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Biomedical subjects

Manabu Honda

Publications and source records attributed to Manabu Honda.

At least 19 recordsLinked to original sources
PubMed2006

Practice makes perfect: the neural substrates of tactile discrimination by Mah-Jong experts include the primary visual cortex.

BACKGROUND: It has yet to be determined whether visual-tactile cross-modal plasticity due to visual deprivation, particularly in the primary visual cortex (V1), is solely due to visual deprivation or if it is a result of long-term tactile training. Here we conducted an fMRI study with normally-sighted participants who had undergone long-term training on the tactile shape discrimination of the two dimensional (2D) shapes on Mah-Jong tiles (Mah-Jong experts). Eight Mah-Jong experts and twelve healthy volunteers who were naïve to Mah-Jong performed a tactile shape matching task using Mah-Jong tiles with no visual input. Furthermore, seven out of eight experts performed a tactile shape matching task with unfamiliar 2D Braille characters. RESULTS: When participants performed tactile discrimination of Mah-Jong tiles, the left lateral occipital cortex (LO) and V1 were activated in the well-trained subjects. In the naïve subjects, the LO was activated but V1 was not activated. Both the LO and V1 of the well-trained subjects were activated during Braille tactile discrimination tasks. CONCLUSION: The activation of V1 in subjects trained in tactile discrimination may represent altered cross-modal responses as a result of long-term training.

Adult↗
PubMed2006

The role of biological system other than auditory air-conduction in the emergence of the hypersonic effect.

Although human beings cannot perceive elastic vibrations in the frequency range above 20 kHz, nonstationary sounds containing a wealth of inaudible high-frequency components (HFC) above the human audible range activate deep-lying brain structures, including the brainstem and thalamus and evoke various physiological, psychological, and behavioral responses. In the previous reports, we have called these phenomena collectively "the hypersonic effect." It remains unclear, however, if vibratory stimuli above the audible range are transduced and perceived solely via the conventional air-conducting auditory system or if other mechanisms also contribute to mediate transduction and perception. In the present study, we have examined the emergence of the hypersonic effect when inaudible HFC and audible low-frequency components (LFC) were presented selectively to the ears, the entrance of an air-conducting auditory system, or to the body surface including the head which might contain some unknown vibratory sensing mechanisms. We used two independent measurements based on differing principles; one physiological (alpha 2 frequency of spontaneous electroencephalogram [alpha-EEG]) and the other behavioral (the comfortable listening level [CLL]). Only when the listener's entire body surface was exposed to HFC, but not when HFC was presented exclusively to the air-conducting auditory system, did both the alpha-EEG and the CLL significantly increase compared to the presentation of LFC alone, that is to say, there was an evident emergence of the hypersonic effect. The present findings suggest that the conventional air-conducting auditory system alone does not bring about the hypersonic effect. We may need to consider the possible involvement of a biological system distinct from the conventional air-conducting auditory nervous system in sensing and transducing high-frequency elastic vibration above the human audible range.

Adult↗
PubMed2006

Brain activity during visuomotor behavior triggered by arbitrary and spatially constrained cues: an fMRI study in humans.

Rule-based behavior associating nonspatial visual stimuli with learned responses is called arbitrary visuomotor mapping, an ability that enriches behavioral repertoire. To better understand the underlying neural correlates, the present functional magnetic resonance imaging (fMRI) study explored brain activity during visually informed movement involving two different types of cues and two different effectors. After being trained on the tasks, six healthy subjects performed right or left finger tapping tasks according to either arbitrary cues or spatially constrained cues. An event-related fMRI experiment was conducted on a 3-T MRI. The image data were analyzed with statistical parametric mapping. With the aid of the probabilistic architectonic map in the stereotaxic space, we identified three types of task-related brain activity: cue-selective, effector-selective, and nonselective. The left ventrolateral prefrontal cortex and the rostral part of the right dorsal premotor cortex (PMd) exhibited cue-selective activity, which was greater during the arbitrary condition than the spatially constrained condition. The left ventral prefrontal activity may reflect retrieval of visuomotor association from memory in arbitrary context. The rostral part of the left PMd showed nonselective activity while the caudal part of the PMd on each side showed conspicuous effector-selective activity to the contralateral movement. These findings suggest functional demarcation of the PMd between its rostral and dorsal parts during visuomotor mapping.

Adult↗
PubMed2005

Neural correlates of the spontaneous phase transition during bimanual coordination.

Repetitive bimanual finger-tapping movements tend toward mirror symmetry: There is a spontaneous transition from less stable asymmetrical movement patterns to more stable symmetrical ones under frequency stress but not vice versa. During this phase transition, the interaction between the signals controlling each hand (cross talk) is expected to be prominent. To depict the regions of the brain in which cortical cross talk occurs during bimanual coordination, we conducted event-related functional magnetic resonance imaging using a bimanual repetitive-tapping task. Transition-related activity was found in the following areas: the bilateral ventral premotor cortex, inferior frontal gyrus, middle frontal gyrus, inferior parietal lobule, insula, and thalamus; the right rostral portion of the dorsal premotor cortex and midbrain; the left cerebellum; and the presupplementary motor area, rostral cingulate zone, and corpus callosum. These regions were discrete from those activated by bimanual movement execution. The phase-transition-related activation was right lateralized in the prefrontal, premotor, and parietal regions. These findings suggest that the cortical neural cross talk occurs in the distributed networks upstream of the primary motor cortex through asymmetric interhemispheric interaction.

Action Potentials↗
PubMed2005

Brain processing of the signals ascending through unmyelinated C fibers in humans: an event-related functional magnetic resonance imaging study.

Event-related functional magnetic resonance imaging was used to investigate brain processing of the signals ascending from peripheral C and Adelta fibers evoked by phasic laser stimuli on the right hand in humans. The stimulation of both C and Adelta nociceptors activated the bilateral thalamus, bilateral secondary somatosensory cortex, right (ipsilateral) middle insula, and bilateral Brodmann's area (BA) 24/32, with the majority of activity found in the posterior portion of the anterior cingulate cortex (ACC). However, magnitude of activity in the right (ipsilateral) BA32/8/6, including dorsal parts in the anterior portion of the ACC (aACC) and pre-supplementary motor area (pre-SMA), and the bilateral anterior insula was significantly stronger following the stimulation of C nociceptors than Adelta nociceptors. It was concluded that the activation of C nociceptors, related to second pain, evokes different brain processing from that of Adelta nociceptors, related to first pain, probably due to the differences in the emotional and motivational aspects of either pain, which are mainly related to the aACC, pre-SMA, and anterior insula.

Adult↗
PubMed2005

The representation of the human oral area in the somatosensory cortex: a functional MRI study.

The tactile sensation of the teeth is involved in various oral functions, such as mastication and speech. Using functional magnetic resonance imaging, we investigated the cortical sensory representation of the oral area, including the teeth. First, we identified the somatotopic representation of the lips, teeth and tongue in the postcentral gyrus (GpoC). Tactile stimuli were applied to the lower lip, tongue and teeth. The foci activated by each stimulus were characterized by the center of gravity (COG) of activated areas. Secondly, we examined the rostro-caudal changes in the somatotopic organization in the GPoC in terms of the overlap between each sensory representation. In the rostral portion of the GPoC, the COG of the representation of teeth was located significantly superior to that of the tongue and inferior to that of the lip, consistent with the classical 'sensory homunculus' proposed by Penfield; however, this somatotopic representation became unclear in the middle and caudal portions of the GPoC. The overlap between each representation in the middle and caudal portions of the GPoC was significantly greater than that in the rostral portion of the GPoC. These findings support the theory that the input from oral structures converges hierarchically across the primary somatosensory cortex.

Adult↗
PubMed2005

Functionally segregated neural substrates for arbitrary audiovisual paired-association learning.

To clarify the neural substrates and their dynamics during crossmodal association learning, we conducted functional magnetic resonance imaging (MRI) during audiovisual paired-association learning of delayed matching-to-sample tasks. Thirty subjects were involved in the study; 15 performed an audiovisual paired-association learning task, and the remainder completed a control visuo-visual task. Each trial consisted of the successive presentation of a pair of stimuli. Subjects were asked to identify predefined audiovisual or visuo-visual pairs by trial and error. Feedback for each trial was given regardless of whether the response was correct or incorrect. During the delay period, several areas showed an increase in the MRI signal as learning proceeded: crossmodal activity increased in unimodal areas corresponding to visual or auditory areas, and polymodal responses increased in the occipitotemporal junction and parahippocampal gyrus. This pattern was not observed in the visuo-visual intramodal paired-association learning task, suggesting that crossmodal associations might be formed by binding unimodal sensory areas via polymodal regions. In both the audiovisual and visuo-visual tasks, the MRI signal in the superior temporal sulcus (STS) in response to the second stimulus and feedback peaked during the early phase of learning and then decreased, indicating that the STS might be key to the creation of paired associations, regardless of stimulus type. In contrast to the activity changes in the regions discussed above, there was constant activity in the frontoparietal circuit during the delay period in both tasks, implying that the neural substrates for the formation and storage of paired associates are distinct from working memory circuits.

Acoustic Stimulation↗
PubMed2005

Cross-modal binding and activated attentional networks during audio-visual speech integration: a functional MRI study.

We evaluated the neural substrates of cross-modal binding and divided attention during audio-visual speech integration using functional magnetic resonance imaging. The subjects (n = 17) were exposed to phonemically concordant or discordant auditory and visual speech stimuli. Three different matching tasks were performed: auditory-auditory (AA), visual-visual (VV) and auditory-visual (AV). Subjects were asked whether the prompted pair were congruent or not. We defined the neural substrates for the within-modal matching tasks by VV-AA and AA-VV. We defined the cross-modal area as the intersection of the loci defined by AV-AA and AV-VV. The auditory task activated the bilateral anterior superior temporal gyrus and superior temporal sulcus, the left planum temporale and left lingual gyrus. The visual task activated the bilateral middle and inferior frontal gyrus, right occipito-temporal junction, intraparietal sulcus and left cerebellum. The bilateral dorsal premotor cortex, posterior parietal cortex (including the bilateral superior parietal lobule and the left intraparietal sulcus) and right cerebellum showed more prominent activation during AV compared with AA and VV. Within these areas, the posterior parietal cortex showed more activation during concordant than discordant stimuli, and hence was related to cross-modal binding. Our results indicate a close relationship between cross-modal attentional control and cross-modal binding during speech reading.

Adult↗
PubMed2005

Intracerebral pain processing in a Yoga Master who claims not to feel pain during meditation.

We recorded magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) following noxious laser stimulation in a Yoga Master who claims not to feel pain when meditating. As for background MEG activity, the power of alpha frequency bands peaking at around 10 Hz was much increased during meditation over occipital, parietal and temporal regions, when compared with the non-meditative state, which might mean the subject was very relaxed, though he did not fall asleep, during meditation. Primary pain-related cortical activities recorded from primary (SI) and secondary somatosensory cortices (SII) by MEG were very weak or absent during meditation. As for fMRI recording, there were remarkable changes in levels of activity in the thalamus, SII-insula (mainly the insula) and cingulate cortex between meditation and non-meditation. Activities in all three regions were increased during non-meditation, similar to results in normal subjects. In contrast, activities in all three regions were weaker during meditation, and the level was lower than the baseline in the thalamus. Recent neuroimaging and electrophysiological studies have clarified that the emotional aspect of pain perception mainly involves the insula and cingulate cortex. Though we cannot clearly explain this unusual condition in the Yoga Master, a change of multiple regions relating to pain perception could be responsible, since pain is a complex sensory and emotional experience.

Aged↗
PubMed2005

Modality-specific cognitive function of medial and lateral human Brodmann area 6.

Despite the fact that human Brodmann area 6 (BA6), a traditional "motor" area, is active during higher motor control involving various cognitive operations, the functional specialization within BA6 in the cognitive domain is essentially unknown. Furthermore, its functional relevance in cognition has been questioned because brain activity in BA6 during cognitive tasks has often been explained away as a concomitant, latent motor process. Therefore, we examined the structural-functional relationship of human BA6 in nonmotor cognitive functions and its functional relevance using both functional magnetic resonance imaging (fMRI) and repetitive transcranial magnetic stimulation (rTMS). Subjects performed mental-operation (MO) tasks in which they serially updated verbal and spatial mental representations (MO-v and MO-s). In the fMRI experiments, activity in the medial BA6 was more increased in MO-v, whereas the activity in the lateral BA6 in both hemispheres was more in MO-s. Low-frequency rTMS to the medial BA6 disrupted only the performance of MO-v, whereas rTMS to the lateral BA6 in both hemispheres disrupted only MO-s. Hence the converging results demonstrate a functional double dissociation in which medial BA6 has a critical role in updating verbal information and lateral BA6 has a role in updating spatial information. The present study provides direct physiological evidence of modality-specific cognitive function within human BA6.

Adult↗
PubMed2004

Cross-modal integration and plastic changes revealed by lip movement, random-dot motion and sign languages in the hearing and deaf.

Sign language activates the auditory cortex of deaf subjects, which is evidence of cross-modal plasticity. Lip-reading (visual phonetics), which involves audio-visual integration, activates the auditory cortex of hearing subjects. To test whether audio-visual cross-modal plasticity occurs within areas involved in cross-modal integration, we used functional MRI to study seven prelingual deaf signers, 10 hearing non-signers and nine hearing signers. The visually presented tasks included mouth-movement matching, random-dot motion matching and sign-related motion matching. The mouth-movement tasks included conditions with or without visual phonetics, and the difference between these was used to measure the lip-reading effects. During the mouth-movement matching tasks, the deaf subjects showed more prominent activation of the left planum temporale (PT) than the hearing subjects. During dot-motion matching, the deaf showed greater activation in the right PT. Sign-related motion, with or without a lexical component, activated the left PT in the deaf signers more than in the hearing signers. These areas showed lip-reading effects in hearing subjects. These findings suggest that cross-modal plasticity is induced by auditory deprivation independent of the lexical processes or visual phonetics, and this plasticity is mediated in part by the neural substrates of audio-visual cross-modal integration.

Adult↗
PubMed2004

Asymmetrical neural substrates of tactile discrimination in humans: a functional magnetic resonance imaging study.

The left-hand advantage seen during tactile discrimination tasks suggests hemispheric-processing asymmetry, although its neural substrates are not well known. We used functional magnetic resonance imaging to evaluate the laterality of the neural substrates involved in tactile discrimination in 19 normal volunteers. Passive tactile discrimination tasks, along with appropriate control tasks, were performed with both the right and left hands to evaluate the effects of the hand used and hemispheric effects (i.e., laterality of the activation pattern). Regardless of the hand used, the right dorsolateral prefrontal cortex, posterior parietal cortex, pre-supplementary motor area, and rostral portion of the dorsal premotor cortex (PMdr) were activated asymmetrically during tactile discrimination. This confirms the previous finding of a right-sided asymmetry for tactile shape discrimination. Hand effects were found in the left caudal portion of PMd (PMdc) adjacent to the central sulcus, which showed prominent activation during right-handed but not left-handed discrimination tasks. This asymmetric activation in the left PMdc might be related to the asymmetric interhemispheric interaction during right-handed tactile discrimination.

Adult↗
PubMed2004

Activation of the primary and association auditory cortex by the transition of sound intensity: a new method for functional examination of the auditory cortex in humans.

During functional MRI image acquisition, the scanning equipment generates substantial auditory noise, the effects of which are usually ignored. To investigate the neural activity in response to the transition of noise, we measured cerebral responses to short silent periods (1 and 5 s) during which the slice readout gradients were switched off. In all 15 normal volunteers, the 1 s silence bilaterally activated the primary and association auditory cortex. Subtraction of the response to the 1 s silent period from that to the 5 s silent period revealed the activation related to the onset (transition of sound from OFF to ON) event, indicating that the 1 s response is offset (transition of sound from ON to OFF) related. The complex response of the auditory cortex to the transition of the noise should be considered in designing functional MRI with auditory tasks.

Acoustic Stimulation↗
PubMed2003

Modulatory effect of inaudible high-frequency sounds on human acoustic perception.

We evaluated the effects of the intensity of an inaudible high-frequency component (HFC) of sound on human responses by employing a multi-parametric approach consisting of behavioral measurements of the comfortable listening level (CLL), psychological measurements of the subjective impression of sounds, and physiological measurements using electroencephalogram (EEG). Increasing the intensity of the inaudible HFC resulted in a significant increase in the CLL, the subjective impression of sounds, and the occipital alpha frequency component of the spontaneous EEG. These effects peaked with an increase of 6 dB in HFC intensity. The results of the present study suggest that the intensity of inaudible HFC non-linearly modulates human sound perception.

Acoustic Stimulation↗
PubMed2003

Differential activity in the premotor cortex subdivisions in humans during mental calculation and verbal rehearsal tasks: a functional magnetic resonance imaging study.

To investigate a possible role of the lateral premotor cortex in human cognitive processes, we compared brain activity during mental-operation numeral (MO-numeral) and verbal rehearsal (VR) tasks, using block-design functional MRI. Sixteen healthy subjects serially added a series of single-digit numbers during the MO-numeral task and silently rehearsed a memorized seven-digit number during the VR task. Each task condition was contrasted with a visual fixation task. Both MO-numeral and VR tasks revealed activity within the lateral premotor cortex among others. The rostral and dorsal part of the lateral premotor cortex (PMdr) showed significantly greater activity during the MO-numeral task than the VR task whereas its caudal part (PMdc) was similarly active during the two tasks. The present study suggests that the PMdr and PMdc are involved in different non-motor cognitive processes.

Adult↗
PubMed2003

Neural correlates underlying mental calculation in abacus experts: a functional magnetic resonance imaging study.

Experts of abacus operation demonstrate extraordinary ability in mental calculation. There is psychological evidence that abacus experts utilize a mental image of an abacus to remember and manipulate large numbers in solving problems; however, the neural correlates underlying this expertise are unknown. Using functional magnetic resonance imaging, we compared the neural correlates associated with three mental-operation tasks (numeral, spatial, verbal) among six experts in abacus operations and eight nonexperts. In general, there was more involvement of neural correlates for visuospatial processing (e.g., right premotor and parietal areas) for abacus experts during the numeral mental-operation task. Activity of these areas and the fusiform cortex was correlated with the size of numerals used in the numeral mental-operation task. Particularly, the posterior superior parietal cortex revealed significantly enhanced activity for experts compared with controls during the numeral mental-operation task. Comparison with the other mental-operation tasks indicated that activity in the posterior superior parietal cortex was relatively specific to computation in 2-dimensional space. In conclusion, mental calculation of abacus experts is likely associated with enhanced involvement of the neural resources for visuospatial information processing in 2-dimensional space.

Adult↗
PubMed2002

Superior digit memory of abacus experts: an event-related functional MRI study.

Abacus experts exhibit superior short-term memory for digits, but the underlying neurophysiological mechanism remains unknown. Using event-related fMRI, we examined the brain activity of abacus experts and non-experts during the memory retention period of a delayed match-to-sample task using digits as stimuli. In controls, activity was greater in cortical areas related to verbal working memory, including Broca's area. In contrast, in experts, activity was greater in cortical areas related to visuo-spatial working memory, including the bilateral superior frontal sulcus and superior parietal lobule. This provides neurophysiological evidence that abacus experts utilize a visuo-spatial representation for digit memory.

Adolescent↗