Growth and splitting of neural sequences in songbird vocal development

Neural sequences are a fundamental feature of brain dynamics underlying diverse behaviours, but the mechanisms by which they develop during learning remain unknown. Songbirds learn vocalizations composed of syllables; in adult birds, each syllable is produced by a different sequence of action potential bursts in the premotor cortical area HVC. Here we carried out recordings of large populations of HVC neurons in singing juvenile birds throughout learning to examine the emergence of neural sequences. Early in vocal development, HVC neurons begin producing rhythmic bursts, temporally locked to a prototype syllable. Different neurons are active at different latencies relative to syllable onset to form a continuous sequence. Through development, as new syllables emerge from the prototype syllable, initially highly overlapping burst sequences become increasingly distinct. We propose a mechanistic model in which multiple neural sequences can emerge from the growth and splitting of a commo n precursor sequence.National Institutes of Health (U.S.) (Grant R01DC009183)National Science Foundation (U.S.) (Grant DGE-114747

Analysis of Differentially Expressed Genes in Neuroendocrine Carcinomas of the Lung

IntroductionLarge cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC) show considerable differences in their histology but share neuroendocrine (NE) characteristics and also genetic and/or expression patterns.MethodsWe used the subtractive expression method to identify differences in gene expression that would allow discrimination between these two types of NE lung carcinoma.ResultsEight cDNA fragments were transcribed at a higher level in LCNEC compared with SCLC, and these corresponded to five mitochondrial genes, two ribosomal genes, and one fetal regulation factor, neuronatin (NNAT). Immunohistochemically, NNAT protein was detected in 43% (6/14) of LCNECs but in only 8% (1/13) of SCLCs (p < 0.05). Positive staining for NNAT was observed in areas that did not show the NE morphology, such as palisading and rosettes.ConclusionsThe present results suggest that NNAT has the potential to be used as a differential maker between LCNEC and SCLC

Neural mechanisms underlying the emergence of rhythmic and stereotyped vocalizations in juvenile songbirds

Thesis: Ph. D. in Neuroscience, Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, 2016.Cataloged from PDF version of thesis.Includes bibliographical references (pages 243-252).Complex motor behaviors in humans, such as speech, are not innate, but instead are learned. How does the brain construct neural circuits that generate these motor behaviors during learning? To understand the neural mechanisms underlying learned motor skills, I use vocal learning in songbirds as a model. While previous studies have shown that a premotor area in the songbird brain, HVC, is important for stereotyped adult song, the role of HVC in juvenile song is less known. This thesis characterizes how activity in HVC develops during song learning in juvenile birds. Early in song learning, temporal structure emerged in HVC. During the earliest vocalization of juvenile birds (subsong), HVC neurons exhibit bursts of action potentials. However, only half of the neurons show bursts that are temporally aligned to syllables, and most of these bursts are clustered around onsets of subsong syllables. Over several days, as the bird starts producing the earliest stereotyped vocalization called protosyllables, HVC neurons start exhibiting rhythmic bursts at 5-10 Hz. These rhythmic bursts are aligned to protosyllables, and bursts from different neurons are active at different latencies relative to protosyllables. Thus, as a population, HVC neurons start forming a rhythmic neural sequence. As the bird matures, multiple distinct syllable types emerge from a protosyllable. During this process, some neurons are active only during a specific syllable type ('specific neurons') while others are active during both syllable types ('shared neurons'). These shared neurons are active at similar latencies for both syllable types, and therefore form a shared neural sequence. Over development, fraction of shared neurons decrease and more neurons become specific. These results demonstrate that splitting of a neural sequence into multiple sequences underlies the emergence of a multiple syllable types. Moreover, this sequence splitting is observed during different song learning strategies, suggesting that this is a fundamental neural mechanism for song learning. This work demonstrates how the growth of a rhythmic neural sequence and its subsequence splitting gives rise to complex vocalization in songbirds. This may be a general neural mechanism in which the brain constructs neural circuits during learning of a complex motor behavior.by Tatsuo Okubo.Ph. D. in Neuroscienc

In Vivo Recording of Single-Unit Activity during Singing in Zebra Finches

The zebra finch is an important model for investigating the neural mechanisms that underlie vocal production and learning. Previous anatomical and gene expression studies have identified an interconnected set of brain areas in this organism that are important for singing. To advance our understanding of how these various brain areas act together to learn and produce a highly stereotyped song, it is necessary to record the activity of individual neurons during singing. Here, we present a protocol for recording single-unit activity in freely moving zebra finches during singing using a miniature, motorized microdrive. It includes procedures for both the microdrive implant surgery and the electrophysiological recordings. There are several advantages of this technique: (1) high-impedance electrodes can be used in the microdrive to obtain well-isolated single units; (2) a motorized microdrive is used to remotely control the electrode position, allowing neurons to be isolated without handling the bird, and (3) a lateral positioner is used to move electrodes into fresh tissue before each penetration, allowing recordings from well-isolated neurons over the course of several weeks. We also describe the application of the antidromic stimulation and the spike collision test to identify neurons based on the axonal projection patterns.National Institutes of Health (U.S.) (Grant R01DC009183)National Institutes of Health (U.S.) (Grant R01MH067105)Nakajima FoundationSchoemaker FellowshipUnited States. Dept. of Defense. National Defense Science & Engineering Graduate Fellowship Progra

Sector-field CP-MS in Marine Radioecological Studies

13th European Winter Conference on Plasma Spectrochemistr

Radionuclides and particles in seawater with the large volume in situ filtration and concentration system in the coastal waters off Japan

The activities of anthropogenic and natural occurring radionuclides in marine environment have been monitored near the nuclear facilities. These data has been used to construct a dynamic model in the ocean. However, some radionuclides have been used as a tool to elucidate particle dynamics on time scales ranging from day to year in the ocean. Because the concentrations of radionuclides and particles are very low in the ocean, it is difficult to concentrate and fractionate the particulate matters with the filtration systems in seawater. The large volume in situ filtration and concentration system (LV-FiCS) was developed to collect various forms of trace radionuclides and particles in seawater. The LV-FiCS has been operated during several cruises in the coastal waters off Japan, and four to eleven m3 of seawaters were filtered through different kinds of filters and then pass through the adsorbents to concentrate radionuclides simultaneously. We report the vertical profiles of plutonium and thorium with the size-fractionated method and those of cesium and technetium. These results suggested the behavior of these nuclides in the ocean

Radionuclides and particles in seawater with the large volume in situ filtration and concentration system in the coastal waters off Japan

The 16th Pacific Basin Nuclear Conferenc

Vertical distribution of particulate plutonium in the western North Pacific Ocean

005年6月および2006年6月の六ヶ所村沖の調査航海では、超大容量現場型濾過装置を用いて、5000Lの海水を各層において濾過し、粒子態のプルトニウム同位体の鉛直分布を測定した。プルトニウムの比放射能は深度とともに増加し、生物生産の活発な表層では、試料中のプランクトン破砕物によって、プルトニウムが希釈されていた。International Symposium Environmental Modeling and Radioecolog

Variations of Polonium-210 and Lead-210 in Surface Waters During the Iron Fertilization Experiment (SEEDS-II) in the Western Subarctic North Pacific

Western Pacific Geophysics Meeting 200