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Lateral Magnocellular Nucleus (lateral + magnocellular_nucleus)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Lateral magnocellular nucleus of the anterior neostriatum (LMAN) in the zebra finch: Neuronal connectivity and the emergence of sex differences in cell morphology

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2001
Barbara E. Nixdorf-Bergweiler
Abstract The song system of birds provides a model system to study basic mechanisms of neuronal plasticity and development underlying learned behavior. Song learning and production involve discrete sets of interconnected nuclei in the avian brain. One of these nuclei, the lateral magnocellular nucleus of the anterior neostriatum (LMAN), is the output of the so-called anterior forebrain pathway known to be essential for learning and maintenance of song, both processes depending on auditory feedback. In zebra finches, only males sing and this sexually dimorphic behavior is mirrored by sexual dimorphism in neuronal structure that develops during ontogeny. Female zebra finches are not able to sing and nuclei of the song system are strongly reduced in size or even lacking, when compared to male brains. Only LMAN can be delineated as easily in females as in males. Since female zebra finches, despite being unable to sing, recognize song just as males do and form a memory for song (model acquisition) early in life, LMAN is a putative candidate for song acquisition in both sexes. Therefore, development of LMAN was studied at the cellular and ultrastructural level in both male and female zebra finches. Regressive development of dendritic spines, enlargement of neuronal cell body and nuclei size, as well as changes at the nucleolar level are events all occurring exclusively in males, when song learning progresses. The decline in synapse number and the augmentation in synaptic contact length at synapses in LMAN in males are indicative for synaptic plasticity, whereas in females synapse number and synaptic contact length remain unchanged. Microsc. Res. Tech. 54:335,353, 2001. © 2001 Wiley-Liss, Inc. [source]

The pallial basal ganglia pathway modulates the behaviorally driven gene expression of the motor pathway

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2007
Lubica Kubikova
Abstract The discrete neural network for songbird vocal communication provides an effective system to study neural mechanisms of learned motor behaviors in vertebrates. This system consists of two pathways , a vocal motor pathway used to produce learned vocalizations and a vocal pallial basal ganglia loop used to learn and modify the vocalizations. However, it is not clear how the loop exerts control over the motor pathway. To study the mechanism, we used expression of the neural activity-induced gene ZENK (or egr-1), which shows singing-regulated expression in a social context-dependent manner: high levels in both pathways when singing undirected and low levels in the lateral part of the loop and in the robust nucleus of the arcopallium (RA) of the motor pathway when singing directed to another animal. Here, we show that there are two parallel interactive parts within the pallial basal ganglia loop, lateral and medial, which modulate singing-driven ZENK expression of the motor pathway nuclei RA and HVC, respectively. Within the loop, the striatal and pallial nuclei appear to have opposing roles; the striatal vocal nucleus lateral AreaX is required for high ZENK expression in its downstream nuclei, particularly during undirected singing, while the pallial vocal lateral magnocellular nucleus of the anterior nidopallium is required for lower expression, particularly during directed singing. These results suggest a dynamic molecular interaction between the basal ganglia pathway and the motor pathway during production of a learned motor behavior. [source]

Lateral magnocellular nucleus of the anterior neostriatum (LMAN) in the zebra finch: Neuronal connectivity and the emergence of sex differences in cell morphology

The excitatory thalamo-"cortical" projection within the song control system of zebra finches is formed by calbindin-expressing neurons

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 6 2007
Raphael Pinaud
Abstract The learning and production of vocalizations in songbirds are controlled by a system of interconnected brain nuclei organized into a direct vocal motor pathway and an anterior forebrain (pallium-basal ganglia-thalamo-pallial) loop. Here we show that the thalamo-pallial ("thalamo-cortical") projection (from the medial part of the dorsolateral thalamic nucleus to the lateral magnocellular nucleus of the anterior nidopallium,DLM to LMAN) within the anterior forebrain loop is composed of cells positive for the calcium-binding protein calbindin. We show that the vast majority of cells within DLM express calbindin, based both on immunocytochemistry (ICC) for calbindin protein and in situ hybridization for calb mRNA. Using a combination of tract-tracing and ICC we show that the neurons that participate in the DLM-to-LMAN projection are calbindin-positive. We also demonstrate that DLM is devoid of cells expressing mRNA for the GABAergic marker zGAD65. This observation confirms that the calbindin-expressing cells in DLM are not GABAergic, in accordance with previous electrophysiological data indicating that the DLM-to-LMAN projection is excitatory. Furthermore, we use ICC to determine the trajectory of the fibers within the DLM-to-LMAN projection, and to demonstrate a sex difference in calbindin expression levels in the fibers of the DLM-to-LMAN projection. Our findings provide a clear-cut neurochemical signature for a critical projection in the songbird vocal control pathways that enable song learning. J. Comp. Neurol. 504:601,618, 2007. © 2007 Wiley-Liss, Inc. [source]