Expert athletes activate somatosensory and motor planning regions of the brain when passively listening to familiar sports sounds

The present functional magnetic resonance imaging study examined the neural response to familiar and unfamiliar, sport and non-sport environmental sounds in expert and novice athletes. Results revealed differential neural responses dependent on sports expertise. Experts had greater neural activation than novices in focal sensorimotor areas such as the supplementary motor area, and pre- and postcentral gyri. Novices showed greater activation than experts in widespread areas involved in perception (i.e. supramarginal, middle occipital, and calcarine gyri; precuneus; inferior and superior parietal lobules), and motor planning and processing (i.e. inferior frontal, middle frontal, and middle temporal gyri). These between-group neural differences also appeared as an expertise effect within specific conditions. Experts showed greater activation than novices during the sport familiar condition in regions responsible for auditory and motor planning, including the inferior frontal gyrus and the parietal operculum. Novices only showed greater activation than experts in the supramarginal gyrus and pons during the non-sport unfamiliar condition, and in the middle frontal gyrus during the sport unfamiliar condition. These results are consistent with the view that expert athletes are attuned to only the most familiar, highly relevant sounds and tune out unfamiliar, irrelevant sounds. Furthermore, these findings that athletes show activation in areas known to be involved in action planning when passively listening to sounds suggests that auditory perception of action can lead to the re-instantiation of neural areas involved in producing these actions, especially if someone has expertise performing the actions.     

Central fatigue mechanisms are responsible for decreases in hand proprioceptive acuity following shoulder muscle fatigue

Muscle fatigue is a complex phenomenon, consisting of central and peripheral mechanisms which contribute to local and systemic changes in motor performance. In particular, it has been demonstrated that afferent processing in the fatigued muscle (e.g., shoulder), as well as in surrounding or distal muscles (e.g., hand) can be altered by fatigue. Currently, it is unclear how proximal muscle fatigue affects proprioceptive acuity of the distal limb. The purpose of the present study was to assess the effects of shoulder muscle fatigue on participants’ ability to judge the location of their hand using only proprioceptive cues. Participants’ (N = 16) limbs were moved outwards by a robot manipulandum and they were instructed to estimate the position of their hand relative to one of four visual reference targets (two near, two far). This estimation task was completed before and after a repetitive pointing task was performed to fatigue the shoulder muscles. To assess central versus peripheral effects of fatigue on the distal limb, the right shoulder was fatigued and proprioceptive acuity of the left and right hands were tested. Results showed that there was a significant decrease in the accuracy of proprioceptive estimates for both hands after the right shoulder was fatigued, with no change in the precision of proprioceptive estimates. A control experiment (N = 8), in which participants completed the proprioceptive estimation task before and after a period of quiet sitting, ruled out the possibility that the bilateral changes in proprioceptive accuracy were due to a practice effect. Together, these results indicate that shoulder muscle fatigue decreases proprioceptive acuity in both hands, suggesting that central fatigue mechanisms are primarily responsible for changes in afferent feedback processing of the distal upper limb.     

Ethanol state-dependent memory: involvement of dorsal hippocampal muscarinic and nicotinic receptors

In the present study, the effects of bilateral injections of cholinergic agents into the hippocampal CA1 regions (intra-CA1) on ethanol state-dependent memory were examined in mice. A single-trial step-down passive avoidance task was used for the assessment of memory retention in adult male NMRI mice. Pre-training intraperitoneal injection (i.p.) of ethanol (0.25, 0.5 and 1 g/kg) dose dependently induced impairment of memory retention. Pre-test administration of ethanol (0.5 and 1 g/kg, i.p.) induced state-dependent retrieval of the memory acquired under pre-training ethanol (1 g/kg, i.p.) influence. Pre-test intra-CA1 injection of physostigmine (2.5 and 5 μg/mouse, intra-CA1) or nicotine (0.3 and 0.5 μg/mouse, intra-CA1) improved pre-training ethanol (1 g/kg)-induced retrieval impairment. Moreover, pre-test administration of physostigmine (2.5 and 5 μg/mouse, intra-CA1) or nicotine (0.3 and 0.5 μg/mouse, intra-CA1) with an ineffective dose of ethanol (0.25 g/kg) significantly restored the retrieval and induced ethanol state-dependent memory. Pre-test intra-CA1 injection of the muscarinic receptor antagonist, atropine (4 and 8 μg/mouse, intra-CA1) or the nicotinic receptor antagonist, mecamylamine (2 and 4 μg/mouse, intra-CA1) 5 min before the administration of ethanol (1 g/kg, i.p.) dose dependently inhibited ethanol state-dependent memory. Pre-test intra-CA1 administration of physostigmine (0.5, 2.5 and 5 μg/mouse), atropine (2, 4 and 8 μg/mouse), nicotine (0.1, 0.3 and 0.5 μg/mouse) or mecamylamine (1, 2 and 4 μg/mouse) alone cannot affect memory retention. These findings implicate the involvement of a dorsal hippocampal cholinergic mechanism in ethanol state-dependent memory and also it can be concluded that there may be a cross-state dependency between ethanol and acetylcholine.     

Upregulation of hippocampal TrkB and synaptotagmin is involved in treadmill exercise-enhanced aversive memory in mice

Cognitive functions usually involve various synaptic proteins and neurotrophic factors in the hippocampus. However, whether treadmill exercise can improve learning and memory by upregulating some of these molecules remain unraveled. To address this question, male BALB/c mice were divided into control and exercise groups, the latter group went through 4 weeks of treadmill exercise training. At the end of exercise training period, they were either tested for passive avoidance (PA) performance or sacrificed for quantifying the hippocampal levels of brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase B (TrkB, the BDNF receptor), synaptotagmin (a Ca²⁺-dependent synaptic vesicle protein), and SNAP-25 (a presynaptic vesicular fusion protein). Our results showed that treadmill exercise training (1) increased the retention latency without affecting the fear acquisition in the PA test, (2) transiently increased the hippocampal BDNF level at 1, 2, and 4 h after the completion of exercise training, and (3) persistently increased the hippocampal protein levels of full-length TrkB, phosphorylated TrkB and synaptotagmin, but not truncated TrkB or SNAP-25. Moreover, the protein expression level of full-length TrkB or synaptotagmin was positively correlated with PA performance in mice. Finally, inhibition of TrkB signaling by K252a abolished the exercise-facilitated PA performance and upregulation of TrkB and synaptotagmin. Taken together, these data suggest that the upregulation of TrkB and synaptotagmin in the hippocampus contributes to the exercise-facilitated aversive memory.     

Intrahippocampal insulin improves memory in a passive-avoidance task in male wistar rats

The main impacts of insulin favor the peripheral organs. Although it functions as a neuropeptide, insulin possesses also some central effects. The aim of this study was to determine the effect of intrahippocampal infusion of insulin on passive avoidance learning in healthy male rats. Thirty male wistar rats were divided into three groups (n=10 each). The experimental group had posttraining insulin infusion into the CA1 region of dorsal hippocampus, after which they were compared with sham (saline) and control (intact) groups. Insulin treated animals had greater latency to enter the dark compartment in compare with saline treated (p=0.023) or control groups (p=0.017). Upon our results, we concluded that intrahippocampal injections of insulin may enhance memory for a simple learning task which supports the concept that insulin possibly plays an endogenous role in memory formation.     

Passive leadership,role stressors,and affective organizational commitment: A time-lagged study among health care employees

IntroductionThis study examines the relationships of passive leadership and role stressors to affective organizational commitment among hospital employees.ObjectiveThis study's objective was to understand the mediating effect of role stressors (conflict, overload, and ambiguity) in the relation between passive leadership and affective organizational commitment.MethodWe used a structural equation modeling approach on a sample of 185 hospital employees and a time-lagged design in which predictor and mediators were assessed at Time 1 and affective organizational commitment was obtained 3 years later.ResultsFindings revealed that passive leadership was positively related to all three role stressors and that role ambiguity fully mediated a negative relationship between passive leadership and affective organizational commitment. Moreover, the relationship between passive leadership and role conflict was stronger when role overload was high.ConclusionThis study suggests organizations should strive to limit the emergence of passive leadership behaviors among supervisors due to their detrimental effects on the long-term development of affective commitment via role ambiguity.     

童年中后期儿童同伴接纳知觉准确性与偏差及其对社交退缩的影响

以小学三年级至六年级的儿童为被试,探讨同伴接纳知觉准确性的年级和性别差异,同时考察同伴接纳知觉准确性及偏差对社交退缩行为的预测作用。儿童完成同伴评定、知觉评定、社交自我知觉和班级戏剧量表。结果表明：（1）随着年级的升高,儿童的同伴接纳知觉越来越准确;儿童的同性同伴接纳知觉准确性不存在显著的性别差异;四年级男生的异性同伴接纳知觉准确性显著低于女生;（3）同伴接纳知觉准确性显著正向预测安静退缩和活跃退缩;同伴接纳知觉偏差显著负向预测安静退缩,但对活跃退缩不具有显著的预测效应。     

A preliminary study on the relationship between characteristics of TV content and delayed speech development in young children

Our previous population survey of 18-month-old children suggested an association between delayed language development and heavy TV viewing. We therefore collected all 85 videos described as children's favorites in that questionnaire to examine relationships between the characteristics of habitually viewed videos and language development. In the language delayed group, compared to the non-delayed group, the types of videos preferred more were “realistic animations” and “baby education” and the characteristics of videos were contained few close-ups of characters facing viewers, continued uninterruptedly between stories, had constant movement or transformation of characters, had a high frame rate of animation, and that adults readily kept on watching the videos even with the sound off. These characteristics were seen more in videos the above two types. These findings imply that habitual television/video viewing with characteristics that are not apt to elicit parent–child communication for long hours may affect delayed language development in young children.     

Influence of intracerebroventricular administration of dopaminergic drugs on morphine state-dependent memory in the step-down passive avoidance test

The effects of dopaminergic drugs on morphine state-dependent memory of passive avoidance task were examined in mice. Pre-training administration of morphine (5mg/kg) led to state-dependent learning with impaired memory retrieval on the test day which was reversed by pre-test administration of the same dose of the opiate. The pre-test intracerebroventricular (i.c.v.) administration of the dopamine D1 receptor agonist (SKF38393), dopamine D2 receptor agonist (quinpirole) and dopamine D2 receptor antagonist (sulpiride) not only reversed the effect of pre-training morphine treatment, but also increased this action of the drug. Furthermore, the pre-test i.c.v. administration of dopamine D1 receptor antagonist (SCH23390) prevented the restoration of memory by morphine. In conclusion, the morphine-induced recovery of memory, on the test day, seems to be induced, at least in part, through dopamine receptors.     

An Evaluation of the Response Modulation Hypothesis in Relation to Attention–Deficit/Hyperactivity Disorder

Several hypotheses related to Newman's (e.g., Patterson & Newman, 1993) response modulation hypothesis were examined among adolescents with attention-deficit/hyperactivity disorder (ADHD; n=18) and normal controls (n=23). Consistent with predictions, youth with ADHD committed more passive avoidance errors (PAEs) than controls during the latter trials of a computerized go/no go task with mixed incentives, and this effect remained significant or marginally significant even after common variance associated with variables that covary with ADHD (i.e., IQ, oppositional-defiant/conduct disorder [ODD/CD] symptoms, anxious/depressed mood) was removed. While a moderate inverse association was observed between PAE frequency and the amount of time spent viewing response feedback following punishment, both categorical (diagnostic) and dimensional analyses of ADHD symptomatology indicated that ADHD and reflection on punishment feedback are uniquely associated with PAE commission. Findings from this study are discussed in relation to models of disinhibition applicable to youth with ADHD.