Variables Contributing to the Coordination of Rapid Eye/Head Gaze Shifts

Abstract

In this article results of several published studies are synthesized in order to address the neural system for the determination of eye and head movement amplitudes of horizontal eye/head gaze shifts with arbitrary initial head and eye positions. Target position, initial head position, and initial eye position span the space of physical parameters for a planned eye/head gaze saccade. The principal result is that a functional mechanism for determining the amplitudes of the component eye and head movements must use the entire space of variables. Moreover, it is shown that amplitudes cannot be determined additively by summing contributions from single variables. Many earlier models calculate amplitudes as a function of one or two variables and/or restrict consideration to best-fit linear formulae. Our analysis systematically eliminates such models as candidates for a system that can generate appropriate movements for all possible initial conditions. The results of this study are stated in terms of properties of the response system. Certain axiom sets for the intrinsic organization of the response system obey these properties. We briefly provide one example of such an axiomatic model. The results presented in this article help to characterize the actual neural system for the control of rapid eye/head gaze shifts by showing that, in order to account for behavioral data, certain physical quantities must be represented in and used by the neural system. Our theoretical analysis generates predictions and identifies gaps in the data. We suggest needed experiments.

Differential Influence of Attention on Gaze and Head Movements

“…Recently, evidence has been presented for an independent head controller in addition to the gaze controller, which can modulate the head component of the gaze shift. This is supported by findings reporting contextdependent head contributions to gaze shifts in addition to a stereotypical close coupling between the eye and the head (Bizzi et al 1972;Freedman and Sparks 1997b;Hanes and McCollum 2006;Monteon et al 2005;Oommen and Stahl 2005;Oommen et al 2004;Zangemeister and Stark 1982). This separate head drive could involve areas such as M1, FEF, and/or SEF and link to brain stem areas controlling the head, bypassing the superior colliculus (SC), which we assume to be part of the neural pathway involved in driving gaze.…”

“…However, we believe this is not likely the case. There is much independent evidence for a separate pathway for the head that is used during combined eye-head gaze shifts (Bizzi et al 1972;Freedman and Sparks 1997b;Hanes and McCollum 2006;Oommen and Stahl 2005;Oommen et al 2004;Zangemeister and Stark 1982). In contrast, although evidence has been shown for a saccade drive pathway from FEF to the brain stem that bypasses the SC, it appears that this pathway is not normally used by the brain, as evidenced by major deficits in saccade production when the SC is lesioned with moderate to little recovery, especially with respect to saccade latency (Albano and Wurtz 1982;Hanes et al 2005;Mohler and Wurtz 1977;Schiller et al 1980;Wurtz and Goldberg 1972).…”

Investigating the midline effect for visual focus of attention recognition

“…Exploiting results on human gazing behavior and head-eye dynamics involved in saccadic gaze shifts [6,5], they introduced a linear gaze model relating the head pose, gaze direction, and head reference (coined gaze midline in [5]) as illustrated in Fig. 1(a).…”

“…In absence of shoulder orientation measures, we introduce an implicit estimation of the midline direction, and propose two approaches inspired by [5] to improve gaze-to-head mapping and gaze shift models. Experiments on meeting benchmark data and on data recorded by a robot (Nao) shows the benefit of several modeling components.…”

Recognizing the Visual Focus of Attention for Human Robot Interaction

“…As an alternative we can exploit results from cognitive science studies about human gazing behavior and the dynamics of the head-eye motions involved in saccadic gaze shifts [10,8,11] to automatically determine which head poses should be associated with looking at a given target. This is done using a gaze model relating the head pose, a head-to-gaze ratio, and a head reference direction [3].…”