Reduction of dopamine synaptic activity: Degradation of 50-khz ultrasonic vocalization in rats.

Abstract

Vocal deficits are prevalent and debilitating in Parkinson's disease. These deficits may be related to the initial pathology of the nigrostriatal dopamine neurons and resulting dopamine depletion, which contributes to dysfunction of fine motor control in multiple functions. Although vocalization in animals and humans may differ in many respects, we evaluated complex (50-kHz) ultrasonic mate calls in two rat models of Parkinson's disease, including unilateral infusions of 6-hydroxydopamine to the medial forebrain bundle and peripheral administration of a non-akinesia dose of the dopamine antagonist haloperidol. We examined the effects of these treatments on multiple aspects of the acoustic signal. The number of trill-like (frequency modulated) 50-kHz calls was significantly reduced, and appeared to be replaced by simpler (flat) calls. The bandwidth and maximum intensity of simple and frequency-modulated calls were significantly decreased, but call duration was not. Our findings suggest that the nigrostriatal dopamine pathway is involved to some extent in fine sensorimotor function that includes USV production and complexity.

Targeted Training of Ultrasonic Vocalizations in Aged and Parkinsonian Rats

“…13 Typically, we see a reduction in quality of the ultrasonic vocalizations characterized by a reduction of the following quantitative acoustic parameters: bandwidth, peak frequency, duration, and intensity. Figure 6 shows the frequency modulated vocalizations of a rat in the PD model at three different time points: baseline, after induction of PD, and after vocalization training.…”

Ultrasonic output from the excised rat larynx

“…[16][17][18] Although it is unlikely that USVs are created by vocal fold vibration, 4 they are similar to human vocalizations in that they require control of airflow, subglottal pressure, and glottal adduction and share some common neural pathways. 19,20 Therefore, rat USVs may be a useful model to study the underlying peripheral and central neural mechanisms of vocal control, as well as the effects of interventions and disease.…”

Regulation of bat echolocation pulse acoustics by striatal dopamine

“…In rats, Ciucci and colleagues found that striatal dopamine depletions produced symptoms similar to hypokinetic dysarthria, namely reduced call loudness and bandwidth (Ciucci et al, 2009). Those symptoms can be accounted for by reduced laryngeal and respiratory muscle tone.…”

“…It remains unclear however if the effects of MPTP on call structure are attributable solely to changes in respiratory drive or whether the drug also degraded the bats' ability to articulate the laryngeal apparatus in a complex way. Ciucci and colleagues speculated that striatal dopamine depletion may have constrained fine sensorimotor processes needed for the articulation of more complex broadband vocalizations in rats (Ciucci et al, 2009). It may also be the case that hypertonic laryngeal conditions similarly interfere with articulatory mechanisms in both bats and humans.…”

“…In rats, unilateral lesions of the dopamine-producing cells of the substantia nigra reduced mating call amplitudes and bandwidths in a manner similar to the symptoms of Parkinsonian dysarthria in humans (Ciucci et al, 2009;Ciucci et al, 2007). An alternative method for knocking down dopamine production is through the use the neurotoxin 1-methyl-4-phenylpyridine (MPTP).…”