Experimental evidence indicates that the superior colliculus (SC) is important but neither necessary nor sufficient to produce accurate saccadic eye movements. Furthermore both clinical and experimental points cerebellum as an indispensable component of system. Accordingly, we have devised a new model system in which characteristics saccades are determined by cooperation two pathways, one through SC other cerebellum. Both pathways influenced feedback information: determines decay activity...

Human observers are experts at face recognition, yet a simple 180 degrees rotation of photograph decreases recognition performance substantially. A full understanding this phenomenon-which is believed to be important for clarifying the nature our expertise in recognition-is still waiting. According long-standing and influential hypothesis, an inverted cannot perceived as holistically upright has analyzed local feature by feature. Here, we tested holistic perception hypothesis inversion...

Through highly precise perceptual and sensorimotor activities, the human tactile system continuously acquires information about environment. Mechanical interactions between skin at point of contact a touched surface serve as source this information. Using dedicated custom robotic platform, we imaged deformation area finger flat during onset tangential sliding movements in four different directions (proximal, distal, radial ulnar) with varying normal force speeds. This simple event evidenced...

Humans can detect and discriminate between fine variations of surface roughness using active touch. It is hitherto believed that perception mediated mostly by cutaneous subcutaneous afferents located in the fingertips. However, recent findings have shown following abolishment afferences resulting from trauma or pharmacological intervention, ability subjects to textures was not significantly altered. These suggest somatosensory system able collect textural information other sources than...

The dynamics of fingertip contact manifest themselves in the complex skin movements observed during transition from a stuck state to fully developed slip. While investigating this transition, we found that it depended on hydration. To quantify dependency, asked subjects slide their index glass surface while keeping normal component interaction force constant with help visual feedback. Skin deformation inside region was imaged an optical apparatus allowed us relative sizes slipping and...

The brain makes use of noisy sensory inputs to produce eye, head, or arm motion. In most instances, the combines this information with predictions about future events. Here, we propose that Kalman filtering can account for dynamics both visually guided and predictive motor behaviors within one simple unifying mechanism. Our model relies on two filters: (1) processing visual retinal input; (2) maintaining a dynamic internal memory target outputs filters are then combined in statistically...

The temporal evolution of surface strain, resulting from a combination normal and tangential loading forces on the fingerpad, was calculated high-resolution images. A customized robotic device loaded fingertip with varying force, direction speed. We observed strain waves that propagated periphery to centre contact area. Consequently, different regions area were subject degrees compression, stretch shear. spatial distribution both strains energy densities depended stimulus direction....

Human tactile afferents provide essential feedback for grasp stability during dexterous object manipulation. Interacting forces between an and the fingers induce slip events that are thought to information about stability. To gain insight into this phenomenon, we made a transparent surface against fixed fingerpad while monitoring skin deformation at contact. Using microneurography, simultaneously recorded activity of single innervating fingertips. This unique combination allowed us describe...

When tracking moving visual stimuli, primates orient their axis by combining two kinds of eye movements, smooth pursuit and saccades, that have very different dynamics. Yet, the mechanisms govern decision to switch from one type movement other are still poorly understood, even though they could bring a significant contribution understanding how CNS combines control strategies achieve common motor sensory goal. In this study, we investigated oculomotor responses large range combinations...

During visual tracking of a moving stimulus, primates orient their axis by combining two very different types eye movements, smooth pursuit and saccades. The purpose this paper was to investigate quantitatively the catch-up saccades occurring during sustained pursuit. We used ramp-step-ramp paradigm evoke In general, followed unexpected steps in position velocity target. observed same direction as movement (forward saccades) well opposite (reverse saccades). made comparison main sequences...

Selective impairment of face recognition following brain damage, as in acquired prosopagnosia, may cause a dramatic loss diagnosticity the eye area and an increased reliance on mouth for identification ( Caldara et al. , 2005 ). To clarify nature this phenomenon, we measured fixation patterns case pure prosopagnosia (PS, Rossion 2003 ) during her photographs personally familiar faces (27 children kindergarten). Her age‐matched colleague served control. Consistent with previous evidence,...

Previous studies recording eye gaze during face perception have rendered somewhat inconclusive findings with respect to fixation differences between familiar and unfamiliar faces. This can be attributed a number of factors that differ across studies: the type extent familiarity faces presented, definition areas interest subject analyses, as well lack consideration for time course scan patterns. Here we sought address these issues by fixations in recognition task personally After first common...

During tactile exploration, partial slips occur systematically at the periphery of fingertip-object contact prior to full slip. Although mechanics are well characterized, perception such events is unclear. Here, we performed psychophysical experiments assess slip detection ability on smooth transparent surfaces. In these experiments, index fingertip human subjects was stroked passively by a smooth, glass plate while imaged slipping against glass. We found that were able detect before...

Alzheimer's disease (AD) is characterized by amyloid beta (Aβ) plaques and hyperphosphorylated tau in the brain. Aβ precede cognitive impairments can be detected through amyloid-positron emission tomography (PET) or cerebrospinal fluid (CSF). Assessing plasma Aβ42/Aβ40 ratio seems promising for non-invasive cost-effective detection of brain accumulation. This approach involves some challenges, including accuracy blood-based biomarker measurements establishment clear, standardized thresholds...

Visual tracking of moving objects requires prediction to compensate for visual delays and minimize mismatches between eye target position velocity. In everyday life, often disappear behind an occluder, is required align at reappearance. Earlier studies investigating motion during blanking showed that velocity first decayed after disappearance but was sustained or recovered in a predictive way. Furthermore, saccades were directed toward the unseen trajectory therefore appeared correct errors...

Coordination between the normal force exerted by fingers on a held object and tangential constraints at fingertips helps to successfully manipulate objects. It is well established that minimal grip required prevent an from slipping strongly depends frictional properties finger-object interface. Moreover, interindividual variation in modulation of suggests moisture level skin could influence strategy. In present study we asked subjects perform horizontal point-to-point task holding with...

The planning and control of motor actions requires knowledge the dynamics controlled limb to generate appropriate muscular commands achieve desired goal. Such imply that CNS must be able deal with forces constraints acting on limb, such as omnipresent force gravity. present study investigates effect hypergravity induced by parabolic flights trajectory vertical pointing movements test hypothesis are optimized respect gravity limb. Subjects performed in normal hypergravity. We use a model...

In behavioral neuroscience, many experiments are developed in 1 or 2 spatial dimensions, but when scientists tackle problems 3-dimensions (3D), they often face new challenges. Results obtained for lower dimensions not always extendable 3D. motor planning of eye, gaze arm movements, sensorimotor transformation problems, the 3D kinematics external (stimuli) internal (body parts) must be considered: how to describe position and orientation these objects link them together? We motors (dual...

Motor adaptation to an external perturbation relies on several mechanisms such as model-based, model-free, strategic, or repetition-dependent learning. Depending the experimental conditions, each of these has more less weight in final state. Here we focused conditions that lead formation a model-free motor memory (Huang VS, Haith AM, Mazzoni P, Krakauer JW. Neuron 70: 787–801, 2011), i.e., does not depend internal model size direction errors experienced during The was hypothesized schedule...

Abstract Humans and other animals adapt motor commands to predictable disturbances within tens of trials in laboratory conditions. A central question is how does the nervous system natural conditions when exactly same movements cannot be practiced several times. Because sensory feedback together carry continuous information about limb dynamics, we hypothesized that could unexpected online. We tested this hypothesis two reaching experiments during which velocity-dependent force fields (FFs)...