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The numerical sense of animals includes identifying the numerosity of a sequence of events that occur with specific intervals, e.g., notes in a call or bar of music. Across nervous systems, the temporal patterning of spikes can code these events, but how this information is decoded (counted) remains elusive. In the anuran auditory system, temporal information of this type is decoded in the midbrain, where "interval-counting" neurons spike only after at least a threshold number of sound pulses have occurred with specific timing. We show that this decoding process, i.e., interval counting, arises from integrating phasic, onset-type and offset inhibition with excitation that augments across successive intervals, possibly due to a progressive decrease in "shunting" effects of inhibition. Because these physiological properties are ubiquitous within and across central nervous systems, interval counting may be a general mechanism for decoding diverse information coded/encoded in temporal patterns of spikes, including "bursts," and estimating elapsed time. [ABSTRACT FROM AUTHOR]

Syntactical cues play an important role in song learning in songbirds. White-crowned sparrows (Zonotrichia leucophrys), whose song typically consists of four to five different phrases, fail to construct normal songs if exposed to all phrase types presented singly (Plamondon, Goller, & Rose, 2008; Soha & Marler 2001b). The specific role of acquired syntax information in guiding ontogenetic trajectories of syntax, however, and the respective contributions of instructive and selective processes to syntax ontogeny remain unknown. We tutored white-crowned sparrows with syntax information ranging from acoustic isolation to full song. Manipulation of tutor syntax influenced developmental trajectories of syntax assembly, suggesting that instructive processes contribute to syntax ontogeny. Early in development, birds tutored with full song or phrase pairs preferentially produced phrase pairings matching tutor syntax. Birds tutored with single phrases showed decreased diversity of pairwise syntactical combinations immediately after tutoring compared with other tutor groups, further illustrating the role of instructive processes. Overproduction of song material was also observed, suggesting that selective forces play a role in syntax development as well. Finally, consistent with the notion that innate influences guide syntax ontogeny, birds from all groups exhibited many similarities in trajectories of syntax assembly. Keywords: white-crowned sparrow, Zonotrichia leucophrys oriantha, birdsong, vocal learning, song development DOI: 10.1037/a0017229

Author(s): Gary J. Rose (corresponding author); Franz Goller; Howard J. Gritton; Stephanie L. Plamondon; Alexander T. Baugh; Brenton G. Cooper Modern theories of learned vocal behaviours, such as human speech [...]

A phonotaxic assay has been used to compare the responses of female Pacific treefrogs to playback of the advertisement and encounter calls of male Pacific treefrogs. This research was designed to test the hypothesis that female Pacific treefrogs prefer the advertisement call to the encounter call. All of the females that showed a phonotaxic response preferred the disphasic advertisement call to the encounter call. It is likely that females distinguish between calls on the basis of temporal cues.

The plasticity of the aggressive advertisement calls of male Pacific treefrogs, Hyla regilla, was analyzed via general playback methods. Analysis of vocal interaction in natural populations of male Pacific tree frogs indicated rapid accommodation of frogs to playbacks of encounter calls that are above their aggressive thresholds. Furthermore, the duration of accommodation to playbacks of male aggressive responses was similar to advertisement calls.

Study of the calling behavior of Hyla regilla suggests that higher, central levels of the auditory system determine the plasticity of the aggressive threshold to encounter call. The removal of a male frogs' closest calling neighbors reduces aggression thresholds. The advertisement call playback increases aggressive threshold towards the call.