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Biomedical subjects

E B Montgomery

Publications and source records attributed to E B Montgomery.

At least 37 records · Page 2Linked to original sources
PubMed1995

Central nervous system toxicity of manganese. I. Inhibition of spontaneous motor activity in rats after intrathecal administration of manganese chloride.

The intrathecal administration of MnCl2 to young male rats caused dopamine depletion in the caudate-putamen and a decrease in spontaneous motor activity. Our experiments demonstrate that in the young rat: (a) the lateral choroid plexus protects the cerebrospinal fluid (CSF) from high concentrations of Mn in the blood by sequestering and thus preventing large amounts of this metal ion from entering the CSF. As blood Mn levels rise, the lateral choroid plexus may become overwhelmed and leak an increasing amount of Mn into the CSF. (b) The lateral choroid plexus does not remove Mn2+ from the CSF. (c) The injection of MnCl2 into the CSF of rats caused a rapid decrease in spontaneous motor activity which is dose-dependent and reversible under the present experimental conditions. Intrathecal Mn results in a substantial decrease in striatal dopamine but not homovanillic acid or 3,4-dihydroxyphenylacetic acid (DOPAC) concentrations and is associated with an increase in the Mn concentration of the substantia nigra and caudate-putamen.

Animals↗
PubMed1995

Using motion perimetry to detect visual field defects in patients with idiopathic intracranial hypertension: a comparison with conventional automated perimetry.

Motion perimetry, a method of visual field testing that uses computer graphics to measure motion perception, quantitates a subject's ability to detect a coherent shift in position of dots in a defined circular area against a background of fixed dots. Motion size threshold is defined as the smallest detectable circular target in which dot motion is detected. Subjects respond by touching a computer monitor screen with a light pen, first when they see a target (reaction time) and a second time where motion targets are detected (localization). Reaction time (msec) to the stimulus and localization error (number of pixels from target center) are then calculated and stored. We tested on eye in each of 20 idiopathic intracranial hypertension (IIH) patients and 40 age-matched normal subjects by conventional automated perimetry (Humphrey visual field analyzer, program 24-2) and motion perimetry. Pointwise probability plots of individual abnormal test points for size threshold responses were generated for the IIH patients based on the 95% confidence limits of the normal subject responses. An analysis of the subjects' visual field pairs (motion versus conventional automated perimetry) was performed based on these probability plots. The IIH patients had an elevated mean motion threshold (p < 0.001) and reaction time (p < 0.001) compared with the normal subjects. There were no significant differences for the localization errors. Based on the probability plot analysis, there was good correlation of the visual field defects between the two perimetry tests. In addition, motion perimetry identified nerve fiber bundle-shaped defects in nine patients in whom they were not detected with conventional automated perimetry.

Adult↗
PubMed1994

Patient education and health promotion can be effective in Parkinson's disease: a randomized controlled trial. PROPATH Advisory Board.

We performed a randomized controlled trial to evaluate the effectiveness of a patient education and health promotion program in the treatment of Parkinson's disease. The health promotion program (PROPATH) was designed to improve health confidence, provide information and support, improve physical function through exercise, and work with the physician to optimize medical treatment and compliance. The intervention was delivered by mail, with disease assessment questionnaires completed by patient or caregiver at 0, 2, 4, and 6 months, with computer-generated reports and individualized recommendation letters returned to patients and reports to physicians. Two hundred ninety patients completed the 6-month trial, 140 patients in the intervention group and 150 in a control group of patients who received only questionnaires. The intervention group had significantly increased exercise, decreased "time off" and percentage of time off, reduced side effects, and decreased summary Parkinson's scores by approximately 10% (P > 0.05). Twelve of 13 variables showed differences favoring the intervention group. The rate of progression of summary scores became essentially flat during the program for the intervention group and continued to rise sharply for controls (P > 0.01). Levodopa dose rose for controls and slightly decreased for the intervention group. Doctor visits, hospital days, and sick days were reduced in the intervention group. The quality-of-life assessment demonstrated improvement in patient global, self-efficacy scores, and spouse or caregiver assessments. We conclude that a low-cost patient education program provides a useful adjunct to medical therapy of Parkinson's disease, may reduce costs, and can improve intermediate term outcomes.

Activities of Daily Living↗
PubMed1993

Generative naming in Parkinson disease patients.

The generative naming ability (verbal fluency) of 88 idiopathic Parkinson disease (PD) patients was evaluated and compared to that of 21 Alzheimer disease (AD) patients and 43 normal age- and education-matched normal control subjects. The PD patients were classified according to whether they scored within the normal range on the Mini-Mental State Examination (MMSE), a score of 27 or higher, or in the abnormal range, a score of 26 or lower. Semantic and letter generative naming tasks were administered to assess verbal fluency. Results of the study provide evidence that letter category naming is inherently more difficult than semantic category naming; that age significantly affects generative naming; that PD patients with normal MMSE scores were significantly inferior to normal control subjects in generative naming even after the effects of age and mental status are controlled; that PD patients with non-normal MMSE scores performed like AD patients after controlling for the effects of age and mental status; and, that ideational perseveration is the most common type of error response for all subject groups.

Aged↗
PubMed1992

Neuronal multipotentiality: evidence for network representation of physiological function.

Extracellular action potentials of single neurons in motor cortex and rectified and integrated electromyographic activity (EMG) of gastrocnemius and anterior tibialis were recorded while a monkey performed isometric ankle plantar and dorsal flexion tasks. This study determined the consistency of neuronal behaviors across different tasks. Methods characterized neuronal behaviors by determining which behavioral event within a single task, such as the appearance of the 'go' signal, force onset, or agonist and antagonist EMG onset, was best related to changes in neuronal activity. Another method compared the temporal profiles of discharge modulation across different tasks. Of 220 neurons recorded, 44 were selected because they were consistently active in the tasks. Of these, 37 were in the precentral cortex and the remaining seven were in the postcentral cortex. Only 14 of the 33 in motor cortex were consistent in their behavioral correlations. Several had multiple changes in activity within a single task that were related to different behavioral events. Half were consistent for direction of force and a third were consistent for magnitude of force. Furthermore, there was little consistency in the temporal profiles of discharge activity for all 44 neurons across tasks. Similar modulations of discharge activity among neurons in one task were different in another task. Such inconsistencies are evidence against the cardinal cell hypothesis of physiological representation. We offer a new hypothesis analogous to connectionism in parallel distributed processing.

Action Potentials↗
PubMed1992

Pharmacokinetics and pharmacodynamics of levodopa.

Levodopa is effective in relieving symptoms of Parkinson's disease. However, long-term complications make sustained control problematic. Most management problems are related to the pharmacokinetic and pharmacodynamic properties of levodopa. Careful titration based on pharmacologic principles may achieve optimal therapeutic effects.

Administration, Oral↗
PubMed1991

The striatum and motor cortex in motor initiation and execution.

The participation of striatal and motor cortex neurons in motor initiation and execution was studied using single neuronal recording in 3 monkeys performing wrist flexion and extension stimulus-initiated reaction time tasks. Observations of 46 striatal neurons whose activity correlated with the tasks were compared to recordings of 59 task-related motor cortex neurons. Neurons were classified as best related to the appearance of the go signal, movement onset, agonist or antagonist electromyographic changes, or the movement reaching target. Timing of neuronal activity changes in both striatum and motor cortex suggested that go signal-related neurons represent input function while most movement onset-related neurons represent output function. In the striatum, those related to reaching target represent output function. Furthermore, go signal-related neurons usually change activity before movement onset-related neurons which change activity prior to target attainment-related neurons. These observations suggest a hierarchical organization within the striatum and motor cortex. Also the striatum participates in programming target acquisition as well as motor initiation.

Animals↗
PubMed1991

Motor initiation versus execution in normal and Parkinson's disease subjects.

We studied motor initiation and execution using wrist extension movements to changing target locations in eight normal subjects and nine Parkinson's disease (PD) patients before and after medications. Late changes resulted in double trajectories, indicating commitment to the initial target acquisition program followed by a correcting movement. There was compensation for earlier changes, even after onset of agonist muscle activity, resulting in a single trajectory, implying that the original trajectory had not yet been specified. However, movements were slowed in PD patients implying an abnormality in the content of the target acquisition program but not in the timing of its specification. In PD patients, the timing of the second movement onset correlated best with the timing of target location change and did not depend on initial movement completion. Thus, PD patients were able to program the second movement while the first movement was under way.

Aged↗
PubMed1991

Reaction time and movement velocity abnormalities in Parkinson's disease under different task conditions.

We examined reaction times, movement velocities, and the associated agonist and antagonist muscle behaviors in nine Parkinson's disease (PD) patients and eight normal subjects before and after medications, using a wrist extension task to changing locations of a visual target. Targets changing 500 msec before an auditory "go" signal act as a preparatory cue, while targets changing at the time of the go signal provide a combined auditory and visual stimulus. Late target changes allowed examination of (1) reaction times during an ongoing movement, and (2) movement in the presence and absence of visual targets. PD prolonged the time from the onset agonist electromyographic activity and reduction of antagonist activity to movement onset. Both were shortened by preparatory cues and combined visual and auditory go signals. PD slowed movement only in a subset of trials in which there was movement to a displayed target.

Adult↗
PubMed1990

The movement speed/accuracy operator in Parkinson's disease.

This study examined the effects of Parkinson's disease (PD) and its treatment on the speed of rapid arm movements to different target sizes in a simple reaction time task in 8 PD and 9 normal subjects. Testing in PD subjects occurred after an overnight fast from their medications and 1 hour after their usual 1st dose. They had longer reaction and movement times, both of which shortened following medication. Like normal subjects, PD subjects had decreased movement times to larger targets, but without drug were unable to maximize speed within the range of target sizes tested whereas PD subjects taking drug and normal subjects could. These findings suggest that a speed/accuracy operator is functioning in PD but at reduced initial gain and at an offset towards longer movement times.

Aged↗
PubMed1989

A new method for relating behavior to neuronal activity in performing monkeys.

A new method is presented for the analysis and interpretation of data from single neuronal recording in behaving monkeys. Most current methods relate changes in neuronal activity to behavior by constructing rasters and histograms centered on specific previously defined behavioral events whose relevance to neuronal activity cannot be determined beforehand. As a consequence false conclusions may result. The new method aligns rasters and histograms of neuronal activity relative to patterns inherent in the neuronal activity irrespective of the animal's behavior. The behavior is then related to the neuronal activity. This frees interpretation from a priori notions as to the relevant behavior. The method also determines the variability of temporal latencies between changes in neuronal activity and any behavioral event on an individual trial by trial basis. With the assumption that the latencies will be least variable between the change in neuronal activity and the most relevant behavioral event, the relatedness of neuronal activity changes to behavior can be tested so that physiological conclusions can be inferred. The same method and subsequent analyses can be applied to electromyographic activity.

Animals↗
PubMed1988

Head restraint device for chronic recording of neural activity in the awake monkey.

An adjustable, stainless steel, head restraining device and small screw-tightened skull clips are described which enable us to record single unit neuronal activity chronically from awake, behaving primates of various sizes. We have used this method of head restraint over the past 4 years on 8 primates, for periods up to 18 months without any mechanical failures. This equipment reduces problems stemming from bone necrosis and is well tolerated.

Animals↗
PubMed1985

Thymectomy in multiple sclerosis: a 3-year follow-up.

We studied 34 MS patients who were treated experimentally by thymectomy with or without 1 year of azathioprine therapy. After 3 years, there was no evidence of benefit. Relapsing-remitting patients had done as well or better clinically than controls, and the chronic progressive group did less well statistically than controls.

Follow-Up Studies↗
PubMed1984

Motor cortical neuronal activity patterns in monkeys performing several force tasks at the ankle.

Normal rhesus monkeys were conditioned at light signals to exert forces with both feet on fixed foot bars. The tasks included small and large sustained forces in plantar and dorsiflexion directions and large phasic forces in both directions. The tasks were selected to relate to behaviors known to be impaired in the upper motor neuron syndrome. Extracellular recordings were made from 226 area 4 motor cortex units (MCUs) in the hindlimb region of area 4. Ninety percent of the MCUs showed increased activity temporally related to force and EMG changes; 10% showed decreased activity exclusively. The 203 MCUs showing increased activity differed in their directional preference: half were active only in relation to development of force in one direction (unidirectional) and the remainder with forces in both directions (bidirectional). Only 28/101 of the bidirectional units were symmetric (equal activity with force in both directions). The majority were asymmetric with a greater degree of activity in one direction. Both unidirectional and bidirectional (symmetric and asymmetric) MCUs often developed increased activity not only with agonist force production but also with force relaxation in the antagonist muscles. Seventy-eight percent of the MCUs showing increased activity had phasic discharge qualities, lacking sustained activity during the prolonged force holds. Thirty-eight percent of the MCUs showing increased activity were more active with larger force, and 14% with smaller force; 48% had closely similar activity with both force levels. None of these characteristics was related to directionality. A spectrum of MCU behaviors was found that ranged in complexity from units which increased or decreased discharge with force in one direction to those responding with force production and force relaxation in both directions.

Animals↗
PubMed1983

Signs and symptoms from a cerebral lesion that suggest cerebellar dysfunction.

Lesions of the cerebral hemispheres can produce signs and symptoms very similar to those produced by cerebellar lesions. I studied a case that demonstrated the signs of dysmetria and intention tremor; it resulted from an infarct of areas 5, 7, and, to a lesser extent, 40, of the contralateral cerebral hemisphere.

Aged↗
PubMed1983

Thymectomy in multiple sclerosis. Two preliminary trials.

In two preliminary trials, thymectomy was performed on 35 multiple sclerosis (MS) patients, with (Group 1) or without (Group II) azathioprine therapy for 1 year. Formal studies of clinical neurologic status were conducted at yearly intervals after operation. Each group was compared with carefully matched control patients. Group I patients showed significant improvement in total functional groups (Kurtzke scale) and pyramidal functions 1 and 2 years following thymectomy. Other individual functions showed no significant difference. There was a statistical improvement in disability status (Kurtzke) for patients with relapsing-remitting MS 1 and 2 years following thymectomy. This subset also had a significant decrease in MS exacerbations. Group II patients showed none of the favorable trends seen in Group I. Functional groups, disability status scale, and exacerbations were similar to those of the control patients. Several studies indicate azathioprine therapy alone is of questionable benefit in MS. In myasthenia gravis (MG), the full immunosuppressive effect of thymectomy may not be realized for several years. Therefore, it is possible that in Group I patients a dual mechanism of immunosuppression--azathioprine and thymectomy--is yielding a favorable response not yet apparent in the Group II patients having thymectomy alone. If our data still appear favorable after a third follow-up year, a formal pilot study will be undertaken.

Adult↗
PubMed1981

Cerebral hemodynamics and metabolism in postoperative cerebral vasospasm and treatment with hypertensive therapy.

A 24-year-old woman developed subarachnoid hemorrhage from an aneurysm at the bifurcation of the right internal carotid artery. Following successful clipping of the aneurysm she developed a left hemiplegia associated with focal cerebral vasospasm, which markedly improved when systemic blood pressure was raised with intravenous dopamine infusion. Regional cerebral blood flow and oxygen utilization were significantly depressed in both cerebral hemispheres, while blood volume was significantly elevated only on the side with vasospasm. Oxygen extraction was significantly elevated in both hemispheres, indicating a generalized impairment in oxygen delivery to the brain.

Adult↗