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Mechanisms behind 'Mexican waves' in the brain are revealed by scientists

Imperial College London

Scientists have revealed the mechanisms that enable certain brain cells to persuade others to create 'Mexican waves' linked with cognitive function.

Ultimately, the team say their work may help researchers understand more about normal brain function and about neurocognitive disorders such as dementia.

Neurons are cells in the brain that communicate chemical and electrical information and they belong to one of two groups- inhibitory or excitatory. While much is known about excitatory neurons, the role of inhibitory neurons is still being debated.

Inhibitory neurons can vibrate and they are equipped with mechanisms that enable them to persuade networks of other neurons into imitating their vibrations - setting off 'Mexican waves' in the brain. The scientists believe these collective, oscillating vibrations play a key role in cognitive function. Their research sheds light on how inhibitory neurons use different communication processes to excitatory neurons, which share information via an internal pulsing mechanism.

This study was carried out by Imperial College London and the Max Planck Institute for Brain Research. It is published today in the journal Nature Communications.

Dr Claudia Clopath, co-author from the Department of Bioengineering at Imperial College London, said: "These brain cells are similar to spectators in a football stadium, encouraging others into imitating them in a Mexican wave. We suspect that there is a very close relationship between the collective vibrations that they set off and many important cognitive functions. When the vibrations are degraded so that the wave is disrupted, we think it may contribute to neurocognitive disorders such as dementia. Our hope is that ultimately our research will lead to new insights into these disorders and how they can be treated."

The researchers developed a mathematical model showing the two mechanisms that inhibitory neurons need in order to convince others to join them in their rhythmical vibrations. The first is the mechanism that enables the inhibitory neurons to vibrate on their own, known as sub threshold resonance.

The second mechanism is a nanoscopic hole known as a gap-junction. There are many of these on the surface of the inhibitory neuron and they allow neurons to communicate directly with one another, enabling inhibitory neurons to set off a collective vibration.

The fact that inhibitory neurons are able to determine how and when whole networks of neurons will vibrate suggests that they are much more important in brain function than scientists had previously thought, say the researchers.

Now that the team have described the mechanisms behind these vibrations, the next step will see them carrying out research on inhibitory neurons to fully understand why vibrations are important for cognitive functions. The team believe that there may ultimately be a way to manipulate inhibitory neurons to improve how they vibrate, which might one day lead to better treatments for people with neurocognitive diseases.

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"Oscillations emerging from noise-driven steady state in networks with electrical synapses and subthreshold resonance", published 18 November 2014 in Nature Communications journal.

Tatjana Tchumatchenko [1] , Claudia Clopath [2] [1] Department Theory of Neural Dynamics, Max Planck Institute for Brain Research, Max-von-Laue Str 4, 60438 Frankfurt am Main, Germany [2] Department of Bioengineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK

About Imperial College London

Imperial College London is one of the world's leading universities. The College's 14,000 students and 7,500 staff are expanding the frontiers of knowledge in science, medicine, engineering and business, and translating their discoveries into benefits for society.

Founded in 1907, Imperial builds on a distinguished past - having pioneered penicillin, holography and fibre optics - to shape the future. Imperial researchers work across disciplines to improve global health, tackle climate change, develop sustainable energy technology and address security challenges. This blend of academic excellence and its real-world application feeds into Imperial's exceptional learning environment, where students participate in research to push the limits of their degrees.

Imperial nurtures a dynamic enterprise culture, where collaborations with industrial, healthcare and international partners are the norm. In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible.

Imperial has nine London campuses, including Imperial West: a new 25 acre research and innovation centre in White City, west London. At Imperial West, researchers, businesses and higher education partners will co-locate to create value from ideas on a global scale.

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