Phase portraits as movement primitives for fast humanoid robot control

Currently, usual approaches for fast robot control are largely reliant on solving online optimal control problems. Such methods are known to be computationally intensive and sensitive to model accuracy. On the other hand, animals plan complex motor actions not only fast but seemingly with little effort even on unseen tasks. This natural sense to infer temporal dynamics and coordination motivates us to approach robot control from a motor skill learning perspective to design fast and computationally light controllers that can be learned autonomously by the robot under mild modeling assumptions. This article introduces Phase Portrait Movement Primitives (PPMP), a primitive that predicts dynamics on a low dimensional phase space which in turn is used to govern the high dimensional kinematics of the task. The stark difference with other primitive formulations is a built-in mechanism for phase prediction in the form of coupled oscillators that replaces model-based state estimators such as Kalman filters. The policy is trained by optimizing the parameters of the oscillators whose output is connected to a kinematic distribution in the form of a phase portrait. The drastic reduction in dimensionality allows us to efficiently train and execute PPMPs on a real human-sized, dual-arm humanoid upper body on a task involving 20 degrees-of-freedom. We demonstrate PPMPs in interactions requiring fast reactions times while generating anticipative pose adaptation in both discrete and cyclic tasks.

Learning attribute grammars for movement primitive sequencing

Movement primitives are a well studied and widely applied concept in modern robotics. However, composing primitives out of an existing library has shown to be a challenging problem. We propose the use of probabilistic context-free grammars to sequence a series of primitives to generate complex robot policies from a given library of primitives. The rule-based nature of formal grammars allows an intuitive encoding of hierarchically structured tasks. This hierarchical concept strongly connects with the way robot policies can be learned, organized, and re-used. However, the induction of context-free grammars has proven to be a complicated and yet unsolved challenge. We exploit the physical nature of robot movement primitives to restrict and efficiently search the grammar space. The grammar is learned by applying a Markov chain Monte Carlo optimization over the posteriors of the grammars given the observations. The proposal distribution is defined as a mixture over the probabilities of the operators connecting the search space. Moreover, we present an approach for the categorization of probabilistic movement primitives and discuss how the connectibility of two primitives can be determined. These characteristics in combination with restrictions to the operators guarantee continuous sequences while reducing the grammar space. In addition, a set of attributes and conditions is introduced that augments probabilistic context-free grammars in order to solve primitive sequencing tasks with the capability to adapt single primitives within the sequence. The method was validated on tasks that require the generation of complex sequences consisting of simple movement primitives using a seven-degree-of-freedom lightweight robotic arm.

Learning Trajectory Distributions for Assisted Teleoperation and Path Planning

Several approaches have been proposed to assist humans in co-manipulation and teleoperation tasks given demonstrated trajectories. However, these approaches are not applicable when the demonstrations are suboptimal or when the generalization capabilities of the learned models cannot cope with the changes in the environment. Nevertheless, in real co-manipulation and teleoperation tasks, the original demonstrations will often be suboptimal and a learning system must be able to cope with new situations. This paper presents a reinforcement learning algorithm that can be applied to such problems. The proposed algorithm is initialized with a probability distribution of demonstrated trajectories and is based on the concept of relevance functions. We show in this paper how the relevance of trajectory parameters to optimization objectives is connected with the concept of Pearson correlation. First, we demonstrate the efficacy of our algorithm by addressing the assisted teleoperation of an object in a static virtual environment. Afterward, we extend this algorithm to deal with dynamic environments by utilizing Gaussian Process regression. The full framework is applied to make a point particle and a 7-DoF robot arm autonomously adapt their movements to changes in the environment as well as to assist the teleoperation of a 7-DoF robot arm in a dynamic environment.

Reinforcement learning of motor skills using Policy Search and human corrective advice

Robot learning problems are limited by physical constraints, which make learning successful policies for complex motor skills on real systems unfeasible. Some reinforcement learning methods, like Policy Search, offer stable convergence toward locally optimal solutions, whereas interactive machine learning or learning-from-demonstration methods allow fast transfer of human knowledge to the agents. However, most methods require expert demonstrations. In this work, we propose the use of human corrective advice in the actions domain for learning motor trajectories. Additionally, we combine this human feedback with reward functions in a Policy Search learning scheme. The use of both sources of information speeds up the learning process, since the intuitive knowledge of the human teacher can be easily transferred to the agent, while the Policy Search method with the cost/reward function take over for supervising the process and reducing the influence of occasional wrong human corrections. This interactive approach has been validated for learning movement primitives with simulated arms with several degrees of freedom in reaching via-point movements, and also using real robots in such tasks as “writing characters” and the ball-in-a-cup game. Compared with standard reinforcement learning without human advice, the results show that the proposed method not only converges to higher rewards when learning movement primitives, but also that the learning is sped up by a factor of 4–40 times, depending on the task.

Assisting Movement Training and Execution With Visual and Haptic Feedback

In the practice of motor skills in general, errors in the execution of movements may go unnoticed when a human instructor is not available. In this case, a computer system or robotic device able to detect movement errors and propose corrections would be of great help. This paper addresses the problem of how to detect such execution errors and how to provide feedback to the human to correct his/her motor skill using a general, principled methodology based on imitation learning. The core idea is to compare the observed skill with a probabilistic model learned from expert demonstrations. The intensity of the feedback is regulated by the likelihood of the model given the observed skill. Based on demonstrations, our system can, for example, detect errors in the writing of characters with multiple strokes. Moreover, by using a haptic device, the Haption Virtuose 6D, we demonstrate a method to generate haptic feedback based on a distribution over trajectories, which could be used as an auxiliary means of communication between an instructor and an apprentice. Additionally, given a performance measurement, the haptic device can help the human discover and perform better movements to solve a given task. In this case, the human first tries a few times to solve the task without assistance. Our framework, in turn, uses a reinforcement learning algorithm to compute haptic feedback, which guides the human toward better solutions.

Learning movement primitive libraries through probabilistic segmentation

Movement primitives are a well-established approach for encoding and executing movements. While the primitives themselves have been extensively researched, the concept of movement primitive libraries has not received similar attention. Libraries of movement primitives represent the skill set of an agent. Primitives can be queried and sequenced in order to solve specific tasks. The goal of this work is to segment unlabeled demonstrations into a representative set of primitives. Our proposed method differs from current approaches by taking advantage of the often neglected, mutual dependencies between the segments contained in the demonstrations and the primitives to be encoded. By exploiting this mutual dependency, we show that we can improve both the segmentation and the movement primitive library. Based on probabilistic inference our novel approach segments the demonstrations while learning a probabilistic representation of movement primitives. We demonstrate our method on two real robot applications. First, the robot segments sequences of different letters into a library, explaining the observed trajectories. Second, the robot segments demonstrations of a chair assembly task into a movement primitive library. The library is subsequently used to assemble the chair in an order not present in the demonstrations.

Phase estimation for fast action recognition and trajectory generation in human–robot collaboration

This paper proposes a method to achieve fast and fluid human–robot interaction by estimating the progress of the movement of the human. The method allows the progress, also referred to as the phase of the movement, to be estimated even when observations of the human are partial and occluded; a problem typically found when using motion capture systems in cluttered environments. By leveraging on the framework of Interaction Probabilistic Movement Primitives, phase estimation makes it possible to classify the human action, and to generate a corresponding robot trajectory before the human finishes his/her movement. The method is therefore suited for semi-autonomous robots acting as assistants and coworkers. Since observations may be sparse, our method is based on computing the probability of different phase candidates to find the phase that best aligns the Interaction Probabilistic Movement Primitives with the current observations. The method is fundamentally different from approaches based on Dynamic Time Warping that must rely on a consistent stream of measurements at runtime. The resulting framework can achieve phase estimation, action recognition and robot trajectory coordination using a single probabilistic representation. We evaluated the method using a seven-degree-of-freedom lightweight robot arm equipped with a five-finger hand in single and multi-task collaborative experiments. We compare the accuracy achieved by phase estimation with our previous method based on dynamic time warping.

Inhibition of TGF-β and EGF pathway gene expression and migration of oral carcinoma cells by mucosa-associated lymphoid tissue 1

Background:

Expression of mucosa-associated lymphoid tissue 1 (MALT1) is inactivated in oral carcinoma patients with worse prognosis. However, the role in carcinoma progression is unknown. Unveiling genes under the control of MALT1 is necessary to understand the pathology of carcinomas.

Methods:

Gene data set differentially transcribed in MALT1-stably expressing and -marginally expressing oral carcinoma cells was profiled by the microarray analysis and subjected to the pathway analysis. Migratory abilities of cells in response to MALT1 were determined by wound-healing assay and time-lapse analysis.

Results:

Totally, 2933 genes upregulated or downregulated in MALT1-expressing cells were identified. The subsequent pathway analysis implicated the inhibition of epidermal growth factor and transforming growth factor-β signalling gene expression, and highlighted the involvement in the cellular movement. Wound closure was suppressed by wild-type MALT1 (66.4%) and accelerated by dominant-negative MALT1 (218.6%), and the velocities of cell migration were increased 0.2-fold and 3.0-fold by wild-type and dominant-negative MALT1, respectively.

Conclusion:

These observations demonstrate that MALT1 represses genes activating the aggressive phenotype of carcinoma cells, and suggest that MALT1 acts as a tumour suppressor and that the loss of expression stimulates oral carcinoma progression.

Effects of water-soluble hemicellulose from soybean hull on serum antibody levels and activation of macrophages in rats

Effects of soybean hull water-soluble hemicellulose (WSHC) on serum immunoglobulin (Ig) concentration and production of NO and IL-1beta from peritoneal macrophages were examined and compared with those of Agaricus blazei in the rat system. WSHC consisted of arabinose, galactose, xylose, glucose, and rhamnose, and the molecular weight was approximately 500000. Rats were ip administrated each sample at a dose of 0.67, 13.4, or 26.9 mg/kg/day for 14 days. The administration of WSHC resulted in significantly higher productions of IgM (p < 0.01 on day 6, p < 0.05 on day 14) and IgG (p < 0.05 on day 6) than those in other groups. When peritoneal macrophages were stimulated with various concentrations of sample (0.67, 13.4, or 26.9 mg/mL), WSHC significantly increased both NO and IL-1beta productions only at the concentration of 13.4 (mg/mL) compared with those of a saline group. These findings demonstrate that WSHC enhances humoral immunity and activation of macrophages, thereby leading to the augmentation of immune responses in rats.

Regional metabolic changes in the pedunculopontine nucleus of unilateral 6-hydroxydopamine Parkinson's model rats

The pedunculopontine nucleus (PPN) located in the mesopontine tegmentum is innervated by descending projections from nuclei in the basal ganglia. The present study was performed to determine whether nigrostriatal dopaminergic neuron degeneration is associated with changes in PPN metabolic activity. Unilateral nigrostriatal lesioning was performed by injecting 6-hydroxydopamine (6-OHDA) into the substantia nigra pars compacta in 10 rats. Six of these animals exhibited apomorphine-induced rotations contralateral to the lesion and were included in the experimental group for determination of regional cerebral metabolic rate for glucose (rCMRglucose) along with five sham-lesioned and five normal controls. All studies were performed 13-15 days after lesioning using [14]C-2-deoxyglucose autoradiography. Significant hemispheric differences in metabolic activity were observed only in the 6-OHDA lesioned animals. Increased rCMRglucose was found in the globus pallidus (+63%) ipsilateral to the lesion as compared to the contralateral hemisphere, and reduced rCMRglucose in the primary motor, sensory, and auditory cortex (-7%, -12% and -7%, respectively), and in the subthalamic nucleus (-6%). Metabolic activity within the PPN ipsilateral to the lesion was significantly greater than the contralateral hemisphere (P<0.05; lesion 57+/-8, nonlesion 52+/-5), and significantly greater than the sham-lesioned side of the sham rat (P<0.05; sham lesion 47+/-5). No hemispheric differences were observed in the lateral dorsal tegmental nucleus. These observations offer further support for a role of the PPN in Parkinson's and for the utility of the rodent unilateral 6-OHDA model in defining the pathophysiologic significance of the mesopontine tegmental striatal-motor interfaces in basal ganglia disease.

Ganglion cells in Ewing's sarcoma following chemotherapy: a case report

A case of Ewing's sarcoma of the bone, arising in the right radius of a 12-year-old girl, which showed unique histologic features after pre-operative treatment, is reported. The light microscopic features of a biopsy sample were those of a small round cell tumor showing positive immunoreaction with antibodies against the product of the MIC 2 gene (O13), neuron-specific enolase, neurofilament, and synaptophysin, but no morphological differentiation. The patient received combined intensive multi-drug chemotherapy and radiation before surgery. Examination of the surgical specimen showed that the tumor was less cellular than that in the biopsy specimen, and was composed mainly of loosely textured large cells mimicking ganglion cells, occasionally forming Homer-Wright rosettes. An immunohistochemical study revealed that neural differentiation was enhanced. Immunoreactivity for Leu-7 also became positive. Although the patient underwent postoperative chemotherapy, she died of multiple lung and bone metastases 30 months after the diagnosis. Autopsy showed that metastatic foci were made up of densely packed small round cells like those seen in the biopsy samples, but associated with prominent Homer-Wright rosettes. To the authors' knowledge, this is the first report of a tumor being replaced almost entirely by ganglion cells after pre-operative chemotherapy and radiotherapy.

Concentrations of indoleamine metabolic intermediates in the ventricular cerebrospinal fluid of advanced Parkinson's patients with severe postural instability and gait disorders

Postural instability and gait disorders (PIGD) are the primary causes of disability in many but not all advanced Parkinson's disease (PD) patients. We have measured the concentrations of serotonin, 5-hydroxytryptophan (5-HTP), 5-hydroxy-3-indoleacetic acid (5-HIAA), and homovanillic acid (HVA) in samples of ventricular cerebrospinal fluid from ten PD patients with severe disability from PIGD and from ten PD patients with tremor and levodopa induced dyskinesia as their predominant motor dysfunction. The two groups were prospectively matched for duration of disease and age. No significant differences between the two groups were found in the concentration (mean +/- SD in ng/ml, PIGD dominant vs. tremor-dyskinesia dominant) of 5-HIAA (106 +/- 50 vs. 99 +/- 34) or HVA (1,068 +/- 595 vs. 881 +/- 469). Serotonin concentration was significantly lower (0.7 +/- 0.5 vs. 1.5 +/- 0.9) and 5-HTP concentration was substantially higher (684 +/- 1,054 vs. 6 +/- 5) in the patient group with PIGD as their predominant symptoms. Thus, the distinguishing feature of patients with severe PIGD appears to be a derangement in indoleamine metabolism at the reaction step catalyzed by aromatic amino acid decarboxylase (AADC). These findings suggest that aggravation of PIGD in advanced Parkinson's may be related in part to impaired serotonergic transmission secondary to inhibition or down regulation of AADC.

Endothelium-dependent vascular smooth muscle relaxation activated by electrical field stimulation

Electrical field stimulation (EFS) produced relaxation of contracted arteries in the presence of tetrodotoxin. In the present study the contributions of vascular smooth muscle repolarization and endothelial release of nitric oxide to the relaxation response were investigated using isolated rat tail arteries and bovine aortic endothelial cells (BAEC). Intact and endothelium-denuded rings or intact, pressurized artery segments were contracted with either phenylephrine or KCl prior to EFS. Electrical field stimulation induced a small relaxation in denuded, phenylephrine contracted rings that was inhibited by the K+ channel blockers glibenclamide and BaCl2. In intact, phenylephrine-contracted rings, EFS induced significantly larger relaxations that were inhibited by BaCl2 as well as by L-NAME, an inhibitor of nitric oxide (NO) synthase, and methylene blue. EFS-induced relaxations were completely inhibited when BaCl2 and L-NAME or methylene blue were combined. Exposure to Ca(2+)-free buffer or diltiazem also inhibited the relaxation while ascorbic acid had no effect. Effluent from electrically stimulated BAEC caused denuded, phenylephrine contracted rings to relax. The ability of the effluent to cause relaxation was almost completely blocked by exposure of the BAEC to L-NAME or exposure of the recipient vascular smooth muscle to methylene blue; glibenclamide caused partial blockade. Simultaneous measurements of membrane potential and intraluminal pressure showed that EFS-induced membrane repolarization preceded changes in steady-state pressure. It is concluded that (1) the smooth muscle cells possess an endothelium-independent repolarization mechanism, (2) EFS causes endothelial cells of intact arteries to release NO and possibly a hyperpolarizing factor, (3) EFS of BAEC causes release of NO, and (4) EFS-induced relaxation depends on vascular smooth muscle cell membrane repolarization and endothelial cell release of vasoactive substances.

Lipoprotein and apoprotein profiles of hyperlipidemic atherosclerosis-prone Japanese quail

The purpose of this study was to characterize the lipoprotein and apoprotein profiles of hyperlipidemic atherosclerosis-prone (HAP) Japanese quail. HAP and commercially available (CA) Japanese quail were fed either a semi-purified diet containing 1% cholesterol or a cholesterol-free diet for two weeks. The lipoproteins of CA and HAP quail fed cholesterol-free diet were composed of two fractions: densities ranging from 1.02 to 1.09 and from 1.09 to 1.21. The lipoprotein distribution patterns obtained from both strains showed an HDL-predominant pattern. A protein of 26 kDa was the major apoprotein in the entire density range of the lipoprotein class. Marked increases in the cholesterol ester levels were observed in the lower density fractions (1.006 < d < 1.055: chylomicron and VLDL fractions) of the cholesterol-fed quail, accounting for 46% of the total lipids in CA quail and 54% in HAP quail. In addition, the presence of a protein of 470 kDa was exclusively observed in the lower density fractions (1.006 < d < 1.055) of the cholesterol-fed HAP quail. The fatty-acid compositions of the chylomicron and VLDL fractions were affected by the dietary cholesterol in both strains: a decrease in concentration of 16: 0 and increase in 18: 0 (weight %). However, cholesterol feeding had no effect on the level of cholesterol, chemical composition or fatty-acid composition of the HDL fractions in either strain. Although the lipoprotein and apoprotein profiles of HAP quail showed resemblances to those of the CA quail, expression of the 470 kDa protein in the lipoproteins (d < 1.055) appeared to be pronounced in HAP quail. The relevance of these lipoprotein and apoprotein profiles to the genesis of atherosclerosis was discussed in this study.

Electrophysiologic target localization in posteroventral pallidotomy

The current interest in stereotactic posteroventral pallidotomy (PVP) for treating Parkinson's disease and the variability of published results have raised questions regarding techniques for target localization. In our technique the probe is guided to the optimum target at the most ventral pallidum and ansa lenticularis by macroelectrode stimulation of the internal capsule and optic tract from within the globus pallidus, with the thresholds providing a relative measure of the electrode proximity to these structures. We have characterized these localizing macroelectrode stimulation parameters in 57 posteroventral pallidotomies with consistent anatomic lesion placement, excellent outcome, and no complications. Using a 1.8 x 2.0 mm radiofrequency electrode for macroelectrode stimulation (RFG-3C, Radionics Inc.), minimum voltages (thresholds) to activate motor (at a frequency of 2 Hz) or visual (at a frequency of 100 Hz) responses as well as impedance measurements were obtained at the final target (Tf) and at distances proximal to Tf along the electrode trajectory. The visual and motor threshold voltages at Tf via our standard approach angles (50 degrees above base plane, 20 degrees from the sagittal plane), had a range of 1.0 to 1.5 V, and 2.0 to 3.5 V respectively. We also found that as the probe approaches Tf there is a significant decrease in voltage thresholds for motor (P < .0001) and visual (P < .0001) responses in an individual patient indicating that the probe is converging on these structures. Increases in impedance between Tf, 2-3 mm, and 4-5 mm proximal to Tf were also statistically significant (P < .0001). Microelectrode recording to electrophysiological neuronal activity at various points along the trajectory towards the target showed distinct firing patterns providing identification of the globus pallidus externus and internus, ansa lenticularis, and optic tract. Macroelectrode electrophysiological stimulation within the target volume, inducing threshold responses in the internal capsule and optic tract, provides for accurate localization of the most effective PVP target in the ansa lenticularis. In unresponsive patients, the utilization of microelectrode recording for the identification of the pallidal borders and the optic tract improves safety.

Osteochondroma after total body irradiation in bone marrow transplant recipients: report of two cases

We present two cases of osteochondroma after total body irradiation in bone marrow recipients, the first in a 6-year-old boy with juvenile chronic myelogenous leukemia and the second in a 13-year-old boy with acute myelogenous leukemia. The patients developed multiple osteochondromas three years and seven years, respectively, after 12 Gy of total body irradiation. Neither had a family history of hereditary multiple osteochondromatosis. A review of the English literature revealed only one report describing five cases of osteochondroma after 12 Gy of total body irradiation in bone marrow transplant recipients. Osteochondroma should be considered as an additional adverse effect of total body irradiation.

Thallium-201 scintigraphy to assess effect of chemotherapy in osteosarcoma

Imaging results in patients with high-grade osteosarcoma of the extremities were reviewed to determine whether scintigraphic appearance correlated with histologic response to preoperative chemotherapy.

METHODS

Histologically, the percent tumor necrosis in specimens from 30 patients were classified into three grades: grade 1 = necrosis less than 60%, grade 2 = 60%-89% necrosis and grade 3 = diffuse necrosis greater than 90% based upon whole transverse sections. Scintigraphically, we analyzed 201TI uptake before and after preoperative chemotherapy. The changes in the tumor-to-background ratio were defined by an alteration ratio.

RESULTS

Of the 11 patients with a grade 1 response, the ratio showed -67.1% +/- 45.4% (mean +/- s.d.). Of the 9 patients with a grade 2 response, the ratio showed 37.9% +/- 29.9% of the 10 patients with a grade 3 response the ratio showed 105.5% +/- 12.4%. The ratios correlated well with the histologic grades (p < 0.0001; analysis of variance).

CONCLUSION

Thallium-201 scintigraphy accurately assesses the effect of chemotherapy on osteosarcoma.

Simultaneous bilateral pallidoansotomy for idiopathic dystonia musculorum deformans

A 17-year-old Russian male with a 9-year diagnosed history of dystonia musculorum deformans manifested as severe tortipelvis, lordosis, and axial and appendicular spastic dystonia, refractory to medical therapy, is reported. This patient underwent a simultaneous bilateral pallidoansotomy with dramatic results. Postoperative evaluation revealed sustained alleviation of all dystonic symptoms and abnormal movements. Rapid recovery of useful strength in all limbs as well as dramatic improvement in coordination occurred. Bilateral posteroventral pallidotomy and pallidoansotomy in the past have proven effective in alleviation of all parkinsonian symptoms, including dyskinesia and dystonia, without the concurrent risk of intransigent side effects associated with bilateral thalamotomy or other stereotactic surgical procedures. Pallidoansotomy may prove to be the treatment of choice for idiopathic torsion dystonia and merits further investigation.

The results, indications, and physiology of posteroventral pallidotomy for patients with Parkinson's disease

In the past, stereotactic surgical intervention for Parkinson's disease was considered indicated only in those patients with active motor manifestations that were refractory to pharmacological therapy, manifestations such as tremor, rigidity, dystonia, and dyskinesia. With the reintroduction and refinement of Leksell's posteroventral pallidotomy, both akinetic and hyperkinetic symptoms are now amenable to surgical treatment. We have analyzed the results of 126 patients who underwent either unilateral (n = 58) or bilateral (n = 68) posteroventral pallidotomies. The Unified Parkinson's Disease Rating Scale and Hoehn and Yahr Staging Scale were used for preoperative and postoperative objective assessments. Postoperative follow-up evaluation occurred initially at 1 week and subsequently at intervals between 1 and 12 months (mean = 4.5 months) after surgery. Although individual motor subscores on the Unified Parkinson's Disease Rating Scale were significantly reduced (n = 126, P < or = 0.01), the most dramatic findings were the reversal of akinetic symptoms and the elimination of dyskinesia and profound "off" periods. These clinical results, combined with intraoperative microelectrode records revealing pallidal neuronal hyperactivity, suggest a reconsideration of the pathophysiology of akinesia and point to possible mechanisms of akinesia improvement by posteroventral pallidotomy in some parkinsonian subgroups.

Chronic anterior pallidal stimulation for Parkinson's disease

We present the case of a 51-year-old female who had a four-year history of Parkinson's disease with severe "on-off' and disabling progression of symptoms on chronic levodopa therapy. After obtaining FDA approval, we implanted a Medtronic deep brain stimulation lead stereotactically into the right anterior pallidum contralateral to her most symptomatologic side. Intra-operative stimulation trials at 100 Hz caused reproducible reversal of akinetic symptoms and simultaneous microelectrode recording of the posteroventral pallidum revealed decreased neural activity during anterior pallidal stimulation. The patient was evaluated pre-operatively and postoperatively using the Hoehn and Yahr Staging Scale, the Unified Parkinson's Disease Rating Scale (UPDRS), videotape, and a computerized data glove. Six months after implantation, the total UPDRS score was decreased from 68 to 8 and Hoehn and Yahr Staging improved from 3.0 to 1.5 during periods of chronic high frequency stimulation. Dramatic improvements in tremor, dystonia, bradykinesia, and akinesia were noted within seconds of stimulator activation and were also objectively measured using a computerized data glove. This case reveals the potential for therapeutic pallidal stimulation for Parkinson's akinetic symptomatology.

EEG frequency patterns in the cat prepyriform cortex during sleep and waking

The cellular populations in the prepyriform cortex are a primary processing station for sensory information from the olfactory bulb. These populations are also influenced from forebrain and other brain systems involved in behaviour. Recording electrodes can be precisely placed in this cortex compared to many other brain structures. This permits straddling the cortical superficial pyramidal cell layer with a bipolar recording configuration and the ability to obtain information about awake-vigilant and other state conditions from this brain structure. Methadone, a vigorously arousing drug in the cat, and a short acting barbiturate was administered to compare the differences of EEG patterns obtained during normal awake and sleep conditions. Fourier analysis was used in this study and combined with computer profiles of spectra to show time relationships of the state conditions in the cortex. Good separation of the spectra, between the major states in the cat, were observed using this technique for both natural and drug-induced changes.

The principal projection pathway between the olfactory bulb and the prepyriform cortex in the cat

The anatomy and neuroelectric properties of the lateral olfactory tract (LOT) were investigated in the cat. Electron micrographs were obtained from sampled areas across the rostro-caudal projection of the pathway. Fiber diameters were estimated and axon spectra were obtained from three regions corresponding to peduncle, mid-LOT, and caudal-LOT. The mean inside diameter for all measured axons was 1.13 +/- 0.53 microns. The greatest number was found in the peduncle (approximately 600,000 axons). Mid-LOT and caudal-LOT each contained approximately 250,000 axons. Unmyelinated processes were estimated to be more numerous than the myelinated axons. Synaptic structures were also observed in the LOT. Cross-sectional area measurements of the LOT were obtained from tissue prepared for light microscopy. The area decreased from about 0.3 to 0.2 mm2 across the projection from olfactory bulb to cortex. The anatomical data were used to predict the conduction properties of transmission over the LOT. The olfactory bulb mitral cells were stimulated electrically and conduction velocity and temporal dispersion were evaluated in the tract. The strength-duration and stimulus-response curves and the potential profile during stimulation were also obtained. The time constant for LOT axons was 0.3 msec. The stimulus-response curve was sigmoidal in shape for both presynaptic and postsynaptic responses. The relationship between input (the action potentials) and output (cortical postsynaptic potentials) was linear up to 90 times threshold. Action potentials were conducted at 20 m/sec across the pathway over the peduncle and decreased to about 10 m/sec in caudal aspects. The potential profile for action potentials decayed exponentially into the depths of the cortex whereas the synaptic potential was a surface negative dipole field. The axon spectra were convolved with the electrophysiological properties of the LOT to mathematically reconstruct action potentials. The empirically derived mono- and biphasic curves fitted reasonably well with experimentally derived data under various stimulus conditions.

Oxidative metabolism during and following ischemia of cat spinal cord

Spinal cord ischemia was produced by an occlusion of the thoracic descending aorta on experimental cats for the periods of 3, 5, 10, and 15 minutes. The reduction/oxidation (redox) ratio of cytochrome a,a3 was measured in vivo by reflectance spectrophotometry, simultaneously with the measurement of the following: blood pressure in the aorta distal to the occlusion; relative blood volume in the cord; oxygen tension in cord tissue; and cord potential in response to dorsal root stimulation. During aortic occlusion, the maximum increase in the redox ratio was reached somewhat more slowly than the maximum decrease in blood pressure, blood volume, and oxygen tension. Interneuron potentials began to decrease as the redox level increased, and completely disappeared soon after the redox ratio increased, and completely disappeared soon after the redox ratio increased maximally. During ischemia, therefore, oxygen consumption in the mitochondria was slightly lower than the decrease in oxygen tension; impairment of ADP phosphorylation, and accordingly that of ion pump, occurs simultaneously with the increase in the redox ratio. Recovery of the redox ratio after completion of aortic occlusion was also slightly slower than the recovery of blood pressure, blood volume, and oxygen tension. Complete recovery of interneuron potentials was much more delayed than that of the redox ratio; after 15-minute ischemia, uncoupling of ADP phosphorylation was noted. It can be concluded that the spinal cord function and metabolism are severely impaired after 15-minute occlusion.

Design for a micropowered multichannel PAM/FM biotelemetry system for brain research

A design for a 12-channel pulse amplitude-modulated/FM biotelemetry system is described. The biotelemeter mounts on an animal's head close to the electrode probes to record and transmit brain electrical data. The size of the unit is 4.5 x 6.5 x 2 cm and it weighs about 60 g. It is designed to acquire EEG and other physiological data where the requirement is to obtain bioelectrical activity without cable encumbrance or confining behavioral restrictions. The telemeter consumes about 800 muW of power and operates for approximately 3 continous days before it is necessary to exchange the utilization of complementary metal oxide semiconductor (CMOS) integrated circuits. Transmission range is typically about 10 m.