Interest on consciousness is growing, but how it arises in the brain remains fundamentally unsolv... more Interest on consciousness is growing, but how it arises in the brain remains fundamentally unsolved. The variety of brain mechanisms, the impairment of which is observed in DoC, has implication in neuroscience, in suggesting that consciousness results of a complex functional arrangement interacting with but distinct from other higher brain processes. Neuroimaging has challenged the current criteria for consciousness and responsiveness by documenting residual high-level aspects of brain activity in DoC. The clinical standards to classify patients as conscious or unconscious are questioned, and neurologists are confronted with unresolved issues about diagnosis, pain, and predictability of recovery. The epistemological issue remains the definition of consciousness beyond subjective feeling, verbal report, probabilistic inference, and pragmatic principles. Classification rests on responsiveness in the absence of a theory about consciousness inclusive of its quantitative characterization. Proper definitions for and an up-to-date scrutiny of the available descriptors are needed to think scientifically about consciousness.
Introduction: It has long been known that many people in space experience sudden phosphenes, or l... more Introduction: It has long been known that many people in space experience sudden phosphenes, or light flashes. Although it is clear that they are related to high-energy particles in the space radiation environment, many details about them are still unknown. In an effort to gain more knowledge about the light flashes, a study was initiated to collect information from people who have recently flown in space. Method: A survey conducted by anonymous questionnaire was performed among astronauts regarding their experience of sudden light flashes in space. In all, 98 surveys were distributed to current NASA and ESA astronauts. Results: Among the 59 respondents, 47 noticed them sometime during spaceflight. Most often they were noted before sleep, and several people even thought the light flashes disturbed their sleep. The light flashes predominantly appear white, have elongated shapes, and most interestingly, often come with a sense of motion. The motion is described as sideways, diagonal, or in-out, but never in the vertical direction. Discussion: Comparisons with earlier studies of light flashes in space and several ground-based studies during the 1970s are made. One interesting observation from this is that it seems that a small fraction of the light flashes is caused by Cherenkov radiation, while the majority is probably caused by some kind of direct interaction with elements in the retina.
There has been clinical and experimental evidence that cholinergic compounds and precursors of ch... more There has been clinical and experimental evidence that cholinergic compounds and precursors of choline are potentially useful in the treatment of dementia. Anticholinergic compounds have also been proposed as a possible acute model for pharmaco-EEG studies focussed on CNS aging. Single doses of scopolamine (0.25-0.75 mg i.m.) and a matching placebo were administered to 8 young healthy volunteers. Quantitative EEG recordings and neuropsychological testing were performed in baseline conditions prior to and 30, 90 and 120 min after drug administration. Scopolamine induced a dose-related increase of relative power in low- and high-frequency components and a decrease in the range 8.0-13.5 Hz and in total signal power. These modifications were found to be limited to the posterior scalp electrode derivations and were observed from the 90-min control onwards. Concomitantly, there was a significant impairment in the subjects' response to neuropsychological testing after the administration of 0.50 and 0.75 mg of scopolamine. At a dose of 0.75 mg, volunteers complained about subjective symptoms which were definitely unpleasant. The effects of this dose on the EEG and the neuropsychological status did not differ significantly from those observed after a dose of 0.50 mg. As regards dose and tolerance, 0.50 mg of scopolamine administered intramuscularly appears to be a suitable dose for pharmaco-EEG studies.
ABSTRACT The SilEye-2 particle telescope was placed on Mir in October 1997 and has been working s... more ABSTRACT The SilEye-2 particle telescope was placed on Mir in October 1997 and has been working since June 2000. It consists of 6 active silicon strip layers which allow charge and energy identification of cosmic ray particles in the energy range ~ 40 - 200 MeV/n. The detector is attached to a helmet with mask, which prevented light from reaching the cosmonaut's eyes. The phenomenon of Light Flashes (LF) in eyes for people in space has been investigated onboard Mir space station. Data on particles hitting the eye have been collected with the SilEye-2 detector, and correlated with human observations. In the period 98/99, we have 17 sessions with simultaneous SilEye-2 detector and LF observation data. 116 LFs were seen during about 800 minutes of observation. An additional 30 LFs were noted during three observation sessions amounting to 250 minutes without the silicon detector. In all 59414 protons and 479 nuclei passed through eyes were registered with SilEye-2 telescope. It is found, that a nucleus are the main reason caused a LF's in the radiation environment of Mir space station and in microgravitation conditions, the proton probability to cause LF is almost three orders of magnitude less.
The SilEye-2 particle telescope was placed on Mir in October 1997 and has been working since June... more The SilEye-2 particle telescope was placed on Mir in October 1997 and has been working since June 2000. It consists of 6 active silicon strip layers which allow charge and energy identification of cosmic ray particles in the energy range ~ 40 – 200 MeV/n. The detector is attached to a helmet with mask, which prevented light from reaching the cosmonaut’s eyes. The phenomenon of Light Flashes (LF) in eyes for people in space has been investigated onboard Mir space station. Data on particles hitting the eye have been collected with the SilEye-2 detector, and correlated with human observations. In the period 98/99, we have 17 sessions with simultaneous SilEye-2 detector and LF observation data. 116 LFs were seen during about 800 minutes of observation. An additional 30 LFs were noted during three observation sessions amounting to 250 minutes without the silicon detector. In all 59414 protons and 479 nuclei passed through eyes were registered with SilEye-2 telescope. It is found, that a nucleus are the main reason caused a LF’s in the radiation environment of Mir space station and in microgravitation conditions, the proton probability to cause LF is almost three orders of magnitude less.
ABSTRACT The suitability of quantitative EEG methodologies in the estimation of cerebral bioavail... more ABSTRACT The suitability of quantitative EEG methodologies in the estimation of cerebral bioavailability and central action of antiepileptic compounds has been tested in 44 patients during single-drug therapy with ethosuximide, diphenylhydantoin, valproic acid, or phenobarbital. Clinical conditions were monitored, and EEG and plasma samples were collected periodically during long-term treatment. The background EEG activity was quantified by spectral power analysis on signal epochs free from specific epileptic phenomena. Drug plasma concentrations were determined by gas liquid chromatographic methods. Consistent EEG modifications were observed during treatment with ethosuximide, valproic acid and phenobarbital, and found to be related to plasma concentration only in the case of phenobarbital. No changes were detected during therapy with diphenylhydantoin.
Interest on consciousness is growing, but how it arises in the brain remains fundamentally unsolv... more Interest on consciousness is growing, but how it arises in the brain remains fundamentally unsolved. The variety of brain mechanisms, the impairment of which is observed in DoC, has implication in neuroscience, in suggesting that consciousness results of a complex functional arrangement interacting with but distinct from other higher brain processes. Neuroimaging has challenged the current criteria for consciousness and responsiveness by documenting residual high-level aspects of brain activity in DoC. The clinical standards to classify patients as conscious or unconscious are questioned, and neurologists are confronted with unresolved issues about diagnosis, pain, and predictability of recovery. The epistemological issue remains the definition of consciousness beyond subjective feeling, verbal report, probabilistic inference, and pragmatic principles. Classification rests on responsiveness in the absence of a theory about consciousness inclusive of its quantitative characterization. Proper definitions for and an up-to-date scrutiny of the available descriptors are needed to think scientifically about consciousness.
Introduction: It has long been known that many people in space experience sudden phosphenes, or l... more Introduction: It has long been known that many people in space experience sudden phosphenes, or light flashes. Although it is clear that they are related to high-energy particles in the space radiation environment, many details about them are still unknown. In an effort to gain more knowledge about the light flashes, a study was initiated to collect information from people who have recently flown in space. Method: A survey conducted by anonymous questionnaire was performed among astronauts regarding their experience of sudden light flashes in space. In all, 98 surveys were distributed to current NASA and ESA astronauts. Results: Among the 59 respondents, 47 noticed them sometime during spaceflight. Most often they were noted before sleep, and several people even thought the light flashes disturbed their sleep. The light flashes predominantly appear white, have elongated shapes, and most interestingly, often come with a sense of motion. The motion is described as sideways, diagonal, or in-out, but never in the vertical direction. Discussion: Comparisons with earlier studies of light flashes in space and several ground-based studies during the 1970s are made. One interesting observation from this is that it seems that a small fraction of the light flashes is caused by Cherenkov radiation, while the majority is probably caused by some kind of direct interaction with elements in the retina.
There has been clinical and experimental evidence that cholinergic compounds and precursors of ch... more There has been clinical and experimental evidence that cholinergic compounds and precursors of choline are potentially useful in the treatment of dementia. Anticholinergic compounds have also been proposed as a possible acute model for pharmaco-EEG studies focussed on CNS aging. Single doses of scopolamine (0.25-0.75 mg i.m.) and a matching placebo were administered to 8 young healthy volunteers. Quantitative EEG recordings and neuropsychological testing were performed in baseline conditions prior to and 30, 90 and 120 min after drug administration. Scopolamine induced a dose-related increase of relative power in low- and high-frequency components and a decrease in the range 8.0-13.5 Hz and in total signal power. These modifications were found to be limited to the posterior scalp electrode derivations and were observed from the 90-min control onwards. Concomitantly, there was a significant impairment in the subjects' response to neuropsychological testing after the administration of 0.50 and 0.75 mg of scopolamine. At a dose of 0.75 mg, volunteers complained about subjective symptoms which were definitely unpleasant. The effects of this dose on the EEG and the neuropsychological status did not differ significantly from those observed after a dose of 0.50 mg. As regards dose and tolerance, 0.50 mg of scopolamine administered intramuscularly appears to be a suitable dose for pharmaco-EEG studies.
ABSTRACT The SilEye-2 particle telescope was placed on Mir in October 1997 and has been working s... more ABSTRACT The SilEye-2 particle telescope was placed on Mir in October 1997 and has been working since June 2000. It consists of 6 active silicon strip layers which allow charge and energy identification of cosmic ray particles in the energy range ~ 40 - 200 MeV/n. The detector is attached to a helmet with mask, which prevented light from reaching the cosmonaut's eyes. The phenomenon of Light Flashes (LF) in eyes for people in space has been investigated onboard Mir space station. Data on particles hitting the eye have been collected with the SilEye-2 detector, and correlated with human observations. In the period 98/99, we have 17 sessions with simultaneous SilEye-2 detector and LF observation data. 116 LFs were seen during about 800 minutes of observation. An additional 30 LFs were noted during three observation sessions amounting to 250 minutes without the silicon detector. In all 59414 protons and 479 nuclei passed through eyes were registered with SilEye-2 telescope. It is found, that a nucleus are the main reason caused a LF's in the radiation environment of Mir space station and in microgravitation conditions, the proton probability to cause LF is almost three orders of magnitude less.
The SilEye-2 particle telescope was placed on Mir in October 1997 and has been working since June... more The SilEye-2 particle telescope was placed on Mir in October 1997 and has been working since June 2000. It consists of 6 active silicon strip layers which allow charge and energy identification of cosmic ray particles in the energy range ~ 40 – 200 MeV/n. The detector is attached to a helmet with mask, which prevented light from reaching the cosmonaut’s eyes. The phenomenon of Light Flashes (LF) in eyes for people in space has been investigated onboard Mir space station. Data on particles hitting the eye have been collected with the SilEye-2 detector, and correlated with human observations. In the period 98/99, we have 17 sessions with simultaneous SilEye-2 detector and LF observation data. 116 LFs were seen during about 800 minutes of observation. An additional 30 LFs were noted during three observation sessions amounting to 250 minutes without the silicon detector. In all 59414 protons and 479 nuclei passed through eyes were registered with SilEye-2 telescope. It is found, that a nucleus are the main reason caused a LF’s in the radiation environment of Mir space station and in microgravitation conditions, the proton probability to cause LF is almost three orders of magnitude less.
ABSTRACT The suitability of quantitative EEG methodologies in the estimation of cerebral bioavail... more ABSTRACT The suitability of quantitative EEG methodologies in the estimation of cerebral bioavailability and central action of antiepileptic compounds has been tested in 44 patients during single-drug therapy with ethosuximide, diphenylhydantoin, valproic acid, or phenobarbital. Clinical conditions were monitored, and EEG and plasma samples were collected periodically during long-term treatment. The background EEG activity was quantified by spectral power analysis on signal epochs free from specific epileptic phenomena. Drug plasma concentrations were determined by gas liquid chromatographic methods. Consistent EEG modifications were observed during treatment with ethosuximide, valproic acid and phenobarbital, and found to be related to plasma concentration only in the case of phenobarbital. No changes were detected during therapy with diphenylhydantoin.
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Papers by Walter Sannita