Structural Stability within the Lateral Cerebellar Nucleus of the Rat Following Complex Motor Learning

Complex motor learning, but not mere motor activity, has been previously shown to induce structural modifications within the cerebellar cortex. The present experiment examined whether similar changes occur within one of the primary output targets of the region of the cerebellar cortex in which these structural changes were described, the lateral cerebellar nucleus (LCN; dentate nucleus). Adult female rats were randomly allocated to one of three training conditions. Acrobatic condition (AC) rats were trained to complete a complex motor learning task consisting of a series of elevated obstacles while motor control (MC) condition animals were forced to traverse a flat obstacle-free runway equal in length to the AC task. Inactive condition (IC) animals received no motor training. Unbiased stereological techniques and electron microscopy were used to obtain estimates of synapse number and postsynaptic density (PSD) length within the LCN. Results showed that neither synapse number nor PSD length was significantly altered as a function of training condition. These results indicate that complex motor skill learning is associated with structural plasticity within the cerebellar cortex and with structural stability within the lateral cerebellar nucleus.     

Modulation of Gait During Visual Adaptation to Dark

The authors investigated the modulation of gait during dark adaptation. Twenty-five women (mean age = 72 years, SD = 5 years) walked back and forth on an arbitrarily uneven walkway during normal lighting at speeds ranging from slow to fast. Participants then performed 20 trials at preferred speed after sudden reduction of lighting; the authors compared those trials with point estimates at equivalent speeds representing normal lighting. The authors estimated speed, cadence, mediolateral trunk acceleration, and mediolateral interstep trunk-acceleration variability for each trial. Participants compensated for sudden reduction of lighting by reducing their walking speed. Compared with performance at equivalent speeds during normal lighting, cadence, trunk acceleration, and interstep trunk-acceleration variability initially increased. All variables showed an asymptotic approximation toward normal values during 60-90 s of walking in subdued lighting. The authors suggest that the sudden transition from normal to marginal lighting, rather than marginal lighting itself, may challenge locomotor control.     

The Effects of Repeated Exposure to the ARRAY Program With Offenders With Mental Illness

In an A‐B‐A‐B‐A single‐case research study of 3 incarcerated offenders with mental illness, repeated exposure to the pilot Adult Recidivism Reduction Alternatives (ARRAY) group counseling intervention was an effective or very effective treatment for anxiety, depression, and associated somatic symptoms.     

Interindividual Variability in Use-Dependent Plasticity Following Visuomotor Learning: The Effect of Handedness and Muscle Trained

Motor learning has been linked with increases in corticospinal excitability (CSE). However, the robustness of this link is unclear. In this study, changes in CSE associated with learning a visuomotor tracking task were mapped using transcranial magnetic stimulation (TMS). TMS maps were obtained before and after training with the first dorsal interosseous (FDI) of the dominant and nondominant hand, and for a distal (FDI) and proximal (biceps brachii) muscle. Tracking performance improved following 20 min of visuomotor training, while map area was unaffected. Large individual differences were observed with 18%–36% of the participants revealing an increase in TMS map area. This result highlights the complex relationship between motor learning and use-dependent plasticity of the motor cortex.     

Using Dual Tasks to Test Immediate Transfer of Training Between Naturalistic Movements: A Proof-of-Principle Study

Theories of motor learning predict that training a movement reduces the amount of attention needed for its performance (i.e., more automatic). If training one movement transfers, then the amount of attention needed for performing a second movement should also be reduced, as measured under dual task conditions. The authors’ purpose was to test whether dual task paradigms are feasible for detecting transfer of training between two naturalistic movements. Immediately following motor training, subjects improved performance of a second untrained movement under single and dual task conditions. Subjects with no training did not. Improved performance in the untrained movement was likely due to transfer, and suggests that dual tasks may be feasible for detecting transfer between naturalistic actions.     

Differential Transfer Benefits of Increased Practice for Constant,Blocked, and Serial Practice Schedules

The effects of practice schedule and amount of practice on the development of the generalized motor program (GMP) and on parameter estimation were investigated. Participants (N = 108) practiced the same relative timing but different absolute durations of a multisegment timing task. Practice schedules (constant, blocked, or serial) were crossed with amounts of practice (low and high). Inclusion of a constant practice condition allowed the authors to investigate the variability of practice prediction. Participants practiced the same proportional durations in a serial or a blocked schedule, which enabled the authors to examine contextual interference. A constant practice schedule enhanced GMP performance when task parameters remained the same, but varied practice schedules were beneficial when task parameters changed. A serial as opposed to a blocked practice schedule was superior when the performance of a task governed by a different GMP was required. Increased practice led to a consolidated task representation that was unavailable for updating.     

氟暴露所致脑损伤及硒的干预作用

氟是人体必需的微量元素,但摄入过量能引起骨相系统损害。流行病学和动物实验结果表明,长期过量氟暴露还能损害中枢神经系统,从而损伤动物的学习记忆力和儿童的智商。自由基损伤伤学说可能是氟致脑损伤的机理之一。而硒也是人类必需的微量元素之一,动物实验结果表明,适量硒能拮抗氟致脑功能的损伤,其机理可能与硒的抗氧化性的生物学功能有关     

Concurrent Directional Adaptation of Reactive Saccades and Hand Movements to Target Displacements of Different Size

When eye and hand movements are concurrently aimed at double-step targets that call for equal and opposite changes of response direction (–10° for the eyes, +10° for the hand), adaptive recalibration of both motor systems is strongly attenuated; instead, hand but not eye movements are changed by corrective strategies (V. Grigorova et al., 2013a). The authors introduce a complementary paradigm, where double-step targets call for a –10° change of eye and a ?30° change for hand movements. If compared to control subjects adapting only the eyes or only the hand, adaptive improvements were comparable for the eyes but were twice as large for the hand; in contrast, eye and hand aftereffects were comparable to those in control subjects. The authors concluded that concurrent exposure of eyes and hand to steps of the same direction but different size facilitated hand strategies, but didn't affect recalibration. This finding together with previous one (V. Grigorova et al., 2013a), suggests that concurrent adaptation of eyes and hand reveals different mechanisms of recalibration for step sign and step size, which are shared by reactive saccades and hand movements. However, hand mostly benefits from strategies provoked by the difference in target step sign and size.     

Two Factors to be Considered in the Design of Experiments in Anxiety and Motor Behavior

The authors examined the influence that attentional focus on either a postural or a suprapostural task had on the performance of each task. Participants (N = 32) stood on an inflated rubber disk and held a pole horizontally. All participants performed under 4 attentional focus conditions: external (disk) or internal (feet) focus on the postural task, and external (pole) or internal (hands) focus on the suprapostural task. Compared with internal focuses, external focuses on either task resulted in similar and reduced postural sway. Response frequency on each task increased when participants focused on the respective task. Finally, an external focus on either task produced higher frequencies of responding on the suprapostural task. The authors conclude that suprapostural task goals have a stronger influence on postural control than vice versa, reflecting the propensity of the motor system to optimize control processes on the basis of the desired movement effect.     

Prevalence of Children's Exposure to Domestic Violence and Child Maltreatment: Implications for Prevention and Intervention

The purpose of this paper is to review research on the prevalence of children's exposure to domestic violence, to consider the available literature on the co-occurrence of domestic violence and child maltreatment, and to gain more understanding about the impact of exposure on children. There is clear evidence indicating that both severe and moderate violence occurs frequently in homes among family members and that children are exposed to this violence. However, because of differing definitions of what constitutes domestic violence and variability in research methodologies for collecting the data, there are significant discrepancies in prevalence reports across studies. Of great concern is the immediate impact on the children and the long-term consequences for their later relationships. Fewer studies have been done on the co-occurrence of domestic violence and child maltreatment. However, it is likely that children who live in homes where domestic violence occurs are more likely to be abused and neglected. On the basis of available research, there is little doubt that vast numbers of children are exposed to domestic violence and that children's responses vary widely depending on their risk and vulnerability, as well as the structure of their environments. A developmental risk and protective factors framework will be used to integrate the information on children's exposure to violence.     

The Latent Threat of Community Violence: Indirect Exposure to Local Homicides and Adolescents’ Mental Health in Colombia

This study examines the relation between adolescents’ indirect exposure to local homicides and mental health disorders and post‐traumatic stress disorder (PTSD) symptoms. We employ a sample of 300 adolescents ( representative for Bogotá, Colombia, and geocoded data on violent crimes recorded by the national police. Findings show that one SD increment in local homicides is associated with increments by 0.17 SD in the mental health disorder index and a 0.14 SD increase in the PTSD score index, even after accounting for adolescents’ direct exposure to violence. The estimated effect for PTSD was larger for adolescents’ who were directly exposed to violence and for those living in multidimensionally poor households, whereas no detectable effects were found for adolescents who perceived their residential neighborhood as relatively safe.     

Psychological Distress and Symptoms of Posttraumatic Stress Disorder in Jewish Adolescents Following a Brief Exposure to Concentration Camps

We investigated the psychological impact of an organized visit to Polish concentration camps on Jewish-American adolescents. Eighty-seven adolescents who participated in a B'nai B'rith memorial visit to concentration camps in Poland completed measures of general psychological adjustment and posttraumatic stress disorder (PTSD) at four time-points: pretest, posttest, 6-month follow-up and 12-month follow-up. Measures included the SCL-90-R, the Mississippi Scale for PTSD, and the Impact of Events Scale (IES) for PTSD. On the SCL-90-R, changes in somatization, interpersonal sensitivity, obsessive-compulsive tendencies, depression, anxiety, and phobic anxiety were observed over time, with peak symptom scores at posttest and 6-month follow-up. Scores on the Mississippi Scale for PTSD and the IES Intrusion subscale also increased at 6-months. Predictors of PTSD symptoms on the Mississippi Scale included previous psychiatric treatment and SCL-90-R symptoms of paranoia, depression, and psychosis. Elevated psychotic symptoms on the SCL-90-R predicted PTSD symptoms on the IES. Jewish adolescents with preexisting symptoms of generalized distress or psychoticism appeared at increased risk for PTSD symptoms following exposure to Holocaust stimuli. This study contributes a prospective, multi-measure assessment of trauma reactions in adolescents.