Exercise enhances motor skill learning by neurotransmitter switching in the adult midbrain.

Physical exercise promotes motor skill learning in normal individuals and those with neurological disorders but its mechanism of action is unclear. We find that one week of voluntary wheel running enhances the acquisition of motor skills in normal adult mice. One week of running also induces switching from ACh to GABA expression in neurons in the caudal pedunculopontine nucleus (cPPN). Consistent with regulation of motor skills, we show that the switching neurons make projections to the substantia nigra (SN), ventral tegmental area (VTA) and ventrolateral-ventromedial nuclei of the thalamus (VL-VM). Use of viral vectors to override transmitter switching blocks the beneficial effect of running on motor skill learning. We suggest that neurotransmitter switching provides the basis by which sustained running benefits motor skill learning, presenting a target for clinical treatment of movement disorders

LOW RESISTANCE CONNECTIONS BETWEEN CELLS IN THE DEVELOPING ANTHER OF THE LILY

Low resistance junctions were demonstrated between cells in anthers from young buds of Lilium longiflorum Croft by standard electrophysiological techniques. Electrodes containing a dye were used to stain impaled cells for later histological identification. Electrical coupling is widespread; germinal cells are coupled to one another; coupling is also observed between somatic elements, and germinal and somatic cells are similarly interconnected. Cytoplasmic bridges are implicated in the first case; plasmodesmata are probably responsible for the interactions in the other two. Although the physiological role of the low resistance junctions shown here and present in embryonic animal tissues is unknown, the possible function of this form of intercellular communication in the development of the anther is discussed

Brain awareness week and beyond: encouraging the next generation.

The field of neuroscience is generating increased public appetite for information about exciting brain research and discoveries. As stewards of the discipline, together with FUN and others, the Society for Neuroscience (SfN) embraces public outreach and education as essential to its mission of promoting understanding of the brain and nervous system. The Society looks to its members, particularly the younger generation of neuroscientists, to inspire, inform and engage citizens of all ages, and most importantly our youth, in this important endeavor. Here we review SfN programs and resources that support public outreach efforts to inform, educate and tell the story of neuroscience. We describe the important role the Brain Awareness campaign has played in achieving this goal and highlight opportunities for FUN members and students to contribute to this growing effort. We discuss specific programs that provide additional opportunities for neuroscientists to get involved with K-12 teachers and students in ways that inspire youth to pursue further studies and possible careers in science. We draw attention to SfN resources that support outreach to broader audiences. Through ongoing partnerships such as that between SfN and FUN, the neuroscience community is well positioned to pursue novel approaches and resources, including harnessing the power of the Internet. These efforts will increase science literacy among our citizens and garner more robust support for scientific research

Neuronal activity regulates neurotransmitter switching in the adult brain following light-induced stress.

Neurotransmitter switching in the adult mammalian brain occurs following photoperiod-induced stress, but the mechanism of regulation is unknown. Here, we demonstrate that elevated activity of dopaminergic neurons in the paraventricular nucleus of the hypothalamus (PaVN) in the adult rat is required for the loss of dopamine expression after long-day photoperiod exposure. The transmitter switch occurs exclusively in PaVN dopaminergic neurons that coexpress vesicular glutamate transporter 2 (VGLUT2), is accompanied by a loss of dopamine type 2 receptors (D2Rs) on corticotrophin-releasing factor (CRF) neurons, and can lead to increased release of CRF. Suppressing activity of all PaVN glutamatergic neurons decreases the number of inhibitory PaVN dopaminergic neurons, indicating homeostatic regulation of transmitter expression in the PaVN

Mechanism for neurotransmitter-receptor matching.

Synaptic communication requires the expression of functional postsynaptic receptors that match the presynaptically released neurotransmitter. The ability of neurons to switch the transmitter they release is increasingly well documented, and these switches require changes in the postsynaptic receptor population. Although the activity-dependent molecular mechanism of neurotransmitter switching is increasingly well understood, the basis of specification of postsynaptic neurotransmitter receptors matching the newly expressed transmitter is unknown. Using a functional assay, we show that sustained application of glutamate to embryonic vertebrate skeletal muscle cells cultured before innervation is necessary and sufficient to up-regulate ionotropic glutamate receptors from a pool of different receptors expressed at low levels. Up-regulation of these ionotropic receptors is independent of signaling by metabotropic glutamate receptors. Both imaging of glutamate-induced calcium elevations and Western blots reveal ionotropic glutamate receptor expression prior to immunocytochemical detection. Sustained application of glutamate to skeletal myotomes in vivo is necessary and sufficient for up-regulation of membrane expression of the GluN1 NMDA receptor subunit. Pharmacological antagonists and morpholinos implicate p38 and Jun kinases and MEF2C in the signal cascade leading to ionotropic glutamate receptor expression. The results suggest a mechanism by which neuronal release of transmitter up-regulates postsynaptic expression of appropriate transmitter receptors following neurotransmitter switching and may contribute to the proper expression of receptors at the time of initial innervation

Activity-dependent competition regulates motor neuron axon pathfinding via PlexinA3

The role of electrical activity in axon guidance has been extensively studied in vitro. To better understand its role in the intact nervous system, we imaged intracellular Ca2+ in zebrafish primary motor neurons (PMN) during axon pathfinding in vivo. We found that PMN generate specific patterns of Ca2+ spikes at different developmental stages. Spikes arose in the distal axon of PMN and were propagated to the cell body. Suppression of Ca2+ spiking activity in single PMN led to stereotyped errors, but silencing all electrical activity had no effect on axon guidance, indicating that an activity-based competition rule regulates this process. This competition was not mediated by synaptic transmission. Combination of PlexinA3 knockdown with suppression of Ca2+ activity in single PMN produced a synergistic increase in the incidence of pathfinding errors. However, expression of PlexinA3 transcripts was not regulated by activity. Our results provide an in vivo demonstration of the intersection of spontaneous electrical activity with the PlexinA3 guidance molecule receptor in regulation of axon pathfinding.Fil: Plazas, Paola Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular; Argentina. University of California at San Diego. Kavli Institute for Brain and Mind. Division of Biological Sciences. Neurobiology Section and Center for Neural Circuits and Behavior; Estados UnidosFil: Nicol, Xavier. University of California at San Diego. Kavli Institute for Brain and Mind. Division of Biological Sciences. Neurobiology Section and Center for Neural Circuits and Behavior; Estados UnidosFil: Spitzer, Nicholas C.. University of California at San Diego. Kavli Institute for Brain and Mind. Division of Biological Sciences. Neurobiology Section and Center for Neural Circuits and Behavior; Estados Unido

Advice or exercise for chronic whiplash disorders? Design of a randomized controlled trial

BACKGROUND: Whiplash-associated disorder (or "whiplash") is a common condition incurring considerable expense in social and economic terms. A lack of research on effective therapy for patients with chronic whiplash associated disorders prompted the design of the current study. The primary aim of this randomised controlled trial is to determine the effects of a physical activity program for people with chronic (symptoms of > 3 months duration) whiplash. A secondary aim is to determine if pain severity, level of disability and fear of movement/(re)injury predict response to a physical activity program. METHODS / DESIGN: This paper presents the rationale and design of a randomised controlled trial examining the effects of advice and individualized sub-maximal exercise programs in the treatment of whiplash associated disorders. DISCUSSION: This paper highlights the design, methods and operational aspects of a significant clinical trial in the area of whiplash and chronic pain