[Throwback Thursday] 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.

Fig 1 full size

Figure 1 of Eriksson et. al. illustrating BrdU labeled neurons in regions of the adult human hippocampus.

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The winter blues: Is it all in your head?

“February is my favorite month.” said no one living in Boston ever. The short days, cold temperatures, and repetitive snow really throw a dagger (presumably made of ice) into good times. I tend to think of Dec-Feb as my hibernating months; I am more lethargic, less motivated, and my fiancé and labmates can vouch for the fact that I am slightly more irritable than the good natured loving person I always am in better weather.  I’ve come to attribute my noticeable seasonal downswing to Seasonal Affective Disorder, or SAD (an acronym that ironically makes me quite happy), a self-diagnosis I probably made from seeing a commercial. Being the curious graduate student that I am I decided to do a little research on the subject and see what I could learn—really trying to go above and beyond what pharmaceutical advertising taught me.

Boston Winter, 2015. Image from CBS News Feb. 16, 2015

 

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The neuroscience behind mindfulness

Mindfulness is currently a very hot topic. It seems like every health website, magazine and newspaper is touting the benefits of meditation and yoga practices. Wired posted an article on how meditation can calm the anxious mind and help one manage emotions, Shape magazine relays that meditation can provide greater pain relief than morphine, while many other articles convey that mindfulness will help with weight loss, sleep, disordered eating, and even addiction. Amidst all of the articles promoting mindfulness we also see the backlash—a New York Times op-ed from October 2015 calls for us to take a step back and remember that mindfulness has not been proven to be the panacea to our society.  Personally, as a stressed out graduate student, I wonder if a mindfulness practice would increase my happiness and well-being, and as a neuroscientist I wonder what is true and how does it work, so I recently attended a lecture on the topic given by Dr. Sara Lazar, who works at Harvard Medical School and Mass General Hospital as a leading neuroscientist in the field of meditation.

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A microfluidic culture platform for CNS axonal injury, regeneration and transport

Nature Methods – 2, 599 – 605 (2005)
Published online: 21 July 2005; | doi:10.1038/nmeth777

Many memorable journal articles are those that present a new method to the science community. For this week’s TBT I’m posting about an article that literally made the experiments in my own thesis possible. Anne Taylor and colleagues published a novel way to compartmentalize cultured neurons in Nature Methods, 10 years ago (yikes!). One of the fundamental properties of neurons is that they consist of molecularly and functionally distinct compartments. Axons, cell bodies, and dendrites all have their unique roles to ensure proper growth and maintenance of the neuron, as well as for completing the neuron’s mission to transmit information from one neuron to another. The complexity of this compartmentalization is really quite beautiful; and can really be quite difficult to understand. This article presents a microfluidic chamber as a way to isolate (and thus study) separate parts of the cell, in vitro.   (more…)

The battle of the sexes in biomedical research

Women’s rights activist Elizabeth Cady Stanton decreed that “all men and women are created equal,” a proclamation necessary to win women the right to equal representation in the eyes of the government. Ironically, I believe we now need to realize just how differently men and women are created in order to secure a new set of rights for women, that of equal representation in preclinical biomedical research. It isn’t news that males and females are biologically different (duh), but historically, scientists have conducted studies predominantly on male mice, presuming those discoveries would be applicable to both men and women; unsurprisingly, current research is pointing out the many flaws in this logic. In May of last year (2014), the National Institutes of Health (NIH), the agency that is charged with allocating government funds to research grants, announced policies that would require basic scientists to use both male and female mice in their studies.  The announcement of these policies included the following reasoning:

“The over-reliance on male animals and cells in preclinical research obscures key sex differences that could guide clinical studies. And it might be harmful: women experience higher rates of adverse drug reactions than men do. Furthermore, inadequate inclusion of female cells and animals in experiments and inadequate analysis of data by sex may well contribute to the troubling rise of irreproducibility in preclinical biomedical research, which the NIH is now actively working to address.”

As with most changes in funding policies, there was pushback on the NIH’s new policy. Including both male and female mice would almost certainly increase variability, resulting in more time and resources spent on answering experimental questions. As a sixth year graduate student, I whole-heartedly agree that no scientist wants to see those two factors increase. One suggested solution was to increase allocated funds for studies specifically designed for “sex differences research.” This essentially would give scientists the allowance to presume what may or may not differ between the sexes. My personal experience over the past months calls bullshit. (more…)