If you’re reading this blog post, it’s possibly because you have made the decision to sell your soul for the next few years to the noble endeavor of charting the intellectual unknown...and obtaining a PhD. As you embark on that journey, you might find yourself with a preliminary challenge: lab rotations. We are two second-year students in Harvard’s Program in Neuroscience, which means that we recently went through the rotation process. Here is our perspective.Read More
The first recorded case of PD was reported just over two hundred years ago, but our current best treatments still fall short of anything we might call a cure. One leading treatment is electrical stimulation of a group of neurons deep in the brain. How and why does deep brain stimulation actually work?
The daunting complexity of the human brain has led to the use of animal models for neuroscientific research, due to the relative accessibility of animal brains for experimental perturbation. Historically, neuroscience has leveraged diversity across the animal kingdom to uncover fundamental insights into brain function, but recently, a few animal models have dominated the field. Perhaps it is time to revisit non-traditional animal models for neuroscientific research in the 21st Century. Thumbnail from Wikipedia.Read More
Positive social interactions are often rewarding to humans. It is hypothesized that successful social interactions involve the same reward processing circuitry that underlies the pleasure we derive from food or money. Studies in rodents show that social interactions result in the release of dopamine, the neurotransmitter often associated with pleasure, in the nucleus accumbens (NAc), a small region buried deep in the brain (Fig. 1). An interesting observation from rodent studies is that mice often return to the same area they previously met another mouse. Before the advent of cell phones and Facebook (and perhaps even now), we probably did (do) the same, too. If you met interesting people at a bar, you are probably more likely to go that same bar again. But what are the neural circuits that make the association between social interaction and spatial location?Read More
There is an old anecdote of a respected philosopher giving a public lecture on astronomy, in which he explains the data showing that the Earth orbits the Sun, and the Sun in turn, revolves around the center of the Milky Way galaxy. After the lecture, the lore goes, an old lady tells the philosopher that his ideas are nonsense. “The world stands on the back of a giant turtle,” she says.Read More
Pablo Picasso once said “To me painting is a sum of destructions. I paint a motif, then I destroy it.” Unknowingly, he had an intuition about visual processing. In fact, our current understanding is that retinas, quite like Picasso, break an image into its parts. The first man to lay the foundation of this idea was Haldan Keffer Hartline, a contemporary of Picasso. Professor GG Bernhard used this quote to present Hartline in the Nobel prize award ceremony 1967.Read More
The hippocampus is perhaps the most well-known brain region among neuroscientists, not only for its beautiful name (Latin for seahorse), but also for its critical role in learning and memory. Decades ago, another landmark discovery showed that hippocampal neurons seem to encode space1. That is, individual hippocampal neurons fire only when an animal moves into a specific spot of its current room.Read More
We marched for science this past Saturday, April 22nd. Scientists in Cambridge, Boston, and all over the world ventured into the streets on Saturday to remind the world how important science is to our society, and how strong we can be when we unite.Read More
Most of us do not spend much time thinking about breathing (now you are :D). This is because our autonomic nervous system hides its control under our consciousness. But, breathing is not as effortless as it seems. For one, air pressure and oxygen level can change from time to time. Also, diseases such as the common flu often disturb the flow of our airways. For reasons like these, we often have to modulate the rate and depth of our breaths. Therefore, a pre-programmed breathing rhythm does not suffice –breathing also requires constant monitoring and feedback.Read More
For the last couple of years I have been studying the retinal circuits of mice. While it is amazing how similar visual circuitry is among many species, I am always fascinated by surprising unique strategies that have developed in this system. The human visual system (from the retina to visual cortex) is a remarkable network that can see colors, adapt to a wide range of light intensities, perceive depth and distance, and much more. It is perfectly put-together such that each part contributes to a specific function: the lens focuses the image on the retina, different photoreceptors allow for color detection, our two frontal eyes allow for depth perception through parallax. The visual system of some animals has found other strategies to achieve the same functions, sometimes even using the same tools in new ways!Read More
There is an old Monty Python skit where John Cleese and Graham Chapman play airplane pilots. Presumably on a long, tedious flight, they are clearly bored and keen on amusing themselves at the expense of their passengers.
They find entertainment through relaying worrisome, nonsensical messages. Cleese begins their prank with the truism, "Hello, this is your captain speaking. There is absolutely no cause for alarm." And after some internal discussion about what there should be no cause for alarm about, they add: "The wings are not on fire." The messages get more ridiculous, and hilarity (at least for the pilots) ensues.Read More
Prof. Mike Greenberg talks about his research on Immediate Early Genes
Despite similarities in the numbers of genes and structure of neural circuits, primates have evolved vastly more complex brains and behaviors. What do those differences look like in the brain? A recent paper from the labs of Michael Greenberg and Margaret Livingstone at Harvard Medical School examines how a short (85 base pairs!) sequence in the regulatory region of the OSTN gene, which was previously known as a secreted protein in bone and muscle development, has allowed it to be expressed in the brains of primates, but not those of rodents. The expression of OSTN is special for another reason: it is one of the first primate-specific genes regulated by immediate early genes (IEGs) to be found. IEGs are a group of genes whose transcription in neurons is transient and commonly follows a burst of spiking activity. In their short window of expression many IEGs are known to regulate expression of specific downstream genes. The new paper from the Greenberg and Livingstone labs gives us a peak into how small differences in common molecular pathways may be implicated in the diversity of species. The journey of our knowledge and understanding of IEGs and the genetic response to neural activity is also the journey of the scientist who first observed the expression patterns of IEGs, and who has since dedicated a great deal of his scientific career to investigating them: Professor Michael Greenberg. A few weeks ago, I had the pleasure of sitting down with him to talk about his work, past, present and future.Read More
Out of all motivational states, thirst should have been a simple one to understand. One feels thirsty when one is dehydrated, which can be detected from blood volume and osmolarity. Drinking water hydrates one’s body and quenches thirst. This is a homeostatic model. Intuitive, right? Well, the strange thing about thirst is that it is quenched within seconds to minutes after drinking water, which is too fast for any changes in the blood to happen. This is as if the brain gets hydrated before the body, which makes little sense since there is no specialized canal that passes water from mouth to brain (thank goodness). On the other hand, the buildup of the thirst drive is usually rather slow, meaning that thirst state can change on both a fast and slow time scale. How does it work?Read More
Scientists are often portrayed in pop-culture as pedantic types, with personalities as stiff as their starched white lab coats. While they may have a pressing work ethic and incessant care for detail, their work is creative by nature. Scientists must create knowledge by designing and building experiments. In this way, a scientist is closer to a starving artist than to an automaton.Read More
“Beauty is truth, truth beauty,” – that is allYe know on earth, and all ye need to know. - John Keats in ‘Ode on a Grecian Urn’
The scientific field prides itself in its objectivity. Truth is found by a search free of personal biases, personal commitments or emotional involvements. Still, a great many scientists have said beauty guided their way. For example, physicist Paul Dirac stated: “It is more important to have beauty in one’s equations than to have them fit the experiment”.Read More
A few weeks ago I was having a discussion about mathematical models for the prediction of the movements of the stock market. The question was whether there was any use to developing complex algorithms trying to predict these fluctuations. My friend (an economist) argued that while he admits the market value isn’t truly random, incorporating random variables may be the best model we have for it. It turns out that many mathematicians (and quants, economists who analyze market fluctuations using algorithms) have been using “random” models for their predictions. These range from sequences randomly drawn from log-normal distributions, to chaotic systems that may allow for the prediction of market crashes and other rare large movements. I was fascinated by the idea of randomness as a model for complex systems. It seemed particularly interesting to explore this in the context of biological processes, especially when the laws of thermodynamics have described that all physical phenomena drift towards the chaotic state of maximum entropy. Could randomness be a model for circuit wiring and function in the brain?Read More
During these hot summer days, lying in the shadow puffing and sweating, my arms and legs pulling down like bags of sand, it is sometimes difficult to believe that my brain is still functioning fine. How do we manage to keep our head cool, even on hot days like these?Read More
We make decisions every day. Decision-making is a way by which we exert control over our behavior, mood and even the course of our lives. One key element in decision-making is self-control. This is often seen when we have to make that extremely difficult decision between another double cheeseburger and a healthier salad. While that may seem difficult enough on its own, many decisions, such as having to choose which graduate program to join or which answer to circle on an exam, come with substantial amounts of stress. This stress can guide or compromise the decisions we make. So, how do stress and self-control come together during decision-making? What is the neurobiological basis underlying this convergence?
But, before we begin to look at the interaction between stress and decision-making, let us first take a step back and look at the brain regions and circuitry underlying decision-making.Read More
Our sense of touch has an innate connection with our emotions. Gentle touches are soothing for not only us but also other animals. For example, classic experiments by psychologist Harry Harlow in the 1950s found that an infant monkey raised with two robots, one providing food and the other wearing soft cloth, spends more time cuddling with the cloth robot1. When scared, the infant monkey also goes to the cloth robot for protection. Clearly, there is a special pathway that guides touch sensation to the depths of animal instincts. Working out this pathway requires knowledge about the neural circuitry processing touch sensation.Read More