Bilateral brain activity in auditory regions is necessary for successful vocal learning in songbirds.

In humans and songbirds, neuronal activation for language and song shifts from bilateral- or diffuse-activation to left-hemispheric dominance while proficiency increases. Further parallels exist at the behavioural level: unstructured juvenile vocalizations become highly stereotyped adult vocalizations through a process of trial and error learning. Greater left-hemispheric dominance in the songbird caudomedial Nidopallium (NCM), a Wernicke-like region, is related to better imitation of the tutor's song learned early in development, indicating a role for the left NCM in forming auditory memories. Here, we hypothesize that inhibition of the left NCM during interaction with a song tutor would impair imitation of the tutor's song more than inhibition of the right NCM. We infused a transient sodium channel blocker (TTX) immediately prior to tutoring sessions in either the left or right auditory lobule of previously isolated juvenile male zebra finches (Taeniopygia guttata). Upon maturation, both right-infused and left-infused birds' tutor song imitation was significantly impaired. Left-infused birds also showed less consistency in the rhythmic stability of their song as well as increased pitch, suggesting a subtle division of function between the left and right auditory lobules.

Guidelines for evaluating myocardial cell death.

Cell death is a fundamental process in cardiac pathologies. Recent studies have revealed multiple forms of cell death, and several of them have been demonstrated to underlie adverse cardiac remodeling and heart failure. With the expansion in the area of myocardial cell death and increasing concerns over rigor and reproducibility, it is important and timely to set a guideline for the best practices of evaluating myocardial cell death. There are six major forms of regulated cell death observed in cardiac pathologies, namely apoptosis, necroptosis, mitochondrial-mediated necrosis, pyroptosis, ferroptosis, and autophagic cell death. In this article, we describe the best methods to identify, measure, and evaluate these modes of myocardial cell death. In addition, we discuss the limitations of currently practiced myocardial cell death mechanisms.

A sensorimotor area in the songbird brain is required for production of vocalizations in the song learning period of development.

Sensory feedback is essential for acquiring and maintaining complex motor behaviors, including birdsong. In zebra finches, auditory feedback reaches the song control circuits primarily through the nucleus interfacialis nidopalii (Nif), which provides excitatory input to HVC (proper name)-a premotor region essential for the production of learned vocalizations. Despite being one of the major inputs to the song control pathway, the role of Nif in generating vocalizations is not well understood. To address this, we transiently inactivated Nif in late juvenile zebra finches. Upon Nif inactivation (in both hemispheres or on one side only), birds went from singing stereotyped zebra finch song to uttering highly variable and unstructured vocalizations resembling sub-song, an early juvenile song form driven by a basal ganglia circuit. Simultaneously inactivating Nif and LMAN (lateral magnocellular nucleus of the anterior nidopallium), the output nucleus of a basal ganglia circuit, inhibited song production altogether. These results suggest that Nif is required for generating the premotor drive for song. Permanent Nif lesions, in contrast, have only transient effects on vocal production, with song recovering within a day. The sensorimotor nucleus Nif thus produces a premotor drive to the motor pathway that is acutely required for generating learned vocalizations, but once permanently removed, the song system can compensate for its absence. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1213-1225, 2016.