Directed Attention Brain Potentials in Virtual 3-D Space in Weightlessness (Neurocog) - 11.22.16

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Even in space, humans can quickly tell whether a figure is symmetrical when that figure is horizontal or vertical, but not when it is tilted at an angle. This investigation showed that direct perception of gravity or a stable touch reference frame aren’t necessary for this “oblique effect,” but that self-reference alone is sufficient. Brain-wave activity changes in microgravity indicate that the parts of the brain involved in visual perception are affected by microgravity, although higher brain functions (decision-making, planning, and problem-solving) remained unchanged. Data indicated a change of certain brain wave rhythms in space, which could be linked to gravity-related sensory inputs.

The following content was provided by Guy Cheron, and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Erasmus Experiment Archive.
Experiment Details


Principal Investigator(s)
Guy Cheron, • Biomechanics Faculty of Movement Science, Université Libre de Bruxelles, , Brussels, Belgium

Ana Bengoetxea, Universite Libre de Bruxelles, Brussels, Belgium
Mark Lipshits, Institute for Information Transmission Problems, Russian Academy of Science, Moscow, Russia
Joseph McIntyre, College de France, Paris, France
Alain Berthoz, LPPA/CNRS-College de France, Paris, France
Manuel Vidal, LPPA/CNRS, College de France, Paris, France
Caty de Saedeleer, Universite Libre de Bruxelles, Brussels, Belgium

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Sponsoring Space Agency
European Space Agency (ESA)

Sponsoring Organization
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Research Benefits
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ISS Expedition Duration
June 2002 - December 2002; April 2003 - October 2005

Expeditions Assigned

Previous Missions
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Experiment Description

Research Overview
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A key concept in the field of neuromotor control is that of defining the frames of reference used by the central nervous system (CNS) to interpret sensory information and to control movements. At the level of individual sensors and effectors, the coordinate systems employed are well defined. It is not in the coordinate system of an individual receptor, but rather, in examining the coordination of sensory and motor activity that the question of reference frames becomes interesting. In this experiment we test for the role of gravity in defining the reference frames used for 3D navigation and for representing the orientation of our own bodies and the orientation of visual stimuli. In a series of psychophysical tests we compare how human subjects perform these types of task both on the ground and in the weightless conditions of orbital flight. We also measure evoked potentials through surface electrodes applied to the scalp in order to measure the spatial and temporal components of information processing in the brain in the absence of gravity.This experiment has two specific objectives concerning the functioning of the human nervous system for the perception of orientation and the performance of 3D navigation in space:Hypothesis 1: The human perceptual system represents and stores the orientation of visual stimuli in a reference frame that combines egocentric information about the orientation of the body axis with graviceptor information about the vertical axis. Visual stimuli that are aligned with the vertical and horizontal axes are treated preferentially in this multi-modal reference frame. In the absence of gravity, the human nervous system may substitute a cognitive reference frame defined by the stable mechanical base provided by an orbiting spacecraft. When operating in free-floating conditions, subjects will lose the haptic cues that indicate their orientation with respect to the local environment. In this situation, the CNS may use a purely egocentric reference frame aligned with the body, or the system may lose its stable reference frame and treat all orientations equally.Hypothesis 2: We hypothesize that in free floating the cognitive task will be changed by the absence of gravitational reference. In particular, we expect all readiness for movement called Bereitschaftspotential (BP) and late positive component (LPC) amplitudes and latencies to be higher than in normal gravitational environment. This would indicate that alternative spatial motor reference needs to be constructed in free-floating, implying additional cognitive processing at each stage of movement. If BP and LPC amplitudes and latencies are similar to normal gravitational condition, the same type of cognitive processing (independent of graviception) would appear conserved. Finally, gradual normalization of BP and LPC during the task would indicate rapid adaptation of attentional process.This experiment is designed to test each of the above hypotheses through a series of psychophysical tests performed in a simple virtual-reality environment.

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Space Applications
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Earth Applications
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Operational Requirements and Protocols
Cosmonaut subjects will perform a set of 2 psychophysical tasks with simultaneous recording of EEG activity. For each subject, the performance on these tasks will be compared for a set of pre-flight, in-flight and post-flight procedures to test for an effect of weightlessness on the visual perception of orientation and movement and on the ability to navigate in three dimensions. Backup crewmembers will be asked to perform all pre-flight training and baseline data collection (BDC) tests and may be asked to work in parallel with the orbital crew during and after the flight to provide a matched control group for comparison.The subject takes up the position and postural support depending on the gravitational conditions (ground or in-flight) and on the instructions for a particular protocol:Ground Seated The subject is seated upright comfortably in a chair, with the elbowsresting on the adjustable-height elbow supports of the ground support stand. The ground support stand is adjusted to position the mask/tunnel/laptop at the level of the eyes for viewing. The height of the elbow pads is adjusted to allow the subject to comfortable grasp the grips on the laptop support.In-flight Restrained The subject sits in front of the laptop, which is attached to a mechanical support. Waist and foot straps are used to hold the subject securely in a seated posture.In-flight Free floating The subject adopts a free-floating posture and should have no rigid contact with the station structure during the performance of the experiment in this mode. A second cosmonaut aids the subject to stabilize his or her posture at the beginning of this phase of the experiment.In all cases, the subject places the face into the facemask and attaches an elastic band behind the head to help hold the head in place. By manipulating the buttons and trackball, the subject launches the experiment program on the laptop, identifies him or herself to the program and the performs a set of experimental trials consisting of the following: FO1: Virtual Turns The subject is situated in a visually-presented 3D virtual tunnel. On the press of a button, the subject will appear to either move through a tunnel at constant speed, passing through a single bend between two linear segments or the subject may appear to undergo a rotation in place (no apparent translation). At the end of the trial, the subject indicates the extent of the turn (i.e. how many degrees) in one of two different fashions: (1) the subject observes a birds eye view of a planar workspace with two cylindrical tunnels connected by a variable angle. By manipulating the trackball, the subject adjusts the magnitude of the turn to reconstructs a planar representation of the virtual tunnel just experienced. (2) They subject sees a pictogram indicating his or her starting orientation in the plane. By manipulating the trackball, the subjects change the orientation of the pictogram to indicate the amount rotation that was perceived.EEG is recorded during the above trials. EEG will also be recorded under four controlconditions. In condition 1, the subject relaxes and does nothing, first with eyes closed, then while looking at a neutral screen. In condition 2, an alternating checkerboard is presented to the subject on the screen, with the colours switching between black and white every 3 seconds. In control condition 3 the subject follows the movement of a luminous spot as it makes a sinusoidal movement across the screen. In control condition 4 subjects blink their eyes in synchrony with an audible metronome. Control recordings are expected to last no more than 5 minutes.The subject performs a total of 48 such trials for either stimulus type, for a total of 96 trials per session. Trials are broken into blocks of 12 trials each, with pauses programmed between blocks. At a nominal rate of 4-5 trials per minute (including pauses), one complete execution of this protocol (turning in-place or passage through the tunnels) is performed in 20 25 minutes. FO2: Visual Orientation A reference line of a fixed orientation is displayed on the video monitor. At the press of the button by the subject, the stimulus line is erased and a distracter screen (with lines in many orientations) is displayed momentarily. Finally a second response line is displayed at an orientation different from the first. Using the trackball, the subject must adjust the orientation of the second line to match that of the first. The subject performs 6 such trials for each of 7 different reference orientations, for a total of 42 trials. Trials are broken into 3 blocks of 14 trials each, with pauses programmed between each block. At a nominal rate of 4 trials per minute (including pauses), one complete execution of this protocol is performed in10 15 minutes.

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Decadal Survey Recommendations

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Results/More Information

Six cosmonauts total participated in the Neurocog investigation over separate short- and long-term missions to the ISS in 2001, 2002, and 2004. Each cosmonaut was tested on the ground before flight, during space flight, and after return to the Earth. In flight, subjects were tested on two days over the course of their ten-day space flights, with at least one day between sessions. Prior to flight, subjects were tested in two pairs of sessions over the two months prior to launch. Sessions within each pair were separated by at least one day, corresponding to the testing schedule to be used in flight. Subjects were tested on three days during the week immediately following the landing, starting on the day of landing. Three of the subjects were tested two more times two weeks after returning to the Earth.

The so-called 'oblique effect' is when a human observer detects whether a figure is symmetric more quickly and with fewer errors when the axis of symmetry is vertical or horizontal than when it is tilted at an angle. Experiments performed with cosmonaut subjects showed the same patterns of response time and variability in space, and the effect was maintained in both attached and free-floating crewmembers. The lack of difference between these conditions shows not only that direct perception of the direction of gravity is unnecessary to produce the oblique effect but also that a stable touch reference frame is not essential. By contrast, this effect can be eliminated by tilting ground control subjects indicating that when the gravity sensation is present, it has a significant role in perceptual processing. What is clear from the results is that an egocentric (self) reference frame alone is sufficient for the effect when visual, touch, and gravity sense information on the local environment is unavailable. Depending on the task, it is reasonable to expect that the human perceptual system might use egocentric or allocentric (other) reference frames, or both, to perceive and store the orientation of visual stimuli, and one would be dominant with the reduction of the other (Lipshits et al. 2005).

Previous experiments in microgravity have shown that humans acquire and store visual information in a multimodal (a complex perceptual blend both in relation to the observer and to the external environment) reference frame so the loss of gravity related sensory inputs may have an effect on the part of the brain involved in visual perception, in this case, prominent background electrical brain waves known as alpha (visual network) and mu (sensorimotor) rhythms occurring at ~10Hz (cycles/second). An experiment, conducted with 5 cosmonauts over the same period, completed a total of 51 electroencephalographic (EEG) recording sessions on Earth (22 before and 29 after flight) and 38 sessions in the ISS. Results show that, during the initial cessation of all spontaneous activities (eye closed), the power of both alpha and mu rhythms increased in microgravity, and may indicate that the sensorimotor and the visual cortex are linked through a common network that is affected by gravity. This increase in the eye-closed state but not in the eye-opened state may be viewed as the expression of a new level of the internal sensitivity reached by the cosmonauts. Note however, that alpha rhythm of the forebrain region where higher functions such as decision-making, planning, and problem solving remained unchanged in all cases. The study demonstrates a change of mu and (visual) alpha rhythm in space, which could be linked to gravity-related sensory inputs and suggests their enhancement as a result of multimodal sensorimotor conflict resolution and integration (Cheron et al. 2006, Leroy et al. 2007).

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Results Publications

    Cheron G, Leroy A, de Saedeleer C, Bengoetxea A, Lipshits M, Cebolla AM, Servais L, Dan B, Berthoz A, McIntyre J.  Effect of Gravity on Human Spontaneous 10-Hz Electroencephalographic Oscillations During the Arrest Reaction. Brain Research. 2006 November; 1121(1): 104-116. DOI: 10.1016/j.brainres.2006.08.098. PMID: 17034767.

    Leroy A, de Saedeleer C, Bengoetxea A, Cebolla AM, Leurs F, Dan B, Berthoz A, McIntyre J, Cheron G.  Mu and Alpha EEG Rhythms During the Arrest Reaction in Microgravity. Microgravity Science and Technology. 2007; 19(5-6): 102-107. DOI: 10.1007/BF02919462.

    Lipshits M, Bengoetxea A, Cheron G, McIntyre J.  Two Reference Frames for Visual Perception in Two Gravity Conditions. Perception. 2005; 34(5): 545-555. DOI: 10.1068/p5358.

    Cheron G, Leroy A, Palmero-Soler E, de Saedeleer C, Bengoetxea A, Cebolla AM, Vidal M, Dan B, Berthoz A, McIntyre J.  Gravity influences top-down signals in visual processing. PLOS ONE. 2014 January 6; 9(1): e82371. DOI: 10.1371/journal.pone.0082371. PMID: 24400069.

    de Saedeleer C, Vidal M, Lipshits M, Bengoetxea A, Cebolla AM, Berthoz A, Cheron G, McIntyre J.  Weightlessness alters up/down asymmetries in the perception of self-motion. Experimental Brain Research. 2013 April; 226(1): 95-106. DOI: 10.1007/s00221-013-3414-7. PMID: 23397113.

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Ground Based Results Publications

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ISS Patents

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Related Publications

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Related Websites
ESA Erasmus Experiment Archive

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image NEUROCOG mounting frame and tunnel
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image Astronaut Frank de Winne doing the Neurocog experiment(photo courtesy BUSOC)
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