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Abstract: Merino lambs of 90 days of mean age (standard deviation – s.d. – 6 days) and 22.0kg of mean live weight (s.d. 2.7kg) were used to explore the effects of pre-slaughter stressors on physiological characteristics and meat quality attributes. Three stressors were studied in a controlled experiment: fasting (food deprivation for 24h before slaughter), physical exercise (keeping animals walking for 30min at approximately 3km/h) and fear stress (exposing animals to barking dogs for 5min). A fourth treatment was kept as a control. Fasted lambs had greater (P <0.05) urea and cortisol concentrations than control. Exercise had no effects (P >0.05) in physiological indicators and lambs exposed to barking dogs had greater (P <0.05) cortisol concentration compared with control. The stressor treatments studied did not affect meat quality parameters. Therefore, even though the stressors imposed on the lambs induced changes in blood constituents typically associated with the stress response, the intensity and (or) duration of these stressors had no effect on meat quality traits. [Copyright &y& Elsevier]

Abstract: Crossbred Criollo Neuquino castrated male kids, 6 months of age and 24kg of live weight, were used to investigate the effects of pre-slaughter stressors on physiological characteristics and meat quality attributes. On four separate days, 16 kids were randomly assigned to one of the four pre-slaughter stressor treatments (4 kids per treatment per day): (A) no stress (control); (B) 24h of food deprivation (fasting); (C) physical stress of forced exercise by an animal handler for 30min at approximately 3km/h (exercise); or (D) psychological stress by placing kids in a pen with barking dogs for 5min (fear). Fasted goats had greater (P <0.05) hematocrit, urea and total protein concentrations than controls. Exercised kids had greater (P <0.05) cortisol concentration than controls and goats exposed to barking dogs had greater (P <0.05) hematocrit and cortisol concentration compared with controls. Even though the stressors imposed on the kids induced changes in blood constituents typically associated with the stress response, the intensity and/or duration of these stressors had little or no effect on meat quality. [Copyright &y& Elsevier]

Abstract: Carcass characteristics of 336 kids from the Neuquén Criollo breed were evaluated. Two categories were taken into account: three months and 5 to 7 months kids. Live weight, carcass weights, measurement and indexes of 304 kids were calculated in a study done in a commercial slaughterhouse located in Chos Malal town. Thirty two carcass left sides were dissected into the major components: muscle, bone, fat and remaining tissues. Three months kids were compared with 5 to 7 months kids. The slaughter live weight of the former was 16.3kg and the latter was 22.4kg. Cold carcass weight and dressing percentage differed significantly (p <0.001) between age categories. Three months kids had a higher percentage of bones (26.8 vs. 21.7%; p <0.001) and a lower percentage of fat (10.8 vs. 15%; p <0.01) than those at 5–7 months, but both had similar percentages of muscle (56.4 vs. 57%; p =NS). There were significant differences in the percentages of primal carcass cuts: hind leg (32 vs. 34%; p <0.001), shoulder (22 vs. 20%; p <0.001) and neck, (10 vs. 8%; p <0.01) for three months vs. 5–7 months old kids, respectively. [Copyright &y& Elsevier]

Objectives Goal oriented hand movements are the final product of complex interplay between multiple cortical regions of the frontoparietal cortex. Following stroke, recovery of function might be related to structural and functional modifications in the surviving brain networks. Strikingly, the ventral premotor cortex (PMv) plays a crucial role in the sensorimotor processing engaged in shaping finger movements and shares extensive reciprocal projections to the primary motor cortex (M1), making the PMv a promising structure involved in hand motor recovery after stroke. By instance, mapping studies in stroke animal models consistently showed that improvement in forelimb motor performance was associated with reorganization within the PMv. However, precise functional interactions between the PMv and the M1 in the process of hand motor recovery have not been investigated in stroke patients. Paired-pulse transcranial magnetic stimulation (pp-TMS) was used in order to evaluate PMv-M1 interactions in stroke patients and healthy controls. To further disentangle whether recovery-related changes are specific to PMv-M1 or apparent in all interactions between primary and secondary motor areas after stroke, connectivity between posterior parietal cortex (PPC) and M1 have been also assessed. Methods 22 patients (aged 62.3 ± 9.8 SD) with mild to severe unilateral hand motor deficit and 20 healthy controls (aged 59.7 ± 20.9 SD) participated in the present study. Within experiment-1, PMv-M1 interactions were investigated by using neuronavigated-ppTMS in both the affected and unaffected hemisphere, considering 6 interstimulus intervals (ISI; 2, 4, 6, 8, 10 and 15 ms) between conditioning and test pulse. In experiment-2, PPC-M1 interactions were investigated targeting two PPC regions: the anterior intraparietal sulcus (aIPS) and the caudal intraparietal sulcus (cIPS). Results Experiment-1: A consistent difference between patients and controls, with a group by ISI interaction, has been observed for both the affected ( F = 14.9, p < 0.001) as well as the unaffected ( F = 5.3, p < 0.001) hemisphere. Further posthoc analysis confirmed a significant difference at 6 and 8 ms between both groups (ISI 6 ms = T = 3.4, p = 0.002; ISI 8 ms = T = 7.1, p < 0.001), with consistent facilitation in stroke and rather inhibition in healthy controls. Interestingly, the amount of facilitation observed at 8 ms in stroke patients was positively correlated with the level of force production of the paretic hand ( R 2 = 0.33, p = 0.010) assessed by the laterality-index of grip-force. Experiment-2: No group differences have been observed between aiPS-M1 and cIPS-M1 in both hemispheres. Conclusions The present pp-TMS approach enabled us to assess in vivo the specific contributions of individual brain areas to recovery of function after stroke. These findings demonstrate changes in interareal connectivity between the PMv and the M1 associated with recovered hand motor function. These data support a paramount role of the PMv within the process of functional reorganization and successful hand motor recovery, as suggested in previous animal work, contributing significantly to the understanding of the mechanisms underlying cortical reorganization after focal brain lesions. [ABSTRACT FROM AUTHOR]

Introduction The aging population is facing important challenges associated to impairments in cognitive abilities including sensorimotor functions. In our daily life the acquisition and long-term retention of motor skills play a crucial role for the appropriate implementation of motor acts, such as practicing sport or the use of modern communication tools. Notably, motor cortical plasticity is altered in older adults (OA) due to changes in neurotransmission and synaptic functioning. Changes in GABAergic activity and its modulatory capacity has been described, as well as diminished LTP-like mechanisms contributing to associative plasticity and motor memory formation. Strong interest lies in the understanding of age-associated mechanisms underlying impairment of motor performance and motor learning in old and in possible ways of ameliorating age-related deficits in these domains. Methods Experiment 1: We investigated the process of learning of sequential finger tapping in a group of 15 healthy OA (73.9 ± 5.9 years ± standard deviation [SD]) and compared to 15 healthy young subjects (24.4 ± 3.5 SD). The learning process was accompanied by double-pulse transcranial magnetic stimulation (dp-TMS) in order to investigate intracortical effects during the learning process reflecting activity of GABAergic neurotransmission. The task was performed during 5 consecutive training days, with 3 follow-up time points on day 10, 20 and 60. Experiment 2 : In a subsequent experiment, we investigated the effects of transcranial direct current stimulation (tDCS) in a group of 28 healthy OA aged 72.0 ± 5.4 SD. tDCS provides the possibility to modulate cortical excitability and neuroplasticity. We tested the hypothesis that tDCS in combination with training will enhance the effect of skill acquisition in OA. In our double-blind, placebo controlled study tDCS was applied to the motor cortex, contralateral to the training performing hand. Either anodal or placebo/sham stimulation was applied for 20 min while subjects underwent the same training as mentioned above. Results Experiment 1: Analyses revealed impaired skill acquisition in the OA group in relation to the young group during training period (pMOVE). The group of young healthy subjects showed learning related changes of SICI MOVE towards an enhanced event-related disinhibition. This was not the case for OA. Experiment 2: The group receiving real stimulation showed a different learning curve in the 5 days of training with significantly enhanced skill acquisition compared to the sham group ( p = 0.044), a behavioral effect still apparent 60 days after interventions. Conclusions Motor skill acquisition was impaired in healthy older subjects, this effect was mainly driven by a reduction in offline effects. Furthermore, tDCS can ameliorate age-related deficits in the acquisition of a novel motor skill, offering a promising interventional strategy to address age-related cognitive deficits. [ABSTRACT FROM AUTHOR]

Introduction: Neurofibromatosis type 1 (NF-1) is the most common single gene disorder affecting the human nervous system, with an estimated prevalence of two to three cases per 10,000 population. The disorder is inherited in an autosomal dominant manner with equal sex incidence. Cognitive deficits and academic learning difficulties are the most common neurological complication, and can be responsible for significant lifetime morbidity. Recent animal studies proposed increased GABA-mediated inhibition with concomitant deficits in long-term potentiation as a potential mechanism for the learning impairment in these patients. The aim of the present study was to investigate the acquisition of a new motor skill in a group of young NF-1 patients without any neurological impairment. Furthermore, we used double-pulse TMS (dpTMS) in order to determine NF1-related effects on inhibitory (GABAergic) and facilitatory (Glutamatergic) motorcortical circuits during the process of motor skill acquisition. Methods: In this Pilot study, a group of NF-1 patients without any cognitive or learning deficit and healthy controls participated in an explicit motor learning experiment (for details see Zimerman et al. 2012), composed of a sequential pressing of nine-elements sequence on a four-button electronic keyboard with the left hand. All participants attended five consecutive days of training and two follow-up measurements 10 and 20days after training, where the task was re-evaluated. dpTMS measurements were performed at baseline, immediately after the training days and before the follow-up times. Additionally, factors that might potentially influence motor learning, such as level of attention, perception of fatigue or discomfort were evaluated. Results: Preliminary results suggested an impairment in motor skill acquisition in NF-1 patients (F =2.8; p =.05), driven mainly by a decrease on ‘offline improvement’ in NF-1 compared to healthy subjects (T = −2.9; p =.03). In healthy subjects a reduction of intracortical inhibition in the motor cortex was apparent after the learning task compared to baseline, this was not the case for the NF-1 patients, who did not show any change due to learning. Furthermore, reduced intracortical facilitation was obvious in the patients. Conclusions: The present pilot study provides a first hint that the acquisition of a skill might be impaired in even clinically intact NF-1 patients. One potential mechanism that could at least in part contribute to explain these behavioural deficits observed in NF1-patients is alteration of intracortical circuits related to GABAergic and/or glutamatergic neurotransmission. Further experiments are necessary to support the present findings and to gather greater understanding of the pathophysiological mechanisms of NF1, an important basis to design appropriate interventions to support skill acquisition in these patients. [Copyright &y& Elsevier]

Question: GABAergic inhibitory circuits are changed as a function of age marked by a prevailing level of disinhibition during resting-state and deficient event-related modulatory capacity, potential mechanisms underlying age-related speed and dexterity deficits. The driving question for the present work was whether anodal transcranial direct current stimulation (atDCS) can influence age-related deficiency of inhibition and “open a window” for event-related modulatory capacity within the intracortical inhibitory network. Furthermore, if intracortical inhibition is to be influenced by atDCS, do direction and amount of the effect correlate with stimulation-induced changes in dexterous motor behaviour? Methods: N =20 healthy right-handed participants (N =10 young 25.2±1.6years, range 23–28, 5 female, N =10 old 73.6±7.5years, range 65–83, 6 female) volunteered in a double-blind cross-over design. Assessment of short-interval intracortical inhibition (SICI), dexterous hand function, attention and fatigue was performed before, immediately, 45, and 90min (P, P45, P90) after atDCS (1mA, 20min.) or sham stimulation. Dexterous hand function was evaluated with solitary index finger tapping (1FT), alternating index and little finger tapping (2FT), simple reaction time task (SRT), and choice-reaction time task (CRT). Results: Our main finding was that resting-state intacortical inhibition was significantly diminished after a single session of 20min atDCS exclusively in the young but not in old participants (TIME X STIMULATION X GROUP (F (3, 2408)=8.345, p <.0001). In the young, disinhibition increased directly after stimulation (p <0.01), was most pronounced at P45 (p <0.01), and reached baseline levels again at P90 (p >.9). No atDCS stimulation-effect was observed for event-related SICI modulation, neither in young nor in old. The effect of atDCS on motor behaviour differed among age groups and was dependent on the character of the task performed: While the young showed a similar temporal pattern of performance irrespective of stimulation condition, old subjects tended to improve in SRT and 2FT but showed a significant decline in performance speed in CRT accompanied by a marked improvement in CRT error rate under atDCS. Stimulation-induced release of inhibition was associated with faster performance in SRT after atDCS in the old subgroup (R =−.71, p <.05). Independent of stimulation condition, more pronounced event-related SICI modulation was found to correlate with better performance in dexterous tasks requiring higher motor processing load (2FT R =−.6, p <.005, CRTR =−.5, p <.05). Conclusions: Performance improvements with atDCS in old age cannot be explained solely by changes to intracortical inhibition mediated by GABAergic inhibitory interneurons. When prevailing disinhibition dominates resting-state, no perturbation as seen in young is achieved with atDCS. Event-related modulation of intracortical inhibition, i.e. rapid release of inhibition, seems to follow a hard-coded process, which cannot be influenced by atDCS. [Copyright &y& Elsevier]

Background A stroke results in widespread alterations of motor-related brain activity and interregional interactions in the sensorimotor network. Numerous studies have investigated the functional relevance of the primary motor cortices (M1) and predominantly frontal and prefrontal secondary motor areas. Only few studies focused on the functional role of the ventral premotor cortex (PMv) and the posterior parietal cortex (PPC) after stroke. Corticocortical interactions between M1, PMv and posterior parietal motor areas, such as the anterior (aIPS) and caudal intraparietal sulcus (cIPS) are relevant for skilled voluntary hand function. It remains unclear to what extent these brain regions and their interactions also contribute to rather basic motor functions after stroke. We hypothesized that the white matter integrity of the underlying parietofrontal motor pathways between these brain regions might relate to residual motor function after stroke. Methods 25 chronic stroke patients (aged 64 ± 8.8 years, 17 male, 1 left-handed) with a broad spectrum of first-ever cortical and subcortical ischemic strokes were evaluated by means of grip force, pinch force and the Fugl-Meyer score. Principal component analysis was used to calculate one composite motor function score (MF). Diffusion tensor imaging and probabilistic tractography were used to reconstruct probable intrahemispheric trajectories between M1, PMv, aIPS and cIPS in each patient. Tract-related white matter integrity was estimated by means of fractional anisotropy (FA). Generalized linear modeling was used to correlate tract-related FA values with MF. Results We found that the FA values of the fiber tracts connecting PMv and M1 ( p < 0.05) and also aIPS and PMv ( p < 0.05) showed a positive correlation with recovered motor function of the paretic hand. The other tracts investigated did not show a similar structure–behavior association. Conclusion This indicates that the ventral premotor cortex and the posterior parietal cortex, and the structural integrity of their connections within the motor network are crucially involved in recovered motor function after stroke. [ABSTRACT FROM AUTHOR]

Question: Previous studies have suggested that the putative human homologue of the ventral intraparietal area (hVIP) is crucially involved in the remapping of touch into external spatial coordinates and in the realignment of tactile and visual maps. However, it is yet unclear whether hVIP is critical for the remapping process during audio-tactile spatial interactions as well. The audio-tactile ventriloquism effect, where the perceived location of a sound is shifted toward the location of a synchronous but spatially disparate tactile stimulus, was used to probe spatial interactions in audio-tactile processing. Behavioral studies of the audio-tactile ventriloquism effect have shown that with hands crossed over the body midline, auditory localization is biased toward the external location of the tactile stimulus, rather than toward the anatomical side of the hand that was stimulated. Therefore, we hypothesized that interference with the tactile remapping process from anatomical to external coordinates by targeting the hVIP with TMS-induced transient virtual lesions would reverse this effect. Methods: Eighteen healthy young adults participated in the study. Participants were asked to report the perceived location of brief auditory stimuli presented from three different locations (left, −9°; center, 0°; right, +9°). Auditory stimuli were presented either alone (unimodal stimuli) or together with a synchronous but spatially discrepant tactile stimulus applied to the left or right index fingers (bimodal stimuli), which were located to the left and right side of the speaker array at −18.5° and +18.5°. Crucially, arm posture was alternated between experimental blocks, with participants either adopting a parallel hand posture or crossing the hands over the body midline. Single TMS pulses (with an intensity of 120% of the resting motor threshold) were delivered 80ms after the onset of each stimulus, either to the right hVIP or the right primary somatosensory cortex (SI, control site) using online neuro-navigation based on individual high-resolution MRI scans. For a subgroup of ten participants, additional control conditions were run, with either sham stimulation of the hVIP or no TMS at all. Results: In agreement with the hypothesis that hVIP–TMS would interfere with the tactile remapping process, we indeed found an anatomically defined shift of sound localization in the crossed posture condition when TMS was applied to the hVIP. More specifically, when the left hand was crossed over the body midline, we observed a localization shift toward the left (rather than the right) external side selectively when the right hVIP was targeted with TMS. Neither stimulation of the control site (SI) nor sham stimulation of the hVIP led to an anatomically defined ventriloquism effect. Conclusions: Thus, hVIP–TMS interfered with the remapping of touch into an external reference frame. This finding suggests that hVIP is crucially involved in transforming spatial reference frames across audition and touch. Acknowledgments: The study was supported by the European Community‘s Seventh Framework Programme (grant agreement n o 228916) through the NOMS project, by the Werner-Otto-Foundation (to F.H.) and by the SFB 936 C4 (to F.H.). [ABSTRACT FROM AUTHOR]