Evaluating time properly is crucial for everyday activities from fundamental behaviors to refined coordinative movements such as in sport playing. Lately the concept of the existence of a unique internal clock for evaluating time in different scales has been challenged by recent neurophysiology studies. Here we provide evidence that individuals evaluate time durations below and above a second based on two different internal clocks for sub- and suprasecond time ranges: a faster clock for the subsecond range and a slower one for suprasecond time. Interestingly, the level of precision presented by these two clocks can be finely tuned through long-term sport training: Elite athletes, independently from their sport domains, generate better time estimates than nonathletes by showing higher accuracy and lower variability, particularly for subsecond time. We interpret this better time estimation in the short durations as being due to their extraordinary perceptual and motor ability in fast actions.
Yin-Hua Chen and Paola Cesari
Robert L. Sainburg and Pratik K. Mutha
The target article (Smeets, Oostwoud Wijdenes, & Brenner, 2016) proposes that short latency responses to changes in target location during reaching reflect an unconscious, continuous, and incremental minimization of the distance between the hand and the target, which does not require detection of the change in target location. We, instead, propose that short-latency visuomotor responses invoke reflex- or startle-like mechanisms, an idea supported by evidence that such responses are both automatic and resistant to cognitive influences. In addition, the target article fails to address the biological underpinnings for the range of response latencies reported across the literature, including the circuits that might underlie the proposed sensorimotor loops. When considering the range of latencies reported in the literature, we propose that mechanisms grounded in neurophysiology should be more informative than the simple information processing perspective adopted by the target article.
Onno G. Meijer, Yakov M. Kots and V. Reggie Edgerton
In 1963, an article on “Tonus” (tone), written by Nikolai A. Bernstein and Yakov M. Kots. appeared in the second edition of the Bols'aja Medicinskaja Enciclopedija [Grand Medical Encyclopedia]. The paper is now published for the first time in the English language, with Mark L. Latash as translator. In accordance with then contemporary neurophysiology and neuropsychology, the paper presented “tone” as a graded phenomenon (as opposed to all-or-none), serving to prepare the segmental level for phasic contractions. Influenced by Granit and Matthews, the authors proposed that the suprasegmental level controls the threshold and the slope of the stretch reflex. In their introduction to the present edition, the editors understand this proposal in the context of low-dimensional control, that is. control in terms of one or a few variables (as opposed to central commands specifying all the details). Selected episodes from the history of low dimensional control and its logical counterpart, spinal intelligence, are used to illustrate how difficult these ideas were to accept. As so often in new scientific developments, confusion was the rule, and in this respect the paper on “Tonus” is no exception. In the epilogue, Kots gives his personal memories of the context in which the paper was written. At the time, he was working on “equitonometry” (equitonometric), measuring tonic balance with gravity eliminated. Results of equitonometric research quite naturally led to the idea that suprasegmental centers control the threshold and the slope of me tonic stretch reflex. As Kots remembers, that was “no big deal.”
Niamh Reilly, Gavin P. Lawrence, Thomas Mottram and Michael Khan
The perceptual-motor impairments of individuals with Down syndrome (DS) are attributed to central (e.g., neurophysiology deficits that affect the retrieval or initiation of motor programs) and peripheral (e.g., anatomical deficits relating to issues with inertia of limb mechanics and muscle organization) processes. However, recent research suggests that central deficits do not affect the integration between movements. We investigate the impact of central and peripheral DS deficits on movement integration by examining the planning and execution of multiple-target multiple-arm movements. Individuals with DS, typically developing (TD), and individuals with an undifferentiated intellectual disability (UID) completed five aiming tasks: a one target; a one-arm, two-target extension; a two-arm, two-target extension (movement one was performed with one arm and movement two performed with the other); a one-arm, two-target reversal; and a two-arm, two-target reversal. Movement times (MTs) to the first target were longer in the two-target tasks compared with the one-target task. For the one-arm, two-target reversal task, this effect emerged only in individuals with DS. These results indicate that individuals with DS use central processing for movement integration similarly to their TD and UID counterparts but cannot exploit peripheral-level integration to enhance integration in one-arm reversal tasks.
Mark L. Latash
exerted during voluntary movement . Journal of Neurophysiology, 31, 14 – 27 . PubMed ID: 4966614 doi:10.1152/jn.19126.96.36.199 10.1152/jn.19188.8.131.52 Farina , D. , Merletti , R. , & Enoka , R.M. ( 2014 ). The extraction of neural strategies from the surface EMG: An update . Journal of Applied
Kaitlyn C. Jones, Evelyn C. Tocco, Ashley N. Marshall, Tamara C. Valovich McLeod and Cailee E. Welch Bacon
participants recruited from a waiting list of a Portuguese outpatient clinic were randomly assigned to groups with either aquatic therapy alone or combined aquatic therapy and pain neurophysiology. Biopsychosocial education group (n = 129): Age: • 18 < age ≤ 40 (46.6%) • 40 < age ≤ 60 (53.4%) Gender
Momoko Yamagata, Ali Falaki and Mark L. Latash
during antagonist cocontraction and reciprocal inhibition of forearm muscles . Journal of Neurophysiology, 51 , 32 – 49 . PubMed ID: 6693934 doi:10.1152/jn.19184.108.40.206 10.1152/jn.19220.127.116.11 Gelfand , I.M. , & Latash , M.L. ( 1998 ). On the problem of adequate language in movement science
Julie Vaughan-Graham, Kara Patterson, Karl Zabjek and Cheryl A. Cott
. Beyaert , C. , Vasa , R. , & Frykberg , G. ( 2015 ). Gait post-stroke: Pathophysiology and rehabilitation strategies . Clinical Neurophysiology, 45 ( 4–5 ), 335 – 355 . PubMed ID: 26547547 doi:10.1016/j.neucli.2015.09.005 10.1016/j.neucli.2015.09.005 Borich , M. , Brodie , S. , Gray , W
start in the major hemisphere . Clinical Neurophysiology, 127 , 3195 – 3196 . PubMed doi:10.1016/j.clinph.2016.05.367 10.1016/j.clinph.2016.05.367 Gutnik , B. , & Hyland , B. ( 1997 ). Spatial coordination in a bimanual task related to regular switching of movement vectors . Perceptual and
Afshin Samani and Mathias Kristiansen
and muscle coordination complexity post-stroke . Journal of Neurophysiology, 103 ( 2 ), 844 – 857 . PubMed doi:10.1152/jn.00825.2009 10.1152/jn.00825.2009 Danna-Dos-Santos , A. , Shapkova , E.Y. , Shapkova , A.L. , Degani , A.M. , & Latash , M.L. ( 2009 ). Postural control during upper