Reiichi Inoue

Transdermal nicotine administration enhances automatic auditory processing reflected by mismatch negativity.

Mismatch negativity (MMN) is a component of event-related potentials (ERPs) with a wide-ranging applicability to the investigation of neuronal substrates of information processing in normal and psychopathological states. Nicotine has been shown to be implicated in the pathophysiology of psychiatric disorders as schizophrenia or Alzheimers disease, and has also been proposed as a self-administered drug in schizophrenia. The goal of the present study is to elucidate the effect of nicotine on the auditory automatic processing reflected by MMN. Nicotine was administered transdermally under controlled dosage. Ten healthy volunteers attended the laboratory for one baseline session and two test sessions. The test sessions involved administration of a placebo patch and a nicotine skin patch, which were counter-balanced. The ERPs were recorded passively during an auditory oddball paradigm. Nicotine administration shortened the MMN latencies, and these effects were independent of the earlier ERP components, N100 and P200. In conclusion, nicotine enhances preattentive and automatic processing such as MMN system and these effects appear to be quite specific and independent of earlier cognitive stages than preattentive mismatch processing. The shortened MMN latency may be interpreted as a reduction of the amount of time required to complete a neuronal mismatch process through the ascending auditory pathway.

Nicotine Effects on Mismatch Negativity in Nonsmoking Schizophrenic Patients

Background: The goal of the present study is to identify the effect of nicotine on auditory automatic processing, as reflected by mismatch negativity (MMN), in nonsmoking schizophrenic patients. Methods: Ten nonsmoking schizophrenic patients and 10 healthy volunteers underwent a reference session and 2 test sessions. The test sessions involved administration of a placebo patch and a nicotine skin patch, which were counterbalanced. Nicotine was administered transdermally under controlled dosage. Results: Nicotine administration shortened the MMN latencies (at Fz on nicotine/placebo: 134.8 ± 5.7/157.6 ± 6.4 ms) in healthy volunteers. In contrast, there were no significant differences in MMN latencies in schizophrenic patients (169.6 ± 5.7/165.0 ± 6.4 ms). Conclusion: Nicotine activates and accelerates preattentive and automatic processing in healthy controls, whereas there were no such effects observed in nonsmoking patients. The impaired MMN response to nicotine administration in nonsmoking schizophrenic patients may be attributed to low nicotinic receptor function, implicated in dysregulation of the glutamatergic system.

A juvenile case of frontotemporal dementia: Neurochemical and neuropathological investigations

1. An autopsy case of frontotemporal dementia with onset at the early age of 28 years is reported. 2. The neuropathological features consisted of limited, knife-like frontotemporal atrophy with severe neuronal loss, spongiform change and gliosis, which is compatible with the frontotemporal dementia. 3. Biochemical determinations disclosed that biogenic amines and their metabolites, predominant in the dopaminergic markers, were depleted in the damaged regions. 4. Since biochemical data in frontotemporal dementia are few in previous studies, it will be determined whether these biochemical changes are characteristic for the juvenile type of frontotemporal dementia or not.

Relationship of mismatch negativity to background EEG and morphological findings in schizophrenia.

The present study assessed relationships of mismatch negativity (MMN) of schizophrenics with other markers; quantitative EEG (QEEG), computed tomography (CT) and psychopathological ratings. Patients were divided into two groups before treatment; group A consisted of patients with greater MMN amplitudes while patients with lower ones were assigned to group B. In QEEG, group A showed no significant differences compared to controls, except for fast beta in the frontal region. The finding of well-preserved QEEG in group A indicates their function is less distorted than in group B, who showed greater powers in slow waves, slow alpha and fast beta bands. The greater slow-wave power of group B may be related to the cognitive impairment reflected by attenuated MMN, which corresponded to greater dilation in lateral ventricles and Sylvian fissures of group B on CT. Conclusively, MMN have crucial relationships to other biological markers representing the psychopathology of schizophrenia.

Prospective Study of Postoperative Seizure in Intracranial Meningioma

There have been no reports regarding the relationship between postoperative clinical EEG course and the need for prophylactic antiepileptic drug (AED) therapy. AED is often administered for a long period regardless of the change in the postoperative course. We .evaluated the risk of postoperative seizures and investigated the feasibility of early discontinuation of AED therapy, with emphasis on the import of EEG findings.

Frontal Midline Theta Rhythm: Differentiating the Physiological Theta Rhythm from the Abnormal Discharge

The theta rhythm that appears in the frontal midline was studied morphologically and clinically in EEGs performed on 788 patients and 161 normal subjects in their late teens or older. This theta rhythm was classified into 2 types. The Type 1 theta rhythm appeared in short bursts maximally in the Fz lead and spread mainly to the anterior region. It had a high frequency, low voltage and regular waveform. The Type 2 theta rhythm appeared in long runs maximally in the Fz lead and spread mainly to the posterior areas. It had a relatively low frequency, high voltage and irregular waveform. Type 1 was observed in a younger age group (mean age: 20.3 years) that was comprised of healthy subjects and one mentally retarded patient. In no case was the Type 1 theta rhythm accompanied by a paroxysmal EEG abnormality. We therefore believe that Type 1 is a physiological EEG activity (Fm theta). On the other hand, Type 2 was observed in a relatively older age group (mean age: 30.7 years) comprised of patients diagnosed as having epilepsy or intractable headaches. Five of 9 cases showed epileptic EEG abnormalities. We therefore believe that Type 2 might have clinical significance in diagnosis of epilepsy and other cerebral dysfunctions. The EEG pattern that we call the frontal mid-line theta rhythm may be either a physiological theta rhythm or an abnormal discharge. It is possible to determine whether the theta rhythm is the former or the latter, and we believe this differentiation to be clinically important.

Event-Related Desynchronization of Frontal-Midline Theta Rhythm during Preconscious Auditory Oddball Processing

The goal of this study was to explore the frontal-mid-line theta rhythm (Fm theta) generation mechanism employing event-related desynchronization/synchronization (ERD/ERS) analysis in relation to task-irrelevant external stimuli. A dual paradigm was employed: a videogame and the simultaneous presentation of passive auditory oddball stimuli. We analyzed the data concerning ERD/ERS using both Fast Fourier Transformation (FFT) and wavelet transform (WT). In the FFT data, during the periods with appearance of Fm theta, apparent ERD of the theta band was observed at Fz and Cz. ERD when Fm theta was present was much more prominent than when Fm theta was absent. In the WT data, as in the FFT data, ERD was seen again, but in this case the ERD was preceded by ERS during both the periods with and without Fm theta. Furthermore, the WT analysis indicated that ERD was followed by ERS during the periods without Fm theta. However, during Fm theta, no apparent ERS following ERD was seen. In our study, Fm theta was desynchronized by the auditory stimuli that were independent of the video game task used to evoke the Fm theta. The ERD of Fm theta might be reflecting the mechanism of “positive suppression” to process external auditory stimuli automatically and preventing attentional resources from being unnecessarily allocated to those stimuli. Another possibility is that Fm theta induced by our dual paradigm may reflect information processing modeled by multi-item working memory requirements for playing the videogame and the simultaneous auditory processing using a memory trace. ERS in the WT data without Fm theta might indicate further processing of the auditory information free from “positive suppression” control reflected by Fm theta.

A preliminary study on plasma concentrations of bifemelane, indeloxazine and propentofylline in aged patients with organic brain disorders.

1. Plasma concentrations of cerebral metabolic activating drugs (bifemelane, indeloxazine and propentofylline) were studied in 68 patients (male 25, female 43) with dementia or other organic brain diseases. 2. The variations in plasma concentrations of these drugs were much bigger than expected. Measurements of bifemelane level with time course also disclosed that the concentrations were relatively stable for several months, but they varied very much among patients. 3. These findings suggest that drug monitoring are important in terms of evaluation of drug efficacy and prevention of side effects.

Event-Related Potential Study of Illusory Contour Perception in Schizophrenia

Schizophrenic patients and healthy controls participated in event-related potential experiments, in which illusory contour (IC) and control objects [no contour (NC), real contour (RC)] were passively presented. As a result, P100 latency for IC in schizophrenic patients was significantly prolonged (+10.6 ms) compared to those for RC. The present findings indicate that an abnormality of IC processing, including ‘bottom-up’ as well as ‘top-down’ processing, may reflect basal pathogenesis of various clinical representations of schizophrenia. However, the P100 latency difference between IC and RC was very small in the patient group. Rather, ‘cognitive’ in the Positive and Negative Syndrome Scale (PANSS) model of Bell et al. significantly correlated with P100 latencies for NC. Such an association between PANSS and NC processing, where the shape must be inferred with increased attentional demands and ‘top-down’ processing, indicates that the abnormality of schizophrenic patients’ preattentive process might be a problem of ‘top-down’ processing rather than ‘bottom-up’ processing.

The Rolandic mu rhythm: a clinical study of the atypical group.

We studied 241 patients whose electroencephalograms (EEGs) showed 7-13 Hz arch shaped wave patterns (mu rhythm) that are known to appear in the Rolandic area. The patients were then classified into two groups depending on the conditions of appearance of the mu rhythm. Group I (typical group) consisted of 171 cases. In this group, the presence of the wave patterns was not affected by the opening of the eyes, and it was blocked by spontaneous movements, or when sensorimotor stimulation was applied. The characteristic symptoms for this group were observed in patients diagnosed as having well-controlled epilepsy, psychiatric disorders, collagen diseases, etc. In Group I, the peak lay between the ages 6 through 15. Group II (atypical group) consisted of 70 cases. In contrast to Group I, the presence of the wave patterns in this group was reinforced by drowsiness, photic stimulation and hyperventilation. The characteristic symptoms for this group were observed in patients diagnosed as having intractable epilepsy or organic brain disorders. In Group II the peak lay between ages 11 through 15. However, in Group II the cases were almost equally distributed among the various age groups. Paroxysmal abnormal EEG patterns were found to be jointly present with more frequency in the Group II sample of epileptic patients than the Group I sample. Therefore, when the mu rhythm associated with conditions indicating Group II type patients is observed, care must be exercised in the observation of further progression of the illness, and in searching for the possibility of organic brain disorders.