A Caltech Library Service

A `bright zone' in male hoverfly (Eristalis tenax) eyes and associated faster motion detection and increased contrast sensitivity

Straw, Andrew D. and Warrant, Eric J. and O'Carroll, David C. (2006) A `bright zone' in male hoverfly (Eristalis tenax) eyes and associated faster motion detection and increased contrast sensitivity. Journal of Experimental Biology, 209 (21). pp. 4339-4354. ISSN 0022-0949.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


Eyes of the hoverfly Eristalis tenax are sexually dimorphic such that males have a fronto-dorsal region of large facets. In contrast to other large flies in which large facets are associated with a decreased interommatidial angle to form a dorsal `acute zone' of increased spatial resolution, we show that a dorsal region of large facets in males appears to form a `bright zone' of increased light capture without substantially increased spatial resolution. Theoretically, more light allows for increased performance in tasks such as motion detection. To determine the effect of the bright zone on motion detection, local properties of wide field motion detecting neurons were investigated using localized sinusoidal gratings. The pattern of local preferred directions of one class of these cells, the HS cells, in Eristalis is similar to that reported for the blowfly Calliphora. The bright zone seems to contribute to local contrast sensitivity; high contrast sensitivity exists in portions of the receptive field served by large diameter facet lenses of males and is not observed in females. Finally, temporal frequency tuning is also significantly faster in this frontal portion of the world, particularly in males, where it overcompensates for the higher spatial-frequency tuning and shifts the predicted local velocity optimum to higher speeds. These results indicate that increased retinal illuminance due to the bright zone of males is used to enhance contrast sensitivity and speed motion detector responses. Additionally, local neural properties vary across the visual world in a way not expected if HS cells serve purely as matched filters to measure yaw-induced visual motion.

Item Type:Article
Related URLs:
URLURL TypeDescription
Straw, Andrew D.0000-0001-8381-0858
Additional Information:Published by The Company of Biologists 2006. Accepted 29 August 2006. First published online October 18, 2006. This work was supported through a Predoctoral Fellowship from the Howard Hughes Medical Institute to A.D.S. and grants from the United States Air Force Office of Scientific Research/Asian Office for Aerospace Research and Development (FA9550-04-1-0294). We thank the Botanical Gardens of Adelaide for allowing us to collect Eristalis, Sara Juhl for performing the optical measurements, Dr Gaby Maimon for careful reading and discussion of the manuscript, and an anonymous reviewer for detailed, helpful comments.
Funding AgencyGrant Number
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Air Force Office of Scientific Research (AFOSR)FA9550-04-1-0294
Subject Keywords:insect vision, motion detection, sexual dimorphism
Issue or Number:21
Record Number:CaltechAUTHORS:STRAjeb06
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12360
Deposited By: Archive Administrator
Deposited On:13 Nov 2008 05:23
Last Modified:03 Oct 2019 00:27

Repository Staff Only: item control page