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Scientists discover new class of memory cells in the brain

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New study could have implications for people suffering from face blindness, a socially isolating condition.

Scientists believe they have discovered a new class of neurons that links face perception to long-term memory.

Researchers have long searched for a class of brain cells that explains the visceral flash of recognition that we feel when we see a very familiar face, like that of our grandmothers.

But the proposed “grandmother neuron”- a single cell at the crossroads of sensory perception and memory, capable of prioritising an important face over the rabble – has remained elusive to date.

Winrich Freiwald, professor of neurosciences and behavior at The Rockefeller University, says: “When I was coming up in neuroscience, if you wanted to ridicule someone’s argument you would dismiss it as ‘just another grandmother neuron’ – a hypothetical that could not exist.

“Now, in an obscure and understudied corner of the brain, we have found the closest thing to a grandmother neuron: cells capable of linking face perception to memory.”

The idea of  the ‘grandmother neuron’ first emerged in the 1960s as a theoretical brain cell that would code for a specific, complex concept, by itself.

One neuron for the memory of one’s grandmother, another to recall one’s mother, and so on. At its heart, the notion of a one-to-one ratio between brain cells and objects or concepts was an attempt to tackle the mystery of how the brain combines what we see with our long-term memories.

Scientists have since discovered plenty of sensory neurons that specialise in processing facial information, and as many memory cells dedicated to storing data from personal encounters. But a grandmother neuron – or even a hybrid cell capable of linking vision to memory – never emerged.

“The expectation is that we would have had this down by now,” Freiwald says. “Far from it! We had no clear knowledge of where and how the brain processes familiar faces.”

Recently, Freiwald and colleagues discovered that a small area in the brain’s temporal pole (TP) region may be involved in facial recognition.

So the team used functional magnetic resonance imaging as a guide to zoom in on the TP regions of two rhesus monkeys, and recorded the electrical signals of TP neurons as the macaques watched images of familiar faces (which they had seen in-person) and unfamiliar faces that they had only seen virtually, on a screen.

The team found that neurons in the TP region were highly selective, responding to faces that the subjects had seen before more strongly than unfamiliar ones.

And the neurons were fast – discriminating between known and unknown faces immediately upon processing the image.

Interestingly, these cells responded threefold more strongly to familiar over unfamiliar faces even though the subjects had in fact seen the unfamiliar faces many times virtually, on screens.

“This may point to the importance of knowing someone in person,” says neuroscientist Sofia Landi, first author on the paper.

“Given the tendency nowadays to go virtual, it is important to note that faces that we have seen on a screen may not evoke the same neuronal activity as faces that we meet in-person.”

The findings constitute the first evidence of a hybrid brain cell, not unlike the fabled grandmother neuron. The cells of the TP region behave like sensory cells, with reliable and fast responses to visual stimuli.

But they also act like memory cells which respond only to stimuli that the brain has seen before–in this case, familiar individuals–reflecting a change in the brain as a result of past encounters.

“They’re these very visual, very sensory cells – but like memory cells,” Freiwald says. “We have discovered a connection between the sensory and memory domains.”

But the cells are not, strictly speaking, grandmother neurons. Instead of one cell coding for a single familiar face, the cells of the TP region appear to work in concert, as a collective.

“It’s a ‘grandmother face area’ of the brain,” Freiwald says.

The discovery of the TP region at the heart of facial recognition means that researchers can soon start investigating how those cells encode familiar faces.

“We can now ask how this region is connected to the other parts of the brain and what happens when a new face appears,” Freiwald asks. “And of course, we can begin exploring how it works in the human brain.”

In the future, the findings may also have clinical implications for people suffering from prosopagnosia, or face blindness, a socially isolating condition that affects about one percent of the population.

“Face-blind people often suffer from depression. It can be debilitating, because in the worst cases they cannot even recognize close relatives,” Freiwald says.

“This discovery could one day help us devise strategies to help them.”

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Osteoarthritis: breaking the cycle

Medical technology company Ottobock shares its expertise on approaches to the condition.

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Sponsored feature

Why is Cartilage Important?

Bones that come in contact with other bones are covered by cartilage at their contact points. Cartilage does not have blood vessels – it is supplied with nutrients through movement of the joint. That’s why regular exercise is so important!

Cartilage ensures that the joint surfaces move against each other in the most efficient way and with little friction. It absorbs shock, cushioning the joint, and distributes the forces acting on the joint.

If cartilage is damaged and its gliding properties are affected, it can no longer serve its purpose and the joints range of movement can become limited.

Typical Progression of Osteoarthritis

When osteoarthritis of the knee develops due to joint malalignment, an accident, advancing age, obesity or excessive strain, the damaged cartilage is no longer able to properly fulfil its function.

This results in pain and re­duced mobility. The affected patient instinctively assumes a relieving posture to reduce strain on the knee.

However, this often leads to new prob­lems in other places, such as the hip, and reduces the supply of nutrients to the cartilage, for which movement is required – sparking a vicious circle.

The cartilage develops cracks and begins to break down. At the same time, the bone thickens at the site of the damage.

When the cartilage layer is completely worn away, the affected bones come into direct contact and rub against each other causing joint pain and inflammation.

The thickest joint cartilage is located behind the kneecap (patella). This is an area of high stress. Osteoarthritis occurring in this area is known as patellafemoral osteoarthritis

Signs and Symptoms

There are several common symptoms that signal knee osteoarthritis. They can occur individually or together. However, with the initial onset, you may not notice any of these symptoms

When symptoms appear they usually occur in the following order:

  • Cracking in the joint
  • Pain during load bearing activities, such as carrying a heavy object
  • Pain during every day activities, such as climbing the stairs
  • Reduced mobility
  • Swelling and inflammation

Non-Invasive Treatments

Joint specific exercises: with regular exercise mobility can be maintained and muscle strengthened, ensuring the cartilage is supplied with the nutrients it needs.

Temperature: with acute inflammation, cold relieves pain and reduces swelling. Heat relaxes the muscles and tendons and increases the flow of nutrients. Heat may only be applied when the joint is not inflamed.

Creams: various over the counter products are available at your local pharmacy including gels and creams that can help relieve pain.

Orthopaedic devices (braces and supports): these are applied externally to the knee, reducing pain and improving mobility.

Lifestyle: living a healthy lifestyle can help to combat osteoarthritis. A healthy diet and an active lifestyle reduces the chance of obesity, putting less stress and strain through the knee joints.

Orthotic Options

An orthotic fitting is a key component in the treatment of osteoarthritis. It can provide the following:

  • Pain relief
  • Support daily activities
  • Support during activities that affect the joint, whether at work or during sports

Did you know?

An osteoarthritis patient takes an average of around 1,200 tablets a year to manage pain. But this can lead to damage to the stomach, bowel and liver.

An orthosis from the Agilium line is therefore a good alternative. It’s worth-while for anyone with knee osteoarthritis to test the effectiveness of the orthoses themselves.

The Agilium Line

The braces in our Agilium line are designed specifically to target the symptoms of osteoarthritis of the knee.

Each works in a different way to address the various characteristics of osteoarthritis of the knee. At the same time, we placed great emphasis on their comfort and suitability for daily use.

The Agilium Freestep, the Agilium Reactive and the Agilium Softfit are used to treat unicompartmental osteoarthritis of the knee.

The Agilium Patella is used for patients with patellofemoral arthritis.

The Agilium Freestep is used to treat OA, although it is not applied directly to the knee. Instead is worn on the foot, right inside the shoe! For targeted relieve, it alters the load-line of the knee – the point where the body weight impacts the cartilage.

The Agilium Softfit is a pull on knee brace with a textile base and single upright that stabilises and relieves the knee using a three point force system to offload the affected compartment (side) of the knee.

The Agilium Reactive also uses a three point force system to offload the affected compartment (side) of the knee. However, the innovative closure system in the upper calf provides comfort while sitting without compromising the stable position when standing.

The Agilium Patella combines a textile structure and stabilising component with a dynamic re-alignment mechanism enabling it to maintain the central alignment of the knee cap, reducing pressure behind the knee cap.

Find the appropriate brace with Agilium Select.

Visit our website or go to ottobock.com/agilium-select

If you would like to know more about any of these products please get in touch via orthoticsuk@ottobock.com or visit our website for more information: www.ottobock.co.uk

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Masturbation linked to stroke in medical case study

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Doctors in Japan have reported how masturbation sparked a bleed on the brain of a 51-year-old man; as published in the Journal of Stroke and Cerebrovascular Diseases.

Doctors at the Nagoya City University Graduate School of Medical Sciences in Japan explained that the man attended hospital after orgasming, with the sudden onset of a searing headache that lasted for around a minute. This was followed by an intense bout of vomiting.

A CT scan showed an acute subarachnoid hemorrhage in the left hemisphere.

The researchers note that masturbation causes an increase in heart rate, blood pressure, and noradrenaline plasma levels – which are likely to contribute to the risk of splitting a blood vessel in the brain and result in a hemorrhagic stroke.

The man was treated with stents and coiling, two techniques used to bolster the blood vessel and maintain blood flow to the brain, and he went on to make a full recovery.

The study authors say that they found just two other cases of masturbation-linked strokes in other scientific literature.

The Japanese man survived and was discharged after nearly two weeks in hospital in an “excellent” condition.

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Engineers develop ultrasound patch to monitor blood flow

Breakthrough could help to better predict stroke and other cardiovascular conditions earlier.

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Engineers at the University of California San Diego have developed an ultrasound patch that can be worn on the skin. It monitors the blood flow through major arteries and veins deep within the body.

It is hoped that it could help clinicians diagnose cardiovascular conditions faster. It could also help to diagnose blockages in the arteries which could lead to strokes or heart attacks.

The ultrasound patch continuously monitors blood flow as well as blood pressure and heart function in real-time. Assessing how much blood flows through a patient’s blood vessels could help diagnose blood clots, heart valve problems and poor circulation in the limbs.

For many patients, blood flow is not measured during a regular visit to their doctors. It is usually assessed after a patient shows signs of cardiovascular problems.

The patch can be worn on the neck or chest and can measure cardiovascular signals up to 14 centimetres inside the body non invasively with high accuracy.

How the patch works

The patch is made of a thin, flexible polymer that sticks to the skin.

There is an array of millimetre-sized ultrasound transducers on the patch known as an ultrasound phased array.

These are individually controlled by a computer. Another feature is that the ultrasound beam can be tilted at different angles to areas in the body that are not directly below the patch.

It can operate in two modes. In one, all of the transducers can be synched together to transmit ultrasound waves which produce a high-intensity beam that focuses on one spot.

This can be up to 14cm deep in the body.

A wearable ultrasound patch on the skin

The other mode allows the transducers to be programmed to transmit out of sync producing beams at different angles.

In being able to manipulate the beams, it gives the device multiple capacities for monitoring central organs as well as blood flow with high resolution.

When the electricity flows through the transducers, they vibrate while emitting ultrasound waves that travel through the skin into the body.

When they penetrate a blood vessel, they encounter the movement of red blood cells flowing inside. The cell movement changes how the waves are transmitted back to the patch.

This change is recorded by the patch and creates a visual recording of the blood flow. It can also be used to create moving images of the heart’s walls.

The benefits:

Sheng Xu, professor of nanoengineering at the UC San Diego Jacobs School of Engineering said:

“This type of wearable device can give you a more comprehensive, more accurate picture of what’s going on in deep tissues and critical organs like the heart and the brain, all from the surface of the skin.”

Xu added: “This is a first in the field of wearables because existing wearable sensors typically only monitor areas right below them.

“If you want to sense signals at a different position, you have to move the sensor to that location. With this patch, we can probe areas that are wider than the device’s footprint. This can open up a lot of opportunities.”

The researchers say that the easy to use patch could allow patients to wear the patch and monitor the results themselves. It doesn’t depend on a technician to read the results

The next stage

The patch is not yet ready for clinical use. The researchers are currently working on a way to make the electronics wireless as it currently needs a power source and benchtop machine.

Image credit: Nature Biomedical Engineering

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