Spinal cord injury (SCI) induces incapacitating neuropathic pain in the form of allodynia-a painful response to normally non-noxious stimuli. Unfortunately, the underlying mechanisms of these sensory changes are not well understood, and effective treatments for allodynia have proven elusive. We examined whether physical exercise can improve sensory function after experimental SCI by promoting neurotrophin expression in the spinal cord and periphery, which modulates synaptic transmission and function. Female rats with moderate spinal cord contusion participated in treadmill training, swim training, stand training or were untrained. Exercise training began 4 days post surgery, lasted 20-25 min per day, 5 days a week for 7 weeks. Allodynia, as measured using von Frey hairs of different bending forces to the plantar hind paw, developed in the untrained group 3 weeks after SCI. Treadmill training ameliorated allodynia and restored normal sensation by 5 weeks. Swim training had a transient beneficial effect, but allodynia returned by 7 weeks. Stand training had no effect. Resolution of allodynia after treadmill training was associated with normal mRNA levels of brain-derived neurotrophic factor (BDNF) in both the lumbar spinal cord and soleus muscle. No other exercise paradigm restored BDNF centrally and peripherally. Greater recovery from allodynia correlated significantly with the degree of normalization of central and peripheral BDNF levels. These findings suggest that rhythmic, weight-bearing exercise may be an effective intervention to counter SCI-induced allodynia.

Previous theories of both social influence and persuasion have maintained a dichotomy between influence which is seen as thoughtful, grounded in objective reality and is longlasting, and influence which is impressionistically based and involves more superficial processing. Many theorists have suggested that groups are influential by means of the latter form of influence. Itfollowsfrom such a perspective that differences in the persuasive power of ingroups and outgroups should be mediated by peripheral cues rather than the persuasive nature of the message. In two experiments (Ns = 129 and 90) it was found that outgroups were less persuasive than ingroups when group memberships were made salient by having subjects commit themselves to groups. This is inconsistent with the traditional view but consistent with self-categorization theory. There was also evidence of more accurate recall by subjects in the salient ingroup condition. These effects are evidence against the view that group-based processing involves peripheral processing of the message.

The concept of entitativity was developed by Campbell (1958) to refer to the extent to which a group is perceived as a coherent whole or entity. This concept is relevant to research in both social perception (e.g. the categorization effects approach to the study of social stereotyping) and social influence (e.g. the consistency attributed to minority groups in theories of minority influence). On the basis of previous research, four variables were expected to play a role in group entitativity judgements. These were intra-group variability, group size, diversity (or variety) and extremity. In two empirical studies it was found that entitativity decreased as variability and diversity increased and that it increased with group size. These effects and interactions between group size and extremity, size and diversity, and variability and extremity are consistent with the idea that entitativity is a function of how meaningful a stimulus pattern is. This is in turn (in part) a function of how unlikely the pattern is.

Movement of the COB toward the center of the base of support accompanied closing of the eyes, narrowing of the base of support, and movement of the support surface. These findings are consistent with the need to move the center of gravity away from the limits of stability under more challenging stance conditions. This study contributes to the existing knowledge base related to standing balance function in young adults without musculoskeletal or neurological impairments and provides data that can be used for criterion-based comparisons of young adult patients. [Nichols DS, Glenn TM, Hutchinson KJ. Changes in the mean center of pressure during balance testing.

Experimental spinal cord injury (SCI) via contusion of moderate severity results in residual locomotor deficits, including a lack of coordination and trunk stability. Given that muscle contractile properties and fiber composition adapt to reduced neural input and/or weight bearing, contusion-induced locomotor deficits may reflect changes in hindlimb skeletal muscle. Therefore, we examined muscle adaptations during early (1 week), intermediate (3 week), and late (10 week) stages of motor recovery after moderate SCI. Forty-two Sprague Dawley rats underwent SCI via 1.1mm cord displacement with the OSU impact device or served as age and weight-matched or laminectomy controls. Subsets of rats had soleus (SOL) in vitro physiological testing or SOL and extensor digitorum longus (EDL) myosin heavy chain (MHC) fiber type analysis. At 1 week post-SCI during paralysis/paresis, a significant decrease in wet weight occurred in the plantaris, medial/lateral gastrocnemius (MG/LG), tibialis anterior, and SOL. Changes in contractile properties of the SOL did not accompany muscle wet weight changes. By 3 weeks, the loss of weight-bearing activity early after SCI induced significant decreases in SOL peak twitch and peak tetanic tension as well as significantly greater IIx MHC expression in the EDL. By 10 weeks post-SCI, after several weeks of weight supported stepping, muscle wet weight, contractile properties and MHC composition returned to baseline levels except for MG/LG atrophy. Thus, muscle plasticity appears to be extremely sensitive to locomotor deficits and their resolution after moderate spinal cord contusion.