Rapid motor responses quickly integrate visuospatial task constraints
- 369 Downloads
We have recently shown that subjects can appropriately modulate their rapid motor responses (traditionally termed reflexes) to move their hand to a spatial target when the target is displayed ~2 s before a mechanical perturbation (Pruszynski et al. in J Neurophysiol 100:224–238, 2008). The goal of this study was to investigate how quickly visual information can be used to modulate rapid motor responses to an impending mechanical perturbation. Following a 2 s to 10 ms target preview delay (PD), a perturbation either displaced the subject’s hand into or out of the previewed target. We also included a condition, where the target appeared after perturbation onset (target PD = +90 ms). In all cases, subjects were instructed to react as quickly as possible to the perturbation by reaching into the displayed target. Our results indicate that subjects began to incorporate visual information into their rapid motor responses with PDs as small as 70 ms. Interestingly, subjects reacted faster when the target was presented ~150 ms before the perturbation than when they had 2 s to prepare a response. Using receiver operative characteristic (ROC) analysis, we examined modulation of muscle activity as a function of preview delay in three predefined epochs. No modulation was found in the short-latency epoch (R1; 20–45 ms). In contrast, both the long-latency (45–105 ms) and voluntary (120–180 ms) epochs were modulated at essentially the same time, 140 ms from visual presentation of the target to the beginning of each respective epoch.
KeywordsReflex Visual integration Long-latency response EMG Task-dependent Upper limb
This work was supported by the National Science and Engineering Research Council of Canada (NSERC). J.A.P received a salary award from the Canadian Institute for Health Research (CIHR). We thank Kim Moore and Justin Peterson for their technical support and Isaac Kurtzer for his input into the experiments.
Conflict of interest
S.H.S. is associated with BKIN Technologies, which commercializes the KINARM device used in this study.
- Green DM, Swets JA (1966) Signal detection theory and psychophysics. Wiley, New YorkGoogle Scholar
- Hagbarth KE (1967) EMG studies of stretch reflexes in man. Electroencephalogr Clin Neurophysiol 25:74–79Google Scholar
- Hammond PH (1956) The influence of prior instruction to the subject on an apparently involuntary neuro-muscular response. J Physiol 132:17P–18PGoogle Scholar
- Mackinnon CD, Bissig D, Chiusane J, Miller E, Rudnick L, Jager C, Zhang Y, Mille ML, Rogers MW (2006) Preparation of anticipatory postural asjustments prior to stepping. J Neurophysiol 6:4368–4379Google Scholar
- Pashler HE (1999) The psychology of attention, 2nd edn. MIT Press, MassachusettsGoogle Scholar
- Pruszynski JA, Kurtzer I, Lillicrap TP, Scott SH (2009) Temporal evolution of “Automatic Gain-Scaling”. J Neurophysiol 97(6):4368–4379Google Scholar
- Shedmehr R, Wise S (2005) The computational neurobiology of reaching and pointing: a foundation for motor learning. MIR Press, Cambridge, MAGoogle Scholar
- Tianji J, Evarts EV (1976) Anticipatory activity of motor cortex neurons in relation to direction of an intended movement. J Neurophysiol 39:1062–1068Google Scholar
- Wolpaw JR (1980) Correlations between task-related activity and responses to perturbation in primate sensorimotor cortex. J Neurophysiol 44:1122-1138Google Scholar
- Wolpert DM, Selen L, Shadlen M (2009) Reflex gains are dynamically modulated based on accumulated evidence. Annual meeting of the society for neuroscience. Abstract #658.14Google Scholar