Leslie Jellen, PhD – Brain Blogger http://brainblogger.com Health and Science Blog Covering Brain Topics Sat, 30 Dec 2017 16:30:10 +0000 en-US hourly 1 https://wordpress.org/?v=4.9.1 Your Baby’s Brain on Sunshine – Vitamin D and Neurodevelopment http://brainblogger.com/2012/09/29/your-babys-brain-on-sunshine-vitamin-d-and-the-neurodevelopment/ http://brainblogger.com/2012/09/29/your-babys-brain-on-sunshine-vitamin-d-and-the-neurodevelopment/#comments Sat, 29 Sep 2012 11:00:03 +0000 http://brainblogger.com/?p=13065 We’ve long associated vitamin D deficiency with rickets, but autism? Schizophrenia? Depression? The past decade of research has cast light on a new role for the sunshine vitamin and there’s a growing consensus: vitamin D deficiency doesn’t just harm developing bones—it harms the developing brain.

Known as the sunshine vitamin because its primary source in humans is UVB radiation, Vitamin D is an essential nutrient that aids in calcium and phosphorus absorption, bone formation, and immunity. Without adequate Vitamin D, an infant can develop rickets, a softening of the bones. His immune system can be compromised. And, as recent critical reviews suggest, any number of more subtle effects may be occurring inside his developing nervous system.

In the brain, vitamin D is a neurosteroid thought to be widely distributed. It’s a master-controller of gene expression, regulating that of a large number of genes, with direct effects on many proteins as well.

For obvious reasons, the effects of vitamin D deficiency in the brain are difficult to study in humans. Instead, scientists are looking to animal and cellular models of deficiency. While many questions remain unanswered, research on the topic is hot. Turns out vitamin D may be every bit as important as the other heavy-hitting neuroactive steroids — estrogen, testosterone, glucocorticoids — for brain development and function.

Here’s just a few of the processes critical to brain development for which vitamin D is now thought to be important:

  • Cellular differentiation — it helps tell cells what to become as they develop.
  • Proliferation — it helps control when cells divide and grow in number.
  • Apoptosis — it helps guide programmed cell death, such as in neurons that are no longer needed.
  • Dopamine production and metabolism — it helps shape the dopamine system, important for motor and reward pathways.
  • Reactive oxygen species buffering — it helps protect the brain from oxidative stress.
  • Neurotrophic factor expression — it modulates nerve growth factor (NGF) expression, for instance, which helps neurons grow, survive, and migrate.
  • Regulation of hippocampal L-type voltage-sensitive calcium channels — it may be important for learning and memory.

So what effects might vitamin D deficiency have on the developing brain?

It’s hard to tell. Vitamin D deficiency early in development has been associated with several neuropsychiatric disorders, including schizophrenia and autism — but at this time the evidence linking these to vitamin D is at best mixed and preliminary.

The role for vitamin D in hippocampal and dopamine system development suggests effects on learning and memory and motor and/or reward systems may be possible. But longitudinal studies in humans are needed to fully address this question. These take time, so it may be years before we get the complete picture. Even with such studies, given the breadth and complexity of its roles in the brain, the sub-clinical effects of vitamin D deficiency may be subtle, diffuse, and difficult to detect. This is particularly the case in the more moderate form of deficiency common in the US and other developed countries.

That being said, until then it’s probably safe to assume that vitamin D deficiency isn’t an ideal state for the developing brain.

References

Eyles DW, Burne TH, & McGrath JJ (2012). Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease. Frontiers in neuroendocrinology PMID: 22796576

Wagner CL, Taylor SN, Dawodu A, Johnson DD, & Hollis BW (2012). Vitamin D and its role during pregnancy in attaining optimal health of mother and fetus. Nutrients, 4 (3), 208-30 PMID: 22666547

Kesby JP, Eyles DW, Burne TH, & McGrath JJ (2011). The effects of vitamin D on brain development and adult brain function. Molecular and cellular endocrinology, 347 (1-2), 121-7 PMID: 21664231

Image via Serg64 / Shutterstock.

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Learn It With Your Eyes Closed http://brainblogger.com/2012/08/13/learn-it-with-your-eyes-closed/ http://brainblogger.com/2012/08/13/learn-it-with-your-eyes-closed/#comments Mon, 13 Aug 2012 11:00:11 +0000 http://brainblogger.com/?p=13066 Wish you could learn a musical instrument but have too little time? Only in your dreams, you say? Well, you’re in luck. Recent findings show you can learn it in your sleep. A team of researchers at Northwestern University has now demonstrated that learning to play a simple melody can be fine-tuned by listening to recordings of it while you snooze.

In a small but well-designed study, the researchers trained subjects to play two simple melodies on a keyboard. Subjects then took a well-deserved afternoon nap. Unbeknownst to them, as the subjects entered slow wave sleep, the researchers selected one of the two melodies and played a recording of it twenty times — loud enough to hear but not enough to awaken them. The recordings lasted only four minutes. Before and after the nap, subjects attempted to play the melody; performance was measured in terms of number of mistakes.

While performance of both melodies improved following sleep, the improvement was significantly greater in the melody replayed during the snooze session.

One of the factors in how much of an effect the music cues had was the percentage of the nap spent in slow wave sleep, or deep sleep. Subjects with a higher percentage of slow wave sleep tended to improve more in response to the recordings. Slow wave sleep is important for memory consolidation and sensorimotor integration.

The idea that we can learn while we sleep is not completely new; similar studies have used odor cues and sound cues to enhance declarative memory formation and spatial learning, respectively. This study extends these findings to auditory tones and sensorimotor performance.

Just what can’t we learn while sleeping? Fortunately for the researchers, there are countless ways future studies could tinker with the type of cue/amount/volume/time exposed/phase of sleep/etc. to attempt to further improve learning and define the limits of this approach.

So if you fall asleep to Chopin, will you wake up with piano chops? Probably not. Should you start voice-recording the Krebs cycle to cram for your biology exam? Whispering times tables to your second-grader while she tosses and turns? French and Italian lessons for your slumbering newborn? Not yet.

First, this was a sensorimotor task, not a linguistic or arithmetic challenge.

Second, this study doesn’t demonstrate new learning in sleep as much as memory reactivation—the subjects learned the melody with good old practice and hard work. By listening to it during nap time they simply reinforced what they’d already practiced. And while this study does show that replaying the melodies tweaked performance within an individual, the effect wasn’t large enough to carry over to a significant difference in performance between the music-listening nappers and those who napped in silence.

Perhaps most importantly, outside of the sleep lab this couldn’t be practically applied to only slow wave sleep, so it’s important to know how it would impact your other sleep cycles if you pressed repeat on your ipod and nodded off. Sleep is critical for learning and, more importantly, for overall well-being, and the authors do point out that their findings do not lend any insight into the potential negative impact auditory cues may have on getting a good night’s sleep.

While the practical implications of this study may be limited, understanding how we learn during sleep will lend insight into learning and memory during waking hours, and — since we do spend a third of our life in dreamland and sleep disruption is a key feature of many neurological and psychological disorders—understanding the biological value of sleep is a major challenge for neuroscience today.

Now go tell your boss you have a legitimate excuse for drooling on your desk earlier this morning!

References

Antony JW, Gobel EW, O’Hare JK, Reber PJ, & Paller KA (2012). Cued memory reactivation during sleep influences skill learning. Nature neuroscience PMID: 22751035

Diekelmann S, & Born J (2010). The memory function of sleep. Nature reviews. Neuroscience, 11 (2), 114-26 PMID: 20046194

Huber R, Ghilardi MF, Massimini M, & Tononi G (2004). Local sleep and learning. Nature, 430 (6995), 78-81 PMID: 15184907

Landsness EC, Crupi D, Hulse BK, Peterson MJ, Huber R, Ansari H, Coen M, Cirelli C, Benca RM, Ghilardi MF, & Tononi G (2009). Sleep-dependent improvement in visuomotor learning: a causal role for slow waves. Sleep, 32 (10), 1273-84 PMID: 19848357

Rasch B, Büchel C, Gais S, & Born J (2007). Odor cues during slow-wave sleep prompt declarative memory consolidation. Science (New York, N.Y.), 315 (5817), 1426-9 PMID: 17347444

Wu XM, Wang C, Zhang KN, Lin AY, Kira J, Hu GZ, Qu XH, Xiong YQ, Cao WF, & Gong LY (2009). Association of susceptibility to multiple sclerosis in Southern Han Chinese with HLA-DRB1, -DPB1 alleles and DRB1-DPB1 haplotypes: distinct from other populations. Multiple sclerosis (Houndmills, Basingstoke, England), 15 (12), 1422-30 PMID: 19965521

Image via Zadorozhnyi Viktor / Shutterstock.

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