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- Title
Visual efference in Limulus: In vitrotemperature-dependent neuromodulation of photoreceptor potential timing by octopamine and substance P.
- Authors
CORRINNE C.M. LIM-KESSLER; AMANDA R. BOLBECKER; JIA LI; GERALD S. WASSERMAN
- Abstract
Efferents from the brain of Limuluscourse toward its lateral eye and release octopamine and substance P into it. These neurotransmitters have previously been found to act as neuromodulators in this visual system by altering the size of its responses to light. We report here that both also modulate the timing of the receptor potentials (RPs) evoked by brief light flashes and that these timing effects are temperature dependent. Specifically: We extend our previous report that octopamine prolongs ambient RPs in a categorical fashion and here demonstrate that it does the same at colder temperatures. Categorical means that a given RP is either clearly prolonged in a dramatic fashion or its duration is otherwise unremarkable. Octopamine also accelerates the onsets of RPs when they are evoked by weak flashes under cold temperatures. Contrariwise, substance P accelerates RPs at all temperatures and this acceleration dramatically reduces the sluggishness that is otherwise typically present at low temperatures. Quantitative analysis of intensity-response functions also demonstrated that light sensitivity under substance P is significantly augmented. The plain temporal antagonism between these two modulators demonstrates that the visual system of Limuluspossesses a well-poised mechanism which could be used to adjust the timing of its neural processing to interface well with the temporal characteristics of those visual stimuli that are currently present.
- Subjects
BRAIN; EYE; NEUROTRANSMITTERS; TEMPERATURE; ANTIBIOSIS; VISUAL learning
- Publication
Visual Neuroscience, 2008, Vol 25, Issue 1, p83
- ISSN
0952-5238
- Publication type
Article
- DOI
10.1017/S0952523808080103