Differential patterns of constant frequency 50 and 22 khz usv production are related to intensity of negative affective state.

Adult rat ultrasonic vocalizations (USVs) are a valuable tool for noninvasively assessing an animal's emotional state. USVs are produced in 1 of 2 frequency ranges labeled as 22 kHz or 50 kHz vocalizations. One USV subtype within the 50 kHz call category, constant frequency 50 kHz (CF 50 kHz) calls, is not viewed as signaling an emotional state. The current study tested the hypothesis that CF 50 kHz calls are related to a mild negative affective state. In Experiment 1, diazepam (1, 2.5, or 5 mg/kg), or control injections were administered prior to receiving a sequence of mild footshocks (0.5 mA, 0.5 s). Subjects transitioned from producing CF 50 to 22 kHz USVs as footshocks were repeated; a pattern paralleled by a shift from rearing to increased time freezing. USV production was largely absent in the higher diazepam dose groups, whereas the 1 mg/kg dose attenuated CF 50 kHz USV production prior to and immediately following initial footshocks. The higher doses of diazepam similarly reduced rearing activity and overall freezing behavior. In Experiment 2, pre-exposure to the testing environment with or without access to palatable food elicited CF 50 kHz calls and rearing. During re-exposure to the test chamber the following day, CF 50 kHz USV production was reduced prior to footshock onset compared to the prior test day. The pattern of results support an association between CF 50 kHz USVs and a mild negative affective state; dissociating this call type may increase the sensitivity of behavioral measurements of emotion. (PsycINFO Database Record

HVC contributes toward conspecific contact call responding in male Bengalese finches.

The processes of producing and acquiring birdsong, like human speech, utilize interdependent neural systems for vocal learning and production. In addition to song, these brain areas are undoubtedly used for other affiliative behaviors. Oscine sound production is lateralized because their vocal organ contains two independently controlled sound sources. Therefore, songbirds offer a unique opportunity to study the biological relevance of lateralized behavioral control. Bengalese finches (Lonchura striata domestica) produce different types of sound with each sound source: the left sound generator produces tonal frequencies from 1 to 4 kHz and the right sound source produces the lower frequency (<2 kHz) tonal and broadband sounds. We sought to investigate whether the premotor nucleus HVC contributes toward lateralized auditory processing of conspecific vocalizations. We ablated either the left or the right HVC and tested birds with the callback paradigm using female contact calls that were filtered to accentuate particular frequency ranges. The results show that (a) the acoustic frequency of call stimuli drives different patterns of calling behavior and that (b) both HVC nuclei contribute toward contact call production, but HVC ablation does not alter the number of short calls produced upon hearing a female contact call. These data are consistent with the emerging view that the motor production and auditory processing are linked and suggest that HVC may contribute toward affiliative behaviors by promoting the production of contact call responses.

Need to train your rat? There is an App for that: a touchscreen behavioral evaluation system.

The increasing demand for highly automated and flexible tasks capable of assessing visual learning and memory in nonhuman animals has led to the exciting development of a wide array of prefabricated touchscreen-equipped systems. However, the high cost of these prefabricated systems has led many researchers to develop or modify their own preexisting equipment. We developed a freely downloadable App, the Touchscreeen Behavioral Evaluation System (TBES) for use in conjunction with an iPad (Apple, Cupertino, California) as an alternative to prefabricated touchscreen systems. TBES allows for stimulus presentation and data collection on an iPad. The touchscreen technology offered by the iPad is attractive to researchers due to its affordability, reliability, and resistance to false inputs. We highlight these, as well as the feasibility and procedural flexibility of TBES, in an effort to promote our system as a competitive alternative to those currently available.

Exploring vocal recovery after cranial nerve injury in Bengalese finches.

Songbirds and humans use auditory feedback to acquire and maintain their vocalizations. The Bengalese finch (Lonchura striata domestica) is a songbird species that rapidly modifies its vocal output to adhere to an internal song memory. In this species, the left side of the bipartite vocal organ is specialized for producing louder, higher frequencies (≥2.2kHz) and denervation of the left vocal muscles eliminates these notes. Thus, the return of higher frequency notes after cranial nerve injury can be used as a measure of vocal recovery. Either the left or right side of the syrinx was denervated by resection of the tracheosyringeal portion of the hypoglossal nerve. Histologic analyses of syringeal muscle tissue showed significant muscle atrophy in the denervated side. After left nerve resection, songs were mainly composed of lower frequency syllables, but three out of five birds recovered higher frequency syllables. Right nerve resection minimally affected phonology, but it did change song syntax; syllable sequence became abnormally stereotyped after right nerve resection. Therefore, damage to the neuromuscular control of sound production resulted in reduced motor variability, and Bengalese finches are a potential model for functional vocal recovery following cranial nerve injury.

Syringeal specialization of frequency control during song production in the Bengalese finch (Lonchura striata domestica).

BACKGROUND: Singing in songbirds is a complex, learned behavior which shares many parallels with human speech. The avian vocal organ (syrinx) has two potential sound sources, and each sound generator is under unilateral, ipsilateral neural control. Different songbird species vary in their use of bilateral or unilateral phonation (lateralized sound production) and rapid switching between left and right sound generation (interhemispheric switching of motor control). Bengalese finches (Lonchura striata domestica) have received considerable attention, because they rapidly modify their song in response to manipulations of auditory feedback. However, how the left and right sides of the syrinx contribute to acoustic control of song has not been studied. METHODOLOGY: Three manipulations of lateralized syringeal control of sound production were conducted. First, unilateral syringeal muscular control was eliminated by resection of the left or right tracheosyringeal portion of the hypoglossal nerve, which provides neuromuscular innervation of the syrinx. Spectral and temporal features of song were compared before and after lateralized nerve injury. In a second experiment, either the left or right sound source was devoiced to confirm the role of each sound generator in the control of acoustic phonology. Third, air pressure was recorded before and after unilateral denervation to enable quantification of acoustic change within individual syllables following lateralized nerve resection. SIGNIFICANCE: These experiments demonstrate that the left sound source produces louder, higher frequency, lower entropy sounds, and the right sound generator produces lower amplitude, lower frequency, higher entropy sounds. The bilateral division of labor is complex and the frequency specialization is the opposite pattern observed in most songbirds. Further, there is evidence for rapid interhemispheric switching during song production. Lateralized control of song production in Bengalese finches may enhance acoustic complexity of song and facilitate the rapid modification of sound production following manipulations of auditory feedback.