Musculoskeletal Dimension and Brightness Reference Values in Lumbar Magnetic Resonance Imaging-A Radio-Anatomic Investigation in 80 Healthy Adult Individuals.

Background/Objectives: Magnetic resonance imaging (MRI) is the preferred diagnostic means to visualize spinal pathologies, and offers the possibility of precise structural tissue analysis. However, knowledge about MRI-based measurements of physiological cross-sectional musculoskeletal dimensions and associated tissue-specific average structural brightness in the lumbar spine of healthy young women and men is scarce. The current study was planned to investigate characteristic intersexual differences and to provide MRI-related musculoskeletal baseline values before the onset of biological aging. Methods: At a single medical center, lumbar MRI scans of 40 women and 40 men aged 20-40 years who presented with moderate nonspecific low back pain were retrospectively evaluated for sex-specific differences in cross-sectional sizes of the fifth lumbar vertebrae, psoas and posterior paravertebral muscles, and respective sex- and age-dependent average brightness alterations on T2-weighted axial sections in the L5-level. Results: In women (mean age 33.5 years ± 5.0 (standard deviation)), the investigated musculoskeletal cross-sectional area sizes were significantly smaller (p < 0.001) compared to those in men (mean age 33.0 years ± 5.7). Respective average musculoskeletal brightness values were higher in women compared to those in men, and most pronounced in posterior paravertebral muscles (p < 0.001). By correlating brightness results to those of subcutaneous fat tissue, all intersexual differences, including those between fifth lumbar vertebrae and psoas muscles, turned out to be statistically significant. This phenomenon was least pronounced in psoas muscles. Conclusions: Lumbar musculoskeletal parameters showed significantly larger dimensions of investigated anatomical structures in men compared to those in women aged 20-40 years, and an earlier onset and faster progress of bone loss and muscle degradation in women.

Pain-dependent learning in healthy volunteers.

A state-dependent learning paradigm was studied in which healthy adult volunteers studied/encoded and recalled information from short passages, neutral in their content, in one of the following conditions: (1) Pain during study-Pain during both recall sessions; (2) Pain during study-No Pain during both recall sessions; (3) No Pain during study-Pain during both recall sessions; and (4) No Pain during study-No Pain during both recall sessions. Pain was experimentally induced using the cold pressor technique. In this study, we looked at evidence for state-dependent learning when the context of learning is not emotionally driven, but neutral. The memory task consisted of encoding detailed information about short stories, then recalling as many details as possible 20 min and 48 hr later. The results indicated no occurrence of a state-dependent learning and retrieval effect in this sample: Participants in the pain-no pain and no pain-pain conditions did not significantly perform differently than participants in the pain-pain and no pain-no pain conditions. However, a main effect of the state during study/encoding was significant, suggesting that being in pain during study had a detrimental effect on performance on the memory tests regardless of the state at retrieval. These results oppose previous studies' findings and shed new light on possible implications in various research areas.

Malignancy as a possible complication of complex regional pain syndrome: a case report.

A synovial sarcoma presented in the knee of a young woman 20 years after the onset of pain which was attributed to complex regional pain syndrome (CRPS). Was this a chance occurrence, or could there be any link between the two conditions? Did the pain itself and the persistent inflammatory and immunological response to pain contribute to the development of malignancy, or could the malignancy have been present subclinically for many years and have contributed to the ongoing pain syndrome? This case report looks into the diagnosis of synovial sarcoma and CRPS and the relationship between the neurogenic inflammation seen in CRPS and that seen in malignancies. The diagnosis of CRPS is a diagnosis of exclusion. Constant vigilance of patients with this unpleasant condition is necessary.

Win-shift, lose-stay: contingent switching and contextual interference in motor learning.

Learners (n = 48) practiced three multisegment movements with distinct target movement times. Four practice groups were compared: blocked, random, and two groups who had a win-shift/lose-stay schedule (WSLS1 and WSLS2). For these latter groups switching between practice tasks was performance-contingent: within 5% of target time for 1 or 2 consecutive trials, respectively. During acquisition, blocked performance was more accurate than for both random and WSLS2 groups. The WSLS1 group performed between blocked and random groups, but did not differ from either. In a next-day retention test, the random group scored better than the blocked group. The WSLS1 group performed similarly to the random practice while the WSLS2 group's scores were similar to those of the blocked group. Results encourage further study of similar practice schedules.

Contextual interference effects with two tasks.

The present study was intended to test whether the standard contextual interference effect would be observed when only two patterns were practiced in blocked or random schedules of multisegment movement tasks rather than three patterns which is the norm. In line with the basic effect, Blocked learners' performance was closer to ideal during acquisition, but Random learners had smaller errors at 24-hr. retention. In addition, random learners had better recall of the details of the patterns they had practiced. Learners' predictions of retention performance did not match the group differences actually observed.

Galectin-3 as a novel regulator of osteoblast-osteoclast interaction and bone homeostasis.

Bone tissue undergoes permanent and lifelong remodeling with a concerted action of bone-building osteoblasts and bone-resorbing osteoclasts. A precise cooperation between those two cell types is critical in the complex process of bone renewal. Galectin-3 is a member of the ß-galactoside-binding lectin family playing multiple roles in cell growth, differentiation and aggregation. As it has been described to be expressed in bone, galectin-3 might influence bone homeostasis by regulating the function and/or interplay of osteoblasts and osteoclasts. Here, we investigated the role of galectin-3 in osteoclastogenesis and osteoblast-osteoclast interactions. Bone histomorphometric analysis and µCT measurements revealed a decreased trabecular bone volume and an increased osteoclast number in 12weeks old male galectin-3 knockout mice compared to wildtype littermates. Galectin-3 deficient bone marrow cells displayed a higher osteoclastogenic capacity in ex vivo differentiation assays, associated with elevated TRAF6 mRNA levels, suggesting an intrinsic inhibition of osteoclastogenesis by galectin-3 interfering with RANKL-mediated signaling. Furthermore, the addition of extracellular galectin-3 to murine or human osteoclastogenesis assays inhibited osteoclast formation and osteoclast numbers were higher in co-culture assays with galectin-3 deficient osteoblasts. In conclusion, our data suggest the secretion of galectin-3 as a novel mechanism for osteoblasts to control osteoclastogenesis and to maintain trabecular bone homeostasis independently of the RANKL/OPG-axis.

Relative processing demands influence cerebral laterality for verbal-motor integration in persons with Down syndrome.

The study of cerebral specialization in the Down syndrome (DS) population has revealed an anomalous pattern of organization. In particular, dichotic-listening studies have suggested a left-ear/right hemisphere dominance for speech perception, whereas motor control research has revealed a left hemisphere dominance for executive-motor control. In the present investigation, we employed a recent adaptation of the dichotic listening procedure to examine interhemispheric integration during the performance of a lateralized verbal-motor task. Specifically, using the selective dichotic-listening procedure, participants were required to complete a rapid left or right hand pointing movement to one of two pictorial icons corresponding to the word presented to their precued ear. We observed that persons with DS (N = 17) and age-matched controls (N = 35) exhibited a right-ear advantage (REA) for our dichotic-aiming task. While these results appear to contradict previous dichotic listening studies, we propose that the manifestation of a lateral ear advantage in the DS population may have more to do with the response requirements of the task than with the characteristics or complexity of the stimulus material.

Perceptual and motor contributions to bimanual coordination.

Following earlier work by Mechsner et al. (Nature 414 (2001) 69), the purpose of this experiment was to determine the perceptual and motoric contributions to bimanual coordination. Twenty right-handed, healthy, young adults performed continuous, horizontal, linear movements of both upper limbs at frequencies of 1.5 and 2.0 Hz. The goal was to control the spatial-temporal displacement of two flags by coordinating upper limb movements in two perceptual conditions. In a congruent condition, the movement of the flags matched the movement of the upper limbs. In an incongruent condition, the movement of the flags was opposite to the movement of the upper limbs. Measures of error in coordination provided support primarily for a motor view of bimanual coordination, and failed to replicate the earlier findings of Mechsner et al.

Dichotic ear advantages in adults with Down's syndrome predict speech production errors.

Intellectually challenged adults, with and without Down's syndrome (DS), pointed to drawings of animals following the dichotic presentation of animal names. Although there were no reliable ear differences between the 2 groups, there was tremendous between-persons variability within the group of participants with DS. Moreover, left-ear advantages in persons with DS were associated with more speech production errors when participants either read or repeated a string of 1 syllable words. This was not true for control participants. The relationship between ear advantage and speech errors in persons with DS could reflect their unique pattern of cerebral specialization and brain development.

Speech production errors in adults with and without Down syndrome following verbal, written, and pictorial cues.

Adults with Down syndrome and adults with developmental delays not related to Down syndrome were asked to read, repeat, and formulate speech from a picture following the presentation of 2- and 4-word and picture sequences. The speech sequences were produced either immediately after stimulus presentation or following a 5-sec response delay. Overall, participants with Down syndrome produced more memory errors than persons without Down syndrome. Participants with Down syndrome also committed more speech production errors than the other participants, but only when they were required to repeat what they had heard, or to formulate speech from pictures. The speech production performance of the two groups was equivalent in the read condition. These results are discussed with reference to Elliott, Weeks, and Elliott's (1987) model of cerebral specialization, and to verbal short-term memory in persons with Down syndrome.

Cerebral specialization and verbal-motor integration in adults with and without Down syndrome.

Persons with Down syndrome (DS) tend to exhibit an atypical left ear-right hemisphere advantage (LEA) for the perception of speech sounds. In the present study, a recent adaptation of the dichotic listening procedure was employed to examine interhemispheric integration during the performance of a lateralized verbal-motor task. Although adults with DS (n = 13) demonstrated a right ear-left hemisphere advantage in the dichotic-motor task similar to their peers with (n = 14) and without undifferentiated developmental disabilities (n = 14), they showed an LEA in a free recall dichotic listening task. Based on a comparison of the laterality indices obtained from both dichotic listening procedures, it appears that the manifestation of lateral ear advantages in persons DS may dependent on the response requirements of the task.

Models of performance in learning multisegment movement tasks: consequences for acquisition, retention, and judgments of learning.

Participants learned different keystroke patterns, each requiring that a key sequence be struck in a prescribed time. Trials of a given pattern were either blocked or interleaved randomly with trials on the other patterns and before each trial modeled timing information was presented that either matched or mismatched the movement to be executed next. In acquisition, blocked practice and matching models supported better performance than did random practice and mismatching models. In retention, however, random practice and mismatching models were associated with superior learning. Judgments of learning made during practice were more in line with acquisition than with retention performance, providing further evidence that a learner's current ease of access to a motor skill is a poor indicator of learning benefit.

Diverse range of fixed positional deformities and bone growth restraint provoked by flaccid paralysis in embryonic chicks.

Pancuronium bromide (PB) is used in neonates and pregnant women to induce limp, flaccid paralysis in order to allow mechanical ventilation during intensive care. Such non-depolarizing neuromuscular blocking drugs are administered to 0.1% of all human births in the UK. In this study, we examined PB effects on skeletal development in chick embryos. PB treatment produced skeletal deformities associated with significant reduction in longitudinal growth of all appendicular elements. This was associated with greater cartilage to bone ratios, indicating a preferential reduction in osteogenesis. PB also increased the incidence of knee joint flexion and tibiotarsal joint hyperextension. In addition to limb, spinal and craniofacial deformities, flaccid immobility appears to convert the normal geometric pattern of weight gain to a simple arithmetic accretion. This novel study highlights the potentially harmful effects of pharmacologically induced flaccid immobility on chick embryonic skeletal development. Whilst in ovo avian development clearly differs from human, our findings may have implications for the fetus, premature and term neonate receiving such non-depolarizing neuromuscular blocking drugs.