Anterior forebrain pathway in parrots is necessary for producing learned vocalizations with individual signatures

Parrots have enormous vocal imitation capacities and produce individually unique vocal signatures. Like songbirds, parrots have a nucleated neural song system with distinct anterior (AFP) and posterior forebrain pathways (PFP). To test if song systems of parrots and songbirds, which diverged over 50 million years ago, have a similar functional organization, we first established a neuroscience-compatible call-and-response behavioral paradigm to elicit learned contact calls in budgerigars (Melopsittacus undulatus). Using variational autoencoder-based machine learning methods, we show that contact calls within affiliated groups converge but that individuals maintain unique acoustic features, or vocal signatures, even after call convergence. Next, we transiently inactivated the outputs of AFP to test if learned vocalizations can be produced by the PFP alone. As in songbirds, AFP inactivation had an immediate effect on vocalizations, consistent with a premotor role. But in contrast to songbirds, where the isolated PFP is sufficient to produce stereotyped and acoustically normal vocalizations, isolation of the budgerigar PFP caused a degradation of call acoustic structure, stereotypy, and individual uniqueness. Thus, the contribution of AFP and the capacity of isolated PFP to produce learned vocalizations have diverged substantially between songbirds and parrots, likely driven by their distinct behavioral ecology and neural connectivity.

Dopaminergic error signals retune to social feedback during courtship

Hunger, thirst, loneliness and ambition determine the reward value of food, water, social interaction and performance outcome1. Dopamine neurons respond to rewards meeting these diverse needs2-8, but it remains unclear how behaviour and dopamine signals change as priorities change with new opportunities in the environment. One possibility is that dopamine signals for distinct drives are routed to distinct dopamine pathways9,10. Another possibility is that dopamine signals in a given pathway are dynamically tuned to rewards set by the current priority. Here we used electrophysiology and fibre photometry to test how dopamine signals associated with quenching thirst, singing a good song and courting a mate change as male zebra finches (Taeniopygia guttata) were provided with opportunities to retrieve water, evaluate song performance or court a female. When alone, water reward signals were observed in two mesostriatal pathways but singing-related performance error signals were routed to Area X, a striatal nucleus specialized for singing. When courting a female, water seeking was reduced and dopamine responses to both water and song performance outcomes diminished. Instead, dopamine signals in Area X were driven by female calls timed with the courtship song. Thus the dopamine system handled coexisting drives by routing vocal performance and social feedback signals to a striatal area for communication and by flexibly re-tuning to rewards set by the prioritized drive.

Automated home cage training of mice in a hold-still center-out reach task

An obstacle to understanding neural mechanisms of movement is the complex, distributed nature of the mammalian motor system. Here we present a novel behavioral paradigm for high-throughput dissection of neural circuits underlying mouse forelimb control. Custom touch-sensing joysticks were used to quantify mouse forelimb trajectories with micron-millisecond spatiotemporal resolution. Joysticks were integrated into computer-controlled, rack-mountable home cages, enabling batches of mice to be trained in parallel. Closed loop behavioral analysis enabled online control of reward delivery for automated training. We used this system to show that mice can learn, with no human handling, a direction-specific hold-still center-out reach task in which a mouse first held its right forepaw still before reaching out to learned spatial targets. Stabilogram diffusion analysis of submillimeter-scale micromovements produced during the hold demonstrate that an active control process, akin to upright balance, was implemented to maintain forepaw stability. Trajectory decomposition methods, previously used in primates, were used to segment hundreds of thousands of forelimb trajectories into millions of constituent kinematic primitives. This system enables rapid dissection of neural circuits for controlling motion primitives from which forelimb sequences are built. NEW & NOTEWORTHY A novel joystick design resolves mouse forelimb kinematics with micron-millisecond precision. Home cage training is used to train mice in a hold-still center-out reach task. Analytical methods, previously used in primates, are used to decompose mouse forelimb trajectories into kinematic primitives.

The significance of nuclear diameter in the biologic behavior of thyroid carcinomas: a retrospective study of 127 cases

The relationship between nuclear diameter and biologic behavior was studied in 127 cases of thyroid carcinoma. Using a sonic digitizer coupled to a minicomputer, nuclear diameters of 200 randomly selected cancer cells from each case (hematoxylineosin-stained paraffin sections) projected at X 400 magnification were traced and averaged. A total of 25,400 measurements were made. The nuclear diameters varied from 4.7 to 13.1 micron. By analysis of variance, the nuclear diameters were significantly different (p = 0.0007) among the four types of thyroid cancers, being largest in the undifferentiated cancers (8.7 +/- 0.8 micron) and smallest in the medullary cancers (6.6 +/- 0.1 micron). Nuclear diameter was also significantly correlated with degree of tumor differentiation (p = 0.002), maximal tumor diameter (p = 0.03), mitotic rate (p = 0.002), and 5-year survival (p less than 0.05) for all types of tumors. The correlation between nuclear diameter and disease stage was significant only for undifferentiated cancers (p = 0.04). No significant correlations were seen between nuclear diameter and duration of disease, sex, or age of the patient.

Human fetal breathing response to intravenous glucose is directly related to gestational age

This prospective longitudinal study examined human fetal breathing activity over the second half of pregnancy both in the fasting state and after intravenous glucose administration. There was a linear relationship between gestational age and percent time spent breathing after glucose between 19 and 38 weeks' gestation. However, no such correlation could be demonstrated between gestational age and fetal breathing activity in the fasting state.

The significance of mitotic rate: a retrospective study of 127 thyroid carcinomas

The association between mitotic rate and biologic behavior was studied in 127 cases of thyroid cancer. Based on the observation of 12,700 high-power fields (HPF), the mitotic rate varied from 0 to 316 (33.3 +/- 4.9) mitoses/100 HPF. Mitotic rate differed among the four types of thyroid cancers and correlated inversely with the differentiation of the tumors, being highest (156.8 +/- 32.9) in the undifferentiated tumors and lowest (17.3 +/- 2.4) in the papillary tumors. By analysis of variance (AOVA), the relations between mitotic rate and the sex or age of the patient, maximal diameter of the tumor, and vascular or capsular invasion were assessed, but significant relations were not found (r2 = 44.2 per cent). Follow-up observation, possible in 74 patients, showed mitotic rate to be significantly related to the survival period (Student's t-test; P values ranging from 0.02 to 0.05). The patients who were alive five and ten years after surgery had had lower mitotic rates than those who had died during the same follow-up period. The correlation of low mitotic rate with a high degree of differentiation and low potential for invasion might, in part, explain the better surgical cure rates for papillary thyroid carcinoma than for other types of thyroid cancers.

Procoagulant activity of lymphocyte-macrophage populations in rabbits: selective increases in marrow, blood, and spleen cells during Shwartzman reactions

The present experiments examine leukocyte procoagulant activity using mononuclear cell populations purified or enriched from rabbit bone marrow, blood, spleen, lymph node, thymus, and pulmonary alveoli. Cells from these six sites, obtained from control and endotoxemic animals and assayed without an intermediate culture step, were found to have procoagulant activity identified as tissue factor. Under control conditions, tissue factor activity was found to be at low levels in marrow and blood populations compared to median activities 3- and 11-fold higher in populations from spleen and lymph node, and 33- and 45-fold higher in thymus and alveolar populations. By contrast to respective controls, significantly increased amounts of tissue factor (35-, 15-, and 12-fold at median levels) were found in marrow, blood, and spleen populations from endotoxemic animals. The types of leukocytes in these latter three populations were morphologically and histochemically indistinguishable from respective controls, indicating that endotoxin induced increases of activity in cells with relatively low amounts under control conditions. Activity did not change significantly in lymph node, thymus, or alveolar populations after endotoxemia. These studies show that tissue factor is present in a range of leukocyte populations not previously reported to have procoagulant activity. In addition, the finding of widespread gains of tissue factor in the marrow-blood-spleen pool due to endotoxemia provides new evidence supporting the importance of leukocyte procoagulants in Shwartzman-like reactions.