Dendritic spines were quantified on terminal dendrites of medium spiny neurons (MSNs) in the nucleus accumbens core sub region of selectively-bred high- and low-responder rats following repeated cocaine treatment.
Drugs affect different people in different ways. Take cocaine for example. Not only does the drug have a stronger impact on the behavior of individuals with a particular genetic makeup, it also initiates more profound changes in their brains.
Researchers at the University of Michigan are studying brain plasticity in cocaine-treated rats after a period of abstinence. They’re studying how abstinence from the drug affects different types of rats – those with an “addictive personality” versus their less addicted cousins.
To determine the effects of cocaine abstinence on these two groups, the researchers studied specially bred lines of rats. One group was highly sensitive to cocaine, while the other group didn’t respond as strongly to the drug. Known as “high-responder rats” (bHR) and “low-responder rats” (bLR), the two groups reacted differently to the drug treatment, with bHR rats acting more agitated during cocaine treatment, and their brains displaying more pronounced plastic changes after a period of abstinence.
Continue reading “Researchers at the University of Michigan Analyze Spine Density in Addiction-Prone Rats with Neurolucida” »
A drawing of an L2 pyramidal neuron in the auditory cortex of a mouse brain rendered with Neurolucida. Biocytin-labeled neurons were visualized using the avidin:biotinylated horseradish peroxidase complex. Neurons were completely reconstructed in 3D with Neurolucida using an up-right Zeiss microscope with an oil immersion x100/1.4 numerical aperture objective.
Sensory stimuli are all around us. Street traffic zooms by. A neighbor waves “hello.” A co-worker taps away at his keyboard. Each sight, sound, and motion ignite action within our brains. But even without all these stimuli, the brain is always active.
Known as “spontaneous activity,” the activity happening inside the brain in the absence of direct stimuli follows a pattern of up and down states that scientists say is essential for processing sensory signals. Spontaneous activity may also be involved in memory.
Scientists from the Brain Research Center at the Third Military Medical University (Chongqing, China), the Center for Integrated Protein Science, SyNergy Cluster, and the Institute of Neuroscience at the Technical University of Munich (Germany) are working on figuring out how the activity occurring in the brain during “spontaneous activity” compares with what goes on during periods of sensory stimuli. Specifically, they’re looking at calcium signaling – an important element in synaptic activity during periods of both sensory stimuli and spontaneous activity, that helps neurons transmit information to other parts of the brain and body.
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Life’s little pleasures often elude those suffering from depression, including rats, who show little interest in sugar water after experiencing stress. This behavior leads scientists to speculate that the illness might be characterized by a defect in the brain’s neural reward circuit.
Recent research focuses on a key element of this circuit – the nucleus accumbens (NAc), part of the brain region known as the ventral striatum, which is thought to regulate motivation and reward processing. In a new study of stress-induced depression in rats, researchers at the University of Minho in Braga, Portugal saw morphological changes in the dendrites of medium spiny neurons in the NAc, alongside disturbances in gene expression in this region. They also saw these changes reversed after administering antidepressants.
By using Neurolucida Explorer to analyze 3D reconstructions of medium spiny neurons generated with Neurolucida, the researchers observed longer than normal dendrites and greater spine density in the depressed rats. According to the paper, these findings contrast with studies of the hippocampus and prefrontal cortex, where chronic stress leads to shorter dendrites.
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Scientists hypothesize that seizures occur because brain cells fire in places they’re not supposed to. Dentate granule cells (DGCs), a type of neuron born throughout adulthood, sometimes migrate into a different region of the dentate gyrus, a part of the hippocampus. These abnormal newborn cells sprout axons called “mossy fibers” that form connections with neighboring DGCs in the inner molecular layer, causing synaptic changes that wouldn’t normally occur in healthy brains.
Much research has been done on this phenomenon, but neuroscientists still struggle to understand what exactly its relationship is with epilepsy.
A new study by researchers at the Cincinnati Children’s Hospital Medical Center validates hypotheses about the role of abnormal DGCs in epilepsy. In their study of a transgenic mouse model of temporal lobe epilepsy (TLE), the scientists observed a relationship between the presence of deviant DGCs and seizure frequency.
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Learning a new dance routine or how to ride a bike is possible because of Cerebellar Granule Cells (GCs) according to Galliano and colleagues in The Netherlands. To find out more about the role of these abundant brain cells, and why we have so many of them, the scientists silenced most of the GCs in a group of mutant mice. They found the rodents could balance and run as well as they ever did, but when it came to learning new activities involving motor function, the mice had a harder time.
Continue reading “Neurolucida & Stereo Investigator Help Uncover Cerebellar Granule Cells’ Role in Muscle Memory” »
What does it take to survive that tumultuous time called adolescence? Good friends, exercise, and new brain cells.
Scientists at Michigan State University found evidence of neurogenesis in the brains of adolescent hamsters, according to a study published last month in PNAS. The new cells, which became integrated into neural circuits in adulthood, were discovered in the amygdala and connected limbic regions – areas associated with social learning and mating behavior.
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The importance of studying the brain in three dimentions is something we understand at MBF Bioscience. Every day scientists around the world use our products to reconstruct neurons and analyze brain cells in 3D. That’s why we’re excited to hear about the new possibilities for whole brain analysis coming out of Dr. Karl Deisseroth’s lab at Stanford University.
A press release issued last week describes a whole-organ imaging process called CLARITY that made a postmortem whole mouse brain transparent.
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Courtesy of Thomas Marissal, INMED (France)
There’s a lot to be said for being in the right place at the right time. For a neuron, emerging at a certain place within the brain destines it for a particular function. A new study posits that, for a group of cells in the hippocampus, it’s not only where a neuron is born, but also when it is born, that defines the specific roles it will play. The study, conducted by researchers at the Mediterranean Institute of Neurobiology (INMED, France) and affiliated institutions, identifies a new population of cells in the hippocampus.
The cells identified are “a sub-population of early-generated glutamatergic neurons that impacts network dynamics when stimulated in the juvenile hippocampus,” according to the paper.
“These cells first operate as assemblies, in the developing hippocampus, and later become powerful single units capable of triggering network synchronization in the absence of fast GABAergic transmission,” Marissal et al. say.
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A monkey spots a mango and part of its brain lights up. The action takes place in the inferior temporal cortex, part of the brain that’s essential to object recognition. Using retrograde tracing and anatomical imaging, scientists at the National Institute of Neuroscience, and the RIKEN Brain Science Institute in Japan identified two interwoven, yet distinct, systems within the region’s complex circuitry.
“Our anatomical findings provide evidence for a recurrent network of at least two parallel systems,” the authors say in their paper published last December in Scientific Reports.
One system may send information about an object’s visual characteristics rapidly from one part of the inferotemporal cortex to the other, while the second system might work on a more local level, possibly helping to “compute multipart shape configurations,” the authors hypothesize.
Continue reading “Scientists in Japan Identify Two Brain Circuits Involved in Image Recognition; Neurolucida Plays Part” »
Revving engines, blasting sirens, the drummer next door. Despite the myriad sensory stimuli going on around us at any given moment, humans have the ability to stay focused on the task at hand. This skill is due to a part of the brain known as the neocortex, a six-layer structure whose intricate wiring is largely a mystery. But researchers at the University of Virginia just took a big step toward a broader understanding of how this region works. They discovered two never-before-identified circuits in the rat sensorimotor cortex that help explain how the brain filters information.
Continue reading “UVA Scientists Use Neurolucida in Study Identifying Two New Circuits in Rat Neocortex” »