PubMed · 275073
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
J Talmant. 1977. [Cephalic statics].. https://pubmed.ncbi.nlm.nih.gov/275073/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
With time as the criterion to be optimized, the divergences from optimal head movements show systematic differences in their control signal variables with respect to single behaviours. To clarify these relationships, this study applies manipulation and mathematical analysis of the 6th-order nonlinear head movement model, using the three-fold approach of sensitivity analysis. The sensitivity analysis of the improved and refined head movement model explains the different tasks of the control parameters and their relation to the plant. It shows that width more than height of the agonistic and antagonistic pulses dominate the important behaviours of the movement: acceleration, magnitude and duration.
The origins of chronic headache and the role of the greater occipital nerve in headache syndromes are reviewed. The anatomical pathways and physiological basis of these headaches are discussed with a view to synthesizing some current concepts of headache generation. Studies of occipital nerve blockade for treatment of headaches of various types are assessed and a retrospective analysis of our own experience is presented.
Off-vertical-axis rotation (OVAR) in darkness generates continuous compensatory eye velocity. No model has yet been presented that defines the signal processing necessary to estimate head velocity in three dimensions for arbitrary rotations during OVAR. The present study develops a model capable of estimating all 3 components of head velocity in space accurately. It shows that processing of two patterns of otolith activation, one delayed with respect to the other, for each plane of eye movement is not sufficient. (A pattern in this context is an array of signals emanating from the otoliths. Each component of the array is a signal corresponding to a class of otolith hair cells with a given polarization vector as described by Tou and Gonzalez in 1974.) The key result is that estimation of head velocity in space can be achieved by processing three temporally displaced patterns, each representing a sampling of gravity as the head rotates. A vector cross product of differences between pairs of the sampled gravity vectors implements the estimation. An interesting property of this model is that the component of velocity about the axis of rotation reduces to that derived previously using the pattern estimator model described by Raphan and Schnabolk in 1988 and Fanelli et al in 1990. This study suggests that the central nervous system (CNS) maintains a current as well as 2 delayed representations of gravity at every head orientation during rotation. It also suggests that computing vector cross products and implementing delays may be fundamental operations in the CNS for generating orientation information associated with motion.