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S Jacques

Publications and source records attributed to S Jacques.

At least 37 records · Page 2Linked to original sources

Cognitive information processing and learning mechanisms of the brain.

The view that the two cerebral hemispheres of the human brain are characterized by different cognitive processing modes that handle information received in various forms is commonly accepted by neurobehavioral scientists and neuropsychologists. Selected neuroanatomical, electrophysiological, neurochemical, biochemical, and neuropsychological data that bear on a cognitive information-processing model of the brain are presented. Processes involved in memory functions are discussed in regard to the nature of thought and the characteristics of mental life, e.g., internalization of thought, perception, arousal, attention, cognitive development, problem solving, the development of cognitive encoding, and selective recall. We present a position that argues for the brain as being flexible vs. fixed in its characteristics and limitations, drawing from various theories and viewpoints. We also present a review of selected mechanisms believed to be involved in brain-behavior processes, e.g., learning, cognition, pain, emotion, reward, cognitive development, and memory formation. A major theme addressed in terms of human information processing is that cognitive functioning, in a variety of instances, comprises subsets of more general processes, e.g., selective recall, cueing that is capable of addressing schemas, notions of inhibition and disinhibition, and the modulation of excitatory properties of certain neural transmitter substances. Questions such as "how is information stored in memory in the first place?" and "how do elements of motivation (i.e., goal orientation) get connected and then send their messages to appropriate inbound behaviors?" are addressed from the point of view that learning, although not understood completely, is somehow involved. Another unresolved question of theoretical and practical significance that we address is "how does learning result in neural connections?" Such questions are discussed in light of their implications for human memory, thought, and behavioral events.

Arousal

Development of a protocol for photoradiation therapy of malignant brain tumors: part 1. Photosensitization of normal brain tissue with hematoporphyrin derivative.

The successful application of phototherapy to subcutaneous tumors has suggested that a similar procedure should be developed for treating gliomas. As a result, attempts are being made to determine a set of conditions that would optimize the destruction of tumor cells while minimizing injury to surrounding brain tissue. To initiate this task, we developed a novel assay method to assess the amount of phototoxicity induced in normal brain by light exposure of mice treated with hematoporphyrin derivative (HPD). The application of this procedure demonstrated that a sufficient amount of HPD was retained in brain tissue, even 72 hours after injection, to cause severe cerebral damage in light-treated mice.

Animals

Cerebral gliomas.

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Brain Neoplasms

Dopaminergic (DA) systems: their role in pathological neurobehavioral symptoms.

Two established dopamine (DA) systems (i.e., the nigrostriatal and the mesolimbic-mesocortical) are the focus of this article. Their neuroanatomy is briefly outlined to relate neurochemical with neurobehavioral events and alterations in DA-affected systems with the behavioral consequence. Selected theories and major ideas related to DA systems and their implicated role in neurobehavioral symptoms that have emerged over the last decade are included. Correlations with behavioral consequences of disturbances in DA systems lack clarity as to precisely known clinical effects relating to human behavioral and motor acts. The purpose of this article is to review selectively the literature pertaining to two of the six major DA mechanisms. The principal question addressed in this article is, "How do DA mechanisms promote neurobehavioral consequences such as the symptoms of schizophrenia?" Other topics covered include Parkinson's disease, Huntington's chorea, and intracranial self-stimulation drive-reward mechanisms. These clinical features and their possible underlying basis are discussed in terms of evidence suggesting that DA neurotransmitter alterations are likely to be several steps removed from a primary causal locus, which has more than one biochemical or neurotransmitter mechanism.

Animals

Histological evaluation of neural damage from electrical stimulation: considerations for the selection of parameters for clinical application.

The relationship of charge density per phase, or QD/ph (expressed in units of microcoulombs per cm2 per phase of the charge-balanced wave form), and total charge (QDt) to neural damage has been investigated by light and electron microscopy after surface stimulation of the parietal cortex in normal cats. QD/ph values ranging from 40 to 400 were achieved by varying several stimulus parameters. The least amount of neural damage in this study was observed at QD/ph 40). The extent of neural injury at stimulated sites increased with the charge density and was evident as disruption of cell membranes, intracytoplasmic vacoulation, an increasing glycogen content, the deposition of intracellular calcium hydroxyapatite, and neuronal and astrocytic degeneration. Although individual factors contributing to neural damage are isolated with difficulty, charge density and total charge seem to be predominant among the contributing parameters. In view of these findings, recommendations have been made for the selection of electrical stimulus parameters to be used in central nervous system prostheses.

Animals

A computerized microstereotactic method to approach, 3-dimensionally reconstruct, remove and adjuvantly treat small CNS lesions.

The authors update a novel method recently utilized in humans with various CNS pathology for stereotactic localization, removal, and adjuvant therapy of small CNS lesions using additional computer processing of the date from a GE 8800 CT Scanner. Multiple computer algorithms developed at Cal Tech enhance regions of interest by filtering, magnifying, color-coding and 3-dimensional reconstruction based on routine CT scans. This stereotactic approach is calculated by the computer and coordinates are mated to a modified head fixation system; small lesions can be removed with the apparatus described herein under direct binocular vision with minimal tissue damage. This technique may offer the possibility of successful secondary application of adjuvant therapy to, particularly, a CNS glioma site.

Brain

Current neuropsychological approaches in assessment, rehabilitation, and clinical research of central nervous system disorders.

A current review of selected clinical neuropsychological approaches in the assessment, rehabilitation, and clinical research of central nervous system (CNS) disorders is presented. Clinical neuropsychology occupies a unique place among the sciences of the human nervous system. Over the past 50 years it has been concerned mainly with brain systems involving human psychological activity and its organization and how these systems are altered upon disturbances in brain-behavior functions. The field of clinical neuropsychology differs from other groups of neurological disciplines in that its major goal to introduce selected neuropsychological functions involving the higher cortex, to discriminate between functional and structural disorders, to standardize the collection of base line information needed in assessment of the efficacy of rehabilitation techniques, and to define the role of neuropsychology in building conceptual models of the brain's functional organizaton from research. The topics covered are neuropsychological test batteries, the systems of Luria and Halstead-Reitan, implications for rehabilitation planning, and current research and its application for the future use of neuropsychoclogical test batteries.

Central Nervous System Diseases

Computerized three-dimensional stereotaxic removal of small central nervous system lesions in patients.

The authors describe the results of their recently reported computer-based stereotaxic surgical technique for the indentification, enhancement, three-dimensional reconstruction, localization, and removal of small central nervous system lesions. This technique has been applied to patients with various types of central nervous system pathology, and representative cases are reported.

Adenocarcinoma

A microstereotactic approach to small CNS lesions. Part I. Development of CT localization and 3-D reconstruction techniques.

The authors describe a newly designed and utilized stereotactic methodology for the removal of central nervous system lesions as small as a few millimeters in diameter. These small lesions are detected and localized by non-invasive computerized axial tomography (GE 8800 scanner) with additional computer processing of the digital data by means of a PDP-1145 computer. Multiple computer algorithms have been developed to enhance regions of interest on CT scans by three-dimensional reconstruction and magnification techniques. This same data can then be used to calculate a stereotactic approach to a small CNS lesion. The stereotactic approach coordinates are then mated to a head fixation system modified from the Reichert-Mundinger stereotactic apparatus enabling information transfer from CT scan to the stereotactic surgical system. These small CNS lesions, as small as 5 mm, can be removed with the apparatus described herein under direct binocular 3-D vision with minimal tissue damage, through a small trephine craniotomy or burr hole. Newly designed instruments and instruments in the process of being developed are mounted on a micromanipulator attached to the Riecher-Mundinger frame for guidance at surgery. These new instruments include stereoendoscopes with xenon arc illumination, multiple tissue expanders for exposing the operative site, a radiation tracer probe, a rotary-sucker extractor, and multiple other small instruments for operating and removal of blood and tissue from small CNS lesions. The stereotactic frame accurately defines all areas of the cranium in three-dimensional coordinates, and its combination with the micromanipulator-instrument assembly enables the site of any small CNS lesion, the three-dimensional coordinates of which have been located by additional computer processing of the CT digital data, to be accurately approached by the stereotactic guide micromanipulator assembly. The instrument described herein allows removal of very small tumor burdens, and opens the possibility for successful secondary application of adjuvant immunotherapy to a CNS tumor site as described in part II of this paper.

Brain

A microstereotactic approach to small CNS lesions. Part II; Adjuvant therapy. Clinical potential and toxicity of intraventricular lymph infusion.

A technique is described for adjuvant therapy of small central nervous system tumors after their removal. The feasibility of direct application of lymphocytes from the thoracic duct to the ventricular system of cats has been explored. Reduction of the antigenic mass by techniques described in part I of this paper is probably crucial. Patients with gliomas are known to have circulating tumor-specific lymphocytes which may not have direct access to the CNS. This study demonstrated no toxicity from the chronic intraventricular infusion of thoracic duct lymph in cats.

Animals

Development of a new implantable bio-telestimulator.

The authors describe preliminarily an implantable bio-stimulating device for stimulation of peripheral nerves and the central nervous system. The receiving unit is totally implantable. The system works on radiofrequency transcutaneous coupling across the skin. This new telestimulating device has a wider band width and more flexibility than units currently being used in neurosurgery. The unit is independent of coupling efficiency and is designed to accept any symmetrical or nonsymmetrical waveform within limits listed in this presentation. The unit is designed so as to provide this waveform as a constant current signal at the output of the receiver.

Animals

Benign intracranial hypertension in pregnancy.

Benign intracranial hypertension, an unusual case of headaches, was associated with pregnancy in a gravid female with the chief complaint of headache. Symptoms resolved after three days of prednisone therapy. In benign intracranial hypertension, the possibilities of intracranial mass lesions, intracranial infection, obstruction of the cerebral ventricles, and hypertensive encephalopathy are excluded by evaluation with skull films, computerized axial tomography, electroencephalography and lumbar puncture. The only symptom may be headache and the only physical sign, papilledema. Therefore, neurological examination must include visualization of the fundi.

Adult

Brain stimulation and reward: "pleasure centers" after twenty-five years.

"Self-stimulation" is a phenomenon whereby an animal (including a human being) will repeatedly stimulate its brain electrically, sometimes to the point of exhaustion. This phenomenon is robust and readily reproducible in many areas of the brain, particularly in nuclei and fiber tracts known to be monoaminergic, and it has been the basis for the study of reinforcement and learning mechanisms in the brain. The last 25 years of work on intracranial self-stimulation is reviewed with an emphasis on mechanisms, primarily catecholaminergic. Implications for learning and pain mechanisms are discussed.

Acetylcholine

Evaluation of electrode array material for neural prostheses.

Matrix support materials for brain surface electrodes used in neuroprosthetic applications were evaluated after chronic subdural implantation over the parietal cortex of the cat. Four types of array fabricated with Silastic, Dacron mesh, or platinum wire annuli were implanted for periods ranging from 5 weeks to 1 year. We evaluated the arrays by access resistance measurements and gross and histological observations of the tissue beneath both nonstimulated and stimulated electrodes. A porous type matrix constructed of Dacron mesh proved to be the superior design because of its minimal compression of the cortical surface, facility of handling during implantation and autopsy, and satisfactory electrical characteristics provided by a good electrode-brain interface. (Neurosurgery, 5: 681--686, 1979).

Animals

Microsurgical cannulation of the thoracic duct in cats. Technical note.

The authors describe a new technique for the microsurgical cannulation of the thoracic duct. A small silastic tube is utilized which can be joined to a subcutaneously implanted one-way flow, CSF, Ommaya-type reservoir. Extended drainage is avoided. No deletion or alteration of major venous channels occurs. Lymph collection is accomplished by tapping the subcutaneous reservoir with a small-bore needle.

Animals