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The term ‘whiplash’ was initially used to describe injuries to the neck caused by the head being forced backwards during a rear-end collision in cars without head restraints. The addition of head restraints in the 1970s was expected to solve this problem by preventing excessive extension of the neck but experience suggests the problem still exists. This paper reviews available experimental studies of whiplash and uses the data to construct a finite element model which is capable of dynamically simulating whiplash collisions and predicting the forces in all the relevant neck ligaments. For the first time, it is shown that trauma occurs long before the head hits the head restraint as a result of displacement between the head and the torso caused by the head's inertia leading to markedly different acceleration histories. It is concluded that experimental and computational studies must be used together to produce progress in biomechanical studies.

The mitigation of whiplash associated disorders (WAD) has received increased priority in the last 10 years. Although the exact mechanism(s) for WAD causation have not been established, several have been proposed and it is likely the mechanism(s) are associated with the kinematics of the head relative to the torso. It follows that automotive seat designs that address reductions in certain head-torso kinematics may lead to a reduction in WAD potential. Seat properties that may have an effect on head-neck kinematics include geometry, stiffness and energy absorption. This study evaluated the performance of five seats with varying properties, including the new Volvo 'WHIPS' seat. Seat properties such as geometry relative to the occupant's head, dynamic and static stiffness, and energy absorption were determined via component testing. A new prototype dynamic seat test, which used a pendulum and seat back pan, was evaluated. Human subject impact tests were conducted using three occupants in rear impacts with velocity changes of 4 and 8 km/h. Potentially relevant occupant kinematic parameters were identified, and then correlated with seat properties in an attempt to determine any relative influence of seat properties on potential WAD mechanisms. Two higher velocity human subject tests using the Volvo Whiplash Injury Protection System (WHIPS) seat were also conducted. Vertical and horizontal head to head restraint distances were found to be most influential on occupant head-neck kinematics. Horizontal and vertical head to head restraint offsets were significantly correlated with rearward translational motion of the head center of gravity relative to the upper torso across all occupants. Rearward offset was also significantly correlated with rearward rotation of the head relative to upper torso, while vertical offset was significantly correlated with head acceleration relative to the upper torso during the flexion phase of the impact. Seat constitutive properties such as stiffness and energy absorption were not significantly correlated with occupant head-neck kinematics. The new dynamic seat test posed problems in data interpretation, and suggestions for improvement are made. The Volvo 'WHIPS' seat proved to be very effective in reducing many potential WAD associated head-neck kinematics. The two increased severity impacts activated the additional protective energy absorption elements in the seat, and no injuries were sustained by the occupants.

In high-speed rear crashes, the seatback needs to be sufficiently strong to manage energy transfer while maintaining the occupant on the seat. Integration of occupant load over seatback displacement or moment over angle change gives the energy transfer capability of a seat. Seatback rotation correlates with occupant kinetic energy transfer, which is determined by the rear crash delta V. The energy transfer is about 2000 J in a 32 kmph rear delta V crash. In low-to-high speed crashes, the head restraint and upper seatback need to reduce relative motion between the head and neck, thus controlling kinematics to prevent “whiplash”. A head restraint height above the head center of gravity and close to the back-of-head provides favorable neck responses. However, the trajectory of the head restraint is forward and downward in a rear crash. This promotes neck extension. A self-aligning head restraint gives a more horizontal direction of head restraint motion and a more upright head and neck orientation. The head restraint moves forward and upward by occupant load on the seatback. This closes the gap behind the head.

The purposes of this study were to measure the relative linear and angular displacements of each pair of adjacent cervical vertebrae and to compute changes in distance between two adjacent facet joint landmarks during low posterior-anterior (+Gx) acceleration without significant hyperextension of the head. A total of twentysix low speed rear-end impacts were conducted using six postmortem human specimens. Each cadaver was instrumented with two to three neck targets embedded in each cervical vertebra and nine accelerometers on the head. Sequential x-ray images were collected and analyzed. Two seatback orientations were studied. In the global coordinate system, the head, the cervical vertebrae, and the first or second thoracic vertebra (T1 or T2) were in extension during rear-end impacts. The head showed less extension in comparison with the cervical spine. Relative motion for each cervical motion segment went from flexion at the upper cervical levels to extension at the lower cervical levels, with a transition region at the mid-cervical levels. This rotational pattern formed an "S" shape in the cervical spine during the initial phase of low-speed rear impacts. A pair of facet joint landmarks on each cervical motion segment was used to measure the distance across the joint space. Uni-axial facet capsular strains were calculated by dividing changes in this distance over the original distance in seven tests using three specimens. In 20-degree seatback tests, the average strain was 32+/-11% for the C2/C3 facet joint (17%-43% range), and 59+/-26% for the C3/C4 facet joint (41%-97% range). The C4/C5 and C5/C6 facet joints exhibited peak tensile or compressive strains in different specimens. In 0-degree seatback tests, the average strain was 28+/-11% for the C2/C3 facet joint (21%-41% range), 30+/-9% for the C3/C4 facet joint (21%-39% range), 22+/-4% for the C4/C5 facet joint (19%-25% range), and 60+/-13% for the C5/C6 facet joint (51%-69% range). In 20-degree seatback tests, there was less initial cervical lordosis, more upward ramping of the thoracic spine, and more relative rotation of each cervical motion segment in comparison with the 0-degree seatback tests. Relative to T1, the head went from flexion to extension for 20-degree seatback tests while stayed in extension for 0-degree seatback tests.

There are many new features and devices now being incorporated into the design of automotive vehicles. In addition, there is considerable promise of much more for future vehicles in the context of a rapidly evolving and competitive technology worldwide. Attractive marketing features may be found in terms of entertainment and information choices, occupant comfort options, and vehicle performance. However, those improvements that relate to safety are of special concern. Can the benefits be compromised by the end user? If so, in the future, will there be an effective risk reduction, hazard avoidance, or health promotion effort that could be undertaken by dealers, lessors, or vehicle owners. For the covering abstract see ITRD E108169.

Collision performance of automotive seat systems has been a subject of inquiry since crash research was in its infancy. However, when federal standards were initiated in 1968 regarding seat system performance, they became the baseline for automotive design, and later became the topic of numerous debates in terms of occupant crash force and energy management. This subject of energy management as it relates to seat design has been extended and expanded in the current time period. This paper discusses current design trends in automotive seat design collision performance in terms of new data recently becoming available. Also, due to recent proposals and discussion regarding modification of FMVSS 207, a review of seatback performance data in a dynamic environment will be presented. Any proposals regarding the modification of FMVSS 207 require careful evaluation and quantification of seat system goals. Identification and establishment of beneficial characteristics of seat structures and how these characteristics can be evaluated in both static and dynamic environments is crucial before any discussion of seat system performance goals can be established. (A) For the covering abstract see ITRD E106349.

In a rear-end crash, if an occupant's head is unsupported it lags behind as the torso is accelerated forward. This causes the neck to change shape, first taking an s-shape and then bending backward in a 'whiplash' motion. This sudden differential movement of the head and torso can cause 'whiplash' injuries to the neck. This paper reviews methods to minimize the differential head/torso movement and reduce the resulting injuries, focusing on the necessary first step for prevention, which is a head restraint that is behind and close to the back of an occupant's head during the crash. The history of head restraints since the 1950s is reviewed, with particular attention to advanced restraint designs that are proving effective in reducing whiplash injury risk in dynamic tests using a new crash test dummy neck and a new neck injury criterion.

The aim of this study is to validate the pressure effect theory on human beings during a realistic rear-end impact and to correlate the neck injury criterion to pressure in the spinal canal. Sled experiments were performed using a test setup similar to real rear-end collisions. Test conditions were chosen based on accident statistics and recordings of real accidents. In particular, velocity change and acceleration level were reproduced similar to actual collisions. The head restraint as well as the seat back were adjusted to different positions. Two small pressure transducer were implemented to the spinal canal of postmortem human subjects and pressure measurement similar to the pig experiments (using exactly the same equipment) were performed. A total set of 21 experiments with four different subjects were performed. The subjects were additionally instrumented with triaxial accelerometers that allowed for calculation of the NIC criterion. Results showed that NIC and pressure amplitudes of the CSF correlate well and therefore NIC seems to be able to predict these amplitudes also for human beings. Conclusions whether these pressure effects induce soft tissue neck injuries or not could not be drawn and should be investigated in further research.

It is generally accepted that the incidence of whiplash associated disorders is increasing in all industrialised countries, despite the almost universal fitment of head restraints in at least the front seats of cars. This is usually attributed to the fact that few people can be observed to follow the standard recommendations as regards head restraint positioning, that is, level with the head vertically and as close to the head as possible horizontally. This study set out to determine whether any other factors, in addition to head restraint adjustment, could be found which would influence the severity of whiplash injury. This was done by linking medical assessment of real-world accident victims with engineering assessment of the accident vehicles. A random sample of road accident victims suffering from whiplash associated disorder was studied. The vehicles they had been travelling in were examined to assess impact severity and, where possible, measurements were made of seat and head restraint adjustment with the subject sitting in the vehicle. All subjects were interviewed to assess the disability resulting from their injuries, and their progress was followed for 12 months. The results were subjected to statistical analysis to try to determine relationships between severity of injury (as measured by resultant disability) and a number of occupant- and vehicle-related factors. A significant proportion of the sample had suffered lumbar strain injury in addition to whiplash, and these were excluded from the present analysis. Frontal impact victims suffered symptoms indistinguishable from those of rear impact victims. The beneficial effects of good head restraint adjustment could not be clearly demonstrated, and some trends, especially in rear impacts, where the benefits of a well-adjusted restraint should have been very clear, indicated that larger distances from head to restraint were associated with lower disability. The paper discusses these counter-intuitive results and their implications.

Insurance claims were examined for evidence of neck injuries to drivers of passenger cars struck in the rear. Neck injury rates were significantly lower for male drivers, elderly drivers, and drivers in less severe crashes. Even after accounting for differences in driver demographics and crash severity, neck injury rates were significantly lower for drivers of cars with head restraints that were more likely to be behind the heads of motorists.

Sled tests were conducted with some seats that had different characteristics to understand the relationships between occupant motion and seat characteristics in low-speed rear impacts. The position of the head restraint and the stiffness distribution of the seatback were selected as parameters expressing seat characteristics. Volunteers' cervical vertebral motions were photographed with an x-ray cineradiographic system at a speed of 90 frames/sec as well as the visible motions of the dummies and volunteers. The results indicated that the head restraint position and upper seatback stiffness influenced occupant motions. Correlations between visible motions, such as ramping-up, retraction, and extension were also analyzed, and some correlations were found.

Soft tissue neck injury has become the most frequent type of injury sustained in motor vehicle accidents. Most of these injuries occur in rear-end impacts. Consequently, vehicle head restraint geometry has become an important issue in vehicle design and injury prevention. Vehicle crashworthiness and safety ratings are published by auto insurers around the world including the Insurance Corporation of British Columbia (ICBC) in Canada, the Insurance Institute for Highway Safety (United States), and the New Car Assessment Program (Australia). These vehicle ratings include head restraint ratings based on static measurements of head restraint geometry. The authors developed a device for measuring head restraint geometry used in these ratings. This paper details the results of measurements for 40 current vehicles in North America.

The Experimental Head Restraint Concept (EHRC), a 'safety belt' for the head, is designed to reduce forces to the head and neck, in frontal car crashes. The EHRC was evaluated experimentally in frontal collision for a crash severity of 11 m/s, and numerically in frontal collision for a crash severity of 11 and 15 m/s. Experimental data obtained from a frontal barrier test (11 m/s) showed a 67% reduction of the HIC value from 411 (without EHRC) to 136 (with EHRC). The same level of reduction was also obtained for the higher speed in the numerical simulation. The moment in the neck was shown in experimental configuration to increase a few percent using the EHRC, but as presented in a numerical analysis, the moment was reduced by stiffening the EHRC. The EHRC clearly has a potential role in the search for primary prevention of neurotrauma injuries in frontal related car crashes. However, there is a strong need for more advanced injury criteria for the neck in order to optimize such complex safety systems.

This paper introduces cost effective design alternatives for "out-of-position" occupant safety, including: (1) Extractable passenger side lids which move out of the way before airbag deploys; (2) Multi-stage tether controlled airbag deployment dynamically senses "out-of-position" resistance and controls deployment of further stages; (3) Airbag back pressure activated steering column forward and down movement; (4) Two stage thorax bag with tether control to prevent catapulting "out-of-position" occupants; and (5) two stage headrest that expands forward and sideways to protect occupant heads in rear end crashes. Second stage activates only if no "out-of-position" is detected. (A) For the covering abstract of the conference see IRRD E201404.

Neck injuries resulting from rear-end collisions rank among the top car safety problems and have serious implications for society. Many rear impact sled experiments with volunteers and PMHSs have been performed in the past. However, in most of these studies, T1 kinematics were not obtained so that the kinematic behavior of the neck could not be separated from the motion of the rest of the spine. Also, to the best knowledge of the authors, the effect of anthropometric parameters on the head-neck kinematics was not studied before. The objective of this study is to describe the kinematic response of the head-neck system during low severity rear end impacts. In addition, the effect of anthropometric parameters such as height, weight and neck circumference was investigated. For this purpose, a total of 43 tests with 19 subjects was performed. Values for (delta)V ranged between 6,5 and 9.5 km/h. Linear accelerations of the head-CG and the first thoracic vertebra (T1) and angular accelerations of the head were obtained. Head angle and head-CG trajectories were obtained from film targets. Finally, head restraint impact forces were measured using a strain gauge attached to the support rods of the head restraint. Trajectories of the occipital condyles (OC trajectories) as well as upper neck forces and moments were calculated. All measured and calculated kinematic data were presented in response corridors representing the mean +/- one standard deviation. Although only three females participated in this study, a marked increase in head x-acceleration was observed for the females compared to the males. Also, neck circumference correlated well with peak x-accelerations: a thinner neck resulted in higher values for the x-accelerations. The results of this study can be used for evaluation of biofidelity of crash dummy necks, and for validation of mathematical head-neck models. Also, our finding that thinner necks result in higher head peak accelerations may be a partial answer to the question why women are at higher risk for whiplash injuries compared to men.

To determine what effect seat back stiffness and other seat characteristics have on occupant responses, several seats were evaluated in dynamic Hyge rear impact sled simulations. The results of the sled tests indicate that stiffer seats do not have any consistent advantages over yielding seats for the complete range of speeds tested. Even a seat with a head restraint located closer to the center of gravity of the occupants head did not perform better than the baseline seat. Throughout the testing, the most sensitive response to seat design and crash severity was the lower neck extension moment.

In order to assess the head and neck kinetics of human subjects exposed to low-speed rear-end impacts, a method for measuring the magnitude and line of action of the force between the head and the head restraint was required. In addition to being accurate and repeatable, the design was required to maintain original seat back and head restraint geometry, mass, stiffness, and height adjustment. This paper presents a design using strain gauges applied to the head restraint tubes, upper seat back, and custom replacements for brackets attaching the head restraint to the seat back. The background theory and free-body analysis, the analog math circuitry, and a dynamic calibration procedure are presented. Overall force magnitude and line-of-action errors are quantified, and a sample output from a human subject undergoing a rear-end collision with a speed change of 8 km/h is presented. (A) For the covering abstract see IRRD 893297.

This study enhances the existing database of human subject test exposures with an emphasis on electromyographic activity before, during, and after low speed rear impact. Ten nominal 16 km/h closing speed car-to-car impacts were conducted using instrumented male and female subjects aged 22-54 years, with struck vehicle velocity changes of up to 10 km/h. Two head restraint conditions were studied. One condition was a standard seat integrated head restraint. For the second condition the integrated head restraint was modified by adding 2 padding inches to the existing head restraint. No injuries were sustained by any occupant. In all cases, the subjects exhibited pre-impact muscle activity commensurate with that of a relaxed seated posture. Initial muscle activity typically occurred during the initial impact phase as the occupant's cervical spine was extending. Full muscle tension likely did not develop until the cervical spine was flexing. Initial muscle activity was consistent with being triggered by lumbar spine acceleration, and occurred approximately 90-120 milliseconds after onset of lumbar spine acceleration. No significant differences were noted between muscle response times for the two head restraint conditions. Decreases in rearward head displacement, cervical spine extension, and head acceleration were found for the modified head restraint. For the covering abstract of the conference see IRRD 891635.

Results are presented of a co-operative crash injury study on neck injuries in Great Britain. It is shown that although the risk of sustaining soft tissue neck injury is greatly increased in rear impact, over 50% of the injuries are in fact occurring in frontal impacts with a further 25% occurring in side impacts. Overall, the data show a clear value in conducting future work in engineering circles with regard to vehicle design. Language: en

This paper reports findings from an analysis of kinematic responses to a test series of fourteen rear end impacts including a higher range of impact related delta-V (5.8-10.9 kph or 3.6-6.8 mph) than was previously studied. The resulting head, neck and torso kinematics from a total of eighteen human and four Hybrid III anthropometric test device exposures were recorded using a variety of improved electronic and high speed film based data collection methods. All but one of the observations from the earlier study were confirmed, some of the earlier observations and unanswered questions were able to be refined or corrected and biomechanically rational explanation of human head, neck, torso, seatback and head restraint interaction during rear end collisions can now be offered along with comments suggesting a proposed mechanism of injury related to the often referred to, but ill defined 'whiplash' syndrome. Language: en

The primary objective of this research was to evaluate the implications of extending specific Canadian Motor Vehicle Safety Standards (CMVSS) to light trucks and vans (LTVs). This was accomplished through the examination of the potential safety-related benefits of these standards comparing the injury frequencies and severities of the light trucks and vans and the passenger cars (PCs). The standards considered, which currently apply to passenger cars but not to LTVs, are the head restraint (CMVSS 202), side door strength (CMVSS 214), and roof crush strength (CMVSS 216) standards. The comparison was effected by means of logit models developed from multidimensional tables with injury frequency and severity as dependent variables. There are indications that installing head restraints in light trucks and vans could reduce or prevent minor neck injuries and that modest benefits could be achieved by extending the roof crush standard to the LTVs. It was also determined that the side door strength standard may not necessarily be as beneficial to LTVs in conditions in which the vehicle is struck on the side by another LTV. It is suggested that the general public be made aware of the differences in safety standards between LTVs and PCs.

Anti-whiplash systems for automotive front seats are beginning to spread through the industry. They reduce damage to the neck in rear-end accidents, which cause about 25% of all injuries in North America and Europe.

Modern automobiles are safer than their predecessors owing to the installation of new, more effective vehicular restraint systems. Unfortunately, crash-induced fatality and injury rates remain high because certain data related to human injury responses and tolerances are not available to aid in the design of more effective occupant protection. A one-size-fits-all approach is not always the best way to protect occupants of different ages, sizes and weights. We believe that personalised protection systems will become the future trend in designing restraint systems. In this study, combined post mortem human subject testing, medical imaging segmentation and explicit finite element analyses were used to exemplify the use of patient-specific data in injury analysis. Rear-end impact simulations were run with the FE models to depict the head and neck kinematics during the so-called 'whiplash' event. Simulations of an active head restraint system were conducted to investigate the risk of neck injury.

Objective: To assess the relationship between accident mechanisms and initial findings after whiplash injury.Design: Cohort study. Setting: Outpatient department, Department of Neurology, University of Berne, Switzerland. Patients: A population-based sample of 137 consecutive patients referred by primary care physicians. Fractures or dislocations of the cervical spine, head trauma, and preexisting neurologic disorders were exclusion criteria. Main outcome measures: Patients were interviewed and examined within 7.2 days (SD, 3.9 days) after trauma. Analyzed accident features were position in the car, use of seat belt, head restraint and its point of head contact, damage to seat, head position and state of preparedness at the moment of impact, and type of collision. Analyzed symptoms were intensity and onset delay of post-traumatic head and neck pain; pain in the shoulders, back, and anterior neck; symptoms of neurologic dysfunction according to presumed origin–cranial nerve or brainstem, radicular or myelopathic; and a score of multiple symptoms. Analyzed signs were neck muscle tenderness and restricted neck movement, and signs of cranial nerve, brainstem, or radicular dysfunction.Results: Passenger position in the car, use of seat belt, and the presence of a head restraint showed no significant relationship with findings. Rotated or inclined head position at the moment of impact was associated with a higher frequency of multiple symptoms (p = 0.045 and 0.008) with more severe symptoms and signs of musculoligamental cervical strain (p = 0.048 and 0.038) and of neural, particularly radicular (p = 0.031 and 0.019), damage. Unprepared occupants had a higher frequency of multiple symptoms (p = 0.031) and more severe headache (p = 0.046). Rear-end collision was associated with a higher frequency of multiple symptoms (p = 0.006), especially of cranial nerve or brainstem dysfunction (p = 0.00003).Conclusion: Three features of accident mechanisms were associated with more severe symptoms: an unprepared occupant; rear-end collision, with or without subsequent frontal impact; and rotated or inclined head position at the moment of impact.

This short letter describes the results of a survey undertaken to see if motorists were making full use of their head restraints. 150 male drivers were asked to answer a short questionnaire after leaving a 'do it yourself' store. Each driver was then asked to lean back in his seat, and the position of the headrest was assessed. If the top of the head restraint was above eye level it was considered to be correctly positioned. The results showed that although 136 drivers knew that head restraints were a safety feature, only 36 could identify the correct position. In only 50 cases was the head restraint found to be correctly adjusted. A further 54 could be adjusted to a satisfactory height and 46 remained too low even when fully extended. Although this study population cannot be regarded as typical of car drivers and passengers generally, the results suggest that a substantial proportion of car head restraints are too low. Inexpensive measures to educate the motoring public through car handbooks, at services and at Department of Transport Tests are advocated. (TRRL)

A device allowing head holding and stereotaxic manipulations in both small-sized Marmoset and in relatively large Macaca monkeys is described. Its design permits free access to most targets in the visual system and optimizes presentation of visual stimuli in awake-chronic and anaesthetized semi-chronic preparations. Extra-aural attachments to temporal bone are implanted stereotaxically, under anaesthesia, on both sides of the skull. This provides means for stereotaxic head-holding which minimizes discomfort to the animal. Maintenance of stereotaxic precision over long periods of time, possibility of realignment and use of one device for various monkey species are special features of the method.

A mathematical model of the seated driver subjected to a rear-end impact is developed using a lumped parameter model which,inter alia, allows for the investigation of the effect of an elastic—perfectly plastic head restraint device on the overall motion of the head and torso. The most satisfactory seatback-head restraint combination is found to be a seatback having a high rotational stiffness with a viscous damping coefficient of near ‘critical’ value combined with an energy absorbing head restraint having e plastic collapse load of approximately 890 N. The model confirms recent results which indicate that tensing of neck musculature prior to impact reduces injury potential.

An apparatus for aversive conditioning of adult cats and kittens is described. Animals are held by a cloth harness and head restraint device in a metal frame with a movable treadmill floor. They are supported in a natural standing position, with freedom to flex and move each leg and to walk or run on the treadmill. Various transducers record respiration, EKG, vocalization, leg flexion, and locomotion on the treadmill.

Dittmar, Warm, and Dember (1985) suggested that visual parallax may lead to declines in perceptual sensitivity over time in spatial vigilance tasks involving comparative judgments. The present study tested this possibility by restraining subjects' head movements during a 1-hr vigil in which comparative (simultaneous task) or absolute (successive task) judgments of line length were necessary for signal detection. Under free-viewing conditions, perceptual sensitivity declined over time with both types of tasks. Head restraint eliminated the sensitivity decrement in both cases. The results highlight signal quality as a crucial determinant of perceptual decrements in sustained attention.

Subjects monitored a visual display for occasional increments in the horizontal movement of a bar of light. When the display was viewed without head restraint, detection probability was directly related to the amplitude of the increments in movement which constituted critical signals and inversely related to background event rate (the frequency of neutral events in which critical signals were embedded). When positioning of the head was restrained by a headrest, the detectability of low-amplitude signals was enhanced considerably and the influence of background event rate was attenuated. The results are considered as providing further support for the importance of sense mode coupling in visual monitoring.

We developed a primate restraint system that requires no chronic skin openings or attachments to the animal. The restraining chair has a unique neck clasp; monkeys without chains and collars are easily trained to readily enter the chair and accept restraint with the neck and head held at a comfortable angle. A bite bar, in combination with contact on broad areas of the monkey’s brow and occiput, provides rigid head immobilization. In order to achieve contact with a broad area of the occipital bone, the muscles at the back of the animal’s head are surgically detached from the occiput and reattached to the underlying neck muscles. A strain-gauge, mounted on the head-holder and monitored by a laboratory computer, detects head movements of the monkey and permits the experimenter to teach the monkey to sit still during data acquisition. This system is well accepted by experienced monkeys and helps prevent the risks of infection posed by most earlier methods. Furthermore, the head and shoulders of the monkey are readily accessible for examination and for close positioning of test equipment.

In an effort to investigate the effects of restrictive head movement upon eye movements, two groups of fifteen undergraduate student volunteers, one group with head restricted, the other with no head restriction, tracked a segment of the Aetna Training film. Tracking was done by manipulating the controls of an Aetna Drivo-Trainer Station. Eye movements were recorded simultaneously. The results indicated that restricting the head resulted in more driving errors and fewer long eye movements. Also, it was found that the number of eye movements which adjust for movements of the head (i.e., compensatory) were lower under conditions of head restraint. This was especially true for those compensatory movements characterized by swinging the eyes beyond the desired point of fixation (i.e., overshoots). In general, more eye movements correlated with more driving adjustments and lower numbers of driving errors. /Author/

Surgically implanted head restraint devices have been used in nonhuman primate research for more than a decade. Superficial scalp defects are created by the implantation procedures and remain after the devices are removed, a factor that occasionally hinders continued use of the animals by investigators on esthetic grounds. A technique is described whereby the scalp defects are surgically repaired, resulting in a good cosmetic appearance and effectively increasing the potential for reuse of these animals.

An inexpensive turntable for producing uniform angular accelerations for use in vestibular research is described. The table provides semicircular canal stimulation for cats or smaller animals at moderate accelerations above 3 deg sec−2. A head restraint suitable for use on the table and designed for chronically implanted cats is also described.

A method for rigid head restraint during stereotaxic surgical procedures is described. The method is based on modifications of a conventional rabbit stereotaxic head holder and provides reliable head fixation for accurate implantation of depth and surface electrodes, cannulae, microelectrode wells, etc.

Experiments designed to provide information regarding ocular motor pathways and systems of coordination of the eyes have included, for the human S, those of a descriptive nature which involve the observation and recording of eye movements of pursuit, fixation, and nystagmus. For the animal S, a more analytic approach has been possible with the use of electrical stimulation, surgical intervention, and histological techniques. Teuber and Bender ( 195 1 ) review in detail these various methods of investigation. Studies of eye rnovements of intact animals, however, have been limited. Normally, animals n u n their heads rather than their eyes toward a new fixation, and will not, reliably, exhibit voluntary ocular movements, particularly under conditions of head restraint necessary for recording procedures. Thus, investigation~ of intact animals have been directed toward the analysis of the involuntary ocular movements of vestibular or optokinetic nystagmus. Wendt and Dodge (1938) have discussed such an approach. The present report outlines a method of obtaining, in the intact cat, voluntary ocular movements of varying direction and extent, and offers suggestions for the recording and analysis of such eye movements.

Objective This study aimed (1) to determine whether scanner arm rotation causes significant movement of the head restraint and (2) to measure patient movement and its variation during the scan. Study Design The iCAT scanner and a high-speed camera were used. The 40 patients were divided into 2 groups: the open-eyed group and the blindfolded group. Results The mean level of head restraint movement was 0.130 mm, with a significantly higher level at the beginning, probably owing to the accelerating arm. Mean movement of patients was 1.135 mm and 1.119 mm in the open-eyed and blindfolded groups, respectively. Patient movement was also significantly higher at the beginning of the scan, when noise and vibrations are likely to surprise the patient. Conclusions Patient instruction and a dry-run scan should be done by clinicians. Manufacturers should consider separating the seat and head restraint from the rest of the scanner to avoid vibration transfer.

Police based national accident data from the Netherlands show an enormous increase of both in number and in share of car rear-end collisions resulting in injury over the last 15 years. The average severity of those accidents remains low (illustrated by very low shares of occupants killed or hospitalised). However, the apparent increase in number of less severely injured as well as the personal and societal consequences of their injuries may well impose an increasing threat to the quality of life within the Dutch society.Based on national accident data as well as other relevant injury and traffic exposure data, the current situation in the Netherlands is described. Differences with respect to gender unexpectedly suggest that female drivers have a higher risk of their car being hit from behind than male drivers do. Less unexpectedly, differences are found between males and females with respect to injury susceptibility. These differences are analysed using controlling factors such as type of car, type of road, and exposure to traffic.It appears that not all of the indicators used point the same way; some of the increase mentioned may be due to registration biases. There is also a lack of adequate data with regard to the real number of whiplash injuries, their severity, and the longer-term consequences. Even if the total scope of the problem of whiplash injury in the Netherlands is still not fully known, the current estimate of societal consequences implicates a need for preventive measures. In the first place, accident prevention should be considered and a number of possible preventive measures (such as infrastructural improvement and application of ITS devices in cars to maintain distance in traffic) are discussed. Injury preventive measures (such as in car protection against whiplash) are already more generally available but still need much improvement.

Summary High-throughput operant conditioning systems for rodents provide efficient training on sophisticated behavioral tasks. Combining these systems with technologies for cellular resolution functional imaging would provide a powerful approach to study neural dynamics during behavior. Here we describe an integrated two-photon microscope and behavioral apparatus that allows cellular resolution functional imaging of cortical regions during epochs of voluntary head restraint. Rats were trained to initiate periods of restraint up to 8 s in duration, which provided the mechanical stability necessary for in vivo imaging while allowing free movement between behavioral trials. A mechanical registration system repositioned the head to within a few microns, allowing the same neuronal populations to be imaged on each trial. In proof-of-principle experiments, calcium-dependent fluorescence transients were recorded from GCaMP-labeled cortical neurons. In contrast to previous methods for head restraint, this system can be incorporated into high-throughput operant conditioning systems.

Day to day variation in the visual evoked response recorded from chronic animals is sometimes large enough to mask the effects of an experimental treatment. We have shown that an important source of variation in chronic VER recording is head movement. A simple method for bringing head movement to a minimum is discussed.

A set of devices is described that enables daily handling and restraint of large primates. The animals live in cages and wear a special collar that fits into a modified primate restraining chair. A chain and pole arrangement simplifies the daily chairing procedure. A method of head restraint and earphone mounting is also described.