Neuroscience Letters 501 (2011) 61–66 Contents lists available at ScienceDirect Neuroscience Letters jou rn al h om epage: www.elsevier.com/locate/neulet Electrophysiological analysis of the perception of passive movement Jose Inacio Salles a,e , Heloisa Alves a , Filipe Costa a , Victor Cunha-Cruz b , Mauricio Cagy b,d , Roberto Piedade b , Pedro Ribeiro b,c,∗ a National Institute of Traumatology and Orthopaedics (NITO), Rio de Janeiro, Brazil b Brain Mapping and Sensory Motor Integration, Institute of Psychiatry of the Federal University of Rio de Janeiro (IPUB/UFRJ), Brazil c School of Physical Education, Bioscience Department (EEFD/UFRJ), Brazil d Division of Epidemiology and Biostatistics, Institute of Community Health, Federal Fluminense University (UFF), Rio de Janeiro, Brazil e Brazilian Volleyball Confederation a r t i c l e i n f o Article history: Received 28 February 2011 Received in revised form 29 April 2011 Accepted 1 May 2011 Keywords: qEEG Proprioception Passive movement Perception a b s t r a c t The goal of the present study was to determine the electrophysiological correlate of the threshold of perception of passive motion (TPPM) in a group of healthy individuals. We expect a different pattern of activation over the frontoparietal network produced by the conscious perception of the passive move- ment. Ten right-handed male volunteers, between 20 and 30 years of age, were submitted to the threshold of perception of passive motion (TPPM) task in a proprioception testing device (PTD). The device was designed to passively move the arm in internal and external rotations about the shoulder joint. Partici- pants were instructed to press a hand-held switch every time movement of the shoulder was detected. Electromyographic (EMG) and electroencephalographic (EEG) activities were acquired during the task. Passive movement of the shoulder joint was followed by a clear and prolonged decrease in the signal mag- nitude of the electroencephalogram. The electrophysiological correlate of the TPPM was characterized by the establishment of a frontoparietal network, during the processing of somatosensory information. © 2011 Elsevier Ireland Ltd. All rights reserved. The somatosensory system processes multiple sensations from the body, including pain, pressure, temperature, and proprioception [23]. Proprioception is a specialized form of the sense that encom- passes the ability to detect movement (kinesthesia) [21]. Moreover, proprioception is the sensation of the relative position of neigh- bouring parts of the body. Contrarily, the exteroceptive senses, by which we perceive the outside environment, and interocep- tive senses, by which we perceive the pain and movement of internal organs, proprioception is a third distinct sensory modality that provides feedback solely on the status of the body internally. The assessment of kinesthesia has been traditionally conducted by measuring the threshold of perception of passive motion (TPPM) [7,15,21]. In this context, given that proprioceptive signals con- tribute to the formation of a conscious (i.e., having an awareness of one’s sensations) perception of joint position and motion [8,14,24], the TPPM quantifies one’s ability to consciously detect joint move- ment. Electrophysiology has also been employed in the study of pro- prioception. Specifically, electrophysiological studies have investi- gated the cortical representation of passive motion [1,2,30–32,36]. ∗ Corresponding author at: Brain Mapping and Sensory Motor Integration, Institute of Psychiatry of the Federal University of Rio de Janeiro (IPUB/UFRJ), Rua José Luiz Ferraz 200/1110, 22790-587, Brazil. E-mail address: ribeiropss@yahoo.com.br (P. Ribeiro). However, these studies aimed exclusively at contrasting patterns of brain activation between disabled individuals and healthy control subjects, without considering the perception of limb movement. In this sense, there are still gaps to be filled in our understanding of the patterns of neural activity related to somatosensory perception [9,29]. The general goal of the present study was to develop an experimental paradigm that would combine EEG activity and the TPPM, taking a psychophysical approach to the investiga- tion of proprioception. The specific aim was to determine the electrophysiological, event-related spectral perturbation (ERSP), correlate of the threshold of perception of passive motion (TPPM) in a group of healthy individuals, using an attention-demanding task, and examining the cortical representation (i.e., quantitative electroencephalogram—qEEG) of different stages of propriocep- tive information processing, from motion perception until motor response. The present study is relevant because propose a novel psychophysical approach to the study of kinesthetic perception by developing an experimental paradigm that integrates EEG acqui- sition and a proprioceptive task. Moreover, we expect that the conscious perception of the passive movement could generate a new pattern of the frontoparietal network’s activation. The sample consisted of 10 male volunteers, with ages ranging from 20 to 30 years (mean = 25; SD = 1.92). All participants were healthy, free of cognitive deficits, and were not using any medica- tion or psychoactive substance at the time of the test. Participants 0304-3940/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2011.05.005