A subscription to JoVE is required to view this content. Sign in or start your free trial.
Avoidance is central to chronic pain disability, yet adequate paradigms for examining pain-related avoidance are lacking. Therefore, we developed a paradigm that allows investigating how pain-related avoidance behavior is learned (acquisition), spreads to other stimuli (generalization), can be mitigated (extinction), and how it may subsequently re-emerge (spontaneous recovery).
Avoidance behavior is a key contributor to the transition from acute pain to chronic pain disability. Yet, there has been a lack of ecologically valid paradigms to experimentally investigate pain-related avoidance. To fill this gap, we developed a paradigm (the robotic arm-reaching paradigm) to investigate the mechanisms underlying the development of pain-related avoidance behavior. Existing avoidance paradigms (mostly in the context of anxiety research) have often operationalized avoidance as an experimenter-instructed, low-cost response, superimposed on stimuli associated with threat during a Pavlovian fear conditioning procedure. In contrast, the current method offers increased ecological validity in terms of instrumental learning (acquisition) of avoidance, and by adding a cost to the avoidance response. In the paradigm, participants perform arm-reaching movements from a starting point to a target using a robotic arm, and freely choose between three different movement trajectories to do so. The movement trajectories differ in probability of being paired with a painful electrocutaneous stimulus, and in required effort in terms of deviation and resistance. Specifically, the painful stimulus can be (partly) avoided at the cost of performing movements requiring increased effort. Avoidance behavior is operationalized as the maximal deviation from the shortest trajectory on each trial. In addition to explaining how the new paradigm can help understand the acquisition of avoidance, we describe adaptations of the robotic arm-reaching paradigm for (1) examining the spread of avoidance to other stimuli (generalization), (2) modeling clinical treatment in the lab (extinction of avoidance using response prevention), as well as (3) modeling relapse, and return of avoidance following extinction (spontaneous recovery). Given the increased ecological validity, and numerous possibilities for extensions and/or adaptations, the robotic arm-reaching paradigm offers a promising tool to facilitate the investigation of avoidance behavior and to further our understanding of its underlying processes.
Avoidance is an adaptive response to pain signaling bodily threat. Yet, when pain becomes chronic, pain and pain-related avoidance lose their adaptive purpose. In line with this, the fear-avoidance model of chronic pain1,2,3,4,5,6,7,8 posits that erroneous interpretations of pain as catastrophic, trigger increases in fear of pain, which motivate avoidance behavior. Excessive avoidance can lead to the dev....
The protocols presented here meet the requirements of the Social and Societal Ethics committee of the KU Leuven (registration number: S-56505), and the Ethics Review Committee Psychology and Neuroscience of Maastricht University (registration numbers: 185_09_11_2017_S1 and 185_09_11_2017_S2_A1).
1. Preparing the laboratory for a test session
Acquisition of avoidance behavior is demonstrated by participants avoiding more (showing larger maximal deviations from the shortest trajectory) at the end of an acquisition phase, compared to the beginning of the acquisition phase (Figure 2, indicated by A)20, or as compared to a Yoked control group (Figure 3)23,48.
Acquisition of fear and pain-expecta.......
Given the key role of avoidance in chronic pain disability1,2,3,4,5, and the limitations faced by traditional avoidance paradigms19, there is a need for methods to investigate (pain-related) avoidance behavior. The robotic arm-reaching paradigm presented here addresses a number of these limitations. We have employed the paradigm in a se.......
This research was supported by a Vidi grant from the Netherlands Organization for Scientific Research (NWO), The Netherlands (grant ID 452-17-002) and a Senior Research Fellowship of the Research Foundation Flanders (FWO-Vlaanderen), Belgium (grant ID: 12E3717N) granted to Ann Meulders. The contribution of Johan Vlaeyen was supported by the “Asthenes” long-term structural funding Methusalem grant by the Flemish Government, Belgium.
The authors wish to thank Jacco Ronner and Richard Benning from Maastricht University, for programming the experimental tasks, and designing and creating the graphics for the described experiments.
Name | Company | Catalog Number | Comments |
1 computer and computer screen | Intel Corporation | 64-bit Intel Core | Running the experimental script |
40 inch LCD screen | Samsung Group | Presenting the experimental script | |
Blender 2.79 | Blender Foundation | 3D graphics software for programming the graphics of the experiment | |
C# | Programming language used to program the experimental task | ||
Conductive gel | Reckitt Benckiser | K-Y Gel | Facilitates conduction from the skin to the stimulation electrodes |
Constant current stimulator | Digitimer Ltd | DS7A | Generates electrical stimulation |
HapticMaster | Motekforce Link | Robotic arm | |
Matlab | MathWorks | For writing scripts for participant randomization schedule, and for extracting maximum deviation from shortest trajectory per trial | |
Qualtrics | Qualtrics | Web survey tool for psychological questionnaires | |
Rstudio | Rstudio Inc. | Statistical analyses | |
Sekusept Plus | Ecolab | Disinfectant solution for cleaning medical instruments | |
Stimulation electrodes | Digitimer Ltd | Bar stimulating electrode | Two reusable stainless steel disk electrodes; 8mm diameter with 30mm spacing |
Tablet | AsusTek Computer Inc. | ASUS ZenPad 8.0 | For providing responses to psychological trait questinnaires |
Triple foot switch | Scythe | USB-3FS-2 | For providing self-report measures on VAS scale |
Unity 2017 | Unity Technologies | Cross-platform game engine for writing the experimental script including presentations of electrocutaneous stimuli |
This article has been published
Video Coming Soon
ABOUT JoVE
Copyright © 2024 MyJoVE Corporation. All rights reserved