Electrical stimulation of excitable tissue: design of efficacious and safe protocols.

Proton NMR chemical shift and J-coupling values are presented for 35 metabolites that can be detected by in vivo or in vitro NMR studies of mammalian brain. Measurements were obtained using high-field NMR spectra of metabolites in solution, under conditions typical for normal physiological temperature and pH. This information is presented with an accuracy that is suitable for computer simulation of metabolite spectra to be used as basis functions of a parametric spectral analysis procedure. This procedure is verified by the analysis of a rat brain extract spectrum, using the measured spectral parameters. In addition, the metabolite structures and example spectra are presented, and clinical applications and MR spectroscopic measurements of these metabolites are reviewed.

http://pfeifer.phas.ubc.ca/refbase/files/Govindaraju-NMRBiomed-2000-13-129.pdf

Proton NMR chemical shifts and coupling constants for brain metabolites.

A brain-computer interface (BCI) is a hardware and software communications system that permits cerebral activity alone to control computers or external devices. The immediate goal of BCI research is to provide communications capabilities to severely disabled people who are totally paralyzed or 'locked in' by neurological neuromuscular disorders, such as amyotrophic lateral sclerosis, brain stem stroke, or spinal cord injury. Here, we review the state-of-the-art of BCIs, looking at the different steps that form a standard BCI: signal acquisition, preprocessing or signal enhancement, feature extraction, classification and the control interface. We discuss their advantages, drawbacks, and latest advances, and we survey the numerous technologies reported in the scientific literature to design each step of a BCI. First, the review examines the neuroimaging modalities used in the signal acquisition step, each of which monitors a different functional brain activity such as electrical, magnetic or metabolic activity. Second, the review discusses different electrophysiological control signals that determine user intentions, which can be detected in brain activity. Third, the review includes some techniques used in the signal enhancement step to deal with the artifacts in the control signals and improve the performance. Fourth, the review studies some mathematic algorithms used in the feature extraction and classification steps which translate the information in the control signals into commands that operate a computer or other device. Finally, the review provides an overview of various BCI applications that control a range of devices.

/pdf/brain-computer-interfaces-a-review-2z42gnpdfy.pdf

Brain Computer Interfaces, a Review

http://n-acetylaspartate.com/PDF%20files/NAA%20Review.pdf

N-Acetylaspartate in the CNS: From neurodiagnostics to neurobiology

Cerebral concussion and traumatic unconsciousness: correlation of experimental and clinical observations of blunt head injuries

A wireless, surgically implantable pressure transducer for measuring pressure of fluid or tissue in a body chamber such as brain ventricle of a patient suffering hydrocephalus or a severe head injury. The transducer includes a coaxial variable capacitor electrically connected across an inductor to form a parallel resonant L-C circuit. Alternatively, a coaxially variable inductor may be connected across a capacitor to form the L-C circuit. A bellows is mechanically connected to the variable component to vary the value of capacitance or inductance and hence the resonant frequency of the L-C circuit in response to pressure changes of the fluid in which the bellows is immersed. The transducer is electromagnetically coupled to an external source of variable-frequency oscillatory energy such as a grid-dip oscillator which enables external detection of the transducer resonant frequency which is in turn indicative of the level of fluid pressure being sensed.

Implantable pressure transducer

I N A :PREVIOUS report 23 an experimental surgical technic in which the convex portion of the monkey skull is replaced by a transparent lucite calvarium was described. Because a large area of both cerebral hemispheres is exposed through the lucite window, the method is ideally suited for the study of intracranial phenomena under \"closed box\" conditions. I t may be of interest to mention that the technic was developed primarily to study the effects of cranial trauma on the underlying brain. The patterns of brain motion resulting from blows to both the freely movable and the immobile head were recorded by high-speed cinematography. I t is stressed that these experiments were conducted to study the motion patterns of the cerebral mass and any other visible physical change. I t is not a study of cerebral concussion. Although brain movement and concussion are probably closely interrelated the mechanism of concussion is not explainable in the light of our findings. I t is hoped, however, that this study may furnish additional data toward the eventual solution of the problem of cerebral concussion. HISTORICAL BACKGROUND

The Lucite Calvarium—A Method for Direct Observation of the Brain: II. Cranial Trauma and Brain Movement

The objective of this study was to demonstrate 1H MR spectroscopy (MRS) changes in cerebral metabolites after acute head trauma. Twenty-five patients (12 children, 13 adults) were examined with quantitative 1H MRS after closed head injury. Clinical grade (Glasgow Coma Scale [GCS]) and outcome (Rancho Los Amigos Medical Center Outcome Score [ROS]) were correlated with quantitative neurochemical findings. N-acetylas-partate (NAA), a neuronal and axonal marker, was reduced (P < .03−.001). In children, a reduced NAA/creatine plus phosphocreatine (Cr) level and the presence of detectable lipid/lactate predicted bad outcome (sensitivity, 89%; specificity, 89%). The first MRS examination of all patients correlated with ROS versus NAA (r = .65, P < .0001). Although most patients showed MRS abnormalities, striking heterogeneity of 1H MRS characterized the individual patients. 1H MRS identifies multiple patterns of diffuse brain injury after blunt head trauma. There was a strong correlation between MRS and outcome. Future prospective studies will be needed to determine the clinical usefulness of MRS in predicting outcome from closed head injury.

1H MRS in acute traumatic brain injury.

The surgical treatment of hydrocephalus--an historical review.

I N A :PREVIOUS report 23 an experimental surgical technic in which the convex portion of the monkey skull is replaced by a transparent lucite calvarium was described. Because a large area of both cerebral hemispheres is exposed through the lucite window, the method is ideally suited for the study of intracranial phenomena under "closed box" conditions. I t may be of interest to mention that the technic was developed primarily to study the effects of cranial trauma on the underlying brain. The patterns of brain motion resulting from blows to both the freely movable and the immobile head were recorded by high-speed cinematography. I t is stressed that these experiments were conducted to study the motion patterns of the cerebral mass and any other visible physical change. I t is not a study of cerebral concussion. Although brain movement and concussion are probably closely interrelated the mechanism of concussion is not explainable in the light of our findings. I t is hoped, however, that this study may furnish additional data toward the eventual solution of the problem of cerebral concussion. HISTORICAL BACKGROUND

Robert H. Pudenz

Papers

Implantable pressure transducer

The Lucite Calvarium—A Method for Direct Observation of the Brain: II. Cranial Trauma and Brain Movement

1H MRS in acute traumatic brain injury.

The surgical treatment of hydrocephalus--an historical review.

The Lucite Calvarium—A Method for Direct Observation of the Brain