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(03/31/16 9:31pm)
For example, tiny single-celled organisms called microbes have recently generated interest in the neuroscience field. Light-sensitive proteins called opsins are inserted onto the cell surfaces of some microbes such as algae. These opsins convert the detection of light into cellular changes. Neuroscientists discovered that by inserting these same proteins onto the cell surfaces of neurons, neural activity can be controlled using light.
(03/24/16 5:33pm)
At times, the CSF flow system can occasionally go awry. Hydrocephalus (“hydro” meaning water and “cephalus” meaning head) is a medical condition that describes excessive accumulation of CSF in the brain. As a result, the ventricles widen, and the excessive CSF pushes out onto the brain tissue. This increased pressure essentially compresses the brain like flattening a pancake.
(03/03/16 3:05pm)
A big challenge in dealing with traumatic injuries to the brain is the limited regenerative capacity that the central nervous system has. Unlike skin or muscle, the brain’s ability to completely regenerate following injury is limited, often rendering the loss of brain function permanent following traumatic injuries to the brain or spinal cord.
(02/25/16 9:22pm)
The big rule of thumb is that the model should mimic the human disease as closely as possible. This means that a particular model should have similar biological and physiological characteristics to the human body and should recapitulate salient features of the disease.
(02/18/16 6:10pm)
One way to think about adult neurogenesis is that it is simply a way to modify neural networks on a cellular network. By making new neurons, the brain can form new neural circuits or, alternatively, abolish pre-existing circuits. Based on this framework, the hippocampus could be doing some heavy computations that require neural circuitries to be continuously rewritten and edited in a dramatic way, therefore requiring adult neurogenesis. Indeed, as the center for the formation of new memories, the hippocampus may need adult neurogenesis as a form of plasticity to rapidly process learning.
(02/11/16 10:21pm)
During early development, the nervous system is built by stem cells. These stem cells migrate on tracks laid out by cells called radial glia. A striking feature of radial glia cells is their long processes that extend over long distances. While radial glia cells were classically thought to only play roles in neural migration, it was later discovered that they also act as neural stem cells that give rise to neurons during development.
(02/04/16 7:49pm)
All humans possess an internal biological clock that drives changes in behavior and physiological states throughout the 24-hour day. A cycle of this internal clock lasts for approximately 24 hours, so the biological processes governed by the internal clock are called circadian (“circa” meaning approximate, “dies” meaning day) rhythms. Circadian rhythms include the sleep/wake cycle, fluctuations in body temperature and releases of hormones throughout the day. Some reports have even found morning-evening variations in cognitive function, such as mathematical abilities.
(01/28/16 8:41am)
Here is what we know about the brain in very general terms. Basically there are neurons throughout the nervous system that are wired to talk to each other. These wiring patterns are established during early development, and, as an individual ages, life experiences can modify these preexisting “circuits.” Such modifications can abolish certain circuits, enhance preexisting ones or even form entirely new ones. Activity within these neural circuits leads to computations that encode information from the external world. This information is then further used by neural circuits to generate some form of output, be it taking your hands off a burning stove or reacting to a melody. What is the neural language that encodes these sensory experiences and generates appropriate output?
(04/30/15 8:11pm)
Fifty years ago, a winning science project for a high school science fair might have been building a rocket in the backyard of your house. All you had at your disposal was whatever you could buy at the local stores. Your lab space was most likely the basement or the garage.
(04/23/15 1:21pm)
The fundamental goal of neuroscience is to establish the link between physical events in the brain and human consciousness, from complex thoughts to emotion. Understanding the patterns of brain activity that underlie behavior is a major step toward accomplishing this goal.
(04/16/15 3:23pm)
Drug abuse is a major societal problem. According to the National Institute of Drug Abuse, substance abuse imparts an annual economic burden of more than $600 billion. In particular, cocaine is a powerful stimulant that can cause severe medical consequences, such as heart attacks and strokes. Currently, there is no single medication that can treat cocaine addiction, and psychosocial therapies are often not effective in a significant population of cocaine abusers. Research into how drugs affect the brain is crucial for development of better therapies to reverse addiction and prevent relapse. The most studied cocaine mechanism is how the drug affects the brain’s reward pathway. The reward pathway is a system of neural circuitry that allows us to associate beneficial behaviors with feelings of pleasure. The neurons that are responsible for pleasure form a group called nucleus accumbens (NAc). NAc neurons are activated by a chemical called dopamine, which is released by ventral tegmental area (VTA) neurons. Under normal conditions, the reward pathway is kept in check by the dopamine transporter, which brings back excess dopamine inside the cell. Scientists believe that cocaine produces its addictive effects by blocking these dopamine transmitters, leading to a buildup of dopamine that is responsible for the intense feelings of pleasure and euphoria. Although the reward pathway is an attractive drug target, prevention of abuse is still preferable to treating an already formed addiction. Even if treatment is successful, almost of half of cocaine users will relapse within two and a half months. As a result, identifying risk factors for drug abuse is a critical area of research that will set the stage for strategies to prevent addiction. Outside of the reward pathway, cocaine has been shown to induce changes in the brain’s plasticity. One form of plasticity is neurogenesis (the creation of neurons), which occurs in the hippocampus even during adulthood. What is important to realize is that adult neurogenesis is an elaborate biological pathway in which neural stem cells proliferate to produce neuroblasts, which then migrate and differentiate into newborn neurons. Moreover, the newborn cells have to survive long enough to be able to integrate into preexisting circuitries. Studies have shown that administration of cocaine to rats decreases cellular proliferation in the hippocampus, whereas cocaine’s effect on long-term survival is still unclear. Regardless, these studies at least show that cocaine addiction and decreased neurogenesis appear to be correlated, suggesting a possible role of neurogenesis in the development of cocaine abuse. To investigate the causal role of neurogenesis in drug addiction, one study reduced hippocampal neurogenesis by exposing rats to radiation. The study found that inhibition of adult neurogenesis increased cocaine-seeking behavior and likelihood of relapse. These findings were the first to show that the manipulation of neurogenesis could be an effective strategy in preventing drug abuse behavior. More specifically, increasing neurogenesis could perhaps prevent cocaine addiction. So far, no published study has examined this possibility. Given that there are mice genetically engineered to have more neurogenesis than normal, we can easily test the hypothesis that increasing neurogenesis may prevent cocaine abuse. Why might a decrease in neurogenesis contribute to addiction behavior? Cocaine can rewire the brain through a variety of pathways, and a decrease in neurogenesis could represent changes in neural plasticity that reinforces addiction behavior. Some reports have shown that cocaine can cause neuronal loss, and thus increasing neurogenesis can boost the body’s endogenous regenerative mechanism to compensate for damaged circuits. Additionally, it is known that stress can also reduce neurogenesis. Given that depressed individuals are more vulnerable to drug addiction, decreased neurogenesis might simply be a reflection of stress that puts individuals at risk for drug abuse. Regardless of my interest in neurogenesis, I don’t think that focusing only on neurogenesis will solve the drug addiction problem, given the multitude of other brain processes involved. I envision that a future treatment might be a combination of both social counseling and medications that target multiple neuronal underpinnings of drug addiction. However, a better understanding of how neurogenesis contributes to drug abuse may lead us toward a greater insight into how neurogenesis participates in brain function.
(04/14/15 6:42pm)
Communication between different neurons provides the functional basis for how the nervous system works. For example, neurons in the retina relay visual information to higher-order neurons in the cortex to derive our conscious perception of the external world. As a result, understanding which neurons talk to each other is fundamentally necessary for gaining insight into the biological basis of brain function. One way to understand how neurons connect with each other is through tracing their connectivity patterns. Each neuron sends its axon, a wire-like protrusion, to a nearby or far-away neuron. Electrical ripples known as action potentials travel through the axon to reach the axon terminal, triggering release of chemicals called neurotransmitters. These neurotransmitters will bind to receptors on the adjacent neuron’s dendrites. The functional contact between each neuron is a synapse. As a result, tracing where these axons go can provide a clue to which populations of neurons communicate with each other, and ultimately, a better understanding of the brain’s anatomical wiring diagram. For a long time, tracing was done via injecting a dye that moves throughout neuronal processes. These reagents could either travel backward (retrograde) or forward (anterograde). By following where the dye ends up, it is possible to figure out which region the injected neuron is projecting to, or which neuronal population is sending information to the injected neuron. However, these classical dye tracers suffer from a major drawback. They do not prove the existence of synapses, since localization of the dye at an area does not necessarily imply the presence of synaptic connections. As a result, scientists needed a type of tracer that could not only traverse through axons but also jump across synapses. To that end, rabies viruses have been utilized as tracers due to their ability to infect a large number of neurons via synapse jumping. In addition to providing proof that synapses exist between neurons of interest, another benefit to the rabies virus is that it can be used to map longer pathways that involve more than two distinct populations of neurons. However, the results can be extremely difficult to interpret, since it is difficult to control the number of synapses that the virus crosses. As a result, tracing experiments that utilize rabies viruses must have clearly delineated timelines so that the chronological order by which synapses were crossed can be determined. Recent developments in genetics combined with viral technologies have made vast improvements to rabies virus tracing. By swapping out the comments necessary for infection and transsynaptic spread, the modified version of rabies virus can now only jump one synapse. The new technique is also much more precise because the virus can now infect only neurons that express the necessary molecular components, whereas before, the virus could infect any cell in its vicinity. Termed transsynaptic viral tracing, this technology was first used to trace the brain’s olfactory pathways. The importance of tracing methodologies cannot be overemphasized. The brain is a biological entity composed of interconnected neuronal populations. As a result, the first step toward understanding the circuit mechanism of brain function is to obtain a map of the wiring diagram. This could later lead to developments of brain diseases in which neuronal circuits are perturbed.
(04/02/15 2:25pm)
Seizures are almost like firestorms in the brain, causing neurons to fire uncontrollably and resulting in aberrant motor behavior and the loss of consciousness. Despite their seriousness, we still have no good way to treat them. However, a recent study by Taito Matsuda and colleagues from Japan has uncovered a novel pathway between hippocampal neurogenesis and the immune system, potentially providing a new treatment avenue for epilepsy.
(03/26/15 2:19pm)
The brain is an overwhelmingly complex structure comprised of diverse cell types. Understanding how each population of cells works will lead us toward a deeper insight into the biology of brain function.
(03/12/15 4:14pm)
Our stomachs contain millions of beneficial microorganisms that help us with digestion. Their importance in our health and well-being is highlighted by reports that show the role an abnormal gut microbiome plays in the development of obesity. Other studies also suggest a close interaction between our immune system and the microorganisms. This interaction is large enough that it may even have an impact on certain types of cancer therapy. Indeed, research into the role that the gut microbiome plays on our physiology is becoming one of the most exciting scientific fields.
(03/05/15 6:08pm)
On July 26, 2013, the 341st volume of the world-renowned journal Science delivered news that seemingly took the neuroscience field by storm. Steve Ramirez and colleagues reported that they had created “a false memory in the hippocampus.”
(03/05/15 5:50pm)
The exploration of the mind has always been the center of intense research interest. The brain is the least understood organ in the body, and nobody knows exactly how it works. One approach to solving the brain puzzle is looking at neuronal activities of different brain regions. This strategy has led to important insights within the field of cognitive neuroscience, allowing for investigations into the biological mechanisms of brain function. Even more excitingly, such an analysis of brain activities may allow us to some day be able to delve into a person’s mind and gain access to their deepest thoughts — science fiction transforming into tangible reality. But how can we build a mind reading machine?
(02/19/15 5:16pm)
Henry Molaison (more commonly known as “HM”) is one of the most intriguing gentlemen in the history of neuroscience.
(02/12/15 6:50pm)
Our bodies can can often heal themselves from injuries such as cuts, but is it possible to regrow parts of our brain after damage?
(02/05/15 5:10pm)
Depression is a chronic psychiatric disorder that affects 25 percent of women and 12 percent of men in the United States, and it cost the U.S. $83 billion in 2000.