Keiko Hara

Abnormal mismatch negativity for pure-tone sounds in temporal lobe epilepsy

Auditory processing abnormalities in temporal lobe epilepsy (TLE) were assessed by investigating mismatch negativity (MMN) in a group of 20 TLE patients and 20 healthy control subjects. MMN is an event-related potential (ERP) component that reflects pre-attentive sensory memory function. A passive oddball paradigm using frequency changes in sinusoidal tones was employed to evoke MMN. MMN at frontocentral sites was enhanced in TLE patients relative to controls, while mismatch signals at mastoid sites (i.e., mismatch positivity; MMP) did not differ between the two groups. In the MMP temporal range, greater positivity at mastoid sites in response to standard stimuli was observed in TLE patients than in controls. Both MMN and MMP were significantly delayed in the TLE group. These findings demonstrate that TLE patients have impaired pre-attentive processing of pure-tone sounds. Enhanced frontocentral MMN may reflect hyperexcitability of the frontal lobes in compensation for dysfunction of the temporal lobes. Larger positivity at the mastoids in response to standard stimuli may be attributed to poor neuronal adaptation in the temporal lobe. Taken together, results suggest that evaluation of MMN/P is a useful physiological tool for identifying pre-attentive auditory memory dysfunction in TLE.

Aroma helps to preserve information processing resources of the brain in healthy subjects but not in temporal lobe epilepsy.

PURPOSE Inhalation of ylang-ylang aroma has been shown to reduce the auditory P300, an event-related potential thought to reflect higher-order processing. Because olfactory function is sometimes disturbed in temporal lobe epilepsy (TLE), the objective of the present study was to determine whether the effect of ylang-ylang aroma on the auditory P300 was impaired in patients with TLE. METHOD Fourteen subjects with TLE and 14 healthy controls participated in this study. Electroencephalograms were recorded during an auditory oddball task, and ylang-ylang aroma or odorless air was delivered through a mask. RESULTS We found that the ylang-ylang aroma prolonged the latencies of P300 in both groups. The ylang-ylang aroma significantly reduced the P300 amplitudes of healthy subjects as described previously. However, in TLE patients, the P300 was unaffected by the aroma. CONCLUSION The current results show that exposure to the ylang-ylang aroma reduced information processing resources in healthy subjects but had limited effects in patients with TLE. We suggest that impaired higher-order olfactory processing in TLE patients may inhibit the effects of the ylang-ylang aroma on the P300.

Changes in the duration and frequency of deviant stimuli engender different mismatch negativity patterns in temporal lobe epilepsy

Mismatch negativity (MMN) is an event-related potential (ERP) component that reflects preattentive sensory memory functions. Previous research revealed that MMN is generated by distinct sources in the frontal and temporal lobes. Event-related potential abnormalities have been shown in the vicinity of seizure foci in epilepsy. Additionally, no published study has investigated the MMN in response to variations in both frequency and duration deviants in patients with temporal lobe epilepsy (TLE). The aims of this study were to compare MMN changes between the frontocentral sites and the mastoid sites and to compare MMNs related to deviant stimuli with different durations and frequencies in patients with TLE. We recorded MMNs elicited by duration and frequency changes of deviant stimuli from 15 patients with TLE and 15 healthy control subjects. We found that mean MMN amplitudes related to duration deviants were lower in patients with TLE at the mastoid sites relative to controls, whereas the MMN amplitudes at the frontocentral sites did not differ between the two groups. There were no MMN differences related to frequency deviants between TLE subjects and controls at the frontocentral sites or the mastoid sites. Mismatch negativity parameters related to duration deviants did not correlate with those related to deviant frequencies in the group with TLE. The present findings suggest selective impairments among multiple mismatch generators in TLE and suggest that processing of temporal information of auditory stimuli is selectively disturbed in TLE. Changes in MMN amplitudes related to duration deviants at the mastoid sites may represent deficits in time-dependent processing in TLE.

Pre-attentive auditory processing of non-scale pitch in absolute pitch possessors

Absolute pitch (AP) refers to the ability to identify the pitch of sound without reference. To clarify the neurophysiological characteristics of AP, we compared mismatch negativity (MMN) elicited by scale and non-scale notes between AP possessors and non-AP individuals. Eight individuals who were able to identify pitch with perfect accuracy were defined as AP possessors. Eighteen participants who failed to achieve perfect accuracy were included in the non-AP group. We presented participants with two tone pairs, in a scale condition and a non-scale condition. The frequency ratios of the two pairs were the same. MMN over the frontal region in the non-scale condition was larger in the AP group than the non-AP group. In contrast, no such difference was observed between the two groups in the scale condition. The results suggest that pre-attentive processing of non-scale note sounds in the auditory cortex is a salient neurophysiological characteristic of AP.

Distinct pre-attentive responses to non-scale notes: An auditory mismatch negativity (MMN) study

OBJECTIVE The aim of the present study was to examine patterns of neural activity in response to variations in scale notes and alterations from a scale note to a non-scale note. METHODS Event-related potentials (ERPs) were recorded in response to scale and non-scale violin notes using an odd-ball mismatch negativity (MMN) paradigm. Standard stimuli were set to the scale note A4 (440 Hz). Deviant stimuli included two scale notes (scale-B, B4 = 494 Hz; scale-C, C5 = 523 Hz) and a non-scale note halfway between them (non-scale, B4+42¢ = 506 Hz). RESULTS MMN amplitude elicited by the non-scale was significantly larger than that elicited by the scale-B and scale-C, which did not differ significantly from one another. CONCLUSION The current results suggest that the human brain may possess pre-attentive mechanisms for extracting relational aspects among sounds of the musical scale. SIGNIFICANCE The results indicate that non-scale notes may be processed in a different way even in the pre-attentive stage than scale notes.

Post-operative mismatch negativity recovery in a temporal lobe epilepsy patient with cavernous angioma

Department of Life Sciences and Bio-informatics, Division of Biomedical Laboratory Sciences, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, okyo, Japan Department of Neurosurgery, Tokyo Medical and Dental University, Tokyo, Japan Section of Liaison Psychiatry and Palliative Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan Onda-daini Hospital, Chiba, Japan Hara Clinic, Kanagawa, Japan Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan

Vowel-speech versus pure-tone processing in healthy subjects

To investigate the characteristics of speech perception, we evaluated the differences in mismatch negativity (MMN) between vowel change and frequency change. Additionally, we examined the effects of gender, age, and educational length on MMN. Forty healthy adults (21 females), who were native Japanese speakers, participated in the study. A Japanese vowel-speech pair (standard/a/vs. deviant/o/) and a pure-tone pair (standard 1000 Hz vs. deviant 1050 Hz) were constructed. MMN elicited by vowel-speech sounds was larger and earlier compared with pure-tone sounds. Larger and earlier MMNs for vowel-speech sounds than for pure-tone sounds suggest different processing of linguistically relevant information at the early stage in the auditory cortex. In conclusion, the factors influencing on MMN are different between vowel-speech sounds and pure-tone sounds.

S10-4. Role of the medical doctors in longterm VIDO-EEG monitoring

Long-term video-electroencephalography monitoring (LTM) in epilepsy monitoring units (EMUs) is an essential and most meaningful investigation for diagnosis of epilepsy, classification of epileptic seizures and pre-surgical evaluation of patients with intractable localization-related epilepsy. The tapering of antiepileptic drugs is commonly used to record seizures efficiently. However, this practice may expose patients to serious adverse events, such as falls, status epilepticus, psychiatric complication, cardiac events and pulmonary complications. The issue of patients’ safety during LTM is one of the most important tasks. Before the starting of the LTM, the patients’ information (seizure type and frequency, history of seizure clusters, status epilepticus, and postictalpsychosis, number, dosage, and type of AEDs) must be shared in multidisciplinary conference, Based on these information, the AED tapering and safety plan should be developed for each patient. Furthermore, staff education improve patients’ supervision by nurses and EEG technicians, and immediate review of adverse events. The information and knowledge sharing by all the EMU staff might be most important for the patients‘ safety and efficient seizure recording.

S12-2. Possible application of mismatch negativity in patients with epilepsy in a clinical research

It is well known that the mismatch negativity (MMN) has multiple generators: one in the temporal lobe and another in the frontal lobe. To investigate the effect of an epileptic focus on MMN, we compared the MMN of patients with temporal lobe epilepsy (TLE) with various seizure frequencies with the MMN of healthy controls. The MMN was consistently altered in TLE with the use of multiple types of stimuli. The MMN was enhanced at fronto-central sites and reduced at mastoid sites. TLE patients with lower seizure frequencies showed larger MMN amplitudes for deviant responses to phonetic stimulation at Fz. Taken together, our findings show that epileptic foci in the temporal lobe affect frontal and temporal function differently. The diminished MMN at mastoid sites may reflect dysfunction of the temporal lobe in TLE. In contrast, the enhanced MMN at fronto-central sites may reflect an increase in hyperexcitability or hypersynchronous activity. The results are consistent with previous reports of changes in frontal lobe function in TLE. In addition, we present a case of longitudinal changes of the MMN in TLE.

P16-17 Mismatch Negativity (MMN) to vowel-speech change in patients with temporal lobe epilepsy

K. Hara1,2,3, K. Ohta1,4,5, M. Hara2, M. Miyajima1,4, H. Iino1, T. Maehara6, M. Baba1,5, A. Matsuda1, M. Inaji6, M. Mukawa6, M. Watanabe3, Y. Watanabe3, E. Matsushima5, M. Matsuura1 1Graduate School of Health Care Science, Tokyo Medical and Dental University, Japan, 2Hara Clinic, Yokohama, Japan, 3Department of Psychiatry, National Center Hospital of Neurology and Psychiatry, Tokyo, Japan, 4Onda-Daini Hospital, Chiba, Japan, 5Section of Liaison Psychiatry & Palliative Medicine, Tokyo Medical and Dental University, Tokyo, Japan, 6Department of Neurosurgery, Tokyo Medical and Dental University, Tokyo, Japan