Coffee addiction is a relatively new phenomenon (yes, I’m looking at you, university students), and has been accommodated by the increase in coffee based fast food chains such as Starbucks and Dunkin’ Donuts which in turn has led to the so-called ‘coffee culture’ as coffee drinking becomes a national habit. This infographic explores how caffeine works and the effects it has on you and your brain when it becomes part of your daily routine.
In vertebrates, the eyeballs are direct extensions of the brain; that is, they evolved after the brain, and are literally unimpeded access to the cerebellum and cerebrum. Because of this, many ocular tumors or injuries can be far more dangerous to the brain than growths or injuries on any other part of the skull.
Anatome ex omnium veterum recentiorumque observationibus. Thomas Bartholin, 1673.
Not sure how many of you have read about this by now, but it is such an amazing finding I decided to write about it (even though I retweeted this yesterday).
This study is a clinical case report of a living patient with cerebellar agenesis, an extremely rare condition characterized by the absence of the cerebellum. The cause is currently unknown, there are limited reported cases of complete cerebellar agenesis, and most of what we know about the condition comes from autopsy reports instead of living patients. Moreover, the condition is difficult to study because most individuals with complete primary cerebellar agenesis are infants or children with severe mental impairment, epilepsy, hydrocephaly and other gross lesions of the CNS. The fact that this woman is alive and has a somewhat “normal” life is ground-breaking and presents a unique opportunity to study the condition.
The patient described in the study is 24 years old. She has mild mental impairment and moderate motor deficits. For example, she is unable to walk steadily and commonly experiences dizziness/nausea. She also has speech problems and cannot run or jump. However, she has no history of neurological disorders and even gave birth without any complications.
Importantly, as shown above, CT and MRI scans revealed no presence of recognizable cerebellar structures. Just look at that dark sport towards the back of the brain! In addition to these findings, magnetic resonance angiography also demonstrated vascular characteristics of this patient consistent with complete cerebellar agenesis- meaning that the arteries that normally supply this area were also absent bilaterally. How crazy is that? Futhermore, diffusion tensor imaging indicated a complete lack of the efferent and afferent limbs of the cerebellum.
Given that the cerebellum is responsible for both motor and non-motor functions, these results are pretty amazing. How can the brain compensate for such a heavy blow to its architecture and connectivity? According to the authors of the study:
This surprising phenomenon supports the concept of extracerebellar motor system plasticity, especially cerebellum loss, occurring early in life. We conclude that the cerebellum is necessary for normal motor, language functional and mental development even in the presence of the functional compensation phenomenon.
Every time you play a game of basketball, make a cup of coffee or
flick on a light switch, you are turning on genes in your brain. These
same genes typically are turned off when the activity ceases – but when
that doesn’t happen, damaging consequences can occur.
A study in mice at Washington University School of Medicine in St.
Louis shows how such genes stuck in the “on” position can lead to faulty
brain wiring that affects learning and memory.
“We’ve shown in mice that genes don’t just shut off by themselves;
there’s an active mechanism to turn off genes after they’re turned on,”
said Azad Bonni, MD, PhD, the Edison Professor of Neuroscience and head
of the Department of Neuroscience. “If that mechanism is disrupted in
the brain, you see serious consequences for learning and memory.”
Genes in living cells constantly are being turned on and off in
response to signals as diverse as physical activity, hormones and
microbial infection. Decades of research have gone into understanding
how and why genes turn on, but how genes turn off has consistently
received less attention.
Bonni, Yue Yang, PhD, Tomoko Yamada, PhD, and colleagues decided to
investigate how genes turn off in the brain. In doing so, they found
that the inability to turn off such genes leads to faulty brain wiring.
The researchers studied genes in the cerebellum of mice – the part of
the brain responsible for motor functions such as walking – that turn
on when the mice are physically active.
They found that a large enzyme is bound to the genes that are turned
on when the mice move about, but not to the genes that are not switched
on by movement. The enzyme, known as the nucleosome remodeling and
deacetylase (NuRD) complex, appears to be critical to turning off genes.
Mice that lack the enzyme are unable to turn off the genes after
physical activity ceased.
The enzyme, the scientists found, turns off genes by switching out
one kind of a DNA-associated protein for another. These proteins, called
histones, serve as spools around which the DNA thread is wound, in some
places tightly and other places loosely. By switching out one kind of
histone for another, the enzyme causes the DNA to be more tightly wound,
shutting off any genes in that section of DNA.
“Turning on and off genes is a fundamental property of cell biology,
and this is the first epigenetic mechanism that explains how you turn
off genes after they’re turned on,” Bonni said. “I think we’ll find that
this mechanism turns off genes in many different contexts.”
Epigenetics refers to factors apart from the DNA sequence itself that affect whether genes are on or off.
“We think that the NuRD complex has the potential to rapidly turn off
thousands of genes,” said Yamada, co-lead author on the study and an
assistant professor of medicine at the University of Tsukuba in Japan.
During development, neurons form many connections with each other and
then prune back all but the most important ones. Neurons in the
cerebellum of mice lacking the enzyme do not prune, leaving abnormal
connections in place.
“We were surprised to discover that failure to prune connections
caused abnormal responses of the neurons to the environment,” said Yang,
a postdoctoral researcher and co-lead author on the study. “Our study
reveals the importance of eliminating the excess connections formed in
Such connections did not affect the mice’s ability to walk but did
affect their ability to learn motor skills as adults. In people,
learning a motor skill would include learning how to play the piano or
ride a bicycle.
Adult mice lacking the enzyme were unable to learn how to walk on a
rotating rod that gradually sped up, a task other mice could do easily.
“They’re walking normally, they’re coordinated, but they are really
profoundly impaired in learning,” Bonni said. “What’s really surprising
is that these deficits are due not to failure to activate genes but to
failure to turn them off.”
Bonni and colleagues are working on figuring out the mechanism by
which changes in gene activity lead to changes in brain cell activity.
“This enzyme is related to other enzymes that are mutated in
neurodevelopmental diseases,” Bonni said. “The ability to turn off genes
turns out to have profound consequences for brain wiring and learning,
and we want to figure out how.”
Most popular depictions of the exposed human brain present it from the side or perhaps top-down. This is the ventral view, a look at the bottom of the brain. Some of the elements are commonly seen from other angles, such as the brain’s iconic gyri and sulci, those meandering ridges and grooves that fundamentally increase the number of neurons that can be squeezed into a constrained space, i.e. your skull.
More notable from this perspective, though, is the stubby brainstem at the posterior part of the brain (back end) that connects to the spinal cord. It is the essential passageway for motor and sensory signals traveling between brain and body.
On either side of the brainstem is the striated cerebellum, Latin for “little brain,” which it vaguely resembles. The cerebellum plays an important role in motor control and is involved in some cognitive functions, such as attention and language.
Rarely but remarkably, persons are born with brains missing the cerebellum but learn to compensate due to the brain’s astounding ability to adapt, a concept called plasticity. That fact was recently highlighted in a pair of stories, local and national.
We all know about our uvula - or at least the palatine uvula - the one in our mouths. This hanging mass at the back of our mouth is formed from the soft palate, and is involved in the gag reflex and some languages (but not English). But did you know that we have more uvulas than just that?
Uvula means “little grape"in Latin, and a swollen uvula is called ”ūva“ which is simply ”grape“. Hanging grapes everywhere!
Everyone also has a cerebellar uvula, which is right next to the cerebellar tonsils (more tonsils!) and at the end of the cerebeallar vermis ("cerebellar worm”). This area of the brain is involved in posture and locomotion.
In addition to both of those, males also have a uvula of the urinary bladder. This is less of a “little grape”, and more of a slight elevation in the internal urethral orifice, caused by the prostate.
Scientists have discovered differences in the brain structure of ballet dancers that may help them avoid feeling dizzy when they perform pirouettes.
The research suggests that years of training can enable dancers to suppress signals from the balance organs in the inner ear.
The findings, published in the journal Cerebral Cortex, could help to improve treatment for patients with chronic dizziness. Around one in four people experience this condition at some time in their lives.
Normally, the feeling of dizziness stems from the vestibular organs in the inner ear. These fluid-filled chambers sense rotation of the head through tiny hairs that sense the fluid moving. After turning around rapidly, the fluid continues to move, which can make you feel like you’re still spinning.
Ballet dancers can perform multiple pirouettes with little or no feeling of dizziness. The findings show that this feat isn’t just down to spotting, a technique dancers use that involves rapidly moving the head to fix their gaze on the same spot as much as possible.
Researchers at Imperial College London recruited 29 female ballet dancers and, as a comparison group, 20 female rowers whose age and fitness levels matched the dancers’.
The volunteers were spun around in a chair in a dark room. They were asked to turn a handle in time with how quickly they felt like they were still spinning after they had stopped. The researchers also measured eye reflexes triggered by input from the vestibular organs. Later, they examined the participants’ brain structure with MRI scans.
In dancers, both the eye reflexes and their perception of spinning lasted a shorter time than in the rowers.
Dr Barry Seemungal, from the Department of Medicine at Imperial, said: “Dizziness, which is the feeling that we are moving when in fact we are still, is a common problem. I see a lot of patients who have suffered from dizziness for a long time. Ballet dancers seem to be able to train themselves not to get dizzy, so we wondered whether we could use the same principles to help our patients.”
The brain scans revealed differences between the groups in two parts of the brain: an area in the cerebellum where sensory input from the vestibular organs is processed and in the cerebral cortex, which is responsible for the perception of dizziness.
The area in the cerebellum was smaller in dancers. Dr Seemungal thinks this is because dancers would be better off not using their vestibular systems, relying instead on highly co-ordinated pre-programmed movements.
“It’s not useful for a ballet dancer to feel dizzy or off balance. Their brains adapt over years of training to suppress that input. Consequently, the signal going to the brain areas responsible for perception of dizziness in the cerebral cortex is reduced, making dancers resistant to feeling dizzy.
“If we can target that same brain area or monitor it in patients with chronic dizziness, we can begin to understand how to treat them better.”
Another finding in the study may be important for how chronic dizzy patients are tested in the clinic. In the control group, the perception of spinning closely matched the eye reflexes triggered by vestibular signals, but in dancers, the two were uncoupled.
“This shows that the sensation of spinning is separate from the reflexes that make your eyes move back and forth,” Dr Seemungal said. “In many clinics, it’s common to only measure the reflexes, meaning that when these tests come back normal the patient is told that there is nothing wrong. But that’s only half the story. You need to look at tests that assess both reflex and sensation.”
A woman living in China’s Shandong Province got a bit of a surprise recently when doctors at the Chinese PLA General Hospital told her that her brain was missing one of the most important centers for motor control: the cerebellum. She had initially checked herself into the hospital because of a bad case of dizziness and nausea.
Her diagnosis helped explain some of the challenges she had experienced through the course of her life, including slurred speech, delayed onset of walking until the age of seven and troubles with maintaining balance her entire life.
A single dose of antidepressant is enough to produce dramatic changes in the functional architecture of the human brain. Brain scans taken of people before and after an acute dose of a commonly prescribed SSRI (serotonin reuptake inhibitor) reveal changes in connectivity within three hours, say researchers who report their observations in the Cell Press journal Current Biology on September 18.
“We were not expecting the SSRI to have such a prominent effect on such a short timescale or for the resulting signal to encompass the entire brain,” says Julia Sacher of the Max Planck Institute for Human Cognitive and Brain Sciences.
While SSRIs are among the most widely studied and prescribed form of antidepressants worldwide, it’s still not entirely clear how they work. The drugs are believed to change brain connectivity in important ways, but those effects had generally been thought to take place over a period of weeks, not hours.
The new findings show that changes begin to take place right away. Sacher says what they are seeing in medication-free individuals who had never taken antidepressants before may be an early marker of brain reorganization.
Study participants let their minds wander for about 15 minutes in a brain scanner that measures the oxygenation of blood flow in the brain. The researchers characterized three-dimensional images of each individual’s brain by measuring the number of connections between small blocks known as voxels (comparable to the pixels in an image) and the change in those connections with a single dose of escitalopram (trade name Lexapro).
Their whole-brain network analysis shows that one dose of the SSRI reduces the level of intrinsic connectivity in most parts of the brain. However, Sacher and her colleagues observed an increase in connectivity within two brain regions, specifically the cerebellum and thalamus.
The researchers say the new findings represent an essential first step toward clinical studies in patients suffering from depression. They also plan to compare the functional connectivity signature of brains in recovery and those of patients who fail to respond after weeks of SSRI treatment.
Understanding the differences between the brains of individuals who respond to SSRIs and those who don’t “could help to better predict who will benefit from this kind of antidepressant versus some other form of therapy,” Sacher says. “The hope that we have is that ultimately our work will help to guide better treatment decisions and tailor individualized therapy for patients suffering from depression.”