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M Tonoike

Publications and source records attributed to M Tonoike.

16 recordsLinked to original sources
PubMed1999

Frontal midline theta rhythms reflect alternative activation of prefrontal cortex and anterior cingulate cortex in humans.

Frontal midline theta rhythm (Fm theta) often appears on electroencephalogram (EEG) during consecutive mental tasks. To clarify the source of rhythmic activity, magnetoencephalogram (MEG) and EEG were simultaneously measured in six healthy volunteers during different mental tasks using whole head MEG system. MEG records were averaged every one cycle of Fm theta rhythms using individual positive peaks of Fm theta waves in Fz EEG as a trigger. Averaged theta components of MEG signals were analyzed with a multi-dipole model. Two sources were estimated to the regions both of the prefrontal-medial superficial cortex and anterior cingulate cortex (ACC). These regions were alternatively activated in about 40 to 120 degrees phase shift during one Fm theta cycle. From above results, we hypothesize that appearance of Fm theta during consecutive mental tasks reflects alternative activities of the medial prefrontal cortex and ACC.

Adult↗
PubMed1999

A pitch glide activates an intermediate response between auditory N1 and mismatch negativity.

Pitch glides of a continuous tone elicit auditory N1-like responses. However, their characteristics have not well been investigated, and it remained unclear whether the response is an auditory true N1 or the mismatch negativity (MMN). We found here that a rapid pitch glide activates almost the same response as a true N1. On the contrary, as the rate of the pitch glide decreases, the response continuously varies the characteristics from true N1 to MMN. This suggests that there would exist intermediate responses between auditory N1 and MMN.

Acoustic Stimulation↗
PubMed1999

Dynamic cortical activation in mental image processing revealed by biomagnetic measurement.

The mental rotation task has been reported to activate the human parietal and extra-striate areas, based on the results of fMRI and PET analysis. In the present study, we investigated the dynamic properties of the distributed cortical activity related to mental rotation processes at high temporal resolution by means of brain magnetic field measurements and a linear inversion algorithm. Distributed neural activities during the mental rotation and control tasks were estimated for six subjects, and the differences in the activity distribution were analyzed. Statistically significant differences in the parietal and lateral posterior temporal region were detected 200-300 ms after the visual stimulus, indicating that the dorsal and ventral pathway were included in the mental image processing.

Adult↗
PubMed1999

Interhemispheric asymmetry of event-related fields concerned with logical processing during auditory oddball stimulation.

This study investigated the cortex during logical processing of auditory information using a 122-channel dc-SQUID gradiometer. The experimental task was designed to require a simple logical decision prior to counting rare paired tones, which consisted of two different pitches and were presented to separate ears. Among six subjects, left and right predominant dipolar activity was observed in three subjects each. When the dipolar sources were superimposed on MR images, the inferior region of the supramarginal gyrus showed activation, suggesting that logical processing occurred in the association cortex but not in the auditory cortex. We propose a modified cognitive sequence model in which auditory information processed in Heschl's gyri is transmitted to the supramarginal gyrus to commence automatic detection processing.

Acoustic Stimulation↗
PubMed1998

Ipsilateral dominance of human olfactory activated centers estimated from event-related magnetic fields measured by 122-channel whole-head neuromagnetometer using odorant stimuli synchronized with respirations.

The aim of this study was to measure and analyze olfactory event-related magnetic fields using a whole-cortex biomagnetometer (122-channel SQUID gradiometer). Amyl-acetate gas (approx. 1%) was administered for 300 msec into either the right or left nostril in synchronization with respiration using a mask and an optical fiber sensor. Clear olfactory event-related magnetic fields were asymmetrically obtained on both sides of the forehead in all six subjects. The generators of olfactory magnetic fields were estimated at two regions located fairly asymmetrivally near the bilateral frontal deep areas. The goodness-of-fit was better for the two-dipole model than the one-dipole model in all experiments. In almost all subjects the latency and intensity of ipsilateral olfactory magnetoencephalography (MEG) responses were shorter and larger than those of the contralateral responses, respectively. These results suggest that the olfactory MEG responses on the ipsilateral side are generally larger and more dominant than those on the contralateral side in the human olfactory system.

Brain Mapping↗
PubMed1998

Auditory evoked off-response: its source distribution is different from that of on-response.

Offset auditory responses were investigated by electroencephalography mainly in the 1970s, but since then no particular attention has been paid to them. Among the studies using magnetoencephalography (MEG) devices there are, to our knowledge, only three studies of the auditory off-response, and no significant variance has ever been observed between the source locations of on- and off-responses elicited from pure tones. We measured auditory evoked magnetic fields (AEFs) to various frequency pure tone stimulation in 5 healthy subjects with a 122-channel helmet-shaped magnetometer, and compared the distributions of the source locations of auditory N100m-Off (magnetic off-response around 100 ms) with those of N100m-On. Their spatial distributions were quite close to each other, and yet they were significantly different.

Acoustic Stimulation↗
PubMed1998

Neuromagnetic activity in the human left cerebral hemisphere concerning logical processing during auditory oddball stimulation.

The aim of this study was to examine the cortex during the logical processing of auditory information using a whole-cortex type dc-SQUID gradiometer. The task modified the normal auditory oddball paradigm to require the processing of simple logic before counting a rare stimulus mentally. Although the latency of P300 m did not change, a dipolar magnetic field pattern was observed over the left cerebral hemisphere at approximately 280 ms poststimulus before forming the field pattern of P300 m. The equivalent current dipole source was estimated to be medial to the N100 m source. It was suggested that the additional load of logic processing may activate Heschl's gyri in the left hemisphere.

Acoustic Stimulation↗
PubMed1998

Task-dependent laterality for cue decoding during spoken language processing.

The task-dependent laterality of the auditory cortices was investigated by measuring the magnetic fields elicited by three forms of a Japanese verb, which differed in terms of prosodic and phonetic cues. Significant task-dependent magnetic fields were found in both hemispheres during a prosody-related task, but only in the left during a phoneme-related task. The latency was similar to the mismatch negatively which reflects the neural activity of automatic cue decoding. These results suggest that task-dependent schemata are activated at least partially in parallel with automatic cue-decoding processes such that those in the left hemisphere process linguistic information irrespective of acoustic cues whereas those in the right hemisphere process prosodic information.

Adult↗
PubMed1994

Local distribution of odor responsivities of mouse olfactory receptor neurons.

The local distribution of odor responsivity was studied in isolated mouse olfactory neurons retaining their original spatial relationships in intact tissue. The selectivity for three odorants and population of responsive cells were estimated from the odor-induced increase in cytoplasmic calcium. It was found that cells with different odor selectivities coexisted with a shorter distance than cells of the same type. Cells with a similar odor responsivity were arranged somewhat more densely than a complete random distribution. The results indicated the coexistence of different subtypes of odor responsive cells in the septal epithelium with sparse clustering of similarly responsive cells.

Animals↗
PubMed1994

Tuning specificities to aliphatic odorants in mouse olfactory receptor neurons and their local distribution.

1. Odor responses to two homologous series of n-fatty acids (nFA) and n-aliphatic alcohols (nAA) with a straight chain of three to nine carbons were examined by measuring odor-induced [Ca2+]i increase in mouse olfactory receptor neurons (ORNs) isolated by the tissue-printing method. 2. One-third of the ORNs responsive to nFA and/or nAA were alternately sensitive to either type of odorant. Their sensitivities were usually near maximal for one or two odorants and decreased with differences in the carbon chain length from the tuned odorants. 3. Two-thirds of the ORNs responsive to nFA and/or nAA were sensitive to both types of odorants. Most of them were also tuned to one or two odorants in each series with similar carbon chain lengths and showed a decrease of sensitivity with increasing stereochemical discrepancy, similar to nFA/nAA discriminating ORNs. 4. In 10 of 20 non-nFA/nAA discriminating ORNs, the sensitivity to nFA was > 10 times greater than to nAA, and 80% of them were localized in a central region of olfactory epithelium on the septum wall where ORNs preferentially project to the dorsomedial or centromedial regions of the olfactory bulb. In addition, the sensitivity to three series of n-aliphatic odorants with an added amino group was examined. Sensitivity became higher as the electronegativity of the functional groups increased, suggesting that a hydrogen bond might partly mediate affinity in one type of non-nFA/nAA discriminating ORNs. 5. The diversity in odorant tuning specificity and sensitivity of the individual ORNs indicated that their receptor sites were finely tuned to the stereochemical structures of numerous odorants by changes in the three-dimensional size and intermolecular positions of the hydrophobic domains for hydrophobic bond, as well as the proton-acceptor or donor for the hydrogen bond and the electrical charge for the ionic bond. 6. The subpopulation of ORNs tuned to an individual odorant increased as the length of carbon chain of the odorant increased from three to nine. This tendency was more marked for nFA than for nAA in the case of non-nFA/nAA discriminating ORNs. 7. Data obtained by the in vitro approach using the tissue-printing method suggested that three or more subtypes of ORNs, which were similar in some cases and significantly different in other cases, were located within close proximity to one another.

Animals↗
PubMed1992

Simultaneous recording of [Ca2+]i increases in isolated olfactory receptor neurons retaining their original spatial relationship in intact tissue.

A new method is described for isolating olfactory receptor neurons suitable for simultaneous recording of odorant responses in several cells. This method, called "tissue printing" by Cassab and Varner, was used to isolate cells for measurement of odorant-induced increases in cytosolic-free calcium concentration ([Ca2+]i) using the Ca2+ indicator dye fura-2. A large number of receptors could be isolated from a piece of olfactory epithelium (about 300 microns square), preserving their normal morphology and relative local topology to that in the intact olfactory tissue. The probability that there are one or more receptor cells with odorant-induced responses in [Ca2+]i per preparation was 4 times higher with cells isolated by the tissue printing than with those obtained by the pipetting method. The responses of 2 receptor cells separated by 28 microns in the recording chamber differed for 2 odorants: isoamyl acetate and citralva. The method was useful for isolating receptor neurons without losing their morphological features and for investigating the spatial distribution of odorant responsiveness of each receptor over the olfactory epithelium.

Animals↗
PubMed1991

Two types of increases in free Ca2+ evoked by odor in isolated frog olfactory receptor neurons.

Olfactory transduction involves second messenger-related enzymes and cAMP-gated, K+ and Ca2+ channels, which are known to be regulated by Ca2+. We report here that cytosolic free Ca2+ concentration ([Ca2+]i) in olfactory receptor neuron was increased by odorants or forskolin and Ca2+ influx contributed to the adaptation. The increases in [Ca2+]i were below two to three-fold of resting level and transient for 26 s (mean value, n = 18). The increases were due to two pathways: Ca2+ influx and release. The slow increases in [Ca2+]i by forskolin resembled those by citralva. It was suggested that the responses to citralva were accompanied by increases in intracellular cAMP and Ca2+ influx or release leading to transient increases in [Ca2+]i.

Animals↗
PubMed1980

Neuronal activity in the monkey dorsolateral prefrontal cortex during a discrimination task with delay.

Ninety-nine single neuron activities of the dorsolateral prefrontal cortex of 3 monkeys were recorded during performance of a Konorski task. Green or red lights were presented successively with a separation of fixed delay interval. The monkey responded as soon as the second stimulus was presented. If the two stimuli were color-matched, the 'YES' lever press was rewarded; if the two stimuli were not, the 'NO' lever press was rewarded. In the second task, after paired color stimuli, a tone pip was presented as the 'GO' signal for lever presses. During sample and matching periods 50 neurons increased their discharge rates and 10 decreased. In 86% of increasing type neurons rate increase occurred during both periods. During auditory GO periods, 27 neurons increased their rates and 11 decreased. Discharge peak was before or at the moment of hold key release. In 60% of these neurons were also observed the rate changes to sample and matching stimuli. Differential activations between left and right levers were found in 20%. It was suggested that the prefrontal cortex is related to a sensorial attention mechanism to the visual stimulus which enables correct choice of the behavior to be rewarded.

Animals↗