The vestibular sensory apparatus and associated vestibular nuclei are generally thought to encode angular head velocity during our daily activities. However, in addition to direct inputs from vestibular afferents, the vestibular nuclei receive substantial projections from cortical, cerebellar, and other brainstem structures. Given this diversity of inputs, the question arises: How are the respo...

To investigate the effects of vehicle impact velocity and front-end structure on the dynamic responses of child pedestrians, an extensive parametric study was carried out using two child mathematical models at 6 and 15 years old. The effect of the vehicle impact velocity was studied at 30, 40, and 50 km/h in terms of the head linear velocity, impact angle, and head angular velocity as well as v...

During exploratory behaviors, the velocity of an organism's sensory surfaces can have a pronounced effect on the incoming flow of sensory information. In this study, we quantified variability in the velocity profiles of rat whisking during natural exploratory behavior that included head rotations. A wide continuum of profiles was observed, including monotonic, delayed, and reversing velocities ...

The oculomotor system produces eye-position signals during fixations and head movements by integrating velocity-coded saccadic and vestibular inputs. A previous analysis of nucleus prepositus hypoglossi (nph) lesions in monkeys found that the integration time constant for maintaining fixations decreased, while that for the vestibulo-ocular reflex (VOR) did not. On this basis, it was concluded t...

The present research investigates neonatal sensitivity to optic flow. Twenty five 3-day-old infants were placed inside a dark room and observed while presented with a 10 s bilateral and backward peripheral optic motion. Seven constant flow velocity conditions were used (2.5, 5.0, 10.0, 15.0, 20.0, 25.0 and 30.0 degrees per second) and were compared to a baseline motionless condition. Sagittal d...

Eye-head coordination was measured in patients with Parkinson's disease as they made horizontal gaze shifts in response to predictable and unpredictable target steps and to targets moving smoothly with either constant or sinusoidally varying velocity. Patients preferred not to move their heads for both large and small amplitude gaze shifts. Both eye and head movement reaction times were prolong...

The semi-circular canals and the otolith organs both contribute to gaze stabilization during head movement. We investigated how these sensory signals interact when they provide conflicting information about head orientation in space. Human subjects were reoriented 90 degrees in pitch or roll during long-duration, constant-velocity rotation about the earth-vertical axis while we measured three-d...

The present study was conducted to compare sperm motion characteristics of adult Malpura and Bharat Merino rams by the computer-aided sperm analysis (CASA) technique. Malpura is a hardy native sheep breed of the semi-arid tropical environment and Bharat Merino is a crossbred evolved in the same environment by crossing native sheep with exotic rams. Semen was collected from 8 donor rams of each ...

Saccade planning requires a geometric transformation between the retinal stimulus position and the desired motor plan to acquire the target. This reference frame transformation problem has, however, never been considered for velocity signals. Therefore we asked whether a separate 3D visuomotor transformation of velocity signals was theoretically required by modeling the underlying geometry. We ...

The authors investigated the mechanisms underlying the head shaking shown by some patients with congenital nystagmus (CN). In order to improve visual function by head shaking, a patient with CN must have some visual acuity loss due to retinal image motion created by the nystagmus; an abnormal vestibulo-ocular reflex (VOR); and the head shaking must be correlated with the nystagmus. The authors ...