Effects of Direction and Curvature on Variable Error Pattern of Reaching Movements

Motor Control ◽  
1999 ◽  
Vol 3 (4) ◽  
pp. 414-423 ◽  
Author(s):  
Slobodan Jaric ◽  
Charli Tortoza ◽  
Ismael F.C. Fatarelli ◽  
Gil L. Almeida

A number of studies have analyzed various indices of the final position variability in order to provide insight into different levels of neuromotor processing during reaching movements. Yet the possible effects of movement kinematics on variability have often been neglected. The present study was designed to test the effects of movement direction and curvature on the pattern of movement variable errors. Subjects performed series of reaching movements over the same distance and into the same target. However, due either to changes in starting position or to applied obstacles, the movements were performed in different directions or along the trajectories of different curvatures. The pattern of movement variable errors was assessed by means of the principal component analysis applied on the 2-D scatter of movement final positions. The orientation of these ellipses demonstrated changes associated with changes in both movement direction and curvature. However, neither movement direction nor movement curvature affected movement variable errors assessed by area of the ellipses. Therefore it was concluded that the end-point variability depends partly, but not exclusively, on movement kinematics.

1993 ◽  
Vol 69 (4) ◽  
pp. 1136-1149 ◽  
Author(s):  
P. A. Fortier ◽  
A. M. Smith ◽  
J. F. Kalaska

1. The responses of 262 motor cortex cells and 223 cerebellar neurons were recorded during whole-arm reaching movements toward targets lights in eight evenly distributed directions radiating from a common central starting position. The reaching movements were followed by a 2-s target hold period where a fixed arm posture was actively maintained to stabilize the hand over the target light. 2. Cerebellar neurons had a higher mean tonic discharge rate while holding over the starting position (22.9 imp/s) than did motor cortex cells (12.5 imp/s). The mean population response curve describing the changes in activities with movement direction was likewise shifted toward higher frequencies in the cerebellum compared with the motor cortex, but the amplitude of the two curves was about equal. Therefore, the baseline discharges of cerebellar neurons were higher, but their changes in activity during movement were similar to those of motor cortical cells. 3. Motor cortex neurons were more strongly related to active maintenance of different arm postures than were cerebellar units. This was shown by a larger posture-related population response curve in the motor cortex (half-wave amplitude of cosine function was 11.2 imp/s, compared with 7.0 imp/s for cerebellar neurons), which represented the average response curve calculated from all the cells of the population. Furthermore, the motor cortex population had a higher percentage of single cells with tonic responses while the hand was held over different targets (tonic and phasic-tonic cells composed 57% of motor cortex population, compared with 38% of cerebellar population). Proportionately more cerebellar cells were phasically related to the movements. 4. The majority of motor cortex cells (58%) showed reciprocal changes relative to the center-hold time activity where the activity increased for movements in the preferred direction and decreased for movements in the opposite direction. Most of the remaining cells (40%) showed graded changes where the activity increased gradually as reaching was directed closer to the preferred direction. In contrast, the most common cerebellar response pattern was graded (38%). Only 26% were reciprocal and 18% were non-directional. The remaining 2% of motor cortical cells and 18% of cerebellar neurons could not be readily assigned to any of these three response classes. 5. Sector widths were calculated to measure the dispersion of individual cerebellar and motor cortical cell activities about the eight movement directions. Sector widths calculated from the absolute activities were always broader for cerebellar neurons (i.e., the cells were more broadly tuned).(ABSTRACT TRUNCATED AT 400 WORDS)


1989 ◽  
Vol 62 (1) ◽  
pp. 198-211 ◽  
Author(s):  
P. A. Fortier ◽  
J. F. Kalaska ◽  
A. M. Smith

1. Three monkeys were trained to make whole-arm reaching movements from a common central starting position toward eight radially arranged targets disposed at 45 degrees intervals. A sample of 312 cerebellar neurons with proximal-arm receptive fields or discharge related to shoulder or elbow movements was studied in the task. The sample included 69 Purkinje cells, 115 unidentified cortical cells, 65 interpositus neurons, and 63 dentate units. 2. The reaching task was divided into three movement-related epochs: a reaction time, a movement time, and holding over the target. All neurons demonstrated significant changes in discharge during one or more of these three epochs. Almost all of the cells (95%) showed a significant change in activity during the movement, whereas 68-69% of the cells showed significant changes from premovement activity during the reaction time and holding periods. 3. During the combined reaction time-movement period, 231/312 cells were strongly active in the task. Of these, 151 cells (65.4%) demonstrated unimodal directional responses. Sixty-three had a reciprocal relation to movement direction, whereas 88 showed only graded increases or decreases in activity. A further 37 cells (16.0%) were nondirectional, with statistically uniform changes in discharge in all eight directions. The remaining 43 cells (18.6%) showed significant differences in activity for different directions of movement, but their response patterns were not readily classifiable. 4. The proportion of directional versus nondirectional cells was consistent across the four cell populations. However, graded response patterns were more common and reciprocal responses less common among Purkinje and dentate neurons than among unidentified cortical cells and interpositus neurons. 5. The distribution of preferred directions of the population of cerebellar neurons covered all possible movement directions away from the common central starting position in the horizontal plane. When the preferred direction of each cell in the sample population was aligned, the mean direction-related activity of the cerebellar population formed a bell-shaped tuning curve for the activity recorded during both the reaction time and the movement, as well as during the time the arm maintained a fixed posture over the targets. A vector representation also showed that the overall activity of the cerebellar population during normal reaching arm movements generated a signal that varied with movement direction. 6. These results demonstrate that the cerebellum generates a signal that varies with the direction of movement of the proximal arm during normal aimed reaching movements and is consistent with a role in the control of the activity of muscles or muscle groups generating these movements.


Author(s):  
J. M. Paque ◽  
R. Browning ◽  
P. L. King ◽  
P. Pianetta

Geological samples typically contain many minerals (phases) with multiple element compositions. A complete analytical description should give the number of phases present, the volume occupied by each phase in the bulk sample, the average and range of composition of each phase, and the bulk composition of the sample. A practical approach to providing such a complete description is from quantitative analysis of multi-elemental x-ray images.With the advances in recent years in the speed and storage capabilities of laboratory computers, large quantities of data can be efficiently manipulated. Commercial software and hardware presently available allow simultaneous collection of multiple x-ray images from a sample (up to 16 for the Kevex Delta system). Thus, high resolution x-ray images of the majority of the detectable elements in a sample can be collected. The use of statistical techniques, including principal component analysis (PCA), can provide insight into mineral phase composition and the distribution of minerals within a sample.


2019 ◽  
Vol 62 (1) ◽  
Author(s):  
Dae Young Lee ◽  
Bo-Ram Choi ◽  
Jae Won Lee ◽  
Yurry Um ◽  
Dahye Yoon ◽  
...  

Abstract In Platycodi Radix (root of Platycodon grandiflorum), there are a number of platycosides that consist of a pentacyclic triterpenoid aglycone and two sugar moieties. Due to the pharmacological activities of platycosides, it is critical to assess their contents in PR, and develop an effective method to profile various platycosides is required. In this study, an analytical method based on ultra performance liquid chromatography coupled with quadrupole time-of-flight/mass spectrometry (UPLC-QTOF/MS) with an in-house library was developed and applied to profile various platycosides from four different Platycodi Radix cultivars. As a result, platycosides, including six isomeric pairs, were successfully analyzed in the PRs. In the principal component analysis, several platycosides were represented as main variables to differentiate the four Platycodi Radix cultivars. Their different levels of platycosides were also represented by relative quantification. Finally, this study indicated the proposed method based on the UPLC-QTOF/MS can be an effective tool for identifying the detail characterization of various platycosides in the Platycodi Radix.


2019 ◽  
Vol 73 (5) ◽  
pp. 565-573 ◽  
Author(s):  
Yun Zhao ◽  
Mahamed Lamine Guindo ◽  
Xing Xu ◽  
Miao Sun ◽  
Jiyu Peng ◽  
...  

In this study, a method based on laser-induced breakdown spectroscopy (LIBS) was developed to detect soil contaminated with Pb. Different levels of Pb were added to soil samples in which tobacco was planted over a period of two to four weeks. Principal component analysis and deep learning with a deep belief network (DBN) were implemented to classify the LIBS data. The robustness of the method was verified through a comparison with the results of a support vector machine and partial least squares discriminant analysis. A confusion matrix of the different algorithms shows that the DBN achieved satisfactory classification performance on all samples of contaminated soil. In terms of classification, the proposed method performed better on samples contaminated for four weeks than on those contaminated for two weeks. The results show that LIBS can be used with deep learning for the detection of heavy metals in soil.


Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2936 ◽  
Author(s):  
Xianghao Zhan ◽  
Xiaoqing Guan ◽  
Rumeng Wu ◽  
Zhan Wang ◽  
You Wang ◽  
...  

As alternative herbal medicine gains soar in popularity around the world, it is necessary to apply a fast and convenient means for classifying and evaluating herbal medicines. In this work, an electronic nose system with seven classification algorithms is used to discriminate between 12 categories of herbal medicines. The results show that these herbal medicines can be successfully classified, with support vector machine (SVM) and linear discriminant analysis (LDA) outperforming other algorithms in terms of accuracy. When principal component analysis (PCA) is used to lower the number of dimensions, the time cost for classification can be reduced while the data is visualized. Afterwards, conformal predictions based on 1NN (1-Nearest Neighbor) and 3NN (3-Nearest Neighbor) (CP-1NN and CP-3NN) are introduced. CP-1NN and CP-3NN provide additional, yet significant and reliable, information by giving the confidence and credibility associated with each prediction without sacrificing of accuracy. This research provides insight into the construction of a herbal medicine flavor library and gives methods and reference for future works.


1995 ◽  
Vol 73 (6) ◽  
pp. 2563-2567 ◽  
Author(s):  
S. H. Scott ◽  
J. F. Kalaska

1. Neuronal activity was recorded in the motor cortex of a monkey that performed reaching movements with the use of two different arm postures. In the first posture (control), the monkey used its natural arm orientation, approximately in the sagittal plane. In the second posture (abducted), the monkey had to adduct its elbow nearly to shoulder level to grasp the handle. The path of the hand between targets was similar in both arm postures, but the joint kinematics and kinetics were different. 2. In both postures, the activity of single cells was often broadly tuned with movement direction and static arm posture over the targets. In a large proportion of cells, either the level of tonic activity, the directional tuning, or both, varied between the two postures during the movement and target hold periods. 3. For most directions of movement, there was a statistically significant difference in the direction of the population vector for the two arm postures. Furthermore, whereas the population vector tended to point in the direction of movement for the control posture, there was a poorer correspondence between the direction of movement and the population vector for the abducted posture. These observed changes are inconsistent with the notion that the motor cortex encodes purely hand trajectory in space.


2021 ◽  
Vol 40 (3) ◽  
pp. 93-126
Author(s):  
Michael Lewin

Transcendental philosophy was not born like Athena out of Zeus’s head, mature and in full armour from the very beginning. That is why in both prefaces to the Critique of Pure Reason (1781 and 1787) Kant introduces the concept of transcendental philosophy as an “idea.” The idea understood architectonically develops slowly and only gradually acquires a definite form. As witnessed by the works of Kant himself and of his predecessors and followers, the idea of transcendental philosophy has undergone a series of changes and adjustments compared to the initial plan. In this context, my goal is not simply exegesis and historical investigation of transcendental philosophy, but also to look at it from a systematic and methodological perspective. I examine the concept of transcendental philosophy from the viewpoint of programmatic metaphilosophy. The first part discusses programmatics as a distinct subsection of metaphilosophy. I argue that Kant’s architectonic methodology and the methodology of Lakatos can be used to understand the inception, development and degradation of philosophical systems. In the second part I look at the project of transcendental philosophy and the stages of its development from the standpoint of architectonics. The third part shows that Lakatos’s methodology can provide a detailed insight into the elements of transcendental philosophy, a clear idea of its logic and identify the component parts that can be improved and developed. In spite of the different levels of detailing and epistemological prerequisites, the methodologies of Kant and Lakatos can be combined to achieve a metaphilosophically informed and progressive understanding of philosophical projects.


Author(s):  
Janet R. Meyer

The messages spoken in everyday conversation are influenced by participants’ goals. Interpersonal scholars have distinguished two types of goals thought to influence the wording of a message: instrumental goals (primary goals) and secondary goals. An instrumental goal is related to a speaker’s primary reason for designing the message. Instrumental goals would include goals such as to ask for a favor, seek information, apologize, give advice, or change the other person’s opinion. Secondary goals pertain to more general concerns. They include goals such as to manage one’s impression, avoid offending the hearer, and act consistently with one’s values. The ability to design a message that pursues an instrumental goal effectively while also addressing (or at least not conflicting with) relevant secondary goals is associated with greater communication competence. Considerable research has sought to explain differences in the ability to design messages that effectively address multiple goals. One such factor appears to be the extent to which a speaker can adapt the language of a message to the communication-relevant features of a specific situation or hearer. If a speaker’s primary goal is to seek a favor, relevant situation features may include the speaker’s right to ask, expected resistance, and qualities of the speaker–hearer relationship. A second behavior associated with the ability to produce multiple-goal messages is suggested by research on cognitive editing. The latter research indicates that the likelihood of producing a message that addresses relevant secondary goals will sometimes depend upon whether a speaker becomes aware, prior to speaking, that a planned message could have an unwanted outcome (e.g., the message may offend the hearer). When such outcomes are anticipated in advance, the message may be left unspoken or edited prior to speaking. The ability to produce a message that achieves a speaker’s goals may also depend on the type of planning that precedes the design of a message. The plan-based theory of strategic communication views plans as hierarchical structures that specify goals and actions at different levels of specificity. The theory holds that a person pursuing a goal first tries to retrieve from memory a preexisting plan that could be modified for the current situation. When that is not possible, speakers must formulate a novel plan. Research employing indicants of fluency suggests that formulating a novel plan (which requires changes at a higher, more abstract level of a plan) makes heavier demands on limited capacity than does modifying an existing plan at a lower level of the hierarchy (e.g., speaking more slowly). Insight into how persons plan what to say has also come from research on imagined interactions, conflict management, anticipating obstacles to compliance, and verbal disagreement tasks. In an effort to better understand the design of messages in interpersonal settings, a number of scholars have proposed models of the cognitive processes and structures thought to be involved in designing, editing, and producing such messages. Action models of this sort, which generate testable hypotheses, draw from work in artificial intelligence, cognitive models of language production, and research on social cognition. Three such models are action assembly theory, the cognitive rules model, and the implicit rules model.


Animals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1309
Author(s):  
Veronika Kharzinova ◽  
Arsen Dotsev ◽  
Anastasiya Solovieva ◽  
Olga Sergeeva ◽  
Georgiy Bryzgalov ◽  
...  

To examine the genetic diversity and population structure of domestic reindeer, using the BovineHD BeadChip, we genotyped reindeer individuals belonging to the Nenets breed of the five main breeding regions, the Even breed of the Republic of Sakha, the Evenk breed of the Krasnoyarsk and Yakutia regions, and the Chukotka breed of the Chukotka region and its within-breed ecotype, namely, the Chukotka–Khargin, which is bred in Yakutia. The Chukotka reindeer was shown to have the lowest genetic diversity in terms of the allelic richness and heterozygosity indicators. The principal component analysis (PCA) results are consistent with the neighbor-net tree topology, dividing the reindeer into groups according to their habitat location and origin of the breed. Admixture analysis indicated a genetic structuring of two groups of Chukotka origin, the Even breed and most of the geographical groups of the Nenets breed, with the exception of the Murmansk reindeer, the gene pool of which was comprised of the Nenets and apparently the native Sami reindeer. The presence of a genetic component of the Nenets breed in some reindeer inhabiting the Krasnoyarsk region was detected. Our results provide a deeper insight into the current intra-breeding reindeer genetic diversity, which is an important requirement for future reindeer herding strategies and for animal adaptation to environmental changes.


Sign in / Sign up

Export Citation Format

Share Document