PubMed · 14897671
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1952-03-08. OFFNER electroencephalograph, type D, accepted.. https://pubmed.ncbi.nlm.nih.gov/14897671/
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Due to the multidisciplinary character of psychophysiology, the problem of comparability of psychological and physiological phenomena of different natures and levels of organization has always been raised. This requires the interaction of theory and methodology to appropriately address the specifics of the psychophysiological paradigm, all the while maintaining their grounding in the actual psychological and physiological concepts. The history of EEG studies of mental activity shows that a weak theoretical basis at certain stages can result not only in methodological crises but can also affect empirical data collection and interpretation. An adequate theory can lend strong support to the methodology with "brain-oriented" structuring of psychological tasks and such a theory improves the neurophysiological informative value of the EEG parameters referring to the psychological characteristics of mental processes etc. On the other hand, the great importance of the EEG recording and processing techniques can result in overrating technological progress, hence frequently holding back meaningful interpretation and construction of a comprehensive psychophysiological conceptual framework. This in turn causes demands for higher material and intellectual outlays, due to overspecialization in research, and results in work duplication as well as the creation of a fragmentary knowledge structure. This article illustrates how the multidisciplinary interaction of theory and methodology, when focused on theoretical problems, can yield a series of concepts with escalating levels of integration, bringing together such different branches of psychophysiology as the study of functional states and of individual differences. As a result, this extends the theoretical model based on normal material to encompass borderline constitutional psychopathology.
Despite good seizure outcome with temporal lobectomy, postoperative impairment of verbal memory remains unsolved. To address this problem we developed a new method, applying the rationale of multiple subpial transection (MST) to the hippocampus. The inferior ventricle is accessed without disrupting the neuronal pathways related to verbal memory. Intraoperative electrocorticography is recorded over the hippocampus and amygdala. After the extent of the epileptic area is determined, multiple transections of the pyramidal layer under the alveus is performed using specially designed ring transectors. After this procedure, epileptic discharges from the hippocampus can be completely abolished. Of 21 cases undergoing this operation, 12 left-sided and nine right-sided, 17 were followed up for more than one year. Fourteen (82%) are seizure free, two (12%) have rare seizures, and one (6%) has significantly improved. Of eight patients who underwent a battery of neuropsychometric tests both before and after left hippocampal transection, postoperative verbal memory was completely preserved in seven cases, and one transiently worsened patient recovered within 6 months. However, these results are still preliminary as the number of patients is small and the follow-up time short. The accumulation of cases and follow-up of greater duration will be necessary to precisely confirm the efficacy of this new technique.
An advanced characterization of the complicated dynamical system brain is one of science's biggest challenges. Nonlinear time series analysis allows characterizing nonlinear dynamical systems in which low-dimensional nonlinearity gives rise to complex and irregular behavior. While several studies indicate that nonlinear methods can extract valuable information from neuronal dynamics, others doubt their necessity and conjecture that the same information can be obtained using classical linear techniques. To address this issue, we compared these two concepts, but included furthermore a combination of nonlinear measures with surrogates, an approach that has been designed to specifically focus on nonlinearity. As a benchmark we used the discriminative power to detect the seizure-generating hemisphere in medically intractable mesial temporal lobe epilepsy. We analyzed intracranial electroencephalographic recordings from the seizure-free interval of 29 patients. While the performance of both linear and nonlinear measures was weak, if not insignificant, a very high performance was obtained by the use of surrogate-corrected measures. Focusing on nonlinearity by using a combination of nonlinear measures with surrogates appears as the key to a successful characterization of the spatial distribution of the epileptic process.