Fernando H Lopes da Silva

University of Amsterdam | UVA

Objectives: Childhood absence epilepsy (CAE) is a syndrome with well-defined electroclinical features but unknown pathological basis. An increased thalamic tonic GABA inhibition has recently been discovered on animal models (Cope et al., 2009), but its relevance for human CAE is unproven. Methods: We studied an 11-year-old boy, presenting the ty...

Background Already used at the incept of research on event-related potentials (ERP) over half a century ago, the arithmetic mean is still the benchmark for ERP estimation. Such estimation, however, requires a large number of sweeps and/or a careful rejection of artifacts affecting the electroencephalographic recording.New Method In this article we...

Intentions of specific motor movements are known to generate event-related (de)synchronization (ERD/ERS) patterns which may be interpreted as changes in the degree of synchronization of underlying neuronal networks. When activated, the neural populations in a certain region of the brain de-synchronize, leading to a decrease in the EEG power signal....

Recently we hypothesized that the intention to initiate a voluntary movement at free will may be related to the dynamics of hemodynamic variables, which may be supported by the intertwining of networks for the timing of voluntary movements and the control of cardiovascular variables in the insula. In the present study voluntary movements of 3 healt...

The leading reference on electroencephalography since 1982, Niedermeyer's Electroencephalography is now in its thoroughly updated Sixth Edition. An international group of experts provides comprehensive coverage of the neurophysiologic and technical aspects of EEG, evoked potentials, and magnetoencephalography, as well as the clinical applications o...

Epilepsy is a dynamic disease of neuronal networks. To understand how epileptic seizures occur, it is necessary to take into account that the brain of epileptic subjects is able to function in two very distinct modes: a normal state and a state characterized by abnormal oscillations, i.e. epileptic seizures. A main question is how the transition (i...

This chapter focuses on the basic physiological and biophysical aspects of how magnetic signals are generated in the brain. It begins with a brief description of the main features of magnetoencephalography as a method to study brain functions in man. It then discusses the main features of MEG, some basic notions of cellular neurophysiology and biop...

Systemic interactions in brain networks have been successfully studied in vivo using non-invasive methods such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), for many years. The rate-limiting step, however, is that each method can only map selective aspects of brain function, while missing other key aspects. Furth...

In this paper, we use co-registered EEG-fMRI during rest to investigate inter-subject-variability of BOLD signals in comparison with alpha-BOLD statistical parametric maps. A hierarchical clustering algorithm is used to detect spatial patterns of voxels showing correlated activity. The general- linear model is used to determine which of the identif...

The amount of experimental data concerning physiology and anatomy of the nervous system is growing very fast, challenging our capacity to make comprehensive syntheses of the plethora of data available. Computer models of neuronal networks provide useful tools to construct such syntheses. They can be used to interpret experimental data, generate exp...

Results of "in vivo" measurements of the skull and brain resistivities are presented for six subjects. Results are obtained using two different methods, based on spherical head models. The first method uses the principles of electrical impedance tomography (EIT) to estimate the equivalent electrical resistivities of brain (ρ_brain), skull...

Neuronal loss, gliosis and axonal sprouting in the hippocampal formation are characteristics of the syndrome of mesial temporal sclerosis (MTS). In the post-status epilepticus (SE) rat model of spontaneous seizures these features of the MTS syndrome can be reproduced. To get a global view of the changes in gene expression in the hippocampus we appl...

Reactive gliosis is a prominent morphological feature of mesial temporal lobe epilepsy. Because astrocytes express glutamate receptors, we examined changes in metabotropic glutamate receptor (mGluR) 2/3, mGluR5 and transforming growth factor (TGF)-beta in glial cells of the hippocampal regions in an experimental rat model of spontaneous seizures. R...

The hippocampal system, consisting of the hippocampus, subiculum, and adjacent parahippocampal region, is known to play an important role in learning and memory processes. It is also known that the originally proposed trisynaptic circuit is a simplified representation of the organization of this system. In this paper, we present evidence, both anat...

In central nerve terminals transmitter release is tightly regulated and thought to occur in a number of steps. These steps include vesicle mobilization and docking prior to neurotransmitter release. Intrasynaptic changes in vesicle distribution were determined by electron microscopical analysis and neurotransmitter release was monitored by biochemi...

In many EEG laboratories in Europe, intermittent photic stimulation (IPS) is not performed routinely, and consequently, great variation exists in the type of photo stimulator used, the methodology employed, and the interpretation of the EEG curves, thus leading to different outcomes. It was decided to hold a consensus meeting with experts in the fi...

Patients with frontal-lobe epilepsy comprise the second largest group undergoing epilepsy surgery. It has been reported that the difficulty in localizing the epileptogenic zone in these patients is due to the rapid spread of the epileptiform activity within the frontal lobe and to adjoining regions of the brain. We formulated the question of whethe...

Studies using stereo-EEG (SEEG) and electrocorticography (ECoG) should not only identify a patient's epileptogenic zone, but also should provide prognostic information for surgical outcome. In this respect, seizure-offset patterns have so far been the subject of only one study, in which they were shown to be associated with poor outcome when record...

Established in 1982 as the leading reference on electroencephalography, Drs. Niedermeyer's and Lopes da Silva's text is now in its thoroughly updated Fifth Edition. An international group of experts provides comprehensive coverage of the neurophysiologic and technical aspects of EEG, evoked potentials, and magnetoencephalography, as well as the cli...

The question was investigated whether longlasting transients of activity, observed to occur in the intact cerebral cortex (EEG slow (δ) waves and ‘K’ complexes) as well as in isolated tissues cultured in vitro, can also emerge in a model network of excitatory and inhibitory cells. We show that such transients can indeed occur even if the cells do n...

The effect of long-term potentiation (LTP) on endogenous amino acid release from rat hippocampus slices was studied. LTP was induced in vivo by application of a tetanus (200 Hz, 200 ms) to the Schaffer collateral fibers in unanesthetized rats. Endogenous release of glutamate and -aminobutyric acid (GABA) was investigated 60 min after tetanization i...

The question was investigated whether long-lasting transients of activity, observed to occur in the intact cerebral cortex (EEG slow (delta) waves and 'K' complexes) as well as in isolated tissues cultured in vitro, can also emerge in a model network of excitatory and inhibitory cells. We show that such transients can indeed occur even if the cells...

The existence of a prominent electroencephalogram (EEG) activity within the theta frequency range (4–7 Hz) in the hippocampus has been one of the most studied rhythmic activities of the mammalian brain. However, in lower mammals the hippocampal EEG has a wider frequency range and may extend from 3 to 4 Hz up to 10 to 12 Hz. Therefore, it has become...

Experiments were carried out to test whether changes in the sensitivity of hippocampal pyramidal neurons to the neurotransmitters glutamate, GABA and noradrenaline may be associated with the establishment of an epileptogenic focus induced by kindling. The effects of iontophoretically applied neurotransmitters on the firing rate of single units were...

Afterdischarges (ADs) were elicited in the hippocampus of the rat under halothane anesthesia. Records were made along the septo-temporal axis of the hippocampal formation (dorsal (DHF), splenial (SP) and ventral (VHF) regions). For comparison records were also made from the contralateral DHF. The propagation of ADs was quantified using linear and n...

Field potentials elicited by electrical stimulation of the vomeronasal nerve were measured in the accessory olfactory bulb of the rabbit. Maps were made of the distribution of surface field potentials and of the corresponding depth profiles. The surface maps followed closely the contours of the accessory olfactory bulb: at the frontal border the fi...

Two different types of spontaneous interictal transients (SITs) have been found in the course of the development of an epileptogenic focus by Schaffer collateral kindling in the CA1 region of rat hippocampus. The first type has peak amplitudes of 250 microV up to 1 mV, a duration of about 80 msec and the same polarity as field potentials recorded f...

DOI: 10.1177/0271678X15618219 Studies in rodents suggest that flumazenil is a P-glycoprotein substrate at the blood-brain barrier. This study aimed to assess whether [11C]flumazenil is a P-glycoprotein substrate in humans and to what extent increased P-glycoprotein function in epilepsy may confound interpretation of clinical [11C]flumazenil studie...