Features

Pop psychology assertions about left-brain/right-brain differences are pretty much tosh. Our personalities are not dominated by a battle between the creative skills residing in one half of the brain competing with the hard reasoning in the other.

But that’s not to say there aren’t any differences between the left and right sides of our brains. There are some anatomical details that differ between the opposite hemispheres of the brain. Language appears to be localised more to networks in the left brain, and differences in the brain can be seen according to whether we are right-handed or left-handed.

Understanding the detail of these left-right differences – how they occur and how they underlie the processing going on in our brains – is tricky, though.

A research group based at Oxford and Cambridge universities led by Professor Ole Paulsen has been using some of the latest, most precise neuroscience techniques to get a handle on this problem.

The scientists studied recently discovered asymmetries among nerve cells involved in learning and memory processes in the mouse brain. Their findings were published in Nature Neuroscience.

These particular nerve cells, or neurons, are found in the mouse hippocampus, part of the brain intimately involved in memory.

Neurons in one part of the hippocampus have different numbers of brain-chemical-responding proteins according to whether they are contacted by the left or right side of another region of the hippocampus.

The question is whether this finding of a molecular left-brain/right-brain difference is important: does it play any role in learning and memory?

Standard lab techniques for probing neurons and working out what’s going on tend to use electric currents to stimulate the nerves to fire. But such approaches would not be fine enough or accurate enough to pinpoint differences according to whether signals came from the left or right side of the hippocampus.

So the researchers used laser light and gene technology to gain extra control and be able to define exactly which neurons were being stimulated to fire. The technique, known as optogenetics, was pioneered by Professor Gero Miesenböck at Oxford.

‘It enables us to be far more precise about which cells are being activated. We really gain control over what’s happening in a cell,’ explains Oxford DPhil student Olivia Shipton.

Olivia and her colleagues used this approach to stimulate only the key neurons on the left side of the hippocampus, or alternatively only the neurons on the right.

They then measured what this did in the neurons receiving these connections. They reasoned that if the left-right asymmetry in the hippocampus is important, there may be differences according to which side of the brain the signals came from.

They found that signals coming from the left hippocampus led to a strengthening of long-term electrical connections between neurons. This strengthening of connections is a widely accepted model of learning and memory in the brain.

‘It is thought to be associated with how we lay down new memories,’ says Olivia.

In contrast, there were no such changes with signals coming from the right hippocampus.

‘There was a striking difference. It suggests that the left and right hippocampus in the mouse have distinct functions in learning and memory processes,’ says Olivia.

She adds that it’s possible to speculate that the right hippocampus may provide a constant signal or context against which new learning could be compared through the left side.

The group now want to explore if this functional difference between the left and right sides of the hippocampus is important in guiding the learning of mice.

They believe it should be possible to use the same techniques to control which sides of the hippocampus fire and whether this affects a mouse’s spatial memory as it learns how to navigate mazes.

Diamonds are celebrated for their enduring beauty and hardness but they can also be a physicist’s best friend.

In Nature Photonics and Science an international team of scientists report that a strange quantum state called ‘entanglement’ has been achieved in two 3mm-wide diamond crystals, spaced 15cm apart, at room temperature.

‘One of the weird effects well known from atomic-scale systems is the possibility of superposition - the ability of an object to be in two places at once,’ explains Ian Walmsley of Oxford University’s Department of Physics, a member of the team behind the research.

‘We show that you can take two diamonds - not quite everyday objects, but at least simple and recognizable - and put them in such a state: in particular a superposition of a state of one diamond vibrating and the other not, and vice versa.

‘This special type of superposition is called "entangled" and is of a kind that may be used for applications of quantum physics to new technologies, especially in communications and computing.’

Because it is so easily disturbed by its surroundings entanglement can only normally be observed in isolated systems cooled to temperatures close to absolute zero.

But the structure of diamond makes it different: ‘Exciting a vibrational motion in diamond requires a temperature of about 2000 degrees Celsius,’ comments Joshua Nunn of Oxford University’s Department of Physics, also a member of the research team.

‘So at room temperature the vibrations are non-existent. The system behaves in that sense like a very cold cloud of atoms.’

The researchers, from Oxford University, National University of Singapore, and National Research Council of Canada, also sought to exploit another property of diamond: it tends to scatter light in such a way that a photon striking it can be converted to a lower energy photon, with the remaining energy being converted into a vibration.

This vibration or ‘ringing’ in the diamond crystal can be detected using a laser.

‘We sent bursts of laser light through both diamonds,’ Ian tells me. ‘Most of the time the light would travel straight through the crystals but sometimes the light would dump some energy in one of the crystals, setting it ringing, and the light would then emerge with less energy - a lower frequency.’

The light is combined after the crystals so that when a low frequency pulse is detected, it is possible for scientists to know that one diamond is vibrating, but not which one.

‘In fact, the universe doesn't know which diamond is vibrating!’ Joshua explains. ‘The diamonds are entangled, with one vibration shared between them, even though they are separated in space. We could use a similar technique to measure the diamonds and determine that this was the case.’

The fact that entanglement is occurring inside everyday objects is not a surprise, but up until now most people would have thought that it would be impossible to observe: being ‘washed out’ or otherwise disturbed by noise from the environment.

Joshua suggests that their approach might encourage scientists to look for strange quantum effects in places where previously they wouldn’t have expected to be able to spot them.

Whilst any practical applications for the work are a long way off, the Nature Photonics paper does describe how it might be possible to build a diamond ‘quantum memory’ for photonic quantum computing.

Ian comments: ‘Several groups around the world have built different elements of a nanophotonic processor, and a vibrational quantum memory for photons could be incorporated into these.’

Another possibility is explored in a related piece of work using these diamonds that makes use of the quantum character of "nothingness". It exploits this possibility to generate truly random numbers: something that could help to improve the security of electronic communications and transactions.

Today scientists at the Large Hadron Collider announced tantalising news about the biggest piece missing from the physics jigsaw.

The Higgs boson is a hypothetical particle used to explain why many of the fundamental particles in the Standard Model of particle physics have mass.

Proving if it exists is tricky because the model doesn't predict its exact mass.

Now results from the Large Hadron Collider (LHC) suggest that, if it exists, the Higgs is most likely to have a mass between 116-130 gigaelectronvolts (GeV), according to the ATLAS experiment, and 115-127 GeV according to CMS.

Both experiments saw a ‘spike’ in their data around 124-125 GeV - this might be a random fluctuation or, as BBC News Online reports, it could just be a first glimpse of the Higgs.

Reacting to these early results Alan Barr of Oxford University’s Department of Physics, ATLAS UK physics coordinator, commented:

‘It is a testament to the superb performance of the LHC that we are already finding hints that might be indicative of Higgs bosons so early in the machine’s lifetime.

'The results are not yet conclusive, but during the next year we will know whether the Higgs boson exists in the form predicted by the “Standard Model” of particle physics. The analysis has to be done very carefully, since in scientific research the most interesting results are often found in unexpected places.

'We must bear in mind that the Standard Model is known to be incomplete, since it describes only that 5% of the universe that is made of atoms. What the LHC will tell us about the other 95% of the universe is likely to be an open question for many years to come.'

Chris Hays of Oxford University’s Department of Physics, another member of the ATLAS team, told me:

‘We have seen the first tantalizing hints of the Higgs boson after many years of pursuit. The concurrent signals in several different decay channels are suggestive.

‘Nonetheless the signals are still weak and more data are needed to determine if we are truly seeing the Higgs boson.’

UPDATE: Tony Weidberg, of Oxford University’s Department of Physics, also from the ATLAS team, comments:

'Science is a never ending frontier because as soon as one question is answered, more questions open up. If the hints of a standard model Higgs particle are confirmed next year, then the internal problems with the theory require the existence of new physics in the LHC energy regime.

'So this discovery would be the start of a new adventure. However, if we can exclude the existence of a Standard Model Higgs boson, then it raises the exciting question of just how particles like electrons do acquire mass. Again the LHC would be ideally placed to probe these questions.' 

Today saw the ESO give the go-ahead for work to begin on a series of roads on a mountain in Northern Chile.

But these aren’t just any roads; they will give access to Cerro Armazones, the site that has been chosen for the European Extremely Large Telescope (E-ELT).

E-ELT is planned to be the largest optical and infrared telescope in the world: it will be tens of times more sensitive than any current ground-based optical telescope.

Oxford University scientists are taking a lead role in the instrumentation for this £922m (€1082m) project, so today’s announcement from the ESO, which included funding for the roads and the adaptive optics mirror, is welcome news – even if a final decision to build the telescope won’t be made until mid-2012.

Niranjan Thatte of Oxford University’s Department of Physics led a European consortium that designed the E-ELT's HARMONI spectrograph, one of the proposed telescope's key instruments, he told me back in October:

‘HARMONI is an integral field spectrograph, simultaneously providing images and spectra of astrophysical objects in unprecedented detail, giving a fivefold improvement in spatial resolution over present-day telescopes.

'Combined with the immense light-gathering power of the E-ELT, it will enable ultra-sensitive observations of distant and nearby galaxies, super-massive black holes, young star-forming regions, extra-solar planets and other exotic objects.’

Yesterday, prior to the announcement, Isobel Hook of Oxford University’s Department of Physics, who chairs the E-ELT science working group, told the Today programme's Tom Feilden:

'The main improvement with this telescope over anything that's gone before is its size. The huge area allows you to collect light from much fainter more distant objects, while the diameter is what gives you the superb resolution - the sharpness of the images.'

With events at the LHC likely to dominate the headlines next week and next year, it’s worth considering just how much of an advance astronomy’s biggest science project could be:

The improvement in terms of resolution has been likened to the leap from the naked eye to the first telescopes used by Galileo and Harriot in the 1600s.

You can read more about HARMONI in our news story, whilst for more about E-ELT, and to listen to an interview with Niranjan, check out Tom Feilden's Blog.

It’s still a long road ahead for the E-ELT but, if approved, construction could start next year, with the telescope being operational early in the next decade.

Our galaxy is a relatively quiet neighbourhood with the supermassive black hole at its heart gently dozing: or is it?

The recent discovery of huge gamma-ray emitting ‘bubbles’ around the Milky Way is challenging this assumption and posing a new puzzle: just where do these bubbles come from?

Philipp Mertsch and Subir Sarkar of Oxford University’s Department of Physics recently reported in Physical Review Letters a model that could explain the origins of these strange phenomena. I asked them about bubbles, ‘feeding’ black holes, and how their ideas could be tested…

OxSciBlog: What are 'Fermi bubbles' and where are they found?
Philipp Mertsch: The 'Fermi bubbles' are gigantic structures above and below the centre of our Galaxy which were discovered by astrophysicists at Harvard in a gamma-ray sky map made by NASA's Fermi satellite.

The bubbles extend ~50,000 light years above and below the galactic plane, i.e. they are about the same size as the disk of the Galaxy. A correlated structure can also be seen in the X-ray map made by the ROSAT satellite.

It may seem surprising that such huge structures have gone unnoticed earlier - this is a testimony to how advances in astronomical instrumentation lead to serendipitous discoveries!

OSB: Why is it important to understand them?
Subir Sarkar: The bubbles are important for a variety of reasons. First, their origin is very likely related to an energetic outflow from the the supermassive black hole lurking at our Galactic Centre - it is supposedly not "feeding" but clearly was doing so as recently as a million years ago. Understanding the mechanism of their gamma-ray emission also holds clues as to what is powering them.

Moreover this region of the sky is a prime target for dark matter annihilation signals - while the bubbles are themselves very unlikely to be due to dark matter annihilations, we need to understand them in meticulous detail if we want to look for the much smaller signal in gamma-rays expected from dark matter.

OSB: How have scientists previously tried to explain them?
PM: So far, scientists have considered the same processes that are believed to produce gamma-rays in astrophysical sources, for example decays of neutral pions created by interactions of high energy protons with ambient matter, and inverse-Compton scattering of background photons by high energy electrons.

High-energy protons are certainly present in the disk of the Milky Way, but it is not easy to explain how they could be transported to such large distances from the disk and be contained inside the bubbles for billions of years.

The problem with electrons is that they lose energy rapidly and would need to be reaccelerated - it has been suggested that this happens at hundreds of shock fronts inside the bubbles. However, there is no evidence for such an onion-like structure, in fact, the bubbles have a smooth surface and a well-defined, sharp edge.

OSB: What do you suggest may have produced the bubbles?
SS: The X-ray data from the ROSAT satellite suggest only one shock front which delineates the outer edge of the bubbles. This shock produces turbulence in the plasma behind it which can accelerate electrons to very high energies through a stochastic process first discussed by Enrico Fermi.

These electrons then transfer their energy to low energy photons from the microwave and infrared backgrounds as well as starlight, producing the gamma-rays observed.

It turns out that the variations of the plasma properties inside the bubbles can exactly reproduce the observations, namely the smooth surface and the sharp edges of the bubbles. The other models cannot explain this.

OSB: If you are correct what does this tell us about our galaxy/galaxy formation in general?
PM: An important question is of course where does this shock front come from? Looking at other galaxies we see similar bubbles being produced by jets powered from the central black hole. This is certainly a possibility for our own Galaxy.

In fact it is rather peculiar that the black hole at the centre of the Milky Way is so quiet - it now appears that this may just be a transient phase.

This picture is further supported by numerical simulations which have shown that a jet shooting out from the centre above and below the galactic plane can easily produce structures of the size and shape of the Fermi bubbles.

OSB: How could your ideas be tested?
SS: Our model for the gamma-ray emission predicts a unique energy-dependence: at lower energies, the surface of the bubbles is very smooth but at higher energies, the bubble inside should become fainter while only the edges stay bright. The energies at which this happens are beyond the reach of the Fermi satellite but with data from the forthcoming Cherenkov Telescope Array this shell-like structure should become observable.