Subthalamic deep brain stimulation: neurobehavioral concerns.
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Cognition↗
Biomedical subjects
M C Schiess
Publications and source records attributed to M C Schiess.
Immediate-release and controlled-release carbidopa/levodopa in PD: A 5-year randomized multicenter study.
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Antiparkinson Agents↗
Characterization of the electrophysiological and morphological properties of rat central amygdala neurons in vitro.
Forty central amygdala neurons labelled with 2% Neurobiotin were categorized according to their distinctive bioelectrical membrane properties and classified physiologically by their hyperpolarized resting membrane potential (-74 mV), short duration medium afterhyperpolarization (239.2 ms), and non-accommodating response as Type A neurons (63%; N = 25/40), or as Type B neurons (37%; N = 15/40) by their depolarized resting membrane potential (-66 mV), long slow-afterhyperpolarization (1.8 s), and accommodation response. Visualized within subnuclei of the central amygdala, Neurobiotin-labelled Type A neurons were medium-size cells [16.5 +/- 3 x 10.7 +/- 2 mu m; length x width] with smooth, spine-free ovoid, pyramiform, and fusiform perikarya. Aspinous primary dendrites gave rise to distal dendrites covered with numerous small pedunculated spines; density of spines ranged from sparse to abundant. Type B central amygdala neurons were larger cells [23.9 +/- 5 x 14.9 +/- 4 mu m] with smooth, aspinous ovoid, polygonal, and pyramiform somata. Dendrites were aspinous and covered with variably sized varicosities. Two distinct populations of neurons exist within the central amygdaloid complex: the medium-size, spine-laden Type A defined neuron with its non-accommodating electrophysiological response and the larger aspinous, varicosity-laden Type B defined neuron with its accommodating response. In contrast to their neighboring "cortical-like" amygdala neurons, central amygdala neurons possess a "striatal-like" cytoarchitecture and electrophysiology.
Action Potentials↗
Trail Making Test: issues in normative data selection.
The Trail Making Test (TMT) is one of the most frequently administered neuropsychological instruments, having been used in the evaluation of cognitive dysfunction for over 50 years. Despite the measure's extensive clinical use and proliferation of research, no comprehensive review of the adult TMT normative literature is available. This report examines the available TMT normative reports and provides a summary of the sample characteristics. Significant variability between studies precludes the use of metanorms. Clinically, these findings indicate that biased results may be obtained if the most appropriate normative data set is not used and underscore the importance of identifying the normative comparison group that approximates the relevant patient characteristics. To assist the clinician, selected normative reports (based on certain exclusionary parameters) have been compiled for three nonclinical comparison groups: (a) an adolescent and young adult group (ages 15-24), (b) an adult group (ages 20-54), and (c) an older adult group (ages 55-85). Results are discussed in terms of the influence of moderator variables on TMT performance and other factors, such as procedural differences in administration, that may account for the significant variability between normative samples.
Journal Article↗
Cognitive sequelae of unilateral posteroventral pallidotomy.
OBJECTIVE: To examine the cognitive sequelae of unilateral posteroventral pallidotomy. DESIGN: Single-group pretest and posttest methodologic assessment with baseline evaluation performed 1 to 2 days prior to surgery and follow-up conducted 3 months after pallidotomy. SETTING: Movement disorder clinic at a university medical center. PATIENTS: Fourteen patients (age range, 43-82 years) with Parkinson disease (average disease duration, 7.4 years). INTERVENTION: Unilateral posteroventral pallidotomy procedures were performed on the right (n=8) and left (n=6) side of the brain. MAIN OUTCOME MEASURES: The protocol consisted of a range of neuropsychological instruments sensitive to subcortical dysfunction, including measures of bi-manual coordination, simple-complex reaction time, visual attention, naming, verbal fluency, learning, recognition memory, and problem solving. RESULTS: No significant deterioration in specific cognitive abilities was observed as a function of the procedure. Patients showed a significant improvement in motor coordination speed for both contralateral and ipsilateral upper extremities. CONCLUSIONS: Stereotactic unilateral posteroventral pallidotomy is associated with minimal risk of adverse neuropsychological effects or cognitive decline. Additional research is warranted, with an increased sample size and extended follow-up, to assess any potential lateralized effects of the procedure.
Adult↗
The central nucleus of the rat amygdala: in vitro intracellular recordings.
Membrane properties of neurons from the central nucleus of the rat amygdala (ACe) were analyzed using intracellular current-clamp recordings from in vitro coronal slices of adult rat amygdala. Two types of neurons were identified and classified according to their accommodation characteristics and the nature of their afterhyperpolarizations (AHP). Type A neurons represented 74% of the population and were identified by a lack of accommodation and a medium-AHP (m-AHP) in response to transient (100 ms) depolarizing current injection. The m-AHP was defined by a fast decay time constant with a mean tau AHP = 113.6 ms. In both Type A and Type B ACe cells the m-AHP can be reduced with cadmium and rubidium. Type B neurons represented 26% of the population and were identified by the presence of accommodation and a long duration slow-AHP (s-AHP) following the m-AHP. The s-AHP was defined by a slow decay time constant with a mean tau AHP = 1.7 s. The s-AHP was similar to the AHP mediated by IAHP, a long duration calcium-dependent, noradrenaline-sensitive current present in hippocampal neurons. In Type B cells, the s-AHP was reduced by cadmium and noradrenaline. There was no significant difference between Type A and B ACe neurons in passive electrical properties such as the membrane input resistance (RiA = 113 M omega, RiB = M omega), and the membrane time constant (tau A = 15 ms, tau B = 16 ms). However, there was a statistically significant difference in the resting membrane potentials of Type A and B ACe neurons (RMPA = -67 mV; RMPB = -63 mV). These data suggest that the characteristic active membrane properties displayed by Type A and Type B neurons will determine the ability of each type to integrate and encode neuronal information.
Action Potentials↗
Estrogen priming affects active membrane properties of medial amygdala neurons.
The medial nucleus of the amygdala (MNA) in the rat is a target tissue for estrogen binding and a sexually dimorphic structure. We used an in vivo slice preparation and intracellular recording techniques to study the effects of beta-estradiol priming on active and passive membrane properties of MNA neurons. Two groups of adult female rats were used; ovariectomized (OVX) non-primed rats and OVX rats that were estrogen-primed at least 24 h prior to recording. Estrogen priming increased the occurrence of spontaneous excitatory postsynaptic potentials (EPSPs) in MNA neurons, and of depolarizing afterpotentials (DAPs) observed with a cathodally triggered action potential, and was associated with a lack of accommodation in these cells. Overall, long-term exposure to estrogen markedly increased the spontaneous activity and excitability of the MNA neurons.
Action Potentials↗
Estrogen priming affects the sensitivity of midbrain central gray neurons to microiontophoretically applied LHRH but not beta-endorphin.
In vivo single-unit extracellular recording was used to assess neuronal membrane sensitivity at the level of the midbrain central gray (MCG) to the iontophoresis of luteinizing hormone releasing hormone (LHRH) and beta-endorphin (beta-END). The percentage of change in firing rate was evaluated to determine the effect of exogenously administered estradiol benzoate (EB) and EB plus progesterone (EB + P) on the membrane sensitivity of these MCG neurons to LHRH and beta-END. Ovariectomized adult female rats were primed with EB or EB + P, or nonprimed, 24-48 h prior to recording. EB priming significantly altered the membrane sensitivity of neurons in the MCG to LHRH by increasing the number of cells excited compared to the EB + P group and the nonprimed controls (p less than 0.005). The addition of P appeared to negate this effect. Hormonal priming did not alter the response profile for beta-END iontophoresis. The results suggest an estrogen-dependent sensitivity to LHRH at the MCG which translates into an increased electrical output, ultimately facilitating lordosis behavior. P treatment dampens this excitation. beta-END's effect on neuronal membrane excitability at the MCG was not distinctly characterized under the hormonal conditions our study evaluated and may reflect a regulatory role under physiological extremes.
Action Potentials↗
Use of osmotic minipumps for delivery of parathyroid hormone.
To determine if osmotic minipumps can be used for the local delivery of parathyroid hormone (PTH), we examined the bone resorbing activity of PTH in minipumps, either removed and assayed in bone organ cultures or released over rat calvaria. Biological activity of PTH was maintained for up to 6 days when the hormone solution contained serum and the minipumps and tubing were siliconized and flushed with diluent prior to use. Addition of cysteine did not enhance activity.
Animals↗