What causes aberrant salience in schizophrenia? A role for impaired short-term habituation and the GRIA1 (GluA1) AMPA receptor subunit.

The GRIA1 locus, encoding the GluA1 (also known as GluRA or GluR1) AMPA glutamate receptor subunit, shows genome-wide association to schizophrenia. As well as extending the evidence that glutamatergic abnormalities have a key role in the disorder, this finding draws attention to the behavioural phenotype of Gria1 knockout mice. These mice show deficits in short-term habituation. Importantly, under some conditions the attention being paid to a recently presented neutral stimulus can actually increase rather than decrease (sensitization). We propose that this mouse phenotype represents a cause of aberrant salience and, in turn, that aberrant salience (and the resulting positive symptoms) in schizophrenia may arise, at least in part, from a glutamatergic genetic predisposition and a deficit in short-term habituation. This proposal links an established risk gene with a psychological process central to psychosis and is supported by findings of comparable deficits in short-term habituation in mice lacking the NMDAR receptor subunit Grin2a (which also shows association to schizophrenia). As aberrant salience is primarily a dopaminergic phenomenon, the model supports the view that the dopaminergic abnormalities can be downstream of a glutamatergic aetiology. Finally, we suggest that, as illustrated here, the real value of genetically modified mice is not as 'models of schizophrenia' but as experimental tools that can link genomic discoveries with psychological processes and help elucidate the underlying neural mechanisms.

Analgesics improve the gait of lame dairy cattle.

Pain associated with injuries of the hoof and surrounding tissues is an important cause of lameness. The objective was to detect the attributes of impaired gait that are associated with pain. In 3 separate experiments, lactating Holstein cows (n = 20; n = 21; n = 27) diagnosed with varying degrees of gait impairment were injected i.m. (Exp. 1 and 2) or i.v. (Exp. 3) with the analgesic ketoprofen at 0, 0.3, 1.5, or 3.0 mg/kg of BW. Gait was evaluated subjectively using a numerical rating system (NRS; varying from 1 to 5) and 6 specific gait attributes (back arch, tracking up, joint flexion, asymmetric steps, head bob, and reluctance to bear weight). Each experiment was divided into 3 phases each lasting 3 d: before treatment, after treatment, and during treatment with daily injections of ketoprofen. The NRS improved by 0.25 +/- 0.05 with the highest dose of ketoprofen. Although none of the specific gait attributes showed a consistent response to treatment, there was an interaction between dose and experiment for asymmetric steps and reluctance to bear weight; in Exp. 1, but not Exp. 2 and 3, cow steps were more symmetrical (improving by 7.16 +/- 1.02), and cows distributed their weight more evenly (improving by 5.84 +/- 1.13) at the highest doses of ketoprofen. These results indicated that the NRS was more sensitive than the specific gait attributes in assessing differences in gait associated with pain. The results showed that ketoprofen has only a modest effect on gait, indicating either that this drug has little effect on pain due to lameness or that much variation in NRS was due to factors other than pain.

The role of the GluR-A (GluR1) AMPA receptor subunit in learning and memory.

It is widely believed that synaptic plasticity may provide the neural mechanism that underlies certain kinds of learning and memory in the mammalian brain. The expression of long-term potentiation (LTP) in the hippocampus, an experimental model of synaptic plasticity, requires the GluR-A subunit of the AMPA subtype of glutamate receptor. Genetically modified mice lacking the GluR-A subunit show normal acquisition of the standard, fixed-location, hidden-platform watermaze task, a spatial reference memory task that requires the hippocampus. In contrast, these mice are dramatically impaired on hippocampus-dependent, spatial working memory tasks, in which the spatial response of the animal is dependent on information in short-term memory. Taken together, these results argue for two distinct and independent spatial information processing mechanisms: (i) a GluR-A-independent associative learning mechanism through which a particular spatial response is gradually or incrementally strengthened, and which presumably underlies the acquisition of the classic watermaze paradigm and (ii) a GluR-A-dependent, non-associative, short-term memory trace which determines performance on spatial working memory tasks. These results are discussed in terms of Wagner's SOP model (1981).

Age-dependent and -independent behavioral deficits in Tg2576 mice.

The Tg2576 mouse model of excessive cerebral beta-amyloid deposition is now more than a decade old, yet consensus as to its exact characteristics and utility as a model of Alzheimer's disease is still lacking. Four different cohorts of control and Tg2576 mice, aged approximately 3, 9, 13 and 21 months, were therefore subjected to a battery of tests, principally to assess cognitive and species-typical behaviors. A novel test, the paddling Y-maze, demonstrated an age-dependent deficit in 10 and 14, but not 3 month Tg2576 mice, also in aged (21 month) control mice. However, in many other cognitive tests few Tg2576-related deficits could be shown. This frequently seemed attributable to poor performance of control mice. Tests of species-typical behaviors showed that Tg2576 mice had a deficit in burrowing behavior at all ages. An age-independent deficit was also seen in nest construction, but only when mice were group-housed; most individually housed mice in either group made reasonable nests. Overall, the results suggested that these Tg2576 mice are not a simple, suitable or reliable model for routine screening of treatments for Alzheimer's disease. However, this model might perform better behaviorally on a different genetic background.

Supersmart mice: surprising or surprised? Theoretical comment on Singer, Boison, Möhler, Feldon, and Yee (2007).

The glycine transporter (GlyT1) regulates levels of the neurotransmitter glycine, a coagonist of the N-methyl-D-aspartate receptor (NMDAR), and as such may represent a novel site for developing cognition-enhancing drugs. Genetically modified mice with reduced levels of GlyT1 have been generated to test this hypothesis. P. Singer, D. Boison, H. Möhler, J. Feldon, and B. K. Yee now show, through a spontaneous exploration task, that mice in which GlyT1 has been deleted, specifically in neurons in the forebrain, demonstrate enhanced object recognition memory. Whereas both control and mutant mice show a preference for a novel object over a familiar object 2 min after the initial presentation of 1 of the objects, only the mutant mice show a preference for the novel object when tested after a 2-hr delay. The longer-lasting habituation displayed by the GlyT1 mice is consistent with a role for glycine/NMDAR-dependent synaptic plasticity in supporting a nonassociative, short-term memory trace of a recently experienced stimulus. This short-term habituation process may be independent of associative learning mechanisms and may be best described by A. R. Wagner's (1981) sometimes opponent process model.

Deletion of glutamate receptor-A (GluR-A) AMPA receptor subunits impairs one-trial spatial memory.

Genetically modified mice lacking the glutamate receptor A (GluR-A) subunit of the AMPA receptor (GluR-A-/- mice) display normal spatial reference memory but impaired spatial working memory (SWM). This study tested whether the SWM impairment in these mice could be explained by a greater sensitivity to within-session proactive interference. The SWM performance of GluR-A-/- and wild-type mice was assessed during nonmatching-to-place testing under conditions in which potential proactive interference from previous trials was reduced or eliminated. SWM was impaired in GluR-A-/- mice, both during testing with pseudotrial-unique arm presentations on the radial maze and when conducting each trial on a different 3-arm maze, each in a novel testing room. Experimentally naive GluR-A-/- mice also exhibited chance performance during a single trial of spontaneous alternation. This 1-trial spatial memory deficit was present irrespective of the delay between the sample information and the response choice (0 or 45 min) and the length of the sample phase (0.5 or 5 min). These results imply that the SWM deficit in GluR-A-/- mice is not due to increased susceptibility to proactive interference.

Softer, higher-friction flooring improves gait of cows with and without sole ulcers.

We studied dairy cows (n = 30) walking on concrete and on a soft, high-friction composite rubber surface to examine how flooring influenced gait and how this differed for cows with hoof lesions. Cows had hooves trimmed 9 wk after the trial and were classified as either with or without sole ulcers. Video recordings of the cows while walking were digitized using motion analysis software to calculate stride variables (length, height, overlap, duration, proportion of triple support, and speed). Gait was scored by a subjective scoring system (1 = sound to 5 = severely lame) and by a continuous visual analog scale for each of 7 gait attributes. Cows with sole ulcers walking on a composite rubber surface had longer strides (156.9 +/- 2.6 vs. 149.6 +/- 2.6 cm), higher stride heights (9.7 +/- 0.3 vs. 8.8 +/- 0.3 cm), more stride overlap (0.4 +/- 2.0 vs. -4.3 +/- 2.0 cm), shorter periods of triple support (3 legs in ground contact; 68.6 +/- 2.0 vs. 73.8 +/- 2.0%), walked faster (1.22 +/- 0.04 vs. 1.17 +/- 0.04 m/s) and had lower overall gait scores (2.9 +/- 0.1 vs. 3.1 +/- 0.1), better tracking-up (19 +/- 2 vs. 24 +/- 2), better joint flexion (29 +/- 2 vs. 33 +/- 2), more symmetric steps (31 +/- 3 vs. 36 +/- 3), and less reluctance to bear weight on their legs (12 +/- 2 vs. 16 +/- 2) compared with walking on concrete. Similar results were found for cows without sole ulcers. Most of the subjective gait measures could distinguish between cows with and without sole ulcers, but this was not the case for kinematic measures other than stride height. Cows with higher gait scores (more severe lameness) showed the greatest improvement in stride length (r = -0.51), triple support (r = 0.59), swing duration (r = -0.44), overall gait score (r = 0.46), and reluctance to bear weight (r = 0.66) when walking on the rubber surface compared with cows with lower gait scores. These results indicate that rubber flooring provides a more secure footing and is more comfortable to walk on, especially for lame cattle.

Effects of milking on dairy cow gait.

We studied cows with (n = 6) and without (n = 26) sole ulcers before and after milking to explore how milking influences dairy cattle gait and how this differs for cows with hoof injuries. Video recordings of cows were digitized using motion-analysis software to calculate stride variables for each hoof. Gait was scored using a 1-to-5 numerical rating system (1 = sound, 5 = severely lame) and a continuous 100-unit visual analog scale of gait attributes (back arch, head bob, tracking-up, and reluctance to bear weight). For cows with and without sole ulcers, differences in gait before and after milking were evident; after milking, all cows had significantly longer strides (123.3 vs. 133.5 +/- 2.0 cm, respectively), higher stride height (8.3 vs. 8.9 +/- 0.1 cm), shorter stride durations (1.49 vs. 1.41 +/- 0.03 s), walked faster (0.85 vs. 0.97 +/- 0.03 m/s), and had shorter periods of triple support (3 legs in ground contact; 80.0 vs. 71.7 +/- 2.0%). Tracking-up and reluctance to bear weight improved after milking (20 vs. 16 +/- 2; 20 vs. 15 +/- 1, respectively), but numerical rating scores and back arch did not. Cows with sole ulcers walked differently than cows without for all measures, except swing duration, both before and after milking. Interactions between hoof health and milking were found for swing duration and head bob but when tested separately, the only effect was that cows without sole ulcers had longer swing durations before milking (0.45 vs. 0.44 +/- 0.01 s, respectively). Gait differences were probably due to udder distention and motivation to return to the home pen. Our results suggest that the most suitable time to assess lameness is after milking when differences between cows with and without ulcers are most evident.

Hoof pathologies influence kinematic measures of dairy cow gait.

To explore how hoof pathologies affect the gait of dairy cattle, we studied gait profiles of cows with no visible injuries (n = 17), sole lesions (n = 14), and sole ulcers (n = 7). Video recordings of dairy cows were digitized using motion analysis software to calculate 6 stride variables for each hoof. Compared with cows with sole ulcers, healthy cows walked faster (1.11 +/- 0.03 vs. 0.90 +/- 0.05 m/s, mean +/- SEM), had shorter stride durations (1.26 +/- 0.03 vs. 1.48 +/- 0.05 s), and longer strides (139.5 +/- 2.1 vs. 130.0 +/- 3.2 cm). Percentage of triple support in the gait cycle (time when cattle were supported by 3 legs) more than doubled for cows with sole ulcers compared with healthy cows (42 vs. 18%). Gait differences were likely due to cows reducing the load on an affected leg. Few differences were detected between healthy cows and those with sole lesions, perhaps because of variation in number, severity, and location of injuries. Kinematic gait analysis is a promising approach in understanding how hoof pathologies affect dairy cow gait.

Startle response of human neck muscles sculpted by readiness to perform ballistic head movements.

1. An acoustic startle stimulus delivered in place of a 'go' signal in a voluntary reaction time (RT) task has been shown previously to advance the onset latency of a prepared distal limb movement without affecting the amplitude of the muscle response or movement kinematics. The primary goal of this study was to use muscles with a larger startle response to investigate whether the startling stimulus only triggered the RT movement or whether some form of interaction occurred between a startle response and a temporally advanced RT movement. 2. Twenty healthy male or female subjects were instructed to react as quickly as possible to an acoustic 'go' stimulus by performing a ballistic head flexion or right axial rotation. The 'go' stimulus was periodically replaced by an acoustic stimulus capable of eliciting a startle reflex. Separate startle-inducing stimuli under relaxed conditions before and after the movement trials served as control trials (CT trials). Bilateral surface electromyography of the orbicularis oculi, masseter, sternocleidomastoid and cervical paraspinal muscles, and head-mounted transducers were used to measure the muscle response and movement kinematics. 3. Muscle activation times in startled movement trials (ST trials) were about half those observed in RT trials, and were not significantly different from those observed in the startle CT trials. The duration of head acceleration was longer in ST trials than in RT trials and the amplitude of both the neck muscle electromyogram (EMG) and head kinematics was larger during ST trials than during RT trials. The EMG amplitude of ST trials was biased upward rather than scaled upward compared with the EMG amplitude of RT trials. 4. Over the 14 ST trials used in this experiment, no habituation of the reflex response was observed in the muscles studied. This absence of habituation was attributed to a combination of motor readiness and sensory facilitation. 5. The results of this experiment indicated that the neck muscle response evoked by a startling acoustic stimulus in the presence of motor readiness could be described as a facilitated startle reflex superimposed on a temporally advanced, pre-programmed, voluntary RT movement. Parallel reticular pathways to the neck muscle motoneurones are proposed as a possible explanation for the apparent summation of the startle and voluntary movement responses.

The influence of cadence and power output on force application and in-shoe pressure distribution during cycling by competitive and recreational cyclists.

The aim of this study was to determine the response of cyclists to manipulations of cadence and power output in terms of force application and plantar pressure distribution. Two groups of cyclists, 17 recreational and 12 competitive, rode at three nominal cadences (60, 80, 100 rev x min(-1)) and four power outputs (100, 200, 300, 400 W) while simultaneous force and in-shoe pressure data were collected. Two piezoelectric triaxial force transducers mounted in the right pedal measured components of the pedal force and orientation, and a discrete transducer system with 12 transducers recorded the in-shoe pressures. Force application was characterized by calculating peak resultant and peak effective pedal forces and positive and negative impulses. In-shoe pressures were analysed as peak pressures and as the percent relative load. The force data showed no significant group effect but there was a cadence and power main effect. The impulse data showed a significant three-way interaction. Increased cadence resulted in a decreased positive impulse, while increased power output resulted in an increased impulse. The competitive group produced less positive impulse but the difference became less at higher cadences. Few between-group differences were found in pressure, notable only in the pressure under the first metatarsal region. This showed a consistent pattern of in-shoe pressure distribution, where the primary loading structures were the first metatarsal and hallux. There was no indication that pressure at specific sites influenced the pedal force application. The absence of group differences indicated that pressure distribution was not the result of training, but reflected the intrinsic relationship between the foot, the shoe and the pedal.

Is a joint moment-based cost function associated with preferred cycling cadence?

Eight experienced male cyclists (C), eight well-trained male runners (R), and eight less-trained male noncyclists (LT) were tested under multiple cadence and power output conditions to determine: (1) if the cadence at which lower extremity net joint moments are minimized (cost function cadence) was associated with preferred pedaling cadence (PC), (2) if the cost function cadence increased with increases in power output, and (3) if the association is generalizable across groups differing in cycling experience and aerobic power. Net joint moments at the hip, knee, and ankle were computed from video records and pedal reaction force data using 2-D inverse dynamics. The sum of the average absolute hip, knee, and ankle joint moments defined a cost function at each power output and cadence and provided the basis for prediction of the cadence which minimized net joint moments for each subject at each power output. The cost function cadence was not statistically different from the PC at each power output in all groups. As power output increased, however, the cost function cadence increased for all three subject groups (86 rpm at 100 W, 93 rpm at 150 W, 98 rpm at 200 W, and 96 rpm at 250 W). PC showed little change (R) or a modest decline (C, LT) with increasing power output. Based upon the similarity in the mean data but different trends in the cost function cadence and PC in response to changes in power output as well as the lack of significant correlations between these two variables, it was concluded that minimiking net joint moments is a factor modestly associated with preferred cadence selection.

Ventilation and locomotion coupling in varsity male rowers.

Ventilation and locomotion coupling (entrainment) has been observed and described in rowers during incremental exercise protocols but not during simulated race conditions. The purpose of this descriptive study was to examine ventilation and locomotion entrainment on a breath-by-breath and stroke-by-stroke basis in varsity male rowers during a maximal 2,000-m ergometer test. Eight of eleven rowers entrained ventilation at integral multiples of stroke rate (1:1, 2:1, or 3:1) for at least 120 consecutive seconds, with a 2:1 entrainment pattern being most common. In all 2:1-entrained subjects, inspiration occurred at catch and finish and expiration occurred during the latter portions of drive and recovery. In entrained and unentrained breaths from all rowers, peak flow rates and tidal volumes varied depending on when the breath was initiated during the stroke cycle. Entrained rowers made use of these differences and breathed in a pattern by which they avoided initiating breaths that resulted in reduced tidal volumes. The present data indicated that ventilation was impaired at stroke finish and not at catch, as hypothesized by some previous researchers. Ventilation also appeared to be subordinate to consistent locomotive patterns under race conditions.

Joint kinetics in unilateral below-knee amputee patients during running.

OBJECTIVE: To explore the nature of the accommodations in running gait that persons with below-knee amputations make in response to the limb segment loss. PATIENTS: Two groups of volunteer subjects (n = 6 in each group). Individuals in one group had below-knee amputations; the second group had intact lower limbs. DESIGN: Individuals ran at two nominal speeds, 2.7 m/sec and 3.5 m/sec, over a flush-mounted force platform. Ground reaction force data were combined with simultaneously recorded and subsequently digitized video data of coordinate motion to calculate joint and segment motion and net joint moment data. RESULTS: The degree of left-to-right asymmetry for the amputee group was dependent on the variable of interest. There was symmetry in stride frequency and support moment and a marked asymmetry in ankle, knee, and hip moments. In response to increased running speed, both groups increased the amplitude of each joint moment. The nonamputee group appeared to increase the gain uniformly across the three joints, whereas the intact and prosthetic limbs were not uniformly increased. The temporal sequencing of the components for the intact and prosthetic limbs did not appear to differ from the nonamputee limb. This similarity in timing was unaffected by speed increases. CONCLUSION: There was no need to develop completely new patterns of joint moments; rather, it was sufficient to retune the current moment patterns to account for new segmental properties and thus retain the internal timing characteristics.

Chopart prosthesis and semirigid foot orthosis in traumatic forefoot amputation. Comparative gait analysis.

Gait was analyzed in seven otherwise healthy males at least 11 mo after they had recovered from a traumatic unilateral transmetatarsal amputation incurred during the course of their usual occupation. All seven were fitted with a semirigid foot orthosis. Four were also fitted with a Chopart prosthesis. Gait was evaluated with forceplate measurements of ground reaction force during free walking, by clinical observation of such ambulation on videotape, and by the subjective impression of the men as obtained by a questionnaire. In all men, with unmodified footwear, with the orthosis, and with the prosthesis, the forceplate data showed an abnormal pattern characterized by reduced stance duration and deficient forward propulsion on the amputated side. The abnormality and asymmetry of ground-reaction forces were less with greater preserved stump length and for a given stump length were with the above-ankle concept (Chopart) prosthesis than with the below-ankle concept. These features were recognized during the clinical analysis of all footwear, but there was an extra irregularity of weight progression noted with the fixed ankle of the Chopart prosthesis. The questionnaire reported stump problems to be the principal difficulty, and the follow-up revealed persistent attempts at surgical management including consideration of amputation at a higher level. It was concluded that the patient and the surgeons are likely to choose preservation of limb length over considerations of function during acute care and that the prosthetic concept best suited to deal with the resulting stump should emphasize unloading the distal part of the stump and smoothing out the impulsive force peak on the stump in late stance to minimize pain and to enhance ambulation capacity.

Limitations of kinematics in the assessment of wheelchair propulsion in adults and children with spinal cord injury.

BACKGROUND AND PURPOSE: Recently, there has been a trend for designers to reduce the weight of wheelchairs. Wheelchair performance is frequently evaluated in clinical as well as laboratory settings by kinematic motion analysis. The purpose of this study was to examine the effect of weight on the kinematics of wheelchair propulsion in nonathletic adults and children with spinal cord injury. SUBJECTS AND METHODS: The weight of identical new low-weight test chairs (9.3 kg) was manipulated by adding weight (5 and 10 kg) in two matched groups (n = 10) of adults and children with spinal cord injury. The three-dimensional coordinates of reflective markers were obtained as the subjects performed level wheeling at a speed of 2 m/s. RESULTS: The pediatric group was found to have significantly lower wheeling speeds than the adult group. The addition of weight, however, did not alter the wheeling speeds in either group. Neither the proportions of the wheeling cycle spent in propulsion (24%) nor the angular (shoulder flexion-extension, elbow flexion-extension, shoulder abduction, and trunk flexion-extension) kinematics of wheeling changed with additions of weight in either group. The angular kinematics of the pediatric group, however, were different than those of the adult group. CONCLUSION AND DISCUSSION: These results indicate that adding weight in the range of 5 to 10 kg did not affect wheeling style under the level-wheeling, low-speed conditions of the study. It is possible that performance in wheelchair propulsion may be more appropriately determined by kinetic and energetic outcome measures than by kinematic measures.

The role of external nonrigid ankle bracing in limiting ankle inversion.

The purpose of this study was to measure the effectiveness of the nonrigid subtalar stabilizer (STS) ankle brace under conditions similar to an unexpected fall that could lead to a lateral ligament injury. The calcaneal inversion angles, times, and ground reaction forces were measured when the subject's right foot, bearing body weight, was suddenly inverted to a side slope of 22 degrees. Thirty subjects, 15 women and 15 men, participated in the study. The overall inversion drop was divided into two phases, free fall and loading. Based on the data of this study it is suggested that the major function of a brace is to restrict the amount of foot inversion during the fall before actual landing occurs rather than functioning as a force bypass for the lateral ligaments during loading after foot contact. The results showed that the brace significantly (p < 0.05) reduced the maximum calcaneal inversion angle from 27.4 +/- 6.1 to 18.3 +/- 6.0 degrees for the overall drop, significantly lengthened the inversion time from 0.14 +/- 0.04 to 0.18 +/- 0.04 s for the overall drop, and significantly reduced the calcaneal peak inversion velocity from 324.6 +/- 111.9 to 165.2 +/- 66.5 degrees/s during loading, and from 278.7 +/- 120.0 to 183.0 +/- 108.7 degrees/s for the overall drop. Following exercise, which incorporated lateral movements and sprinting, the STS ankle brace continued to provide significant (p < 0.05) reduction in the calcaneal inversion angle and velocity, although some of its effectiveness was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinematics of wheelchair propulsion in adults and children with spinal cord injury.

This study examined the kinematic features of wheelchair propulsion in two neurologically matched groups of adults and children with uncomplicated spinal cord injury. The average mass and age of the pediatric group was much smaller than the adult group (37.4kg and 11.3 years vs 68.5kg and 33.5 years). Each subject propelled his/her own chairs and new, low-mass wheelchairs at a steady, nominal speed of 2 m/sec across a level surface. Three dimensional video analysis determined the movement of upper body angles (elbow, shoulder, trunk, and shoulder abduction) based on reflective markers placed on the subjects' shoulder, elbow, wrist, and hip joints. Analysis of the temporal factors showed that although the average group overground velocities of the adult group (2.4m/sec) were significantly greater than the pediatric group (2.3 m/sec), the two groups spent comparable proportions of the wheeling cycle in propulsion (24%). Analysis of the angular kinematics (elbow, shoulder, and shoulder abduction angular changes over a time normalized wheeling cycle) showed that whereas the pediatric group did show significant absolute angular differences from the adult group, the angular changes over time were the same in both groups. The implications of this work are that, for the first time, it can be said that children propel their wheelchairs in the same manner as adults. In addition, these data were similar to those previously reported in athletic adult populations. We conclude that published data from adult wheelchair users may be applied to pediatric wheelchair users, thus providing a basis for pediatric wheelchair prescription.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of functional and medical assessment in the classification of persons with spinal cord injury.

For many reasons, persons with spinal cord injury (SCI) are classified according to a set of guidelines in which the term classification refers to a numeric value based on some selection of motor, sensory, and/or functional tests. The resulting classification is used as a means of quantifying the extent of neurological injury. Scales that focus on neurological injury (in the acute phase) differ from those that focus on functional ability (in the chronic phase). The relationship among these scales in grouping persons with SCI has not been ascertained. The purpose of the present study was to compare several classification systems within the same group of spinal cord injured subjects. Thirty subjects with traumatic SCI were classified by the same examiner and grouped according to three classification systems: 1) the American Spinal Injury Association (ASIA) Scale; 2) the Bracken Scale; and, 3) the wheelchair basketball (BB) Sports Test. Calculation of Spearman's Rho correlation coefficients showed positive associations between the ASIA Scale and BB Sports Test (0.81). The Bracken Scale showed a negative correlation with the ASIA system (-0.66) and the BB Sports Test (-0.48). Of the three classification systems, the ASIA Scale showed the greatest discrimination in grouping subjects with SCI in both mixed (complete and incomplete), as well as incomplete injuries. It was clear that these three systems could result in different patterns of subject grouping and thus might affect the outcome of the clinical research studies.