GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-1106
    Keywords: Visual projection ; Cortex ; Geniculostriate pathway ; Hippocampus ; Temporal lobe ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-two patients with psychomotor epilepsy were implanted with depth electrodes along the axis of the mesial temporal lobe to identify an operable unilateral epileptic focus. Neuronal and field potentials were recorded in response to diffuse retinal illumination and clear short-latency responses were found in parahippocampal gyrus. These visual afferents in the mesial temporal lobe are assumed to be both from subcortical and cortical visual areas. There was a clear asymmetry in the ventral trajectory of the geniculostriate pathway as evidenced by asymmetric neuronal and field potential responses to brief flashes in right vs. left hippocampal gyrus and confirmed by a corresponding partial visual field deficit following therapeutic anterior temporal lobectomy. These results demonstrate that there is a retinotopic organization of fibers in the human geniculostriate pathway and that this pathway may have considerable variability in the anterior and ventral course these fibers take through the temporal lobe. These findings adequately account for the presence of direct projections from geniculate to hippocampal cortex and for unexpected hemianopsias with standard resections of the temporal lobe when there is a deviant detour of the geniculostriate pathway.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 11 (1964), S. 609-630 
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Das SystemTalairachs zur Untersuchung des Temporallappens bei psychomotorischer Epilepsie erwies sich als außerordentlich exakt bei der Implantation von Tiefenelektroden bei 8 Fällen von unkontrollierbaren Anfällen. 2. Es traten keine nennenswerten Komplikationen, wie Infektion, Vermehrung der Anfallshäufigkeit oder neurologische Ausfälle auf, mit Ausnahme einer bleibenden teilweisen homonymen Hemianopsie nach Ventrikulographie mit positiven Kontrastmitteln. 3. Es wurden über einen Zeitraum von 2 bis 3 Wochen nach Elektrodenimplantation klinische Beobachtungen, EEG-Ableitungen von der Kopfschwarte und Tiefenableitungen durchgeführt, sowohl im Wachals auch im Schlafzustand, unter elektrischen Reizungen und während spontaner und provozierter Anfälle. 4. Mit dieser Technik langdauernder Tiefenableitungen konnten bei 5 von 6 Fällen, die bei der Kopfschwartenableitung unabhängige temporale Spikes boten und bei einem Fall von psychomotorischer Epilepsie, der im Kopfschwarten-EEG keine pathologischen Veränderungen hatte, große einseitige epileptogene Foci lokalisiert werden. 5. Das Hauptgebiet elektrischer Spike-Tätigkeit waren der Pes hippocampi und Gyrus hippocampi, und zwar mehr als der Nucleus amygdalae. Bei Reizung dieser Gebiete ergaben sich die niedrigsten Schwellen für Nachentladung (afterdischarge) und Ausbreitung von Krampfströmen. Häufig wurden dabei die klinischen Anfallsmuster der Patienten reproduziert. 6. Mit Ausnahme eines Anfalles sind alle Patienten nach Entfernung des vorderen Temporallappens während einer Nachbeobachtungszeit von 2 bis 18 Monaten anfallsfrei geblieben. Die antikonvulsive Medikation wurde in allen Fällen postoperativ fortgesetzt.
    Abstract: Résumé 1. La méthode stéréotaxique deTalairach pour l'exploration du lobe temporal dans l'épilepsie psychomotrice a rendu parfaitement exacte l'implantation d'électrodes profondes permanentes chez huit malades ayant des crises dont on ne pouvait venir á bout. Des coupes en série de la partie antérieure du lobe temporal enlevé dans trois de ces cas, montrérent une correspondance étroite avec la localisation radiologique des électrodes. 2. Nulle complication importante n'est survenue telle qu'infection, augmentation des crises ou déficit nerveux, sauf un cas d'hémianopsie homonyme partielle aprés ventriculographie. 3. On a fait, pendant une période de deux á trois semaines aprés l'implantation des électrodes, des observations cliniques au cours de crises spontanées et provoquées, des électroencéphalogrammes en série et des enregistrements en profondeur á l'état de veille et pendant le sommeil avec stimulation électrique dans différents paramétres. 4. Des foyers épileptogénes unilatéraux majeurs ont été localisés par cette méthode de recherche á l'aide d'électrodes profondes et laissées en place, chez cinq des six malades présentant á l'électroencéphalographie des décharges temporales isolées et chez un malade ayant une épilepsie psychomotrice clinique sans anomalie électroencéphalographique aprés de nombreux tracés pris pendant les crises. 5. La zone d'anomalies électriques la plus importante s'est révélée être le pied de l'hippocampe et la circonvolution de l'hippocampe, plutôt que le noyau amygdaloïde. L'excitation de ces zones a montré le seuil post-critique le plus bas, et reproduisait souvent le type de crise convulsive du malade. 6. A l'exception d'une seule attaque convulsive, tous les malades qui subirent une lobectomie temporale antérieure, n'eurent plus de crise pendant des périodes de 2 á 18 mois. La médication antiépileptique a été poursuivie dans tous les cas.
    Notes: Conclusions 1. TheTalairach stereotactic system for exploration of the temporal lobe in psychomotor epilepsy has been found to be extremely accurate for implantation of chronic depth electrodes in eight patients with uncontrolled seizures. Completed serial sections of the resected anterior temporal lobe in three of these cases correlated closely with the roentgen localization of the electrodes. 2. No significant complications such as infection, increase in seizures, or neurologic deficit have arisen except for one instance of continued partial homonymous hemianopsia after positive ventriculography. 3. Clinical observations during spontaneous and induced convulsions, serial scalp electroencephalograms and depth recordings awake and during sleep, together with electrical stimulation at various parameters have been carried out over a period of two to three weeks after electrode implantation. 4. Major unilateral epileptogenic foci have been localized by this technique of prolonged depth electrode investigations in five of six patients with independent temporal spike discharges on scalp electroencephalograms and in one patient with clinical psychomotor epilepsy without scalp electroencephalographic abnormalities after numerous tracing during seizures. 5. The major area of electrical spike abnormality was the pes hippocampus and hippocampal gyrus rather than the amygdaloid nucleus. Stimulation of these areas showed lowest threshold of afterdischarge and propagation of seizure pattern and frequently reproduced the patient's clinical convulsive pattern. 6. Except for one convulsion, all of the patients after definitive anterior temporal lobectomy have been free of seizures during follow-up periods of 2 to 18 months. Anticonvulsant medications have been continued in all cases.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 82 (1990), S. 279-292 
    ISSN: 1432-1106
    Keywords: Human temporal lobe ; Hippocampus ; Amygdala ; Subiculum ; Electrical stimulation ; Evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Connections in the human mesial temporal lobe were investigated using brief, single pulses of electrical stimulation to evoke field potential responses in limbic structures of 74 epileptic patients. Eight specific areas within these structures were stereotactically targeted for study, including amygdala, entorhinal cortex, presubiculum, the anterior, middle and posterior levels of hippocampus and the middle and posterior levels of parahippocampal gyrus. These sites were studied systematically in order to quantitatively assess the response characteristics and reliability of responses evoked during stimulation of pathways connecting the areas. Specific measures included response probability, amplitude, latency and conduction velocities. The results are assumed to be representative of typical human limbic pathways since all recordings were made interictally and response probabilities across sites were not found to differ significantly between non-epileptogenic vs. identified epileptogenic regions. Field potentials ranging in amplitude from less than 0.1 to greater than 6.0 mV were evoked ipsilaterally, with mean onset latencies and conduction velocities ranging from 4.4 ms and 3.64 m/s in the perforant pathway connecting entorhinal cortex to anterior hippocampus to 24.8 ms and 0.88 m/s in the pathway connecting the amygdala and middle hippocampus. Stimulation of presubiculum and entorhinal cortex were most effective in evoking widespread responses in adjacent limbic recording sites, whereas posterior parahippocampal gyrus appeared functionally separated from other limbic sites since its probability of influencing ipsilateral sites was significantly lower than any other area. It was particularly noteworthy that stimulation did not evoke responses in any sites in contralateral hippocampal formation; even though a large number of sites were tested with bilateral implantation of homotopic electrodes. The absence of evidence for a functional contralateral limbic projection in the human brain stands in marked contrast to the anatomical and physiological evidence in lower animals for strong contralateral connections between subfields of the hippocampus via the hippocampal commissure. In addition, it correlates well with anatomical evidence for reduced hippocampal commissural connections in lower primates.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 85 (1991), S. 174-187 
    ISSN: 1432-1106
    Keywords: Amygdala ; Entorhinal cortex ; Hippocampus ; Subiculum ; Parahippocampal gyrus ; Electrical stimulation ; Evoked potentials ; Epilepsy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a previous investigation of functional limbic pathways in the human mesial temporal lobe, we found evidence for strong connections between ipsilateral mesial temporal structures, but none for contralateral functional connections (Wilson et al. 1990). In the present study, we focused specifically upon the question of functional commissural linkages between these structures by systematic stimulation of a total of 390 electrode placements in 74 epileptic patients with temporal lobe depth electrodes implanted for surgical diagnosis. Eight standard electrode placement regions were targeted: amygdala, entorhinal cortex, anterior, middle and posterior hippocampus, subicular cortex, middle parahippocampal gyrus, and posterior parahippocampal gyrus. Three to six electrodes were implanted bilaterally in each patient, and each electrode was individually stimulated while recording from all the other sites. Out of the 390 electrodes stimulated, 78% were effective in evoking clear responses in adjacent ipsilateral structures, and 75% of 581 ipsilateral recording sites were responsive to stimulation. Only one of the stimulated electrode sites was effective in evoking responses in contralateral recording sites, and only two of 511 contralateral recording sites were responsive to that stimulation. The effective stimulation site was in presubicular cortex, and the responsive contralateral recording sites were in entorhinal and presubicular cortices. Response to this stimulation site was intermittent and variable in latency. The relative ease of obtaining functional verification of significant ipsilateral anatomical pathways in the human limbic system, and the sharply contrasting difficulty of functionally activating commissural pathways to contralateral limbic sites are discussed in the context of decreases in hippocampal contribution to commissural pathways in the primate brain compared to sub-primate mammals, and the significance of this change to normal limbic system function as well as to mechanisms of seizure spread in epilepsy.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 279-288 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This research is part of a continuing program for the development of a coaxial depth electrode for research and diagnostic studies of neurological diseases. The requirements for this electrode include (1) strength and resistance to buckling sufficient to ensure self-forced penetration of brain tissue to a depth of 6 cm; (2) biocompatibility of the materials employed; (3) resistance to brittle fracture; and (4) a total diameter of less than 200 μm to minimize tissue damage. Earlier synthesis efforts using chemical vapor deposition techniques have been successful, although the process yield was 40% and an outer insulating layer had yet to be deposited. Plasma polymerization processes have been employed to realize an increase in the yield and provide an outer insulating layer. The starting material is W-26 at.% Re wire, nominally 125 μm in diameter. Hexamethyldisilazane (CH3)3SiNHSi(CH3)3 is used to deposit the insulating layers. The paper describes factors influencing the choice of materials, deposition techniques, and properties of electrodes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...