Electroencephalographic and rheoencephalographic studies of cerebral meningovascular tumors

For forty-one meningovascular tumors, which were verified pathologically and anatomically, the authors tried to find electroencephalographic and rheoencephalographic criteria of the recognition of the location and particular kind of tumor. Electroencephalographic results obtained for meningovascular tumors are characterized by insignificant to moderate general and focal alterations. The results of rheoencephalographic examinations were found to add to the possibilities of topical diagnosis. Angioarchitectural characteristics of the rheoencephalographic curve, together with bioelectric phenomena, enabled a specific diagnosis to be established for twenty-four of the meningovascular tumors.     

Changes of the visual field with cerebral tumors]

Neurosurgical material of 1,746 tumours is reviewed for the relations between operative and post mortem localization of cerebral tumours and pathological findings of isopteric perimetry; and the incidence of defects of the visual field with the different localizations of tumours is discussed. The aim was to localize the tumours as accurately as possible. At least in brain tumour patients the defect of the visual field does not allow conclusions on the level of lesions to the visual pathway. Only the superior quadranopsia is important for the temporal localization.     

Retention of orienting reaction habituation in patients with epileptogenic cerebral tumors

An electrographic study on habituation of the somatic (EMG), autonomic (finger plethysmogram, galvanic skin reaction, respiration, pulse) and EEG (acoustic evoked potential and EEG-blocking reaction) components of the orienting reaction elicited by a repetitive auditory stimulus during successive (weekly) sessions was performed in 41 patients with epileptogenic cerebral tumors (ECT) and in 128 control subjects. The study evidenced significant retention disturbances of orienting reaction habituation (i.e., of learning), the “saving” of stimulations, achieved from one session to the other to obtain the habituation criterion, being lesser in ECT patients than in control subjects. The severity of habituation retention disturbances depended on the tumor site and size, as well as on the electro-clinical form and frequency of seizures. Thus, the most marked habituation retention disturbances were found in patients with temporal or predominantly temporal epileptogenic tumors, in cases with large hemispheric epileptogenic tumors (over 6 cm), in patients with generalized or generalized plus partial seizures, as well as in those with frequent (daily) seizures.     

Changes of visual fields in intracranial tumors outside the cerebral hemispheres]

Based on neurosurgical material of 1,746 brain tumours, the changes of the visual field determined by isopteric perimetry are discussed with their significe with regard to tumours of corpus callosum, lateral ventricles, brain stem ganglia, IIIrd ventricle, region of the sella and adjacent areas as well as posterior fossa. The proportion of unilateral blindness with primary opticus atrophy and of skotomas is strinkingly high, so that in cases of loss of vision, not readily explicable by ophthalmology, as well as in unilateral defects of the visual field, intracranial processes must be thought of.     

Results of cerebral computer tomography in the diagnosis of tumors of the sella region

Computer tomography (CT) is an important aid to the diagnosis of sella tumours because it images the tumour directly and delineates it from the healthy tissues. The tumour type can be identified to a certain extent, but angiography is necessary to distinguish tumours from aneurysms. The study is based on 140 surgical and histological examinations, the results of which were compared wit those obtained by CT. Suprasellar inflammations could always be identified by CT. Although intrasellar tumours may be identifiable by CT if full use is made of the potential of the equipment, negative CT results do not necessarily mean that there is no tumour. The diagnostic validity of the method is restricted by the absence of "standards", against which the variable images of intrasellar structures can be judged, and the restricted resolution of CT.     

On fineness of grain

A central job for propositions is to be the objects of the attitudes. Propositions are the things we doubt, believe and suppose. Some philosophers have thought that propositions are sets of possible worlds. But many have become convinced that such an account individuates propositions too coarsely. This raises the question of how finely propositions should be individuated. An account of how finely propositions should be individuated on which they are individuated very finely is sketched. Objections to the effect that the account individuates propositions too finely are raised and responses to the objections are provided. It is also shown that theories that try to individuate propositions less finely have serious problems.     

Fracture mechanisms of symmetrical tilt grain boundaries

The mechanisms of failure of symmetrical tilt boundaries have been investigated using an atomistic technique. The fracture process advances in steps that are related to the structural unit of the symmetrical tilt grain boundary. These boundaries are shown to fail through a combined mechanism involving dislocation emission in certain regions of the structural unit, followed by microcleavage, and again dislocation emission. The overall toughness of the boundaries is given by the combination of the toughness of these two processes.     

Strategic regulation of grain size in memory reporting

To increase their report accuracy, rememberers may either withhold information that they feel unsure about or provide relatively coarse information that is unlikely to be wrong. In previous work (A. Koriat & M. Goldsmith, 1996c), the authors delineated the metacognitive monitoring and control processes underlying the decision to volunteer or withhold particular items of information (report option) and examined how these processes are used in the strategic regulation of memory accuracy. This article adapts that framework to address control over the grain size (precision-coarseness) of the information that people report. Results show that rememberers strategically regulate the grain of their answers to accommodate the competing goals of accuracy and informativeness. The metacognitive processes underlying this regulation are elucidated.     

Effect of varying the duration of grain presentation on automaintenance

In a series of three experiments the effects of variation in grain duration on automaintenance were evaluated. In the first experiment, key illumination was followed by grain only when pigeons did not peck the key. Each subject was exposed to 2-, 4-, and 8-second feeder durations in blocks of 10 sessions. Subjects pecked on a high percentage of trials at all feeder durations. The mean peck latency was shorter in the 8-second condition than in the two other conditions in five of six subjects. The conditional probability of pecking given successive keylight-grain pairings did not increase as the number of pairings increased. The second experiment was identical to the first, except that key pecking had no scheduled consequence. Under these conditions, all three subjects showed substantial responding. The recorded measures showed no systematic relationship to feeder duration in this study. In the third experiment, two different stimuli were followed by feeder presentations of either identical (2- or 8-second) or different (2- and 8-second) durations within each session. Subjects tended to respond sooner and with a higher overall rate in the presence of the stimulus associated with the longer feeder duration only when different feeder durations were presented within the same session. This result was confirmed by direct observation of the pigeons. The results of these experiments suggest that the effects of varying grain duration may be small, compared to the effects of varying other variables. The results also suggest that the location as well as the frequency of pecking may be an important measure in the analysis of factors controlling the pigeon's key peck.     

Patterns of cerebral organization

An analysis of the concurrent incidence of aphasia and spatial disorder in 270 patients with unilateral brain damage suggests that the two functions are statistically independent. These data can also be used to estimate the distribution of left, right, and bilateral representation of linguistic and spatial functions in the population. In right-handers, sex affects the pattern of cerebral asymmetries, while the familial history of sinistrality has a stronger effect on the pattern of cerebral asymmetries in left-handers. These findings suggest that complementary specialization exists only as a statistical norm: It is suggested that differences in complementary and noncomplementary specialization may underlie individual differences in cognitive skills.     

Kinetics of interstitial segregation in Cottrell atmospheres and grain boundaries

Trapping of interstitial (e.g. carbon) atoms is driven by the reduction in energy in the system. Diffusion of interstitials, together with their trapping in dislocation cores and/or grain boundaries, is studied by the thermodynamic extremal principle. In addition to the total Gibbs energy, a well-established formulation of the total dissipation is applied. Dimension-free evolution equations are derived, whose solution is well approximated by an easy to handle kinetic equation. Cottrell’s power law can be verified in the initial stage.     

Stimulus correlates of visual pattern discrimination and the problem of grain

Attention, Perception, & Psychophysics - A recent paper by V. J. Polidora (1966) is criticized on the basis that the experimental design did not provide an adequate test of the usefulness of 15...