Pallidal neuronal activity: implications for models of dystonia.

Dystonia is a neurological syndrome involving sustained contractions of opposing muscles leading to abnormal movements and postures. Recent studies report abnormally low pallidal neuronal activity in patients with generalized dystonia, suggesting hyperkinetic disorders result from underactive basal ganglia output. We examined this hypothesis in 11 patients with segmental and generalized dystonia undergoing microelectrode exploration of the internal globus pallidus (GPi) before pallidotomy or deep brain stimulation (DBS) implantation.

Movement-related neurons of the subthalamic nucleus in patients with Parkinson disease.

Object: The subthalamic nucleus (STN) is a target in the surgical treatment of Parkinson disease (PD). Little is known about the neurons within the human STN that modulate movement. The authors' goal was to examine the distribution of movement-related neurons within the STN of humans by using microelectrode recording to identify neuronal receptive fields.

Localization of clinically effective stimulating electrodes in the human subthalamic nucleus on magnetic resonance imaging.

Object: The authors sought to determine the location of deep brain stimulation (DBS) electrodes that were most effective in treating Parkinson disease (PD).

Methods: Fifty-four DBS electrodes were localized in and adjacent to the subthalamic nucleus (STN) postoperatively by using magnetic resonance (MR) imaging in a series of 29 patients in whom electrodes were implanted for the treatment of medically refractory PD, and for whom quantitative clinical assessments were available both pre- and postoperatively. A novel MR imaging sequence was developed that optimized visualization of the STN.

Simultaneous repetitive movements following pallidotomy or subthalamic deep brain stimulation in patients with Parkinson's disease.

Patients with Parkinson's disease (PD) commonly exhibit difficulties performing simultaneous tasks and levodopa has been shown to improve the performance of these movements to a greater extent than movements performed in isolation. The aim of this study was to compare the effects of acute unilateral pallidal lesions (nine patients) and bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) (eight patients) with levodopa therapy (ten patients) on the performance of isolated versus bilateral simultaneous repetitive movements. The STN group was assessed with and without DBS both on and off levodopa.

Clinical and molecular features of adPEO due to mutations in the Twinkle gene.

We have analyzed Twinkle, the causative gene for autosomal dominant progressive external ophthalmoplegia (adPEO) on chromosome 10, in 11 Australian autosomal dominant progressive external ophthalmoplegia families of Caucasian origin, and investigated whether there are distinct molecular and clinical features associated with mutations in this gene. We found two new mutations in Twinkle, in 3 of the 11 pedigrees examined. One resides in the linker region of this gene while the other is in the primase domain.

The globus pallidus, deep brain stimulation, and Parkinson's disease.

Parkinson's disease (PD) is caused by the degeneration of the dopaminergic neurons in the substantia nigra. Loss of dopaminergic innervation leads to hyperactivity in the internal segment of the globus pallidus (GPi), the main output nucleus of the basal ganglia and to a profound disturbance in the function of motor circuits. Lesions of the GPi (or in its upstream modulator, the subthalamic nucleus) can greatly improve the motor symptoms of PD presumably by reducing this pathological activity.

Dependence of subthalamic nucleus oscillations on movement and dopamine in Parkinson's disease.

Local field potentials and pairs of neurones in the subthalamic nucleus (STN) of patients with Parkinson's disease show high-frequency oscillations (HFOs) at 15-30 Hz. This study explores how these HFOs are modulated by voluntary movements and by dopaminergic medication. We examined 15 patients undergoing implantation of bilateral deep brain stimulating electrodes using microelectrode recordings of pairs of STN neurones (eight patients) and macroelectrode recordings of local field potentials from the STN (14 patients).

Microelectrode recordings in the pallidum.

The internal segment of the globus pallidus (GPi) is being targeted in neurosurgical procedures to treat Parkinson's disease and dystonia. Precise targeting of the pallidal complex is important in determining the efficacy of the surgical intervention and for the avoidance of adverse effects. Intraoperative microelectrode recording can be used to characterize the patterns of activity and receptive field properties of single pallidal neurons and to identify important bordering structures, including the optic tract and internal capsule.

Synchronized neuronal discharge in the basal ganglia of parkinsonian patients is limited to oscillatory activity.

It has been proposed that an increase in synchronization between neurons in the basal ganglia contributes to the clinical features of Parkinson's disease (PD). To examine this hypothesis, we looked for correlations in the discharge activity of pairs of neurons in the globus pallidus internus (GPi), globus pallidus externus (GPe), and the substantia nigra pars reticulata (SNr). Recordings were performed in PD patients undergoing functional stereotactic mapping for pallidotomy (eight patients) or subthalamic nucleus deep brain stimulation (four patients).

Strategies and statistics of sampling for rare individuals.

Diverse subdisciplines within entomology recognize the detection of rare individuals as the precursor to effective management of these individuals. Unfortunately, detection methods have often developed on a case-by-case basis, and advances in one subdiscipline have not carried over to similarly related fields. The biology of a particular organism will certainly affect sampling methods, but the underlying principles governing the power of a sampling strategy to detect rare individuals will apply across taxa.

Lidocaine and muscimol microinjections in subthalamic nucleus reverse Parkinsonian symptoms.

Inactivation of neurones in the subthalamic nucleus (STN) of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treated monkey model of Parkinson's disease has been shown to relieve parkinsonian motor symptoms. In patients with Parkinson's disease, neurones in the STN display hyperactive firing rates and rhythmic discharge activity such as tremor-related oscillations (3-8 Hz) and synchronous high-frequency oscillations (15-30 Hz). In this study, microinjections of lidocaine (n = 4) and muscimol, a GABA(A) receptor agonist (n = 2), were performed in the STN of six patients with Parkinson's disease to determine whether the focal suppression of STN neuronal activity can lead to an improvement in tremor, bradykinesia and rigidity.

Effects of apomorphine on subthalamic nucleus and globus pallidus internus neurons in patients with Parkinson's disease.

This study examines the effect of apomorphine (APO), a nonselective D(1)- and D(2)-dopamine receptor agonist, on the firing activity of neurons in the subthalamic nucleus (STN) and internal segment of the globus pallidus (GPi) in patients with Parkinson's disease (PD). Single-unit microelectrode recordings were conducted in 13 patients undergoing implantation of deep brain stimulation electrodes in STN and 6 patients undergoing a pallidotomy. Doses of APO (2.

Field efficacy of sweet corn hybrids expressing a Bacillus thuringiensis toxin for management of Ostrinia nubilalis (Lepidoptera: Crambidae) and Helicoverpa zea (Lepidoptera: Noctuidae).

Field studies were done in 1995-1996 to assess the efficacy of three sweet corn hybrids that express the Bacillus thuringiensis (Bt) toxin, CrylAb, against two lepidopteran pests, Ostrinia nubilalis (Hubner) and Helicoverpa zea (Boddie). The Bt hybrids tested were developed by Novartis Seeds, using the event BT-11, which expresses Bt toxin in green tissue as well as reproductive tissues including the tassel, silk, and kernel. Bt hybrids were compared with a standard non-Bt control or the non-Bt isoline for each hybrid; none of the hybrids were treated with insecticides during the study.

Evaluation of action thresholds and spinosad for lepidopteran pest management in Minnesota cabbage.

Action thresholds, based on the percentage of plants infested, for the lepidopteran pest complex in fresh-market cabbage Brassica oleracea variety capitata were evaluated in 1996 and 1997 in southern Minnesota. Three lepidopteran pests are common in Minnesota, including the imported cabbageworm, Pieris (=Artogeia) rapae (L.), diamondback moth, Plutella xylostella (L.

High-frequency synchronization of neuronal activity in the subthalamic nucleus of parkinsonian patients with limb tremor.

It has been hypothesized that in Parkinson's disease (PD) there is increased synchronization of neuronal firing in the basal ganglia. This study examines the discharge activity of 121 pairs of subthalamic nucleus (STN) neurons in nine PD patients undergoing functional stereotactic mapping. Four patients had a previous pallidotomy.

An in-field screen for early detection and monitoring of insect resistance to Bacillus thuringiensis in transgenic crops.

We present a field-based approach to detect and monitor insects with resistance to insecticidal toxins produced by transgenic plants. Our objective is to estimate the phenotypic frequency of resistance in a population by relating the densities of insects on genetically transformed plants to densities on nontransformed plants. We focus on European corn borer, Ostrinia nubilalis (Hübner), in sweet corn, Zea mays L.

Development of diagnostic concentrations for monitoring Bacillus thuringiensis resistance in European corn borer (Lepidoptera: Crambidae).

Two candidate diagnostic concentrations of the Cry1Ab and Cry1Ac toxins from Bacillus thuringiensis corresponding to the LC99 and EC99 (effective concentration that causes 99% growth inhibition) for European corn borer, Ostrinia nubilalis (Hübner), were determined based on previously obtained baseline data. Validation experiments using field-collected European corn borer populations from across North America showed that for Cry1Ab, a concentration corresponding to the upper limit of the 95% confidence interval of the LC99, produced mortality > 99% for all populations tested. However, for Cry1Ac, adjustments and further validation are probably necessary.

Microstimulation-induced inhibition of neuronal firing in human globus pallidus.

Neurosurgical treatment of Parkinson's disease (PD) frequently employs chronic high-frequency deep brain stimulation (DBS) within the internal segment of globus pallidus (GPi) and can very effectively reduce L-dopa-induced dyskinesias and bradykinesia, but the mechanisms are unknown. The present study examined the effects of microstimulation in GPi on the activity of neurons close to the stimulation site. Recordings were made from GPi using two fixed or independently controlled microelectrodes, with the electrode tips usually approximately 250 or >600 micrometer apart in PD patients undergoing stereotactic exploration to localize the optimal site for placement of a lesion or DBS electrode.

Human anterior cingulate cortex neurons modulated by attention-demanding tasks.

Recent imaging studies have implicated the anterior cingulate cortex (ACC) in various cognitive functions, including attention. However, until now, there was no evidence for changes in neuronal activity of individual ACC neurons during performance of tasks that require attention and effortful thought. We hypothesized these neurons must exist in the human ACC.

Long-term follow-up of unilateral pallidotomy in advanced Parkinson's disease.

Background: Although the short-term benefits of posteroventral pallidotomy for patients with advanced Parkinson's disease have been well documented, little is known about the long-term outcome of the procedure.

Methods: We conducted a long-term follow-up study of a cohort of 40 patients who had undergone unilateral posteroventral medial pallidotomy between 1993 and 1996. Twenty patients were not evaluated because they had undergone a second surgical procedure (11 patients) or had died (2) or because they had dementia or another debilitating illness (4), lived too far away (1), or had been lost to follow-up (2).

Neuronal recordings in Parkinson's disease patients with dyskinesias induced by apomorphine.

Dopaminergic agents reverse parkinsonism but commonly induce dyskinesia in patients with Parkinson's disease (PD) on long-term levodopa therapy. The aim of this study was to determine the neurophysiologic correlates of the amelioration of parkinsonism and the involuntary movements produced by the dopamine agonist apomorphine. Seventeen PD patients were given apomorphine (2-6 mg) before surgery.

Late diagnosis of maternal PKU in a family segregating an arylsulfatase [corrected] E mutation causing symmetrical chondrodysplasia punctata.

Mutations in the arylsulfatase E gene, located on the X chromosome, have been shown to cause chondrodysplasia punctata (CDP). A substitution of arginine with serine at amino acid 12 (R12S) was identified in a patient with typical features of mild symmetrical CDP including mild mental retardation. The proband was institutionalized and was found to have seven full and half siblings all of whom were microcephalic.