QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online May 1, 2009
Journal of Experimental Biology 212, 1568-1575 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.024950

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Voss, J. Articles by Bischof, H.-J. Search for Related Content PubMed Articles by Voss, J. Articles by Bischof, H.-J. Social Bookmarking                         What's this?

Eye movements of laterally eyed birds are not independent

Joe Voss^* and Hans-Joachim Bischof

Lehrstuhl Verhaltensforschung, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany

View larger version (10K): [in this window] [in a new window]   Fig. 1. Schematic drawing of the experimental setup. TFT screens for presenting frontal or bilateral stimuli are inserted in the wall of the arena. CCD cameras record the movements of both eyes. A third camera (not shown in the drawing) records the stimuli from above.

View larger version (23K): [in this window] [in a new window]   Fig. 2. (A) Circular diagram showing the frequency of spontaneous eye movement directions of both eyes without a conspicuous stimulus in 20 deg. wedges (the colours code for different birds, b). The mean axial direction (blue arrow) is based on the mean axial direction of each bird (coloured arrowheads) and shows that the birds move their eyes close to the axis of the visual horizon. 0 deg.–180 deg.=beak axis, 90 deg.–270 deg.=upward–downward directions, h=horizontal plane. (B) Circular diagram showing the directional relationship of simultaneously performed spontaneous eye movements. 0 defines the movement direction of one arbitrary eye (grey arrow), the frequency of directions of the other eyes' corresponding movement is depicted in 20 deg. wedges. The mean corresponding direction 166.3 deg., r-value=0.98 (blue arrow) is based on the mean directions of each bird (coloured arrowheads). If one eye moves in one direction, the other eye performs a saccade in the opposite direction.

View larger version (8K): [in this window] [in a new window]   Fig. 3. Relationship of movement amplitudes of the left and right eye when they are moved spontaneously, sorted into classes. 0, only one eye moves; 1, the two amplitudes are of the same length. Simultaneously performed movements of the two eyes tend to have amplitudes of similar or same length (ANOVA: F=6.057, P=0.0036, N=5; Tukey's multiple comparison test: *P<0.001). Data are means ± s.e.m.

View larger version (19K): [in this window] [in a new window]   Fig. 4. (A) Circular diagram showing the relationship of the movement directions of the targeting eye and of the corresponding eye after simultaneous stimulation in the two lateral fields. 0 defines the movement direction of the targeting eye (grey arrow); the frequency of directions of the other eyes' corresponding movements is depicted in 20 deg. wedges (the colours code for different birds). The outer arrowheads show the mean corresponding direction for each bird. The birds decide on one eye and target the stimulus on its side; the contralateral eye simultaneously moves in the opposite direction (mean corresponding direction=176 deg., r=0.89). (B) Relationship of the saccade amplitudes of the left and right eye, sorted into classes. If one eye is used to target the stimulus, the other eye moves with similar amplitude (ANOVA: F=6.01, P=0.0038, N=5; Tukey's multiple comparison test: *P<0.05, **P<0.01).

View larger version (21K): [in this window] [in a new window]   Fig. 5. (A) Circular diagram showing the directional relationship of simultaneously performed eye movements after stimulation in the frontal visual field. If a stimulus appears frontally, the birds react in two different modes. Either they decide on one of the eyes to target the stimulus, and the other eye simultaneously moves in the opposite direction (wedges around 180 deg.), or in 22% of the cases the two eyes simultaneously perform converging saccades towards the stimulus (wedges around 0 deg.). The outer arrowheads depict the mean direction for each bird for converging movements (around 0 deg.) and for counter-movements (around 180 deg.). The blue arrows show the mean corresponding directions in the two modes (mean corresponding direction of one eye targeting: 168.8 deg. (r=0.98), mean corresponding direction of convergent targeting: 10.0 deg. (r=0.99). (B) Relationship of the saccade amplitudes of the left and the right eye (including both modes) after frontal stimulation, sorted into classes. The two eyes move with equal amplitudes (ANOVA: F=11.6, P=0.0001, N=5; Tukey's multiple comparison test: *P<0.05, **P<0.01, ***P<0.001).

View larger version (7K): [in this window] [in a new window]   Fig. 6. (A) Frequency of single eye targeting after bilateral and frontal visual stimulation. After bilateral stimulation in almost all cases the birds decide on one eye to target one of the two stimuli; in contrast after frontal stimulation only 78% of the targeting saccades are performed with one single eye, and 22% are converging saccades (unpaired t-test: t=4.04, **P=0.0037, N=5). (B) Eye preference scores of each bird (diamonds) in bilateral and frontal stimulus situation (means are given by solid horizontal lines). After bilateral stimulation four out of five birds decide on the left eye to target the left stimulus. After frontal stimulation (single eye targeting mode) only one bird has a preference for the right eye; mean values show no eye preference.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter