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In JoVE (1)
Other Publications (5)
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Articles by Jason Ballweg in JoVE
Nucleofection e Cultura Primária de Neurônios do hipocampo do rato embrionárias e Cortical
Christopher Viesselmann*, Jason Ballweg*, Derek Lumbard*, Erik W. Dent
Department of Anatomy, University of Wisconsin-Madison
Este protocolo descreve os passos necessários para dissecar, transfectar via de eletroporação e neurônios do hipocampo e da cultura do mouse cortical. Curto prazo, as culturas podem ser utilizados para estudos sobre crescimento do axônio e orientação, enquanto culturas a longo prazo podem ser usados para estudos de sinaptogênese e análise espinha dendrítica.
Other articles by Jason Ballweg on PubMed
Positioning and Guidance of Neurons on Gold Surfaces by Directed Assembly of Proteins Using Atomic Force Microscopy
Biomaterials. Jul, 2009 | Pubmed ID: 19342092
We demonstrate that Atomic Force Microscopy nanolithography can be used to control effectively the adhesion, growth and interconnectivity of cortical neurons on Au surfaces. We demonstrate immobilization of neurons at well-defined locations on Au surfaces using two different types of patterned proteins: 1) poly-d-lysine (PDL), a positively charged polypeptide used extensively in tissue culture and 2) laminin, a component of the extracellular matrix. Our results show that both PDL and laminin patterns can be used to confine neuronal cells and to control their growth and interconnectivity on Au surfaces, a significant step towards the engineering of artificial neuronal assemblies with well-controlled neuron position and connections.
PloS One. 2011 | Pubmed ID: 22096612
Most excitatory synaptic terminals in the brain impinge on dendritic spines. We and others have recently shown that dynamic microtubules (MTs) enter spines from the dendritic shaft. However, a direct role for MTs in long-lasting spine plasticity has yet to be demonstrated and it remains unclear whether MT-spine invasions are directly influenced by synaptic activity. Lasting changes in spine morphology and synaptic strength can be triggered by activation of synaptic NMDA receptors (NMDARs) and are associated with learning and memory processes. To determine whether MTs are involved in NMDAR-dependent spine plasticity, we imaged MT dynamics and spine morphology in live mouse hippocampal pyramidal neurons before and after acute activation of synaptic NMDARs. Synaptic NMDAR activation promoted MT-spine invasions and lasting increases in spine size, with invaded spines exhibiting significantly faster and more growth than non-invaded spines. Even individual MT invasions triggered rapid increases in spine size that persisted longer following NMDAR activation. Inhibition of either NMDARs or dynamic MTs blocked NMDAR-dependent spine growth. Together these results demonstrate for the first time that MT-spine invasions are positively regulated by signaling through synaptic NMDARs, and contribute to long-lasting structural changes in targeted spines.
Langmuir : the ACS Journal of Surfaces and Colloids. Jan, 2011 | Pubmed ID: 21121598
Understanding network development in the brain is of tremendous fundamental importance, but it is immensely challenging because of the complexity of both its architecture and function. The mechanisms of axonal navigation to target regions and the specific interactions with guidance factors such as membrane-bound proteins, chemical gradients, mechanical guidance cues, etc., are largely unknown. A current limitation for the study of neural network formation is the ability to control precisely the connectivity of small groups of neurons. A first step in designing such networks is to understand the "rules" central nervous system (CNS) neurons use to form functional connections with one another. Here we begin to delineate novel rules for growth and connectivity of small numbers of neurons patterned on Au substrates in simplified geometries. These studies yield new insights into the mechanisms determining the organizational features present in intact systems. We use a previously reported atomic force microscopy (AFM) nanolithography method to control precisely the location and growth of neurons on these surfaces. By examining a series of systems with different geometrical parameters, we quantitatively and systematically analyze how neuronal growth depends on these parameters.
ACS Nano. Apr, 2011 | Pubmed ID: 21366271
In many neural culture studies, neurite migration on a flat, open surface does not reflect the three-dimensional (3D) microenvironment in vivo. With that in mind, we fabricated arrays of semiconductor tubes using strained silicon (Si) and germanium (Ge) nanomembranes and employed them as a cell culture substrate for primary cortical neurons. Our experiments show that the SiGe substrate and the tube fabrication process are biologically viable for neuron cells. We also observe that neurons are attracted by the tube topography, even in the absence of adhesion factors, and can be guided to pass through the tubes during outgrowth. Coupled with selective seeding of individual neurons close to the tube opening, growth within a tube can be limited to a single axon. Furthermore, the tube feature resembles the natural myelin, both physically and electrically, and it is possible to control the tube diameter to be close to that of an axon, providing a confined 3D contact with the axon membrane and potentially insulating it from the extracellular solution.
The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Oct, 2011 | Pubmed ID: 22031905
Microtubules (MTs) are capable of entering dendritic spines in mature hippocampal neurons through dynamic polymerization. Although these MT invasions are directly associated with neuronal activity, their function remains unknown. Here we demonstrate in mouse hippocampal neurons that MT entries into spines regulate the increase in postsynaptic density-95 (PSD-95) protein after brain-derived neurotrophic factor (BDNF) treatment. Using multiwavelength total internal reflectance fluorescence microscopy, we show that BDNF prolonged the average MT dwell time in spines and that this effect was dependent on TrkB receptor activation. Further examination revealed that peaks of MT polymerization into spines corresponded to rapid PSD-95 increases in the spine head. Over time, spines targeted by MTs after BDNF application, but not before, showed a robust increase in PSD-95. Conversely, spines completely devoid of MT invasions showed no significant change in the level of PSD-95. Pharmacological inhibition of MT dynamics abolished the BDNF-induced increase in PSD-95. Together, these results support the hypothesis that the well known increase in PSD-95 within spines after BDNF treatment is dependent on MT invasions of dendritic spines. Thus, our study provides a direct link between dynamic MTs and the postsynaptic structure, and provides a functional role for MT invasion of dendritic spines.