Impairment of odor recognition in Parkinson's disease caused by weak activations of the orbitofrontal cortex.

Olfactory dysfunction and abnormalities of olfactory brain structures are found in patients with Parkinson's disease (PD), and a number of studies have reported that olfactory dysfunction is caused by abnormalities of the central olfactory systems. We previously analyzed electroencephalograms (EEGs) and respiration simultaneously in normal subjects while testing for detection and recognition of odors. We identified changes in respiration pattern in response to odor stimuli and found inspiratory phase-locked alpha oscillations (I-alpha).

Evidence for a neurophysiologic auditory deficit in children with benign epilepsy with centro-temporal spikes.

Benign focal epilepsy in childhood with centro-temporal spikes (BECTS) is one of the most common forms of epilepsy. Recent studies have questioned the benign nature of BECTS, as they have revealed neuropsychological deficits in many domains including language. The aim of this study was to investigate whether the epileptic discharges during the night have long-term effects on auditory processing, as reflected on electrophysiological measures, during the day, which could underline the language deficits.

The effect of sleep fragmentation on cognitive processing using computerized topographic brain mapping.

Topographic brain mapping of evoked potentials can be used to localize abnormalities of cortical function. We evaluated the effect of sleep fragmentation on brain function by measuring the visual P300 waveform using brain mapping. Eight normal subjects (Epworth Score +/- SD: 5 +/- 3) underwent tone-induced sleep fragmentation and undisturbed study nights in a randomized cross-over design.

Epilepsy in schizencephaly: abnormal cortical organization studied by somatosensory evoked potentials.

Median nerve short-latency somatosensory evoked potentials (MN-SSEP) are recorded from the scalp to assess parietal lobe function and from the cortex to identify primary sensory and motor areas before epilepsy surgery. Nevertheless, the origins of many of the MN-SSEP waveforms and the reliability of this technique for localizing the central sulcus are not definitively known. We studied a child with a unilateral, closed, right parietal schizencephalic cleft and frequent simple partial seizures before the child underwent cortical resection.

Interstitial white matter brain oedema does not alter the electroencephalogram.

An experimental study was performed to determine the effects of interstitial white mater oedema on the electroencephalogram (EEG). Using both rodent and feline infusion models of focal brain oedema no difference was found between the EEG waveforms recorded epidurally from the infused and control hemispheres. It is concluded that where focal slow-wave EEG abnormalities overlie oedematous brain the EEG abnormalities are not primarily related to the brain oedema but arise from either local biomechanical or other pathophysiological mechanisms.

EEG analysis in patients with senile dementia and Alzheimer's disease.

An EEG frequency analysis using the wave-form recognition method was performed in different stages of senile dementia (SD), evaluated according to the Hasegawa Dementia Rating Scale (HDS), and the differences in EEG changes between patients with Alzheimer's disease (AD) and patients with SD were studied. We found that the EEG changes in the SD patients correlated with HDS, and that an increase in slow theta (4-5.8 Hz) and a decrease in fast theta (7-7.

Epileptogenesis of human limbic neurons in psychomotor epileptics.

Different stages of epileptogenesis of neurons in deep temporal lobe structures have been studied with fine wire microelectrodes chronically implanted in patients with drug-refractory psychomotor epilepsy. The interictal firing patterns of single neurons ipsilateral to the focus (identified by EEG seizure onset and/or neuropathology studies and seizure reduction following anterior temporal lobectomy) often exhibited burst when contralateral neurons did not. The intraburst sequence of action potentials was not organized or reliable except in one focal hippocampal neuron.