Behavioural–analytical studies of the role of head movements in depth perception in insects, birds and mammals

The reafference model has frequently been used to explain spatial constancy during eye and head movements. We have found that its basic concepts also form part of the information processing necessary for the control and recalibration of reaching movements. Reaching was studied in a novel force environment–a rotating room that creates centripetal forces of the type that could someday substitute for gravity in space flight, and Coriolis forces which are side effects of rotation. We found that inertial, noncontacting Coriolis forces deviate the path and endpoint of reaching movements, a finding that shows the inadequacy of equilibrium position models of movement control. Repeated movements in the rotating room quickly lead to normal movement patterns and to a failure to perceive the perturbing forces. The first movements made after rotation stops, without Coriolis forces present, show mirror-image deviations and evoke perception of a perturbing force even though none is present. These patterns of sensorimotor control and adaptation can largely be explained on the basis of comparisons of efference copy, reafferent muscle spindle, and cutaneous mechanoreceptor signals. We also describe experiments on human iocomotion using an apparatus similar to that which Mittelstaedt used to study the optomotor response of the Eristalis fly. These results show that the reafference principle relates as well to the perception of the forces acting on and exerted by the body during voluntary locomotion.

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Histological and analytical studies in the role of melatonin in the formation and composition of incremental lines in dentin

Bone Abstracts ◽

10.1530/boneabs.3.pp80 ◽

2014 ◽

Author(s):

Hiroyuki Mishima ◽

Rica Kadota ◽

Atsuhiko Hattori ◽

Nobuo Suzuki ◽

Mitsuo Kakei ◽

...

Keyword(s):

Analytical Studies ◽

Incremental Lines

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Apparent Depth with Retinal Image Motion of Expansion and Contraction Yoked to Head Movement

Perception ◽

10.1068/p270937 ◽

1998 ◽

Vol 27 (8) ◽

pp. 937-949 ◽

Cited By ~ 5

Author(s):

Takanao Yajima ◽

Hiroyasu Ujike ◽

Keiji Uchikawa

Keyword(s):

Motion Parallax ◽

Ccd Camera ◽

Head Movements ◽

Image Motion ◽

Apparent Depth ◽

Motion Cues ◽

Relative Expansion ◽

Retinal Image Motion ◽

Self Motion

The two main questions addressed in this study were (a) what effect does yoking the relative expansion and contraction (EC) of retinal images to forward and backward head movements have on the resultant magnitude and stability of perceived depth, and (b) how does this relative EC image motion interact with the depth cues of motion parallax? Relative EC image motion was produced by moving a small CCD camera toward and away from the stimulus, two random-dot surfaces separated in depth, in synchrony with the observers' forward and backward head movements. Observers viewed the stimuli monocularly, on a helmet-mounted display, while moving their heads at various velocities, including zero velocity. The results showed that (a) the magnitude of perceived depth was smaller with smaller head velocities (<10 cm s−1), including the zero-head-velocity condition, than with a larger velocity (10 cm s−1), and (b) perceived depth, when motion parallax and the EC image motion cues were simultaneously presented, is equal to the greater of the two possible perceived depths produced from either of these two cues alone. The results suggested the role of nonvisual information of self-motion on perceiving depth.

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