We searched for the CP-violating rare decay of the neutral kaon, KL→π0νν¯, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed ...while 0.34±0.16 background events were expected. We set an upper limit of 5.1×10−8 for the branching fraction at the 90% confidence level (C.L.). An upper limit of 3.7×10−8 at the 90% C.L. for the KL→π0X0 decay was also set for the first time, where X0 is an invisible particle with a mass of 135 MeV/c2.
Human and animal data suggest that the mere observation of biological motion activates those premotor areas that also underlie the initiation of the same motion. However, data also indicate that the ...human premotor cortex (PM), in contrast to the monkey PM, responds not only to the observation of goal-directed (transitive) motion but also to intransitive motion. The present study used functional magnetic resonance imaging to test this hypothesis directly. Participants were presented cycles of intransitive motion specified as belonging to the distal (fingers and mouth), proximal (knee, ankle, elbow, and wrist), or axial (trunk and shoulder) motion class. Attention to motion was behaviorally tested by a forced-choice task on motion acceleration and deceleration. Results revealed extended PM activation for each motion condition. However, direct contrasts showed that the most significant activations were elicited in ventrolateral PM by distal motion, in dorsolateral PM by proximal motion, and medial PM (supplementary motor area) by axial motion. Findings confirm observed intransitive motions to engage premotor areas along a gross-scaled somatotopy.
Setting perceptual expectations can be based on different sources of information which determine the functional networks involved in implementing preparatory top-down influences and dealing with ...situations in which expectations are violated. The present study addressed the process of forming and violating expectations based on information of different origin, type and specificity. In the serial prediction task participants monitored ordered perceptual sequences for predefined sequential deviants, while the target detection task entailed a presentation of stimuli which had to be monitored for predefined non-sequential deviants.
Detection of sequential deviants triggered an increase of activity in lateral and mesial premotor and cerebellar areas which were initially supporting regular sequence processing. This pattern of activity is suggested to reflect detection of a mismatch between the expected and presented stimuli and updating of the underlying sequence representation (i.e. forward model). Presented violations additionally triggered activations in frontal areas initially not involved in sequence processing, reflecting the subsequent elaboration of the violation. In contrast, detecting non-sequential deviants triggered primarily bilateral activations within parietal and posterior temporal areas with an additional involvement of right superior and middle frontal gyrus, reflecting an increase in perceptual and attentional processing evoked by the non-sequential deviant. The results of the presented study indicate involvement of distinct networks in detecting different types of deviants which primarily reflect the nature of expectations being violated.
Recent findings have demonstrated that attention to visual events engages the lateral premotor cortex even in the absence of motor planning. Here, we used functional magnetic resonance imaging to ...explore acoustically triggered activations within the lateral premotor cortex. Temporal (
when), object-related (
what), and spatial (
where) auditory patterns were to be monitored for violations in a serial prediction task. As a result, we found a modality-dependent modulation for auditory events within the inferior ventrolateral premotor cortex, an area engaged in vocal plans. In addition, however, auditory activations were distributed within the entire premotor cortex depending on which stimulus property was attended to. Attention to where patterns was found to engage fields for gaze and reaching (dorsolateral premotor cortex), what patterns to engage fields for hand movements (superior ventrolateral premotor cortex), and when patterns to engage fields for vocal plans. Together, the findings confirm the idea of a sensory somatotopy in lateral premotor cortex, according to which a perceptual pattern triggers representations within that motor effector which would be most appropriate to generate it as an action effect.
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