Dynamics of electroencephalogram oscillations underlie right-eye preferences in predatory behavior of the music frogs

Abstract

Visual lateralization is a typical characteristic of many vertebrates, however, its underlying dynamic neural mechanism is unclear. In this study, predatory responses and dynamic brain activities were evaluated in the Emei music frog (Babina daunchina) to assess the potential eye preferences and its underlying dynamic neural mechanism, using behavioral and electrophysiological experiments, respectively. To do this, when prey stimulus (live cricket and leaf as control) was moved around the frogs in both clockwise and anticlockwise directions at constant velocity, the number of predatory responses were counted and Electroencephalogram (EEG) absolute power spectra for each band was measured for the telencephalon, diencephalon and mesencephalon, respectively. The results showed that (1) no significant difference of the number of predatory responses could be found for control (leaf), however, the number of predatory responses for the right visual field (RVF) were significantly greater than those for the left visual field (LVF) when the live cricket was moved into RVF clockwise; (2) compared with no-stimulus in the visual field and stimulus in LVF, the power spectra of each EEG band was greater when the prey stimulus was moved into RVF clockwise; and (3) the power spectra of theta, alpha and beta bands in the left diencephalon were significantly greater than those of the right counterpart for clockwise direction, however, relatively less similar significant differences presented for anticlockwise direction. Together, the results suggested that right-eye preferences for predatory behaviors existed in the music frogs, and that the dynamics of EEG oscillations might underlie this right-eye/left-hemisphere advantage.

Brain Lateralization and Cognitive Capacity

“…There are examples of such right-side bias in predatory response: the cane toad, for example, strikes at prey once the prey has moved into the toad's right visual field, whereas prey items are ignored when they are in the toad's left visual field [11]. A similar result has been found in the music frog [80]. Such preferential use of the right eye in feeding, or predation, originally shown in chicks [35], has also been reported to occur in humpback whales [81] and blue whales [82].…”