a decision-making model is used to assess the influence of decision strategy.
22 patients with cervical dystonia and 22 age-matched controls completed two tasks (i) temporal resolution (a randomized, automated version of existing TDT paradigms) and (ii) interval discrimination (rating the length of two consecutive intervals).
In the temporal resolution task patients had delayed (P = 0.021) and more variable (P = 0.013) response times but equivalent discrimination thresholds. Modelling these effects suggested this was due to an increased perceptual decision boundary in dystonia with patients requiring greater evidence before committing to decisions (P = 0.020). Patient performance on the interval discrimination task was normal.
Our work suggests that previously observed abnormalities in TDT may not be due to a selective sensory deficit of temporal processing as decision-making itself is abnormal in cervical dystonia.
肌张力障碍中感觉功能障碍最广泛研究的感知测量方法之一是时间辨别阈值（TDT）（即受试者能够感知到有两个刺激而非一个刺激的最短间隔）。然而，所描述的升高阈值可能归因于多种潜在机制，因为当前范式不仅测试时间辨别，还测试无关的感觉和决策参数。在本研究中，提出了两种旨在更好地量化时间处理的范式，并使用一种决策模型来评估决策策略的影响。
22例颈部肌张力障碍患者和22例年龄匹配的对照者完成两项任务：（i）时间分辨（现有TDT范式的随机自动化版本）和（ii）间隔辨别（对两个连续间隔的长度进行评分）。
在时间分辨任务中，患者的反应时间延迟（P = 0.021）且变异性更大（P = 0.013），但辨别阈值相当。对这些效应进行建模表明，这是由于肌张力障碍中感知决策边界增加，患者在做出决策前需要更多证据（P = 0.020）。患者在间隔辨别任务中的表现正常。
我们的研究表明，先前在TDT中观察到的异常可能并非由于时间处理的选择性感觉缺陷，因为在颈部肌张力障碍中决策本身是异常的。
