Targeted Training of Ultrasonic Vocalizations in Aged and Parkinsonian Rats

Abstract

Voice deficits are a common complication of both Parkinson disease (PD) and aging; they can significantly diminish quality of life by impacting communication abilities.1, 2 Targeted training (speech/voice therapy) can improve specific voice deficits, 3, 4 although the underlying mechanisms of behavioral interventions are not well understood. Systematic investigation of voice deficits and therapy should consider many factors that are difficult to control in humans, such as age, home environment, age post-onset of disease, severity of disease, and medications. The method presented here uses an animal model of vocalization that allows for systematic study of how underlying sensorimotor mechanisms change with targeted voice training. The ultrasonic recording and analysis procedures outlined in this protocol are applicable to any investigation of rodent ultrasonic vocalizations.The ultrasonic vocalizations of rodents are emerging as a valuable model to investigate the neural substrates of behavior. 5-8 Both rodent and human vocalizations carry semiotic value and are produced by modifying an egressive airflow with a laryngeal constriction. 9, 10 Thus, rodent vocalizations may be a useful model to study voice deficits in a sensorimotor context. Further, rat models allow us to study the neurobiological underpinnings of recovery from deficits with targeted training.To model PD we use Long-Evans rats (Charles River Laboratories International, Inc.) and induce parkinsonism by a unilateral infusion of 7 μg of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle which causes moderate to severe degeneration of presynaptic striatal neurons (for details see Ciucci, 2010). 11, 12 For our aging model we use the Fischer 344/Brown Norway F1 (National Institute on Aging).Our primary method for eliciting vocalizations is to expose sexually-experienced male rats to sexually receptive female rats. When the male becomes interested in the female, the female is removed and the male continues to vocalize. By rewarding complex vocalizations with food or water, both the number of complex vocalizations and the rate of vocalizations can be increased (Figure 1).An ultrasonic microphone mounted above the male's home cage records the vocalizations. Recording begins after the female rat is removed to isolate the male calls. Vocalizations can be viewed in real time for training or recorded and analyzed offline. By recording and acoustically analyzing vocalizations before and after vocal training, the effects of disease and restoration of normal function with training can be assessed. This model also allows us to relate the observed behavioral (vocal) improvements to changes in the brain and neuromuscular system.

Automated detection of 50-kHz ultrasonic vocalizations using template matching in XBAT

“…Aaron Johnson, Paul Clarke, and Michelle Ciucci—all of whom have experience in USV recording and analysis (Johnson et al, 2010, 2011; Ciucci et al, 2007, 2008, 2009; Wright et al, 2010, 2011; Scardochio & Clarke, 2012). These files were used to test the generalizability of the template detector to other recording environments, recording hardware, etc.…”

Assessment of Sensorimotor Function in Mouse Models of Parkinson's Disease

“…These include tests for limb-use asymmetry, movement initiation, somatosensory neglect, reaching abilities, and more recently ultrasonic vocalizations [1][2][3][4][5][6] . These tests are sensitive to varying degrees of nigrostriatal dopamine neuron loss and have been used extensively to evaluate the efficacy of various types of potential therapeutics [7][8][9][10][11] .…”

Automated acoustic analysis of 50-kHz ultrasonic vocalizations using template matching and contour analysis

“…Recordings were made in a wire-mesh walled chamber with an ultrasonic microphone (CM16/CMPA, Avisoft Bioacoustics, Berlin, Germany) and digitized using a 250 kHz sampling rate and 16-bit depth (UltraSoundGate 416, Avisoft Bioacoustics, Berlin, Germany). USVs were elicited from the male rats using a mating paradigm, as described in Johnson et al 11 In brief, female rats in estrus were introduced to each male rat in the recording chamber. The female was removed after the male rat expressed interest in her, which elicited vocalizations from the male.…”

“…For example, in models of Parkinson disease and neurodegeneration, it has been shown that dopamine depleting lesions and aging produce changes in the acoustic features of USVs, such as decreases in amplitude and reductions in fundamental frequency bandwidth. 5,[10][11][12] Notably, these changes affect the acoustic qualities of vocalizations rather than the quantity of observed USVs. Moreover, it has been convincingly shown that repeated training of USVs improves the vocal deficits induced by dopamine depleting lesions.…”

“…Moreover, it has been convincingly shown that repeated training of USVs improves the vocal deficits induced by dopamine depleting lesions. 11,12 Still, quantification of the magnitude of this improvement is tedious and would benefit from increased automation.…”