Rie Inami

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.

Simultaneous resting-state functional MRI and electroencephalography recordings of functional connectivity in patients with schizophrenia

It remains unclear how functional connectivity (FC) may be related to specific cognitive domains in neuropsychiatric disorders. Here we used simultaneous resting‐state functional magnetic resonance imaging (rsfMRI) and electroencephalography (EEG) recording in patients with schizophrenia, to evaluate FC within and outside the default mode network (DMN).

Simultaneous rsfMRI and EEG recordings of functional connectivity in patients with schizophrenia.

It remains unclear how functional connectivity (FC) may be related to specific cognitive domains in neuropsychiatric disorders. Here we used simultaneous resting‐state functional magnetic resonance imaging (rsfMRI) and electroencephalography (EEG) recording in patients with schizophrenia, to evaluate FC within and outside the default mode network (DMN).

Functional Connectivity of the Caudate in Schizophrenia Evaluated with Simultaneous Resting-State Functional MRI and Electroencephalography Recordings

Background: Aberrant functional connectivity (FC) is increasingly implicated in the clinical phenomenology of schizophrenia. This study focused on the FC of the cortico-striatal network, which is thought to be disrupted in schizophrenia and to contribute to its clinical manifestations. Methods: We used simultaneous resting-state functional magnetic resonance imaging (rsfMRI) and electroencephalography (EEG) recordings to investigate FC in patients with schizophrenia. The study included 20 patients with schizophrenia and 20 healthy controls (HCs). Simultaneously recorded rsfMRI and EEG data were collected with an MR-compatible amplifier, and rsfMRI data were analyzed with the CONN toolbox to calculate FC. The study focused on the caudate, which was defined as the seed. We also performed between-group comparisons of standardized low-resolution electromagnetic tomography intracortical lagged coherence for each EEG frequency band. Results: Compared to HCs, patients with schizophrenia showed enhanced FC between the caudate nucleus and the posterior cingulate cortex, temporal, and occipital regions on rsfMRI. It is thus possible that HCs have negative FC between these regions, whereas patients with schizophrenia have non-negative FC. The EEG results showed no significant differences in oscillations or in FC between the groups in any frequency band in any region. Conclusions: Increased FC in the caudate may represent aberrant between-network FC resulting from the disruption of segregation between networks.

S12-4. Simultaneous fMRI-EEG-DTI recording of MMN in schizophrenia

Objectives: Here we investigated cognitive impairments reflected by omission mismatch negativity (MMN) aberration in schizophrenia. Methods: We recorded EEG during event-related functional MRI (fMRI) followed by diffusion tensor imaging (DTI) in 14 healthy volunteers and 12 schizophrenic patients. The fMRI data was analyzed on SPM08 and blood oxygenation level-dependent signals (BOLD) signal changes were calculated in region of interest analysis using MarsBaR software. In DTI analysis, the areas significantly deteriorated in patients compared to controls were detected with tract-based spatial statistics. Fractional anisotropy (FA) in white matter fibers related to each area was compared between groups using tract-specific analysis. The clinical manifestation in the patients was evaluated using the Positive and Negative Syndrome Scale (PANSS). Results: The correlation analysis on SPM revealed significant correlation between FA of the right uncinate fasciculus and BOLD activity in the left Insula. BOLD activity of the right anterior cingulate, the right corpus callosum and right insula significantly correlated with PANSS scores. Conclusion: The dysfunction of Insula, the uncinate fasciculus and the corpus callosum, as well as the temporal lobe and the anterior cingulate gyrus, may specifically contribute to MMN aberration of schizophrenic patients and clinical manifestations reflecting their impaired MMN generation.

S29-5 Simultaneous EEG-fMRI recording of MMN in schizophrenia

The mismatch negativity (MMN) is an electric brain response which is automatically (task-independently) elicited by any discriminable change in a repetitive sound or sound pattern as long as the memory trace of the previous stimuli lasts. When this change is made smaller in magnitude the MMN is attenuated in amplitude, eventually vanishing at around the discrimination threshold. Therefore the MMN provides a unique objective measure for a subject or patient fs discrimination accuracy. Furthermore, with the MMN, these discrimination thresholds can be separately determined for the different auditory attributes. Moreover, the individual’s ability to discriminate even complex sound stimuli and patterns such as different phonemes can be measured by using the MMN. Several studies have shown that training-induced improvements in different kinds of auditory discrimination abilities are accompanied by increased MMN amplitudes, reflecting learning-related plastic changes in the auditory cortex. In fact, some recent data suggest that the improved discrimination in the course of training might even be preceded by an MMN enhancement. In stroke patients with aphasia, the MMN may index the gradual recovery of auditory discrimination abilities as time from stroke onset elapses. In addition, in cochlear-prosthesis patients, the MMN can similarly index the gradual recovery of different auditory discrimination functions. Furthermore, the MMN can also reflect the plastic changes occurring when an individual is exposed to a certain language environment, most typically when a newborn is exposed to his/her mother tongue, but such MMN changes reflecting the emergence of new phonetic categories also occur when an adult learns a foreign language. Finally, the MMN can also be used as an index of the duration of sensory memory in audition. These studies have shown that this duration (of the order of 10 sec in young individuals) gets shorter with normal aging, being very short in patients with degenerative brain diseases such as Alzheimer’s disease. These results suggest that the MMN could be used as an index of general brain plasticity.