Vocal Nuclei Research Articles

Auditory selectivity of neurons in the vocal control nucleus, 1man, of the auditory-isolated male zebra finch

Auditory selectivity of neurons in the vocal control nucleus, 1man, of the auditory-isolated male zebra finch

Neurons in the vocal nucleus of the female zebra finch respond to male songs but do not show song selectivity

Neurons in the vocal nucleus of the female zebra finch respond to male songs but do not show song selectivity

An outline of recent advances in birdsong neurobiology.

Several landmark discoveries have shaped the recent study of brain substrates for birdsong. The failure of deaf birds to reproduce a song from memory lent support for the concept of a song template. An attempt to test this idea resulted in the discovery of lateralization of song control. Search for the brain sites of lateralization and auditory control of voice led to the discovery of the main song control nuclei. Neurophysiological studies have unequivocally shown that auditory information reaches the song control system, but the exact pathway by which the song control system receives auditory inputs needs further investigation. The finding that lesions of the lateral magnocellular nucleus of the anterior neostriatum or area X affect song development in young birds but not the maintenance of song in adults suggested a role of the anterior forebrain pathway to RA in song learning. Another area of research in which much progress has been made concerns the relationships between the vocal and respiratory systems. The archistriatal and midbrain vocal nuclei innervate some of the respiratory centers in the medulla. The old questions of 'mini-breath' during fast singing and independent control of the two sides of the syrinx have been resolved. Finally, comparisons of the vocal and auditory systems between taxa indicate that different groups may use different neural circuits to achieve similar vocal-auditory behavior.

Auditory-responsive units in the midbrain vocal nuclei in the ring dove ( Streptopelia risoria)

The avian midbrain vocal control nucleus n. intercollicularis (ICo), receives inputs from midbrain auditory nucleus and from a subdivision of auditory thalamus, suggesting a possibility of auditory response units in the ICo. Using single-unit recordings, we explored auditory response units throughout the dorsomedial midbrain of female ring doves under deep general anesthesia (acute preparation). We found exclusively in the ICo, units that responded preferentially to taped courtship coos of conspecifics (male or female coos) and units that responded to specific frequencies present in coos. Units in the midbrain auditory nucleus also responded to these auditory stimulation in a tonotopic fashion, and were responsive to tone burst as well. The results, along with data from other experiments, suggest that species-specific sound responsive units within the ICo may mediate acoustically facilitated female coos and endocrine responses of the ring dove.

For whom does the female dove coo? A case for the role of vocal self-stimulation

Abstract A scries of studies on the courtship behaviour of ring doves, Streptopelia risoria , has revealed a hitherto unsuspected function of the female's nest coo, suggesting a new dimension to the, functional analysis of vocal displays. Male and female ring doves perform a predictable sequence of courtship displays that culminate in egg laying. It has been thought the male's displays provoke the endocrine changes in the female that lead to ovulation. However, there is now evidence, reviewed here, that the female's own nest coos affect her endocrine state. Females prevented from performing the nest coo showed little or no follicular growth despite active courtship by the males. This was true whether the female was devocalized through lesioning the midbrain vocal control region nucleus intercollicularis, severing the syringeal nerves, or deflating the interclavicular sac. Other possible examples of vocal self-stimulation are discussed, and it is suggested that the phenomenon may be widespread.

Synaptic connections of thalamo-cerebral vocal nuclei of the canary

The canary vocal nuclei include two systems: hyperstriatum ventrale, pars caudale (HVc), nucleus robustus archistriatalis (RA) and nucleus hypoglossus, pars tracheosyringealis (nXIIts) compose a motor driving system for vocalization. The other group of nuclei including HVc, nucleus X of the lobus parolfactorius (Area X), nucleus dorsointermedius posterior thalami (DIP) and nucleus magnocellularis of anterior neostriatum (MAN) is a modulator of the driving system. The HVc neurons receive mono- or polysynaptic innervation from the MAN and send their fibers to Area X. Axons of Area X terminated in the thalamic nucleus, the DIP, from which neurons extended axons back to the cerebral nucleus, the MAN. Accordingly, the HVc, Area X, DIP and MAN are in a closed loop. Auditory inflow may converge on HVc neurons, partly from either the MAN or Area X during feedback control of the song. Thalamic neurons in the DIP responded to MAN stimulation, and to tonal stimuli, with relatively long latency. The interconnections between the HVc and MAN neurons are presumably central in voco-auditory integration during song-learning.

Auditory input to a vocal nucleus in the frog Rana pipiens: hormonal and seasonal effects.

In Rana pipiens, single unit recordings from the pretrigeminal nucleus (pre-V), a nucleus involved in call production, demonstrated neurons that respond to auditory stimuli. Most of these neurons had V-shaped tuning curves, with best excitatory frequencies between 200-1400 Hz, thresholds between 31-87 dB SPL, latencies between 10-50 ms, and Q (10 dB) between 1.3-5.1. The number of pre-V neurons that responded to acoustic stimulation increased after gonadotropin injections, and appeared to increase during the breeding season. In addition, a small number of neurons with more complex response properties, such as W-shaped tuning curves or sensitivity to white noise but not to pure tones, appeared after hormone treatments. The hormonal and possible seasonal effects on pre-V auditory activity suggest that the auditory input to this vocal nucleus may play a role in reproductive behavior.

Auditory responses in a vocal nucleus of the leopard frog Rana pipiens: Characterization and effects of hormones

Auditory-evoked responses of single neurons were studied in the pretrigeminal nucleus of leopard frogs; this nucleus is involved in the control of vocal output [R. S. Schmidt, J. Comp. Physiol. 108, 99–113 (1976)]. Frogs receiving hormone treatment (human chorionic gonadotropin, 25 u subcutaneously daily for 5 to 14 days) and untreated frogs were used. There was a significantly greater probability (chi-squared = 9.66, df = 1, p < 0.01) of encountering auditory activity in this nucleus in hormone-treated frogs, but there was no apparent difference between the groups in the characteristics of the evoked activity. Most units showed V-shaped tuning curves with best excitatory frequencies ranging from 350–1100 Hz, thresholds from 31–87 dB SPL, and Q(10 dB) from 1.2–5.1. Response latencies varied from 10–50 ms and dynamic ranges from 20–40 dB. Both phasic and tonic response patterns were seen. Approximately 10% of the units would not respond to pure tones except at intensities above 100 dB; these units would respond to white noise, with thresholds between 50 and 70 dB SPL. This auditory input to the vocal system may play a role in acoustically evoked mate calling. [Supported by N.I.H.]

Auditory and vocal nuclei in the frog brain concentrate sex hormones.

Mate calling by South African clawed frogs, Xenopus laevis, is under the control of androgens. Autoradiographic studies demonstrate androgen-concentrating neurons in a motor nucleus that controls mate calling and a midbrain nucleus that is stimulated by sound. Hormone concentration by laryngeal motor neurons suggests that steroids regulate the final common path for vocal behavior. Modulation of auditory sensitivity by hormones could explain seasonal variations in behavioral responsiveness to conspecific vocalizations.