The cerebellum has been implicated in the feedforward control of speech production. However, the role of the cerebellum in the feedback control of speech production remains unclear. To address this question, the present event‐related potential study examined the behavioral and neural correlates of auditory feedback control of vocal production in patients with spinocerebellar ataxia (SCA) and healthy controls. All participants were instructed to produce sustained vowels while hearing their voice unexpectedly pitch‐shifted −200 or −500 cents. The behavioral results revealed significantly larger vocal compensations for pitch perturbations in patients with SCA relative to healthy controls. At the cortical level, patients with SCA exhibited significantly smaller cortical P2 responses that were source localized in the right superior temporal gyrus, primary auditory cortex, and supramarginal gyrus than healthy controls. These findings indicate that reduced brain activity in the right temporal and parietal regions are significant neural contributors to abnormal auditory‐motor processing of vocal pitch regulation as a consequence of cerebellar degeneration, which may be related to disrupted reciprocal interactions between the cerebellum and cortical regions that support the top‐down modulation of auditory‐vocal integration. These differences in behavior and cortical activity between healthy controls and patients with SCA demonstrate that the cerebellum is not only essential for feedforward control but also plays a crucial role in the feedback‐based control of speech production.

No abstract

No abstract

The segmentation of citrus trees in a natural orchard environment is a key technology for achieving the fully autonomous operation of agricultural unmanned aerial vehicles (UAVs). Therefore, a tree segmentation method based on monocular machine vision technology and a support vector machine (SVM) algorithm are proposed in this paper to segment citrus trees precisely under different brightness and weed coverage conditions. To reduce the sensitivity to environmental brightness, a selective illumination histogram equalization method was developed to compensate for the illumination, thereby improving the brightness contrast for the foreground without changing its hue and saturation. To accurately differentiate fruit trees from different weed coverage backgrounds, a chromatic aberration segmentation algorithm and the Otsu threshold method were combined to extract potential fruit tree regions. Then, 14 color features, five statistical texture features, and local binary pattern features of those regions were calculated to establish an SVM segmentation model. The proposed method was verified on a dataset with different brightness and weed coverage conditions, and the results show that the citrus tree segmentation accuracy reached 85.27% ± 9.43%; thus, the proposed method achieved better performance than two similar methods.

No abstract

No abstract

No abstract

The control parameters of the unmanned aerial vehicle (UAV) should be carefully designed to improve UAV spraying performance on citrus trees. The present study investigated the optimal droplet distribution control parameters in citrus trees using a UAV and the Taguchi method, of which optimal results were observed with an inverted triangle citrus tree canopy shape, a spraying height of 1.40 m, and a flight speed of 1.0 m/s. Among the discussed control parameters, the flight speed presented the most significant effect with a contribution percentage of 74.0%. The established multiple regression model predicted an optimal spraying height of 1.27 m and a maximum droplet density of 35.39 droplets/cm 2. In addition, the effects of individual control parameter on the droplet density of the lower layer of citrus trees were systematically analyzed, of which inverted triangle shape more significantly affected the droplet density of the lower layer and presented an 82.0% increase in droplet density as compared to the triangle shape. An improvement of 59.6% in the lower layer droplet density was observed at a spraying height of 1.40 m. In addition, the other spraying heights did not present significant differences in their coefficient of variation (CV) values.