The NeuroTracker System: Its role for perceptual-cognitive training of athletes and its potential impact on injury reductions and concussion management in sports. By Jocelyn Faubert, PhD Professor & NSERC-Essilor Industrial Research Chair University of Montreal & Chief Technology Officer CogniSens Athletics Inc. And Lee Sidebottom, MA Director of Applied Sports Concepts CogniSens Athletics Inc. Abstract: This paper presents a new approach for training high-level athletes’ perceptual-cognitive skills. We first introduce concepts in regards to what is required by athletes to optimally process sportsrelated visual scenes at the perceptual-cognitive level and how complex that is. We then present a method of how it is possible to train this critical capacity in athletes while discussing the necessary features for a successful perceptual-cognitive training outcome. Our experience in the field with the top professional sports teams in the area of soccer, ice hockey and rugby clearly demonstrates that this capacity is highly trainable even in the highest-level athletes. A discussion follows emphasizing how we believe the NeuroTracking approach will become an integral component of athletic training with potential outcomes for profiling, recruiting, rehabilitation, game shape preparation and concussion management among others. We then conclude with thoughts on what the future holds in this regard and how such training programs could be integrated with other methods such as proprioceptive, and neuro/biofeedback training. INTRODUCTION Player Movement Dynamics (PMD): One of the most formidable tasks for the brain of an athlete during game play is to perceive and integrate complex moving patterns while allocating attention resources in different key areas of the dynamic scene. One must integrate the information over variable visual field areas i.e. one cannot attend only to a small area at fixation. Furthermore, the movements of the players and the object of play (ball, puck etc.) can be extremely fast and variable in that they can abruptly change speeds. The trajectory paths of these elements can also be quite unpredictable with sudden changes in direction and shape with numerous occlusions and segmentations such as objects blocking the view of others or disappearing from view for instance. As the level of the sport increases from one level to the next the rapidity at which all of these mental tasks have to be performed increases exponentially. Notwithstanding basic physiological capacities and hard work, the combination of complexity and speed of the perceptual-cognitive processing required by athletes with increasing levels of
play is probably one of the main determining factors as to whether the athletes will graduate at the superior levels. Indeed, a defining characteristic of dynamic team sports, particularly Football, Hockey, Soccer, Rugby and Basketball, is the need to pay attention to several members of the opposition as well as key teammates during critical phases of play. For example, when a defender is responsible for blocking an oncoming attacker in possession of the ball or puck, he must anticipate his strategy by perceiving opportunities for a) oncoming movement into free space by judging distances between himself and other defenders, b) passing to other attackers, c) the likelihood of teammates intercepting a) or b), and d) further passes by potential attacking receivers. At elite levels these perceptions need to be based on moment by moment tracking, especially as attacking play will regularly involve concerted efforts to move along unpredictable paths to temporarily dupe defenders. Sports science research has established that how an athlete perceives and reacts to a set of stimuli is a crucial element of top-level competitive sports (Williams, Williams & Davids 1999). Skilled athletes are proficient in the anticipation of opponent actions, and they are superior to novices in pattern recall and strategic awareness in team sports such as soccer (Williams, 2000). This kind of awareness is a constituent of skill rather than a characteristic of experience (Williams & Davids 1995). Experiments have also shown that playing experience is not a determining factor when testing visually determined anticipatory ability between elite and sub-elite players (Vaeyens, Lenoir, Williams, Mazyn & Philippaerts, 2007). The crux of the matter is that elite players do not obtain these perceptually based skills through traditional training techniques, yet these abilities are trainable at all levels (Williams & Hodges 2005). Training everything except perceptual-cognitive function: If you look at how far high-level sports training has evolved in the last 20 years it is truly amazing. The physical preparation, the training the rehabilitation tools and the coaching and conditioning techniques have all improved dramatically. With the advent of new performance recording and statistical analysis systems such as ProZone across many team sports, high-level game strategy also has the potential of leaping forward dramatically (Barris & Button 2008). As this special issue illustrates well, even techniques that address brain via biofeedback and neurofeedback are making their way into training protocols. Yet, with all of these techniques now available and used, very little if anything has evolved and been introduced into professional sports in the dynamic perceptualcognitive domain. There is a clear performance need for training higher-level perceptual cognitive processing of dynamic scenes and to be able to implement this at a practical level. There is often a misconception that training low-level vision does this job. It does not. Good vision is critical of course including binocular vision, visual field and other visual modalities. However, good visual capacities should not be confused with what the brain has to process in complex dynamic scenes and in particular for PMD. One of classic methods introduced in sports and still present is the reaction time training for lights that appear in the peripheral visual field, such as ‘Batak’. However efficient this process may be to sharpen reflexive responses to lights coming on and off in the periphery, this is nonetheless a very low-level visual processing requirement. It is well recognized by researchers specializing in visual motion perception that what is required to detect and react to a stationary light flash (temporal processing) is quite different to what is required for processing complex motion in dynamic visual scenes. Sports
specific studies show the former does not differentiate elites from novices whereas the latter clearly does (Mori, Ohtani & Imanaka, 2002) and that evidence for training visual function to improve sports performance generally is lacking (Starkes & Anderson 2003, p.221). Rather, it is the ability to process relevant perceptual cues and enhanced search strategies that defines the toplevel athlete, shown in a soccer meta-analysis on cognitive functioning visual systems (Mann, Williams, Ward & Janelle, 2007) and that it is the perceptual-cognitive abilities of sportsmen that give them the edge (Garland & Barry, 1990). Brain plasticity and modulation: If there is a need for this kind of training then the obvious question is: Is this trainable? It is now well recognized in neuroscience that capacities are trainable and the brain is highly plastic (Mahncke, Connor, Appelman, Ahsanuddin, Hardy, Wood, Joyce, Boniske, Atkins & Merzenich, 2006). That is, there are clear underlying neural reorganizations of neural tissue and networks when learning new capacities (Draganski & May, 2008) or when new brain networks take over damaged brain tissue (Bridge, Thomas, Jbabdi & Cowey, 2008). For instance, brain-imaging studies have shown complete reorganization to allow for sensory substitution (Kupers, Chebat, Madsen, Paulson, & Ptito, 2010) and network reorganization has been demonstrated after training (Ma, Wang, Narayama. Hazeltine, Chen, Robin, Fox & Xiong 2010). As we will see later, our experience both in the laboratory and in the field shows clear improvements in perceptual-cognitive capacities for processing fast dynamic visual scenes. Â The NeuroTracker (NT) technique: The NT technique is composed of FOUR critical features as an optimal training condition. It requires; a) distributed attention on a number of separate dynamic elements known in the literature as multiple object tracking or MOT; b) a large visual field; c) speed thresholds; d) stereoscopy (binocular depth cues). We will first describe the NeuroTracker task and then elaborate on the specific required elements mentioned above. Insert Figure 1 about here Figure 1 demonstrates the primary stages of a given NeuroTracker task. First a predetermined number of spheres (typically eight) are presented in a 3D dimensional virtual volumetric cube space (Figure 1a). The spheres are typically all of the same color (here yellow). Then a subset of spheres (typically four) are indexed by changing their color briefly (here red; Figure 1b) for a brief period of one second. Then the spheres return to their original color and start moving within the restricted 3D virtual space. During this movement the spheres can collide and consequently suddenly change direction, they can cross over others occluding their view etc. (Figure 1c). Finally, the spheres stop moving after a predetermined time and the observer has to identify the spheres that were initially indexed by colour with halos (Figure 1d). The subject is then given feedback on the response by having the spheres identified by revealing indexed colors (Figure 1e). The main task starts at a given speed and if all four spheres are not correctly identified the next trial will be slower. If the four spheres are correctly identified, then the next trial is faster. Trials are repeated like this following a staircase procedure and ultimately a speed threshold is established (Levitt, 1971). Insert Figure 2 about here
a) MOT: The MOT task was first introduced by Pylyshyn and colleagues (Pylyshyn & Storm, 1988; Pylyshyn, 1994) to determine how people can track multiple elements. Although the original work was meant to be in support of the FINST theory proposing that multiple elements have individual indexes (Pylyshyn, 1994) recent research generally proposes that multifocal attention mechanisms are necessary to process such information (Cavanagh & Alvarez, 2005). Notwithstanding the mechanisms underlying this capacity, it is clear that the ability to track multiple elements including players and the ball or puck is a capacity that is highly solicited in sports and in particular team sports. Figure 2 illustrates a soccer goalkeeper perspective in a given game situation. Clearly the keeper must be able to attend to the ball, his teammates and opponent players during game play. Therefore, improving on the capacity to maintain the tracking capacity of multiple elements becomes a highly desirable trait to train. Previous studies have shown that most people can generally track four to sometimes five elements depending on the condition and populations (Fougnie & Marois 2006). Healthy adults generally can track four elements while older adults appear to be limited to three in the usual conditions (Trick, Pearl & Sethi, 2005). This ability to track multiple objects in a dynamic sports environment has been identified as perhaps essential to reacting swiftly and effectively in team sports generally (Willams, Hodges, North & Barton, 2006). b) Large visual field: in team sports, critical information arises throughout the athlete’s visual field, and as our central field of focus is approximately 3⁰, most action occurs in the peripheral visual field (Knudson & Kluka 1997). Figure 2 above clearly demonstrates that the critical integration area required to process the dynamic situation is distributed over a large visual field. A general misconception is that team sport athletes continuously change their focus moment by moment to cover variously distributed sources of information (‘search strategy’). However, during intensive play, these distinct attentional needs are so numerous and so widely spread that such a fluidity of temporary fixations would leave the athlete with a very high ratio of perceptual blur - continually saccading from point to point (Williams, Davids, Burwitz & Williams 1994). This segmentation of concatenated snapshots then leaves the athlete largely uniformed on movement evolving throughout the scene. Indeed studies have shown that a defining characteristic between elite and sub-elite athletes is the ability to centralize gaze direction in order to spread attention, thereby increasing rates at which critical information can be acquired and assimilated sometimes referred to as ‘saccadic suppression’. Similarly, as the ball is tracked, critical information can confront the athlete anywhere within the visual field. A further need to centralize gaze comes from the advantage of reading body language cues of key opponents (especially those in possession) in order to anticipate immediate moves or passes (Nagano, Kato & Fukuda 2006; Savelsbergh, Van Der Kamp, Williams & Ward 2005). In these situations players must concentrate on both a localized region and the dynamics of the surrounding scene simultaneously. Overall then, the needs for sustained peripheral attention are frequent, and for the elite team sport athlete, this in turn increases both attentional capacity and attentional load. The capacity to deal with a large and dynamic visual field is a critical advantage for experts across team sports, affording a greater range of game action cues from peripheral sources while fixating on a central point in the scence (Haywood 1984). With
team sports athletes to displaying higher abilities here than non-team sport athletes (Mouton & Oberle 2007; Zwierko 2008). Therefore, a critical requirement of an MOT training system for sports then is a large visual field, for which a CAVE-type environment is employed (Cruz-Neira, Sandin, DeFanti, Kenyon & Hart, 1992). For instance the NeuroTracker uses controlled light conditions and an 8ft wide high quality projection affords a large visual field. To support an effective distribution of attention, an instructed part of the training task is to focus on a ‘visual pivot’ - a small dot in the centre of the screen - throughout the tracking phase. Shifting attention between objects without eye-movement is widely accepted (Sears & Pylyshyn, 2000). The cubed virtual volume means that the tracking demands are spread optimally throughout the visual field with no bias towards horizontal over vertical motion. c) Speed thresholds: The first obvious methodological advantage of using speed as a dependent variable in the NeuroTracker system is that the values can vary on a continuous ratio scale. This contrasts with the limitation of “number of tracked elements” method most frequently used in standard MOT experiments. For instance, a number of observers can be established as being able to track four objects simultaneously as an upper limit but there still could be huge differences in the individual capabilities to track the elements. As will be seen later this becomes quite obvious when using speed as the dependent measure where large individual differences between highlevel athletes are observed. With speed established as a relevant and controllable measure of perceptual-cognitive MOT demands, it is also important to take into account the concept of ‘interaction’ – namely that with greater speed comes a linear increase in the frequency of i) sphere collisions and ii) sphere crossovers. When spheres collide with each other and the boundaries of the virtual volume, sudden changes have to be addressed by the observer to avoid losing track, and are generally anticipated for a better handle on trajectory expectations. Sphere crossovers, once correctly predicted or detected as not being collisions, require allocation of working memory resources to maintain sub-visual tracking while out of sight. The sphere interactions may occur simultaneously and in multiple places within the virtual volume. Competent trajectory tracking then, widens MOT demands on perceptual-cognitive functions. Increases in speed create more of these events, with high speeds generating a near continual second-by-second stream of sphere interactions. An interesting behavior observed at just above threshold levels is a ‘juggling effect’, whereby a relatively small increase in speed creates functional collapse in MOT capability - the equivalent of hitting a mental wall*. (footnote* Speeds above an individual’s threshold tend to be perceived distortedly, seeming far faster and more difficult than they actually are. This can be observed by manually controlling speed like a dial and getting verbal responses from the participant – ‘I can handle that… that’s too fast’, with a fine zone of upper comfort and little tolerance above it). d) Binocular 3D (Visual stereoscopy): When viewing the world with both eyes open, the image from the external world has slightly different perspectives and these differences on the retina are called retinal disparities. It is this information that is used by the brain to construct the solid binocular three-dimensional (3D) impression that we perceive (Julez, 1971). There remain
questions as to what is the additional benefit of stereoscopy over the panoply of monocular depth cues available, but particularly, the champion of all monocular depth cues used to estimate relative depth called motion parallax (Faubert, 2001). This debate has reached heights when a recent paper by Oliver Sacks appeared in The New Yorker magazine reporting a striking recovery of binocular depth perception by Dr. Susan Barry after 50 years of life without it (Sacks, 2006). Nevertheless, there is evidence that stereoscopy does improve the ability to perform natural tasks (Sheedy, Bailey, Buri & Bass, 1986.) and online correction during reaching (Greenwald, Knill and Saunders, 2005). The question then is does the binocular 3D information help with the speed threshold MOT task we are using here? The answer is a definite YES. We have shown that in a number of experimental conditions the binocular 3D condition always generated superior speed thresholds than the binocular condition without disparity with an average of 50% gain in the conditions tested (Tinjust, Allard and Faubert, 2008). Therefore, the binocular 3D advantage is not dependent on afferent-efferent-reafferent combination of brain signals necessary for motor control, rather, it is an inherent property of the visual processing and we propose that the binocular 3D possibly helps to relieve the spatial limitations of attention inherent in two-dimensional scenes (Intrilligator and Cavanagh, 2001) when rapid decisions are required by the perceptual system during fast moving scenes. Finally it should be noted that a general but important design facet of 3D-MOT is the rudimentary simplicity of the task: i) fixate on the visual pivot, ii) track the indexed spheres, iii) repeat with speed changes. This leaves little room for technique or strategy, and the approach after experience with many sessions remains essentially the same, making the effects of ‘practice’ largely negligible. The high degree of functional isolation allows measurement of actual perceptual-cognitive performance and directly associated training gains. Although the MOT task utilizes a high-degree of task specific functional isolation, the mental resources activated are significantly large and require efficient integration across several domains of neurological functions. These perceptual-cognitive demands include complex motion integration, distributed attention, fluid-rapid processing, and visual working memory. Our interest in using the NeuroTracker to improve perceptual-cognitive abilities was not restricted to athletes. Indeed, one can easily envisage that the same kind of ability required to process fast dynamic scenes in sports is analogous to what is required when traveling through dense crowds or when driving. These tasks can be particularly challenging for older individuals or persons that have other neurobiological alterations such as having suffered a stroke or having Parkinson’s or early dementia. We have first introduced the kind of perceptual cognitive processing inherent in the NeuroTracker technique for other populations such as healthy aging (Faubert, Giroud, Tinjust & Allard, 2009). It is well known that healthy aging affects perceptualcognitive processes (Faubert, 2002), which directly affects the capacity to process complex motion information (Bennett, Sekuler & Sekuler, 2007; Habak & Faubert, 2000; Tang & Zhou, 2009) and divide attention throughout the visual field (Richards, Bennet & Sekuler, 2006). See note.1 Previous studies have shown that MOT was reduced in healthy aging (Sekuler, McLaughlin, Yotsumoto, 2008; Trick et al., 1994). The question then is can we improve this 1 The healthy aging analogy is quite interesting because the consequences of healthy aging are not unlike a tired player and this will be discussed latter in the paper. **With NeuroTracker the angle of sphere to sphere deflections can be observed and anticipated through the high resolution and large scale 3D viewing screen.
ability in all populations? We have conducted experiments on perceptual-cognitive training of this task and have shown that both young and older observers can significantly improve (Faubert et al., 2008). For instance, we have placed four groups under a 5-week program. There were two young and older groups. The two control groups were tested the on the first week and the fifth week while the experimental groups were trained further for weeks 2, 3 and 4. The training periods lasted a total of about 30 minutes. The results in week 5 showed dramatic improvements for the experimental conditions as compared to the control conditions even if the experimental groups started initially with identical values for given age category controls. This improvement varied from 30% to 70 % over the controls. Furthermore, the trained older observers obtained scores that were statistically identical to the young control observers. Demonstrating that trained older observers can become as efficient as untrained young adults at this type of task, which has ecological relevance, is quite encouraging. We also did a pilot study with high-level athletes in the laboratory with substantial gains in the order of 50% for this kind of training program. Convergence with Sports Training Methodology As we have presented the strong case for high demands on 3D-MOT ability within elite team sports, it might be assumed that athletes would already be proficient at perceptual tracking from constant exposure and conditioning over their careers. We do see greater initial 3D-MOT capacity in elite athletes, yet clearly major gains are achievable with relatively minimal training. Here it is important to expand on an earlier point regarding a lack of implementation of perceptual-cognitive training, specifically, that two of the central performance conditioning principles in sports science are traditionally left unattended: isolation and overload. There are many skills that need to be managed for high-level sports performance, most particularly attention to biomechanical skill and assertion of physiological resources. Professional training regimes involve breaking these down into their constituent elements, such as passing drills, shot practice and speed, strength and cardio-vascular conditioning. Cognitive skills, however, are rarely isolated to any significant degree, neither in contemporary training approaches, nor in competition. In terms of overload, upper threshold 3D-MOT demands at decisive game moments in the field tend to be sporadic and quite brief, remembering here that threshold is the breaking-point for effective perception and processing of visual information sources. Estimates will vary from sport to sport, but bouts of 3-5 seconds at a time are perhaps typical. Taking into account that both isolation and overload needs for perceptual-cognitive conditioning are inadequately attended to, a key value of NeuroTracker is an ideal fit with sports science driven training methodology. Indeed advantages here are accentuated compared to physical or skill based isolation and overload regimes, principally because neuroplasticity provides scope for significant functional gains within very short training durations and with longer lasting effects. Other qualities include training sessions that can be applied in acute packets (6-8mins per session), precise control of training quantity over time, and accurately recorded measurement and monitoring of the training process. Professional Athlete NT Data In-field NeuroTracker training has been implemented at various stages throughout 2010 with world-class teams in EPL (2), NHL (3), and Rubgy (2) and these are expanding quickly. Although gathered data currently remains confidential, there are broad trends that can be commented on. The most surprising is a very wide spread in initial NeuroTracker baselines
(established after three Core sessions), with the three highest player thresholds being between 90% and 170% greater than the lowest three within the same top tier team. This large ability contrast may indicate a much more diverse variation of overall performance attributes from athlete to athlete than generally estimated, with greater related skillset compensations of strengths over weaknesses. Similarly unexpected has been the consistency with which the majority of athletes improve; there are no distinctly emergent trends that differentiate relative thresholds gains between lower and higher initial scorers. Also, considering the preconditioned state of these elite athletes in general, it has been very surprising how profoundly improvements have evolved over time. Within NHL, a sport renowned for perceptual intensity, players have shown relative gains in average Core thresholds of around 40% with 30 minutes of actual tracking stimulation time (15 sessions). One challenge with obtaining data from competitive elite teams is the lack of control on usage, mainly through inconsistency of use at both individual and team levels (influenced by hectic competition schedules and time on the road). Therefore it has been difficult to ascertain any upper limits on improvements with sustained long-term training. As expected, improvement curves do plateau over time, yet no ceiling has been found, and in some cases sustained training has led to gains in speed thresholds above 300% on a player’s initial baseline. Inconsistency of use, has however, allowed retention of gains to be examined, and interestingly here, losses of NeuroTracking form over extended breaks from training (one to two months) have been negligible. While there can be significant fluctuations in thresholds from session to session, once threshold averages over three sessions or more increase, they remain surprisingly stable on a three-session basis (especially useful for concussion assessments, discussed later). Similarly, there appear to remain positive training gains even when athletes complete sessions interspersed by two or more weeks at a time - overstretching the expectations of distributed learning effects whereby small amounts of neural conditioning spread out over time have more benefit than when compressed into short time frames (likely due to the role of rest and/or sleep). It is tempting to propose the notion of an increased stimulation principle here, where a feedback effect between NeuroTracker training and in-field 3D-MOT conditioning may be mutually supportive. That is, the total movement information the athlete perceives in-field becomes increased, and this provides greater stimulation than pre-trained levels. This may provide some explanation why athletes have such widely contrasting levels of 3D-MOT dexterity initially; once they begin to operate at higher 3D-MOT levels, habitual mental activity sustains the ability. Here it is intriguing that some athletes who have endured prolonged injury bouts have significantly lower initial baselines, perhaps suggesting perceptual-cognitive regression through long-term absence of game conditioning. This would imply that the challenge of returning to ‘game shape’ is relevant cognitively, as well as physically. However the small samples and lack of pre-injury NT data resign these considerations to supposition at this stage. In this sense it will certainly be interesting to follow the evolution professional athlete NT training throughout 2011. Insert Figure 3 about here
Group trends While conserving anonymity, Figure 3 shows the results that have been obtained in the field from three top professional sports teams in three very different sports. We show an example of an English Premier Team club, a hockey team from the National Hockey League and a rugby team from the European Rugby. The data represent geometrical mean thresholds for the teams on a log scale as a function of training session. The data start fluctuating more as the number of sessions increases because less players have completed the sessions as they increase. To compare with the measures made in the laboratory where a threshold was taken as the average of three testing sessions, each measure on the sessions scale represents the average of the three previous sessions. What can be seen from the graph is that, on average, the three professional sports teams show identical progression in NeuroTracker progression. The data are well fit with a simple log regression and the R2 values are extremely high ranging from 0,88 to 0,97. That means that 88 to 97 % of the variance of the data can be explained by this fit. The higher R2 value comes from the team with the most players tested for each session number. The functions show an expected rapid progression that slows down but they also indicate that the teams have not saturated in their improvements.
Benefits: In-field Performance: For performance in the field there are three main advantages to be expected from increasing NeuroTracker thresholds. Firstly, an expanded capability to perceive and process player movement patterns across a wider visual field (for example being able to effectively monitor movements of four players instead of three). Thereby improving the foundation on which tactical awareness and intelligent decision-making are based – though not directly training these skills. Secondly, by improving the efficiency with which a sub-threshold amount of player tracking is managed, in turn freeing up resources for other attentional demands or simply relieving some of the pressure of sustained concentration. And thirdly, by assisting with dual perception tasks, such as reading key opponent body language without compromising awareness of surrounding player movements. The feedback reported by trained elite athletes, albeit subjective and anecdotal, has been consistent: NeuroTracking is relevant to performance and there is a clear experience of elevated NeuroTracking competency. As with all performance-training methods, the ultimate inquiry is transferability. This is notoriously difficult to establish due to the necessary reverse engineering process of selecting elements of competition results and then trying to distentangle the cornucopia of possible influences, not the least of which can be random factors such as refereeing mistakes. The alluring trap is to draw opportunistically superficial correlations that inevitably do not stand the test of time or have applicability outside of their established contexts. In contrast most of the well established training methods in team sports today originally gained their footholds through rationalized principles of expected gains. The basis for NT here is sound, with widespread appreciation of the training concept from professional sports team staff so far introduced - partly from the scientific grounding and partly from the experiental assessment of
NT itself. However, with to the abundance of data automatically generated with NT training and rapid acceptance with elite mutli-sport teams, an opportunity for mass data analysis may well provide a foundation for establishing credible performance transferability. This will be especially relevant if the raw data can be merged with advanced statistical analysis of competitions, which can be achieved retrospectively after the point at which the data on both sides is recorded. The aim then is to develop professional relationships with top tier teams and bridge the gap between the lab and the gym so that mutually beneficial consultancy and analysis can be founded in the longer term. Benefits: Concussion Assessment: NeuroTracking is an excellent candidate for a structured cognitive activity that elicits mental resources, known to be severely degraded by the effects of concussions, also termed mild traumatic brain injuries (mTBIs). The necessary global integration of central cognitive functions outlined earlier, such as complex motion integration and working memory, make NeuroTracking a high level perceptual-cognitive task which will be highly sensitive to the debilitating influences of concussion. Further, it has been demonstrated that complex motion processing is particularly sensitive to concussion-related damage (Brosseau-Lachaine, Gagnon, Forget & Faubert, 2008). Once baselines are established, several advantages present themselves to medical staff monitoring a player post-concussion:1) The ability to retest the player with a controlled and accurately measured perceptualcognitive test that can be compared directly to his own established normative level. In the case of an ‘elevated baseline’, whereby the athlete has made considerable gains in thresholds over his initial baseline (e.g. +40%), the impacted drop in NT test score can be expected to be relatively more pronounced. As NT is a performance-training tool for which the athlete has recorded at threshold his levels while in competitive shape, NT offers an ideal assessment for supporting timing of return to play. This is particularly important for medical staff, as they often have no structured reference point for return to game shape due to dependence on following mTBI symptoms, which are typically alleviated well before return to competition is considered. 2) The NT training conditions are so precise and consistent, both environmentally and functionally, that retesting presents a well-grounded experiential reference for the athlete to judge his own cognitive normality. Although return to play biases have to be taken into account by medical staff, as is standard. 3) There is some evidence that mild cognitive stimulation can improve recovery rate (Novack & Johnston 1998), particularly in post-acute phases (Cappaa, Benkeb, Clarkec, Rossid, Stemmere & van Heugten, 2003). On this principle NT training provides a safe and controlled method for implementing this stimulation in punctual and progressive doses. Benefits: Reduced Injury Risk through Collision Awareness: Although the NeuroTracker technique essentially trains the capacity to track multiple elements generally, it has a particular benefit for increasing this capacity across the peripheral visual field. Mainly this is because attending to the periphery is more demanding and this attention can be easily compromised under demanding performance conditions. But additionally, and contrary to intuition, there is evidence that information may be processed more quickly through peripheral vision rather than via the fovea, providing a significant advantage when under time pressure
(Smeeton, Hodges, Ward & Wiliams 2005). Laboratory research has also shown that peripheral vision search methods have resulted in fewer errors than following objects with changes in gaze direction (Haywood 1984). Due to the time compressed nature of critical phases of team sport games and the abundance of complex visual stimuli, effective peripheral awareness can provide key sports performance advantages, including better utilization of informative cues in order to minimize action-response times and make more effective play decisions (Hagemann, Strauss & Canal-Bruland 2006). On this basis it is important to make a logical assertion that increased awareness of player movement in the peripheral visual field will also assist athletes in pre-emptive avoidance of injury threatening collisions. This could be a crucial edge for reducing injury risks as impact avoidance is an athlete’s first line of defence. A study published in the British Journal of Sports Medicine concludes that, in rugby, 52% of injuries occur when an opponent comes from within the athlete’s peripheral vision (Garraway, Lee, Macleod, Telfer, Deary & Murray, 1999). Another study looked at the effects of peripheral vision narrowing in High School varsity soccer players, finding significant mediating effects of the narrowing of peripheral vision on injury incidence (Rogers & Landers 2005); a similar finding was made with regard to intercollegiate sport (Williams & Andersen 1997). In this context the rapid and substantial gains in NT perceptual cognitive dexterity should be considered seriously by sports teams from both a medical as well as a performance perspective, particularly as injury downtime of key players now commonly threatens a team’s competitive status throughout the season, as well as sometimes having a pivotal influence on the games in which a sudden collision injury is suffered. The future: NHL Concussion Prevention Training The same principle of injury prevention fits equally with avoidance of concussive collisions. An astounding discovery by the Mayo Clinic on NHL concussions throughout 2006-2010 concluded that 44% of reported concussions occurred within 0.3 seconds of puck release (Klein 2010). This strongly characterizes a peripheral narrowing effect, likely compromised by mental resources being acutely reallocated to attention on the pass or shot, and in turn making NHL players opportunistically target during these actions. This kind of attentional overload has been observed in dual action peripheral awareness tests with novices in soccer and ice hockey (Williams et al. 1999 p.47) where over-focus on the primary task causes deficits in performance in the secondary task. Supporting evidence also comes from studies on driving where peripheral vision deficits are known to be a primary cause for vehicular accidents (Owsley 1999), also that drivers suffer significant ‘perceptual narrowing’ under cognitive duress (Underwood, 1998), and that experienced drivers display greater resistance, with these tendencies found at all age ranges (Crundall, Underwood & Chapman1999). The NHL scenario presents an opportunity to address a specific window of perceptual-cognitive and motor-skill overload by integrating NT training with stick handling and puck passing drills. As these can be assessed independently, the degree to which they compromise each other when combined can be measured and differentiated from athlete to athlete, perhaps providing a risk assessment profiling role alongside training dual task proficiency. The approach will involve implementing accurate motion tracking technology within the CogniSens CAVE system to record
and assess subtle influences of biomechanical actions under perceptual-cognitive training, as well as collaborating closely with senior staff within selected NHL teams (in 2011). If well received it could help spearhead a wider proactive, rather than currently mainly reactive, approach to the major problem of concussions across numerous team sports. Shared resources: Players often make low-level motor control mistakes during highly charged game situations that rarely occur during practice. There are two obvious reasons for this. The first is that the extremely high perceptual-cognitive demands that occur in particular game play situations in fact deplete resources that are normally allocated to motor control behaviors such as ball handling or puck manipulation. It is assumed that practicing motor control will increase automaticity and reduce the demands during game situations. We argue that the reverse is also true and that perceptual-cognitive training would reduce processing requirements in critical game situations and consequently reduce the number of errors when manipulating objects. Such experiments, where combined motor control tasks and perceptual-cognitive stress requirements are imposed, are being conducted in our laboratories at the moment. Another situation where athletes also make manipulation or decision mistakes is when the physical or mental fatigue kicks in. We are also conducting studies on the impact of NT training combined with physiological and or mental fatigue to determine whether the impact of fatigue can be reduced for game play situations as a consequence of maintaining good perceptualcognitive abilities. Biofeedback: Finally, within the theme of this special issue, we are also conducting experiments combining perceptual-cognitive training with neurofeedback measures. The assumption here is that successful tracking states will generate measurable EEG waves that can be used to maintain attentional tracking. Preliminary measures already indicate that this is possible and we are anticipating much future development in this regard. Conclusion: In conclusion, we propose a new perceptual-cognitive training tool for sports in the context of the NeuroTracker system. We have shown that this ability, which is critical for sports, can be isolated and trained. We argue that the kind of benefit derived by such training will become evident in the future somewhat analogously to how physical training in sports has become evident and common practice only in recent years. We also demonstrate that such a measure can have many other sports related benefits such as injury reduction, concussion management, and reduction of fatigue-related mistakes so critical in high-level sports.
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Acknowledgements: The authors would like to thank Felix Rehnberg and Adam Lorton for help with editing and data compilation for the manuscript. Jocelyn Faubert would like to acknowledge research grant support from the Natural Sciences and Engineering Research Council of Canada discovery grant program. Figure Captions: Figure 1: Illustration of the four critical phases in the NeuroTracker sessions: a) Presentation of randomly positioned spheres in a virtual volumetric space, b) Identification of the spheres to track during trial, c) Removal of identification and movement of all spheres with dynamic interactions, d) Observer’s response by identifying the spheres, e) Feedback is given to the observer. If the observer gets all four spheres correctly identified the task is repeated at a faster speed. If on the other hand the observer makes a mistake the task is repeated at a slower speed. Figure 2: Figure 2 illustrates several critical principles from a goalkeeper’s (GK) perspective during live action that relates to the NeuroTracker task. 1) The GK must track multiple elements. 2) The GK must track these elements using central but also large portions of the peripheral visual field. 3) The GK must efficiently use information from a large area of the visual field. 4) The GK must process all of this information at very fast speeds. Figure 3: Geometrical speed threshold means for three professional teams at the highest level from three different sports as a function of testing session. The teams represent a Soccer team from the English Premier League (blue circles), an Ice Hockey team from the National Hockey League (yellow triangles), and a Rugby team from the European Rugby League (brown squares). The data represent a cumulative geometrical average of the last three measured thresholds. The three functions are very well fit by logarithmic regression functions, which account for between 88 to 97 % of the variance. The fits show that the teams have not reached asymptotic levels with the measures that are presently available and they also show very good correspondence across sports.
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Figure 3:
Geometrical Means for Three Professional Teams as a Function of Training Session
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Rugby (European League) R² = 0,88 Hockey (NHL) R² = 0,92 Soccer (Premier League) R² = 0,97 1 0
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