Biocompatible sponge can be injected to deliver stem cells and drugs into the body

Biocompatible scaffolds, like those developed to stimulate the repair of heart tissue and bone and cartilage in the body, would normally need to be implanted surgically. Now bioengineers at Harvard University have developed a compressible bioscaffold that can be delivered via a syringe before popping back to its original shape inside the body. The material is also able to be loaded up with drugs or living cells that are gradually released as the material breaks down.

The injectable sponge is made up primarily of a seaweed-based jelly called alginate. It is actually a sponge-like gel that is formed through a freezing process called cryogelation. When the water in the alginate solution starts to freeze, pure ice crystals are formed and the surrounding gel becomes more concentrated as it sets. Later, the ice crystal melt to leave a network of large pores that allow liquids and large molecules to easily flow through it. Live cells can be attached to the walls of this network and large and small proteins and drugs can also be held within the alginate jelly itself.

Unlike other alginate gels that are brittle, using this method the researchers were able to produce a strong, compressible gel by carefully calibrating the alginate mixture and the timing of the freezing process.

The research team led by principal investigator David J. Mooney, the Robert P. Pinkas Family Professor of Bioengineering at the Harvard School of Engineering and Applied Sciences (SEAS), demonstrated that cells and drugs can be delivered into the body intact along with the sponge through a small bore needle. Once inside the body, the sponge returns to its original shape and gradually releases its cargo as it breaks down.

“What we’ve created is a three-dimensional structure that you could use to influence the cells in the tissue surrounding it and perhaps promote tissue formation,” explains Mooney. “The simplest application is when you want bulking. If you want to introduce some material into the body to replace tissue that’s been lost or that is deficient, this would be ideal. In other situations, you could use it to transplant stem cells if you’re trying to promote tissue regeneration, or you might want to transplant immune cells, if you’re looking at immunotherapy.”

Sensorimotor Learning Biases Choice Behavior: A Learning Neural Field Model for Decision Making

According to a prominent view of sensorimotor processing in primates, selection and specification of possible actions are not sequential operations. Rather, a decision for an action emerges from competition between different movement plans, which are specified and selected in parallel. For action choices which are based on ambiguous sensory input, the frontoparietal sensorimotor areas are considered part of the common underlying neural substrate for selection and specification of action. These areas have been shown capable of encoding alternative spatial motor goals in parallel during movement planning, and show signatures of competitive value-based selection among these goals. Since the same network is also involved in learning sensorimotor associations, competitive action selection (decision making) should not only be driven by the sensory evidence and expected reward in favor of either action, but also by the subject’s learning history of different sensorimotor associations. Previous computational models of competitive neural decision making used predefined associations between sensory input and corresponding motor output. Such hard-wiring does not allow modeling of how decisions are influenced by sensorimotor learning or by changing reward contingencies. We present a dynamic neural field model which learns arbitrary sensorimotor associations with a reward-driven Hebbian learning algorithm. We show that the model accurately simulates the dynamics of action selection with different reward contingencies, as observed in monkey cortical recordings, and that it correctly predicted the pattern of choice errors in a control experiment. With our adaptive model we demonstrate how network plasticity, which is required for association learning and adaptation to new reward contingencies, can influence choice behavior. The field model provides an integrated and dynamic account for the operations of sensorimotor integration, working memory and action selection required for decision making in ambiguous choice situations.

Linguistics as a Window to Understanding the Brain

Why is it so hard to give good directions?

We’ve all been there – the directions sounded so clear when we were told them. Every step of the journey seemed obvious, we thought we had understood the directions perfectly. And yet here we are miles from anywhere, after dark, in a field arguing about whether we should have gone left or right at the last turn, whether we’re going to have to sleep here now, and exactly whose fault it is.

The truth is we shouldn’t be too hard on ourselves. Psychologically speaking giving good directions is a particularly difficult task.

The reason we find it hard to give good directions is because of the “curse of knowledge”, a psychological quirk whereby, once we have learnt something, we find it hard to appreciate how the world looks to someone who doesn’t know it yet. We don’t just want people to walk a mile in our shoes, we assume they already know the route. Once we know the way to a place we don’t need directions, and descriptions like “its the left about halfway along” or “the one with the little red door” seem to make full and complete sense.

But if you’ve never been to a place before, you need more than a description of a place; you need an exact definition, or a precise formula for finding it. The curse of knowledge is the reason why, when I had to search for a friend’s tent in a field, their advice of “it’s the blue one” seemed perfectly sensible to them and was completely useless for me, as I stood there staring blankly at hundreds of blue tents.

This same quirk is why teaching is so difficult to do well. Once you are familiar with a topic it is very hard to understand what someone who isn’t familiar with it needs to know. The curse of knowledge isn’t a surprising flaw in our mental machinery – really it is just a side effect of our basic alienation from each other. We all have different thoughts and beliefs, and we have no special access to each other’s minds. A lot of the time we can fake understanding by mentally simulating what we’d want in someone else’s position. We have thoughts along the lines of “I’d like it if there was one bagel left in the morning” and therefore conclude “so I won’t eat all the bagels before my wife gets up in the morning”. This shortcut allows us to appear considerate, without doing any deep thought about what other people really know and want.

Read more

Swimming kids are smarter

Children who learn how to swim at a young age are reaching many developmental milestones earlier than the norm.

Researchers from the Griffith Institute for Educational Research surveyed parents of 7000 under-fives from Australia, New Zealand and the US over three years.

A further 180 children aged 3, 4 and 5 years have been involved in intensive testing, making it the world’s most comprehensive study into early-years swimming.

Lead researcher Professor Robyn Jorgensen says the study shows young children who participate in early-years swimming achieve a wide range of skills earlier than the normal population.

“Many of these skills are those that help young children into the transition into formal learning contexts such as pre-school or school.

“The research also found significant differences between the swimming cohort and non-swimmers regardless of socio-economic background.

“While the two higher socio-economic groups performed better than the lower two in testing, the four SES groups all performed better than the normal population.

The researchers also found there were no gender differences between the research cohort and the normal population.

As well as achieving physical milestones faster, children also scored significantly better in visual-motor skills such as cutting paper, colouring in and drawing lines and shapes, and many mathematically-related tasks. Their oral expression was also better as well as in the general areas of literacy and numeracy.

“Many of these skills are highly valuable in other learning environments and will be of considerable benefit for young children as they transition into pre-schools and school.”

Socrates Method Of Memory Works Just As Well Using Virtual Reality

In the episode of NOVA that aired October 24 of this year, host David Pogue posed the question, “How Smart Can We Get?” At one point in the episode, he met with Chester Santos, who was the 2008 US Memory Champion, to pick his brain on how he manages to learn long strings of numbers and words. Santos taught him a technique that involved visualization of objects that were in Pogue’s own house and associating them with the string of non-related words. It turns out this technique is nothing new. Its roots stem all the way back to the time of Socrates, in fact.

A new research study conducted by a team from the University of Alberta has revisited this age old technique giving it a modern-day twist.

The memory technique, called loci, or location, by the ancient Greeks, was used by Socrates, according to classic scholars, to memorize his oratories. To do this, Socrates would wander around his home and assign a word or fact that he needed to memorize some familiar object or structure in his home.

At the time that Socrates needed to recall this information in front of an audience, he would simply conjure up his home and, in his mind, the words that he had linked to things like his window or table would instantly be recalled.

“Nowadays many contestants in memory competitions use this same technique,” said lead researcher Eric Legge. “They use the location method to instantly recall everything from words to a long list of random numbers.”

Legge, along with his U of A research colleague Christopher Madan, developed a virtual living-space environment. This virtual living room would allow their test subjects to use the ancient Greek technique to increase their memory ability.

How we “hear” with our eyes

In everyday life we rarely consciously try to lip-read. However, in a noisy environment it is often very helpful to be able to see the mouth of the person you are speaking to. Researcher Helen Blank at the MPI in Leipzig explains why this is so: “When our brain is able to combine information from different sensory sources, for example during lip-reading, speech comprehension is improved.” In a recent study, the researchers of the Max Planck Research Group “Neural Mechanisms of Human Communication” investigated this phenomenon in more detail to uncover how visual and auditory brain areas work together during lip-reading.

In the experiment, brain activity was measured using functional magnetic resonance imaging (fMRI) while participants heard short sentences. The participants then watched a short silent video of a person speaking. Using a button press, participants indicated whether the sentence they had heard matched the mouth movements in the video. If the sentence did not match the video, a part of the brain network that combines visual and auditory information showed greater activity and there were increased connections between the auditory speech region and the STS.

“It is possible that advanced auditory information generates an expectation about the lip movements that will be seen”, says Blank. “Any contradiction between the prediction of what will be seen and what is actually observed generates an error signal in the STS.”

How strong the activation is depends on the lip-reading skill of participants: The strong-er the activation, the more correct responses were. “People that were the best lip-readers showed an especially strong error signal in the STS”, Blank explains. This effect seems to be specific to the content of speech - it did not occur when the subjects had to decide if the identity of the voice and face matched.

The results of this study are very important to basic research in this area. A better understanding of how the brain combines auditory and visual information during speech processing could also be applied in clinical settings. “People with hearing impairment are often strongly dependent on lip-reading”, says Blank. The researchers suggest that further studies could examine what happens in the brain after lip-reading training or during a combined use of sign language and lip-reading.

Foetus suffers when mother lacks vitamin C

Maternal vitamin C deficiency during pregnancy can have serious consequences for the foetal brain. And once brain damage has occurred, it cannot be reversed by vitamin C supplements after birth. This is shown through new research at the University of Copenhagen just published in the scientific journal PLOS ONE.