| Sign In to gain access to subscriptions and/or personal tools. |
Circadian Organization and Photoreception in an Australian Dasyurid Marsupial (Sminthopsis macroura)Department of Neurology, Health Sciences Center, State University of New York at Stony Brook, Stony Brook, New York 11794, Department of Psychology, La Trobe University, Bundoora, Victoria, Australia 3083
Much is known about the formal properties of circadian rhythm regulation and the physiological substrates underlying rhythmicity in nocturnal rodents, but relatively few studies have addressed circadian rhythm regulation in other mammalian taxonomic groups. In this study, some formal and functional aspects of circadian organization in a nocturnal dasyurid marsupial, the stripe-faced dunnart (Sminthopsis macroura), were analyzed. To determine phasic responses to discrete pulses of light, dunnarts were placed in constant darkness (DD) and were periodically administered pulses of bright light at different times of the animals' circadian day. Analysis of phase shifts in response to light indicated a phase response curve that was similar to responses observed in nocturnal rodents. To determine the possibility of extraretinal photoreception mediating photic entrainment, dunnarts were anesthetized and orbitally enucleated while maintained in a light-dark regimen (LD 14:10). All blinded dunnarts free-ran with periods (
Journal of Biological Rhythms, Vol. 2, No. 4,
261-268 (1987) This article has been cited by other articles:
|
|
||||||||||||||
 |
|
|
 |
|
Sign In to gain access to subscriptions and/or personal tools.
) that were similar to those observed in DD, indicating that entrainment is mediated through ocular photoreception. However, the data also indicated a decrease in activity in blind dunnarts during the last 3-5 hr of the dark phase, raising the possibility of some retention of photoreceptive capacities. 
