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1.  Excitability decreasing central motor plasticity is retained in multiple sclerosis patients 
BMC Neurology  2012;12:92.
Compensation of brain injury in multiple sclerosis (MS) may in part work through mechanisms involving neuronal plasticity on local and interregional scales. Mechanisms limiting excessive neuronal activity may have special significance for retention and (re-)acquisition of lost motor skills in brain injury. However, previous neurophysiological studies of plasticity in MS have investigated only excitability enhancing plasticity and results from neuroimaging are ambiguous. Thus, the aim of this study was to probe long-term depression-like central motor plasticity utilizing continuous theta-burst stimulation (cTBS), a non-invasive brain stimulation protocol. Because cTBS also may trigger behavioral effects through local interference with neuronal circuits, this approach also permitted investigating the functional role of the primary motor cortex (M1) in force control in patients with MS.
We used cTBS and force recordings to examine long-term depression-like central motor plasticity and behavioral consequences of a M1 lesion in 14 patients with stable mild-to-moderate MS (median EDSS 1.5, range 0 to 3.5) and 14 age-matched healthy controls. cTBS consisted of bursts (50 Hz) of three subthreshold biphasic magnetic stimuli repeated at 5 Hz for 40 s over the hand area of the left M1. Corticospinal excitability was probed via motor-evoked potentials (MEP) in the abductor pollicis brevis muscle over M1 before and after cTBS. Force production performance was assessed in an isometric right thumb abduction task by recording the number of hits into a predefined force window.
cTBS reduced MEP amplitudes in the contralateral abductor pollicis brevis muscle to a comparable extent in control subjects (69 ± 22% of baseline amplitude, p < 0.001) and in MS patients (69 ± 18%, p < 0.001). In contrast, post-cTBS force production performance was only impaired in controls (2.2 ± 2.8, p = 0.011), but not in MS patients (2.0 ± 4.4, p = 0.108). The decline in force production performance following cTBS correlated with corticomuscular latencies (CML) in MS patients, but did not correlate with MEP amplitude reduction in patients or controls.
Long-term depression-like plasticity remains largely intact in mild-to-moderate MS. Increasing brain injury may render the neuronal networks less responsive toward lesion-induction by cTBS.
PMCID: PMC3488470  PMID: 22974055
Multiple sclerosis; LTD; Motor plasticity; TMS; Motor cortex
2.  Structural abnormality of the substantia nigra in children with attention-deficit hyperactivity disorder 
Structural abnormality of the substantia nigra can be detected by transcranial sonography in neuropsychiatric disorders such as Parkinson disease and restless legs syndrome. We investigated echogenicity of the substantia nigra as a potential structural marker for dysfunction of the nigrostriatal dopamine system in children with attention-deficit hyperactivity disorder (ADHD).
We used a blinded design and determined echogenicity of the substantia nigra by use of transcranial sonography in 22 children with ADHD and 22 healthy controls matched for age and sex.
The echogenic substantia nigra area was significantly larger in ADHD patients than in healthy controls (F1,42 = 9.298, p = 0.004, effect size = 0.92). We found no effects of age or sex.
Owing to a lack of dimensional assessment, we could not analyze the correlation between echogenicity and clinical symptoms.
Our results support the hypothesis that the nigrostriatal dopaminergic system is abnormal in children with ADHD.
PMCID: PMC2799505  PMID: 20040247
3.  Age-Related Differences in Responses to Thoughts of One’s Own Death: Mortality Salience and Judgments of Moral Transgressions 
Psychology and aging  2007;22(2):341-353.
Two experiments explored age differences in response to reminders of death. Terror management research has shown that death reminders lead to increased adherence to and defense of one’s cultural worldview. In Study 1, the effect of mortality salience (MS) on evaluations of moral transgressions made by younger and older adults was compared. Whereas younger adults showed the typical pattern of harsher judgments in response to MS, older adults did not. Study 2 compared younger and older adults’ responses to both the typical MS induction and a more subtle death reminder. Whereas younger adults responded to both MS inductions with harsher evaluations, older adults made significantly less harsh evaluations after the subtle MS induction. Explanations for this developmental shift in responses to reminders of death are discussed.
PMCID: PMC2396593  PMID: 17563189
terror management; fear of death; moral judgments and aging; healthy aging

Results 1-3 (3)