A sum of destructions

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.

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A map of whatever

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.

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With every breath

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.

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I spy, I spy with my little eye

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!

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Sleeping on the Wing

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.

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Shortly after the burst

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.

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Thinking Fast and Slow about Thirst

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?

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Consider the Fun

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.

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True Beauty

“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”.

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As simple as random can be

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?

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The deciding brain and the effects of stress

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.

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The touch of a fly

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.

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The secret life of our brains

In our everyday lives we are aware of ourselves, our behavior, and the sensory perception of our environment. This awareness during awake states is known as consciousness. As much as it is central to our brain activity, it has also been one of the greater mysteries of neuroscience. In our lifetimes we all experience changes in our state of consciousness, particularly in the alternation between sleep and wake states. We may also experience changes in consciousness state when fainting, during an epileptic seizure, and through the effects of psychoactive drugs. What is happening in our brains when our conscious selves are not present?

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Animal Welfare in Research

I recently had the opportunity to write a post for Nautilus on a subject that is dear to me - the use of crows and other intelligent members of the corvid family for neuroscience research. Corvid intelligence has been noticed by humans for millennia, and more recently by ethologists and psychologists. The fascinating thing about these animals is that like all birds, they do not have a neocortex - the part of the mammalian brain that has countless times been implicated in intelligence. Now, there is just one lab in the world - Andreas Nieder at the University of Tübingen -  that has started peering into the brains of these fascinating creatures to try to understand how crows’ cortex-less brains enable them to perform amazing cognitive feats. You can read the full story on Nautilus.

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Sharing while caring

Today, let’s throwback to the multiple comparisons problem and relate it to something new: Open Science.

In the past years, more and more researchers, legislators and politicians have started to campaign for an open and transparent scientific conduct. The fact that the majority of scientific articles are locked behind the walls of expensive magazines and thus unreachable for the general tax payer (even though they funded the research) is upsetting. Moreover, the scientific community is struggling with reproducibility – the center for open science reproduced 100 psychology studies and found that only 39% of the effects were rated to have replicated the result of the original study! Sharing raw data and code, and publishing in open access journals can hopefully solve these problems.

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Degenerative protein aggregates: a whole body view

A few weeks ago, Vivian wrote a post about prion disease, discussing how understanding the mechanisms of Kuru could help us design treatments for other neurodegenerative disorders characterized by protein aggregations. The accumulation of protein as a pathological process has also been investigted outside the brain. Aging and degeneration are complex system-wide phenomena and studies like the one by Demontis and Perrimon (2011) show that by looking outside the brain we can unveil new whole-body regulatory mechanisms for neurodegeneration.

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The New View that our Brains Generate New Neurons

This week I’m re-visiting adult human neurogenesis: the seminal neuroscience finding that new neuronal cells are born in adult human brains after the normal developmental period in which neurons are generated. This remarkable discovery was made by Peter Eriksson and colleagues in the lab of Fred Gage at The Salk Institute for Biological Studies. Prior consensus in the field was that once neurons died (a hallmark of neurodegenerative diseases such as Alzheimer’s and Parkinson’s) there was no regeneration of neurons. The view was that brains generated a finite number of neurons for the life of the organism, and these neurons networked to handle all learning of new knowledge and the making of new memories and associations—quite an incredible feat! However, the Gage group questioned the current model and found that there was neurogenesis in specific areas of rodent brains, a huge finding in and of itself. But this generated some controversy-- another group published that neurogenesis was not taking place in marmosets (a higher mammal than rodents) and therefore it was likely not happening in other primates, i.e., humans. Therefore, the publication of “Neurogenesis in the Adult Human Hippocampus” in Nature (Eriksson et al., 1998) helped to resolve what had become a contentious issue and definitively showed that indeed, new neurons are being born and incorporated into the hippocampal region of adult brains.

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A Primer on Sleep

If you aren’t asleep when the clock strikes three in the early morning, your eyelids get heavy and your brain feels like mush. You still have that paper to finish writing and you want to stay awake but staying awake is a struggle, a fight against our own brain. We have all been there (especially during finals week). With today’s post, lets look at how our brain regulates sleep and why we spend our days alternating between sleep and wakefulness?

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