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4.  Differing effects of intracortical circuits on plasticity 
Practice of a motor task leads to an increase in amplitude of motor-evoked potentials (MEP) in the exercised muscle. This is termed practice-dependent plasticity, and is abolished by the NMDA antagonist dextromethorphan and the GABAA agonist lorazepam. Here, we sought to determine whether specific subtypes of GABAA circuits are responsible for this effect on MEPs by comparing the action of the non-selective agonist, lorazepam with that of the selective GABAA-alpha1 receptor agonist, zolpidem. In 7 healthy subjects, transcranial magnetic stimulation (TMS) was used to quantify changes in amplitude of motor-evoked potentials (MEP) after practice of a ballistic motor task. In addition we measured how the same drugs affected the excitability of a number of MEP amplitudes and cortical inhibitory circuits (short-interval intracortical inhibition (SICI), short-interval afferent inhibition (SAI) and long-interval intracortical inhibition (LICI)). This allowed us to explore correlations between drug effects on measures of cortical excitability and practice dependent plasticity of MEPs.
As previously reported, lorazepam increased SICI and decreased SAI, while zolpidem only decreased SAI. The new findings were that practice-dependent plasticity of MEPs was impaired by lorazepam but not zolpidem, and that this was negatively correlated with lorazepam-induced changes in SICI but not SAI. This suggests that the intracortical circuits involved in SICI (and not neurons expressing GABAA-alpha1 receptor subunits that are implicated in SAI) may be involved in controlling the amount of practice-dependent MEP plasticity.
PMCID: PMC3019102  PMID: 19048237
plasticity; motor cortex; transcranial magnetic stimulation; GABA; SICI
Brain : a journal of neurology  2009;132(Pt 10):2871-2877.
Dystonia is characterised by two main pathophysiological abnormalities: reduced excitability of inhibitory systems at many levels of the sensorimotor system, and increased plasticity of neural connections in sensorimotor circuits at a brainstem and spinal level. A surprising finding in two recent papers has been the fact that abnormalities of inhibition similar to those in organic dystonia are also seen in patients who have psychogenic dystonia. To try to determine the critical feature that might separate organic and psychogenic conditions, we investigated cortical plasticity in a group of 10 patients with psychogenic dystonia and compared the results with those obtained in a matched group of 10 patients with organic dystonia and 10 healthy individuals. We confirmed the presence of abnormal motor cortical inhibition (short interval intracortical inhibition, SICI) in both organic and psychogenic groups. However, we found that plasticity (paired associative stimulation, PAS) was abnormally high only in the organic group, while there was no difference between the plasticity measured in psychogenic patients and healthy controls. We conclude that abnormal plasticity is a hallmark of organic dystonia; furthermore it is not a consequence of reduced inhibition since the latter is seen in psychogenic patients who have normal plasticity.
PMCID: PMC2997979  PMID: 19690095
associative plasticity; organic dystonia; psychogenic dystonia; paired associative stimulation; transcranial magnetic stimulation
7.  A diagnostic score for ischemic colitis in the elderly 
BMC Geriatrics  2010;10(Suppl 1):A18.
PMCID: PMC3290158
8.  Elderly surgical “not transfusible” patients 
BMC Geriatrics  2010;10(Suppl 1):A19.
PMCID: PMC3290159
10.  Sentinel lymph node biopsy in elderly breast cancer 
BMC Geriatrics  2010;10(Suppl 1):A29.
PMCID: PMC3290170
11.  Informed consent: results of a study in a geriatric surgery division 
BMC Geriatrics  2010;10(Suppl 1):A36.
PMCID: PMC3290178
12.  Thyroid surgery in an elderly population 
BMC Geriatrics  2010;10(Suppl 1):A37.
PMCID: PMC3290179
14.  Site of ulcer lesions in diabetic foot of the elderly 
BMC Geriatrics  2010;10(Suppl 1):A47.
PMCID: PMC3290190
16.  Estimating Sample Size and Persistence of Entomogenous Nematodes in Sandy Soils and Their Efficacy Against the Larvae of Diaprepes abbreviatus in Florida 
Journal of Nematology  1996;28(1):56-67.
In two studies to estimate sampling requirements for entomogenous nematodes in the field, highest persistence of Heterorhabditis bacteriophora after application occurred beneath the canopies of mature citrus trees. Nematode persistence declined with distance from the center-line of the tree row toward the row-middles. Immediately after nematode application to soil, 32 samples (15 cm deep, 2.5-cm diameter) beneath a single tree were required to derive 95% confidence intervals that were within 40% of mean nematode population density. The estimated probability of measuring the mean density within 40%, using 32 samples, declined to 88% at 2 days post-application and to 76% at 7 days. The persistence in soil of Steinernema carpocapsae, S. riobravis, and two formulations containing H. bacteriophora and their efficacy against the larvae of Diaprepes abbreviatus were compared in a grove of 4-year-old citrus trees. Within 6 days, the recovered population densities of all nematodes declined to <5% of levels on day 0. The recovery of H. bacteriophora during the first 2 weeks was lower than that of the other two species. Steinemema riobravis and both formulations of H. bacteriophora reduced recovery of D. abbreviatus by more than 90% and 50%, respectively. Steinernema carpocapsae did not affect population levels of the insect.
PMCID: PMC2619672  PMID: 19277346
control; Diaprepes abbreviatus; efficacy; entomopathogenic nematode; Heterorhabditis bacteriophora; sampling; Steinernema riobravis; survival

Results 1-16 (16)