- 29th October
2012 - 29
- 13th October
2012 - 13
Meet My Class: Due to the wide variety of topics in neuroscience and my specific interests, I have decided to introduce you to some of my fellow classmates at the NYU Sackler Institute. These people are all very bright and amazingly talented individuals who are very passionate about their work and are willing to share it with a broader audience- you!
First up in the Meet My Class series- Dave Marzan. Dave Marzan received his B.S. from University of California- San Diego (UCSD, one of the top neuroscience institutions in the country). Dave and I met during NYU interviews a little over 3 years ago and have been friends ever since. He has an amazing attitude and his excitement regarding neuroscience is contagious. He is also part of the Society for Neuroscience Scholars Program (NSP). Needless to say, I feel very lucky to have him as a fellow classmate and he has happily accepted my invitation to write about his work. The image above was captured by him recently and was presented today at the NSP Diversity Poster session at SfN NOLA.
Here it goes, in Dave’s own words…
Contrary to popular belief, the brain is not comprised of only neurons. 90% of central nervous system cells (CNS) are glia. One type of glia in the CNS, oligodendrocytes, form the wrapping around axons and support proper neuron function. Multiple sclerosis (MS) is the most common cause of inflammatory neurological disability in young adults. Inflammation and autoimmune reactivity against the myelinating cells of the nervous system causes demyelination, axonal damage andneurodegeneration. The CNS is capable of spontaneous remyelination by stem cells and oligodendrocyte precursor cells (OPCs). However,remyelination significantly decreases with age; this failure of remyelination is thought to be a major contributor to MS progression.While there has been progress in slowing autoimmune mediated demyelination, there has been none in promoting regeneration and reversing disease progression. Research in regenerative therapies has the potential to benefit the 400,000 MS patients in America as well as countless others suffering from neurodegenerative diseases.
As a graduate student at NYU, I work in the lab of James Salzer,
a leading expert in the genetic and cellular mechanisms governing
myelination. My project focuses on studying how the brain’s immune
cells , microglia, contribute to the process of demyelination and
remyelination in vivo. To this end, I employ a novel trangenic mouse
line that allows for inducible deletion of microglia from the CNS. I
remove microglia at time points critical for developmental myelination, toxin induced demyelination and endogenous remyelination in order to study their function. Understanding how these immune cells contribute to degeneration and regeneration can provide insight into the pathophysiology of MS and in the development of regenerative therapies.
The image above is a immunofluorescent confocal projection taken from an adult mouse. The green cells are PDGFRα+ oligodendrocyte precursor cells (OPCs) migrating into the corpus callosum to differentiate into oligodendrocytes and form new myelin (red). Green OPCs are enriched in the corpus callosum because the mouse was placed on a demyelinating diet and these cells are migrating to site of injury to remyelinate. Blue is a nuclear hoechst stain that stains all cell types.
To visit the Salzer Lab page, click here.
- 15th July
2012 - 15
![ikenbot:
Marijuana Reveals Memory Mechanism
Glial cells, not neurons, are responsible for marijuana-induced forgetfulness
Until recently, most scientists believed that neurons were the all-important brain cells controlling mental functions and that the surrounding glial cells were little more than neuron supporters and “glue.” Now research published in March in Cell reveals that astrocytes, a type of glia, have a principal role in working memory. And the scientists made the discovery by getting mice stoned.
Marijuana impairs working memory—the short-term memory we use to hold on to and process thoughts. Think of the classic stoner who, midsentence, forgets the point he was making. Although such stupor might give recreational users the giggles, people using the drug for medical reasons might prefer to maintain their cognitive capacity.
To study how marijuana impairs working memory, Giovanni Marsicano of the University of Bordeaux in France and his colleagues removed cannabinoid receptors—proteins that respond to marijuana’s psychoactive ingredient THC—from neurons in mice. These mice, it turned out, were just as forgetful as regular mice when given THC: they were equally poor at memorizing the position of a hidden platform in a water pool. When the receptors were removed from astrocytes, however, the mice could find the platform just fine while on THC.
The results suggest that the role of glia in mental activity has been overlooked. Although research in recent years has revealed that glia are implicated in many unconscious processes and diseases [see “The Hidden Brain,” by R. Douglas Fields; Scientific American Mind, May/June 2011], this is one of the first studies to suggest that glia play a key role in conscious thought. “It’s very likely that astrocytes have many more functions than we thought,” Marsicano says. “Certainly their role in cognition is now being revealed.”
Unlike THC’s effect on memory, its pain-relieving property appears to work through neurons. In theory, therefore, it might be possible to design THC-type drugs that target neurons—but not glia—and offer pain relief without the forgetfulness.](http://24.media.tumblr.com/tumblr_m77h2z5zRB1qbn5m1o1_500.jpg)
Marijuana Reveals Memory Mechanism
Glial cells, not neurons, are responsible for marijuana-induced forgetfulness
Until recently, most scientists believed that neurons were the all-important brain cells controlling mental functions and that the surrounding glial cells were little more than neuron supporters and “glue.” Now research published in March in Cell reveals that astrocytes, a type of glia, have a principal role in working memory. And the scientists made the discovery by getting mice stoned.
Marijuana impairs working memory—the short-term memory we use to hold on to and process thoughts. Think of the classic stoner who, midsentence, forgets the point he was making. Although such stupor might give recreational users the giggles, people using the drug for medical reasons might prefer to maintain their cognitive capacity.
To study how marijuana impairs working memory, Giovanni Marsicano of the University of Bordeaux in France and his colleagues removed cannabinoid receptors—proteins that respond to marijuana’s psychoactive ingredient THC—from neurons in mice. These mice, it turned out, were just as forgetful as regular mice when given THC: they were equally poor at memorizing the position of a hidden platform in a water pool. When the receptors were removed from astrocytes, however, the mice could find the platform just fine while on THC.
The results suggest that the role of glia in mental activity has been overlooked. Although research in recent years has revealed that glia are implicated in many unconscious processes and diseases [see “The Hidden Brain,” by R. Douglas Fields; Scientific American Mind, May/June 2011], this is one of the first studies to suggest that glia play a key role in conscious thought. “It’s very likely that astrocytes have many more functions than we thought,” Marsicano says. “Certainly their role in cognition is now being revealed.”
Unlike THC’s effect on memory, its pain-relieving property appears to work through neurons. In theory, therefore, it might be possible to design THC-type drugs that target neurons—but not glia—and offer pain relief without the forgetfulness.
(via scinerds)
- 5th March
2012 - 05
List: Astrocyte Functions
Astrocytes are a special kind of stellate-shaped brain cells that are found throughout the central nervous system and that play a supportive role for neurons. For a long time, astrocytes were thought of as merely providing “assistance” for neuron function and survival. However, the discovery that astrocytes express voltage-gated channels and neurotransmitter receptors suggests the possibility of an active role for astrocytes in neuronal communication. Astrocytes primarily originate come from either radial glia cells or from cells in the sub ventricular zone and can be visualized with glial fibrillary acidic protein (GFAP). Below is an image of GFAP staining for astrocytes.
Other groups of glia:
- Oligodendrocytes: Provide myelin sheath in neurons present in the central nervous system (CNS). Each oligodendrocyte can myelinate multiple axons.
- Schwann Cells: Myelinate axons of neurons present in the peripheral nervous system (PNS). Schwan cells, however, only myelinate one axon.
- Microglia: Derived from bone marrow and function as antigen presenting cells. Microglia have phagocytic activity, which means they “eat up” (or clear) cellular debris and their roles are predominantly host defense.
Astrocyte Functions:
- Regulation of brain extracellular pH via secretion of acid into the extracellular space (aka potassium buffering). Other regulatory functions of astrocytes include limiting the rise of both extracellular potassium (K+) and pH during neural activity. In addition, astrocytes can take up potassium in a variety of ways: Na+-K+ exchange, K+-Cl- cotransport and other K+ channels characterized by distinct properties.
- Regulating the uptake of glutamate near the synaptic cleft.
- Astrocytes can serve as signaling elements within an astrocyte network, between astrocytes and blood vessels, and/or between astrocytes and neurons. For example, astrocytes can signal to other neurons via Ca+2 oscillations (otherwise known as calcium waves). These calcium waves can come about in two ways: they are either triggered by neural activity (such as activation of astrocyte glutamate receptors) or spontaneoulsy via calcium release from internal stores and activation of IP3 receptors. Astrocytes may also serve as neurotransmitter transporters and receptors as well as aiding in neurotransmitter catabolism.
- Modulate synaptic and neural activity via “gliotransmission”. Known gliotransmitters (chemicals that can act on neighboring neurons, glial cells or vessels) include glutamate, cytokines, ATP, and D-serine. As illustrated below, astrocyte processes govern the amount of neurotransmitter spillage around synapse, thus controlling lateral spread of excitation.
- Modulation of brain vascular tone (i.e. vasodilation/vasoconstriction) and promotion of neurovascular coupling. Basically, astrocytes regulate cerebral blood flow. Moreover, vascular tone depends on the release of vascular agents into the perivascular space.
- Control of synapse formation, stabilization and function as well as neurogenesis. These roles have been predominantly explored in the context of brain pathology and psychiatric disorders like ALS, Alzheimer’s, brain tumors, traumatic brain injury and ischemia.
Sources:
Chesler, Mitch. Properties of the brain, extracellular space and astrocyte function. Lecture given as part of the cellular neuroscience course. Fall 2009.
- 23rd July
2010 - 23
Precursor neural cells, derived from human embryonic stem cells, were grown in a lab dish at University of Wisconsin-Madison. These cells generated either mature neurons (red) or glial cells (green).
Dr.Su-Chun Zhang 2001
- 20th May
2010 - 20
Hippocampal neurons (green), and glia cells (red)
- The hippocampus is the main memory area in the brain.
- Glia cells were originally thought as having only a supportive role. Studies show that glia also have communication properties with neurons and that they can influence transmission.
Source:
http://www.greenspine.ca/en/framed.html
2010, Paul de Koninck
