Detection of biomagnetic signals from induced pluripotent stem cell-derived cardiomyocytes using deep learning with simulation data.

The detection of spontaneous magnetic signals can be used for the non-invasive electrophysiological evaluation of induced pluripotent stem cell-derived cardiomyocytes (iPS-CMs). We report that deep learning with a dataset that combines magnetic signals estimated using numerical simulation and actual noise data is effective in the detection of weak biomagnetic signals. To verify the feasibility of this method, we measured artificially generated magnetic signals that mimic cellular magnetic fields using a superconducting quantum interference device and attempted peak detection using a long short-term memory network. We correctly detected 80.0% of the peaks and the method achieved superior detection performance compared with conventional methods. Next, we attempted peak detection for magnetic signals measured from mouse iPS-CMs. The number of detected peaks was consistent with the spontaneous beats counted using microscopic observation and the average peak waveform achieved good similarity with the prediction. We also observed the synchronization of peak positions between simultaneously measured field potentials and magnetic signals. Furthermore, the magnetic measurements of cell samples treated with isoproterenol showed potential for the detection of chronotropic effects. These results suggest that the proposed method is effective and has potential application in the safety assessment of regenerative medicine and drug screening.

Clinical trials of Cry j 1 and Cry j 2 T-cell epitope peptide-expressing rice in patients with Japanese cedar pollinosis.

BACKGROUND: In allergic models, administration of rice that expresses a hybrid peptide consisting of 7 major T cell epitopes of Cry j 1 and Cry j 2 (7Crp), suppressed allergic symptoms, IgE elevation and specific T cell response to Japanese cedar pollen. OBJECTIVE: To evaluate the efficacy and safety of 7Crp-expressing rice in patients with Japanese cedar pollinosis. METHODS: A 24-week randomized, double-blind, placebo-controlled study was performed to see the efficacy of 7Crp on allergic symptoms using scoring systems, in which 45 patients were assigned to take either 5 g, 20 g test rice, or placebo daily. A 96-week open study was also conducted to determine its inhibitory effect on serum IgE and T cell proliferative response for Japanese cedar pollen, in which 10 patients consumed 5 g test rice daily. RESULTS: No adverse events associated with the test rice occurred, and the intake rate was more than 96%. The test rice did not show suppression of symptoms related to Japanese cedar pollinosis within 24 weeks. However, intake of 5 g test rice led to a significant decrease in T cell response to Japanese cedar pollen during and after the second disperse season in a 96-week open trial, whereas the specific IgE titer remained unchanged. CONCLUSIONS: Tolerability and safety of 7Crp-expressing rice was accepted. Daily intake of up to 20 g transgenic rice did not provide beneficial effects on Japanese cedar pollinosis within 24 weeks, however, continuous intake of 5 g rice might reduce allergen specific T cell response.

Effects of Optogenetic Suppression of Cortical Input on Primate Thalamic Neuronal Activity during Goal-Directed Behavior.

The motor thalamus relays signals from subcortical structures to the motor cortical areas. Previous studies in songbirds and rodents suggest that cortical feedback inputs crucially contribute to the generation of movement-related activity in the motor thalamus. In primates, however, it remains uncertain whether the corticothalamic projections may play a role in shaping neuronal activity in the motor thalamus. Here, using an optogenetic inactivation technique with the viral vector system expressing halorhodopsin, we investigated the role of cortical input in modulating thalamic neuronal activity during goal-directed behavior. In particular, we assessed whether the suppression of signals originating from the supplementary eye field at the corticothalamic terminals could change the task-related neuronal modulation in the oculomotor thalamus in monkeys performing a self-initiated saccade task. We found that many thalamic neurons exhibited changes in their firing rates depending on saccade direction or task event, indicating that optical stimulation exerted task-specific effects on neuronal activity beyond the global changes in baseline activity. These results suggest that the corticothalamic projections might be actively involved in the signal processing necessary for goal-directed behavior. However, we also found that some thalamic neurons exhibited overall, non-task-specific changes in the firing rate during optical stimulation, even in control animals without vector injections. The stimulation effects in these animals started with longer latency, implying a possible thermal effect on neuronal activity. Thus, our results not only reveal the importance of direct cortical input in neuronal activity in the primate motor thalamus, but also provide useful information for future optogenetic studies.

Temporal Prediction Signals for Periodic Sensory Events in the Primate Central Thalamus.

Prediction of periodic event timing is an important function for everyday activities, while the exact neural mechanism remains unclear. Previous studies in nonhuman primates have demonstrated that neurons in the cerebellar dentate nucleus and those in the caudate nucleus exhibit periodic firing modulation when the animals attempt to detect a single omission of isochronous repetitive audiovisual stimuli. To understand how these subcortical signals are sent and processed through the thalamocortical pathways, we examined single-neuron activities in the central thalamus of two macaque monkeys (one female and one male). We found that three types of neurons responded to each stimulus in the sequence in the absence of movements. Reactive-type neurons showed sensory adaptation and gradually waned the transient response to each stimulus. Predictive-type neurons steadily increased the magnitude of the suppressive response, similar to neurons previously reported in the cerebellum. Switch-type neurons initially showed a transient response, but after several cycles, the direction of firing modulation reversed and the activity decreased for each repetitive stimulus. The time course of Switch-type activity was well explained by the weighted sum of activities of the other types of neurons. Furthermore, for only Switch-type neurons the activity just before stimulus omission significantly correlated with behavioral latency, indicating that this type of neuron may carry a more advanced signal in the system detecting stimulus omission. These results suggest that the central thalamus may transmit integrated signals to the cerebral cortex for temporal information processing, which are necessary to accurately predict rhythmic event timing.SIGNIFICANCE STATEMENT Several cortical and subcortical regions are involved in temporal information processing, and the thalamus will play a role in functionally linking them. The present study aimed to clarify how the paralaminar part of the thalamus transmits and modifies signals for temporal prediction of rhythmic events. Three types of thalamic neurons exhibited periodic activity when monkeys attempted to detect a single omission of isochronous repetitive stimuli. The activity of one type of neuron correlated with the behavioral latency and appeared to be generated by integrating the signals carried by the other types of neurons. Our results revealed the neuronal signals in the thalamus for temporal prediction of sensory events, providing a clue to elucidate information processing in the thalamocortical pathways.

Connectivity-based localization of human hypothalamic nuclei in functional images of standard voxel size.

Despite their critical roles in autonomic functions, individual hypothalamic nuclei have not been extensively investigated in humans using functional magnetic resonance imaging, partly due to the difficulty in resolving individual nuclei contained in the small structure of the hypothalamus. Areal parcellation analyses enable discrimination of individual hypothalamic nuclei but require a higher spatial resolution, which necessitates long scanning time or large amounts of data to compensate for the low signal-to-noise ratio in 3T or 1.5T scanners. In this study, we present analytic procedures to estimate likely locations of individual nuclei in the standard 2-mm resolution based on our higher resolution dataset. The spatial profiles of functional connectivity with the cerebral cortex for each nucleus in the medial hypothalamus were calculated using our higher resolution dataset. Voxels in the hypothalamus in standard resolution images from the Human Connectome Project (HCP) database that predominantly shared connectivity profiles with the same nucleus were subsequently identified. Voxels representing individual nuclei, as identified with the analytic procedures, were reproducible across 20 HCP datasets of 20 subjects each. Furthermore, the identified voxels were spatially separate. These results suggest that these analytic procedures are capable of refining voxels that represent individual hypothalamic nuclei in standard resolution. Our results highlight the potential utility of these procedures in various settings such as patient studies, where lengthy scans are infeasible.

Neuronal activity in the sagittalis nucleus of the hypothalamus after ovarian steroid hormone manipulation and sexual behavior in female rat.

During extended observation of estrogen receptor (ER) α-immunoreactive neurons in the hypothalamus, we previously identified a novel nucleus, the Sagittalis Nucleus of the Hypothalamus (SGN), in the interstitial area between the arcuate nucleus and the ventromedial hypothalamic nucleus. The SGN exhibits sexual dimorphism in its volume and cell count, and estrous cycle related variations in ERα-immunoreactivity. These characteristics of the SGN implicate the nucleus in sex-biased brain functions and behaviors. In this study, we examined involvement of the SGN in sexual arousal in female rats. Immunohistochemical staining of c-Fos, a marker of neuronal activity was performed after administration of an estrus-inducing dose of estrogen and progesterone in ovariectomized female rats. Analysis of microscopic images showed a significant increase in the number of c-Fos-expressing neurons in the SGN following hormonal manipulation. Moreover, neuronal activity in the region exhibited a further increase after each animal was coupled with a male and allowed to mate. These results suggest that the SGN plays an important role in sexual activity in female rat.

Sexual behavior-associated c-Fos induction in the sagittalis nucleus of the hypothalamus in male rat.

The sagittalis nucleus of the hypothalamus (SGN) is a small nucleus located in the interstitial area between the arcuate and ventromedial nuclei of the hypothalamus in rats. The SGN exhibits male-biased sexual dimorphism and expresses estrogen receptor α and calbindin-D28K. This suggests a contribution of the SGN to sexually differentiated brain function, but its functional role is unknown. In this study, neuronal activation in the SGN during sexual behavior in male rats was examined by c-Fos immunohistochemistry. The number of c-Fos-immunoreactive (c-Fos-ir) cells was elevated with only exposure to chemosensory cues of estrous females and significantly increased after the first mount. The first intromission and ejaculation did not induce further increases in the number of c-Fos-ir cells in the SGN. These findings suggest that the SGN is involved in regulation of the early phase of male sexual behavior, including motivation.

Brain atrophy in the visual cortex and thalamus induced by severe stress in animal model.

Psychological stress induces many diseases including post-traumatic stress disorder (PTSD); however, the causal relationship between stress and brain atrophy has not been clarified. Applying single-prolonged stress (SPS) to explore the global effect of severe stress, we performed brain magnetic resonance imaging (MRI) acquisition and Voxel-based morphometry (VBM). Significant atrophy was detected in the bilateral thalamus and right visual cortex. Fluorescent immunohistochemistry for Iba-1 as the marker of activated microglia indicates regional microglial activation as stress-reaction in these atrophic areas. These data certify the impact of severe psychological stress on the atrophy of the visual cortex and the thalamus. Unexpectedly, these results are similar to chronic neuropathic pain rather than PTSD clinical research. We believe that some sensitisation mechanism from severe stress-induced atrophy in the visual cortex and thalamus, and the functional defect of the visual system may be a potential therapeutic target for stress-related diseases.

Functional subdivisions of the hypothalamus using areal parcellation and their signal changes related to glucose metabolism.

The hypothalamus consists of numerous nuclei, and is regarded as the highest center for various autonomic functions. Although each hypothalamic nucleus implements a distinct function, it remains difficult to investigate the human hypothalamus at the nucleus level. In the present high-resolution functional MRI study, we utilized areal parcellation to discriminate individual nuclei in the human hypothalamus based on areal profiles of resting-state functional connectivity. The areal parcellation detected ten foci that were expected to represent hypothalamic nuclei, and the locations of the foci were consistent with those of the hypothalamic nuclei identified in previous histological studies. Regions of interest (ROI) analyses revealed contrasting brain activity changes following glucose ingestion: decrease in the ventromedial hypothalamic nucleus and increase in the lateral hypothalamic area in parallel with blood glucose increase. Moreover, decreased brain activity in the arcuate nucleus predicted future elevation of blood insulin during the first 10 min after glucose ingestion. These results suggest that the hypothalamic nuclei can putatively be determined using areal parcellation, and that the ROI analysis of the human hypothalamic nuclei is useful for future scientific and clinical investigations into the autonomic functions.

Predictive and tempo-flexible synchronization to a visual metronome in monkeys.

Predictive and tempo-flexible synchronization to an auditory beat is a fundamental component of human music. To date, only certain vocal learning species show this behaviour spontaneously. Prior research training macaques (vocal non-learners) to tap to an auditory or visual metronome found their movements to be largely reactive, not predictive. Does this reflect the lack of capacity for predictive synchronization in monkeys, or lack of motivation to exhibit this behaviour? To discriminate these possibilities, we trained monkeys to make synchronized eye movements to a visual metronome. We found that monkeys could generate predictive saccades synchronized to periodic visual stimuli when an immediate reward was given for every predictive movement. This behaviour generalized to novel tempi, and the monkeys could maintain the tempo internally. Furthermore, monkeys could flexibly switch from predictive to reactive saccades when a reward was given for each reactive response. In contrast, when humans were asked to make a sequence of reactive saccades to a visual metronome, they often unintentionally generated predictive movements. These results suggest that even vocal non-learners may have the capacity for predictive and tempo-flexible synchronization to a beat, but that only certain vocal learning species are intrinsically motivated to do it.

[Functional analysis of the thalamocortical pathways in eye movements].

Although the roles of the thalamocortical pathways in somatic movements are well documented, their roles in eye movements have only recently been examined. The oculomotor-related areas in the frontal cortex receive inputs from the basal ganglia and the cerebellum via the thalamus. Consistent with this, neurons in the paralaminar part of the ventrolateral (VL), ventroanterior (VA), and mediodorsal (MD) nuclei and those in the intralaminar nuclei exhibit a variety of eye movement-related responses. To date, the thalamocortical pathways are known to play at least 2 roles in eye movements. First, they are involved in the generation of volitional, but not reactive, saccades. Thalamic neurons discharge during anti-saccades, which are known to be impaired in several neurological and psychiatric disorders, such as Parkinson's disease, attention deficit/hyperactivity disorder, and schizophrenia. In addition, neurons in the thalamus also exhibit a gradual increase in firing rate that predicts the timing of self-initiated saccades. Recent inactivation experiments have established the causal roles of these thalamic signals in the generation of volitional saccades. Second, the thalamocortical pathways transmit the efference copy signals for eye movements. During inactivation of the MD thalamus, which relays signals from the superior colliculus to the frontal eye field (FEF), the accuracy of the saccade is reduced in tasks requiring efference copy signals. In addition, inactivation of the same pathways reduces the predictive visual response associated with saccades in neurons in the FEF. Moreover the VL thalamus has been reported to play a role in monitoring smooth pursuit. While the functional analysis of thalamocortical pathways in eye movements is just a beginning, the anatomical data suggest their important roles. Analysis of eye movement control may shed light on the functions of the thalamocortical pathways in general, and may reveal the neural mechanisms of cerebro-cerebellar, cerebro-basal ganglia, and cerebro-thalamic interactions.

Contribution of the central thalamus to the generation of volitional saccades.

Lesions in the motor thalamus can cause deficits in somatic movements. However, the involvement of the thalamus in the generation of eye movements has only recently been elucidated. In this article, we review recent advances into the role of the thalamus in eye movements. Anatomically, the anterior group of the intralaminar nuclei and paralaminar portion of the ventrolateral, ventroanterior and mediodorsal nuclei of the thalamus send massive projections to the frontal eye field and supplementary eye field. In addition, these parts of the thalamus, collectively known as the 'oculomotor thalamus', receive inputs from the cerebellum, the basal ganglia and virtually all stages of the saccade-generating pathways in the brainstem. In their pioneering work in the 1980s, Schlag and Schlag-Rey found a variety of eye movement-related neurons in the oculomotor thalamus, and proposed that this region might constitute a 'central controller' playing a role in monitoring eye movements and generating self-paced saccades. This hypothesis has been evaluated by recent experiments in non-human primates and by clinical observations of subjects with thalamic lesions. In addition, several recent studies have also addressed the involvement of the oculomotor thalamus in the generation of anti-saccades and the selection of targets for saccades. These studies have revealed the impact of subcortical signals on the higher-order cortical processing underlying saccades, and suggest the possibility of future studies using the oculomotor system as a model to explore the neural mechanisms of global cortico-subcortical loops and the neural basis of a local network between the thalamus and cortex.

Relaxin-3/INSL7 regulates the stress-response system in the rat hypothalamus.

Relaxin-3 (RLN3) is a neuropeptide belonging to the insulin-relaxin superfamily. RLN3-expressing neurons are predominantly located in the dorsal pons known as the nucleus incertus, and project their axons to the forebrain including the hypothalamus. RLN3 has been suggested to be involved in the stress response. In the present study, we investigated the hypothalamic action of RLN3 in the stress-response system by intracerebroventricular (icv) administration of RLN3. Compared with saline icv injection, 1 nmol icv RLN3 injection induced c-Fos expression in the paraventricular nucleus of the hypothalamus (PVN) at 1 h after administration. Some RLN3-induced c-Fos-positive cells in the PVN were also corticotropin-releasing factor (CRF)-expressing neurons. CRF and c-fos mRNA levels in the PVN were increased at 2 h after RLN3 administration. Plasma adrenocorticotropic hormone (ACTH) levels were also increased after RLN3 administration. These results suggest that RLN3 is able to stimulate the hypothalamopituitary CRF-ACTH system during the acute response.

Roles of the primate motor thalamus in the generation of antisaccades.

In response to changes in our environment, we select from possible actions depending on the given situation. The underlying neural mechanisms for this flexible behavioral control have been examined using the antisaccade paradigm. In this task, subjects suppress saccades to the sudden appearance of visual stimuli (prosaccade) and make a saccade in the opposite direction. Because recent imaging studies showed enhanced activity in the thalamus and basal ganglia during antisaccades, we hypothesized that the corticobasal ganglia loop may be involved. To test this, we recorded from neurons in the paralaminar part of the ventroanterior (VA), ventrolateral (VL) and mediodorsal (MD) nuclei of the thalamus when 3 monkeys performed pro/antisaccade tasks. For many VL and some VA neurons, the firing rate was greater during anti- than prosaccades. In contrast, neurons in the MD thalamus showed much variety of responses. For the population as a whole, neuronal activity in the VA/VL thalamus was strongly enhanced during antisaccades compared with prosaccades, while activity in the MD nucleus was not. Inactivation of the VA/VL thalamus resulted in an increase in the number of error trials in the antisaccade tasks, indicating that signals in the motor thalamus play roles in the generation of antisaccades. Enhancement of firing modulation during antisaccades found in the thalamus and those reported previously in the supplementary eye field and the basal ganglia suggest a strong functional linkage between these structures. The neuronal processes through the thalamocortical pathways might be essential for the volitional control of saccades.

Cognitive signals in the primate motor thalamus predict saccade timing.

We often generate movements without any external event that immediately triggers them. How the brain decides the timing of self-initiated movements remains unclear. Previous studies suggest that the basal ganglia-thalamocortical pathways play this role, but the subcortical signals that determine movement timing have not been identified. The present study reports that a subset of thalamic neurons predicts the timing of self-initiated saccadic eye movements. When monkeys made a saccade in response to the fixation point (FP) offset in the traditional memory saccade task, neurons in the ventrolateral and the ventroanterior nuclei of the thalamus exhibited a gradual buildup of activity that peaked around the most probable time of the FP offset; however, neither the timing nor the magnitude of neuronal activity correlated with saccade latencies, suggesting that the brain is unlikely to have used this information to decide the times of saccades in the traditional memory saccade task. In contrast, when monkeys were required to make a self-timed saccade within a fixed time interval after an external cue, the same neurons again exhibited a strong buildup of activity that preceded saccades by several hundred milliseconds, showing a close correlation between the times of neuronal activity and the times of self-initiated saccades. The results suggest that neurons in the motor thalamus carry subjective time information, which is used by cortical networks to determine the timing of self-initiated saccades.

Spatiotemporal properties of eye position signals in the primate central thalamus.

Although both sensory and motor signals in multiple cortical areas are modulated by eye position, the origin of eye position signals for cortical neurons remains uncertain. One likely source is the central thalamus, which contains neurons sensitive to eye position. Because the central thalamus receives inputs from the brainstem, these neurons may transmit eye position signals arising from the neural integrator or from proprioceptive feedback. However, because the central thalamus also receives inputs from many cortical areas, eye position signals in the central thalamus could come from the cerebral cortex. To clarify these possibilities, spatial and temporal properties of eye position signals in the central thalamus were examined in trained monkeys. Data showed that eye position signals were decomposed into horizontal and vertical components, suggesting that the central thalamus lies within pathways that transmit brainstem eye position signals to the cortex. Further quantitative analyses suggested that 2 distinct groups of thalamic neurons mediate eye position signals from different subcortical origins, and that the signals are modified dynamically through ascending pathways. Eye position signals through the central thalamus may play essential roles in spatial transformation performed by cortical networks.

Inactivation of the central thalamus delays self-timed saccades.

The central thalamus transmits corollary discharge signals for eye movement control, but its role in eye movement generation remains uncertain. Inactivation of the paralaminar part of the ventrolateral thalamus delayed the initiation of contraversive saccades, particularly during a new memory-guided saccade task that required self-triggering of the movement. The results suggest that signals through the thalamus regulate the timing of self-initiated saccades.

Involvement of the central thalamus in the control of smooth pursuit eye movements.

During maintenance of smooth pursuit eye movements, the brain must keep track of pursuit velocity to reconstruct target velocity from motion of retinal images. Although a recent study showed that corollary discharge signals through the thalamus to the cortex are used for internal monitoring of saccades, it remains unknown whether signals in the thalamus also contribute to monitoring and on-line regulation of smooth pursuit. The present study sought possible roles of the thalamocortical pathways in pursuit by recording activities of single thalamic neurons and by analyzing the effects of local inactivation. Data showed that many neurons in the ventrolateral thalamus exhibited directional modulation during pursuit. Most neurons discharged before or during initiation of pursuit, and the firing rate was proportional to the speed of target motion in a preferred direction. When the tracking target was extinguished briefly during maintenance of pursuit, these neurons continued firing, indicating that they carried extra-retinal, eye movement signals. The majority of neurons showed no change in activity around the time of small catch-up saccades during pursuit but responded transiently to large (16 degrees) memory-guided saccades in the preferred pursuit direction. Local inactivation of the recording sites did not alter pursuit latency but reduced eye velocity modestly during initiation and maintenance of ipsiversive pursuit. The results suggest that the central thalamus lies within pathways that regulate and monitor smooth pursuit eye movements.