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Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
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Home | Pregnancy Timeline | News Alerts |News Archive Nov 12, 2013

 

Ventro medial cortex of human brain.







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What are you scared of?

What makes mice freeze with fear? A neural switch was discovered using the same neuron-blocking technique, indicating different brain regions process different types of fear. The discovery could have implications for phobias and panic attacks.

What do bullies and sex have in common? Based on work by scientists at the European Molecular Biology Laboratory (EMBL) in Monterotondo, Italy, it seems that the same part of the brain reacts to both.

In a study published in Nature Neuroscience, researchers found that – at least in mice – different types of fear are processed by different groups of neurons, even if the animals act out those fears in the same way. The findings could have implications for addressing phobias and panic attacks in humans.

“We found that there seems to be a circuit for handling fear of predators – which has been described anatomically as a kind of defence circuit – but fear of members of the same species uses the reproductive circuit instead,” says Bianca Silva, who carried out the work, “and fear of pain goes through yet another part of the brain.”

Working in the lab of Cornelius Gross at EMBL, Silva exposed mice to three threats: another mouse (chosen for being particularly aggressive), a rat (the mouse’s natural predator) or a mild electric shock to the feet. The mice showed the same typical fearful behaviours – running away, freezing – in response to all threats, but their brains painted a different picture.


When the scientists mapped the brain activity of mice exposed to the aggressive mouse and the rat , they saw that different parts of a region called the ventromedial hypothalamus (VMH) ‘lit up’ depending on the threat.

Fear of the mouse seemed to activate the bottom and sides of the VMH, while fear of the rat seemed to be processed by the VMH’s central and upper areas.

This was confirmed when the scientists used drugs to block only the neurons in those ‘rat fear’ areas: mice were no longer afraid of the rat, but were still afraid of the mouse, showing that mice need this brain circuit specifically to process fear of predators.


The human brain has similar circuits, and we too experience different kinds of fear, so the results hint at the possibility of developing more efficient treatments for specific phobias or panic attacks, by targeting only the relevant region of the brain.

For their part, the EMBL scientists plan to probe these fears further.

“What we’re interested in, in the long-run, is if these results represent a kind of mental state,” says Cornelius Gross, who led the work. “If so, mice should be able to be in that state without expressing it in their behaviour – do they re-live that fear, for example? These are not easy questions to ask in the mouse, but we’re looking into them.”


Gross’s lab is also looking at how these different fears – and the neural circuits that process them – may have evolved.

Working with Detlev Arendt’s group at EMBL Heidelberg, they have discovered a similar brain region in a marine worm thought to closely resemble our ancestors from 600 million years ago.

Now the team is exploring the possibility that this represents an ancestral core fear circuit that those ancestors handed down to us all, from worms to man.


Article Abstract
The neural circuits mediating fear to naturalistic threats such as predators and aggressive members of the same species are poorly understood. Here we demonstrate that functionally independent populations of neurons in the ventromedial hypothalamus (VMH), a region implicated in feeding, sex, and aggression, are essential for predator and social fear. Our study establishes a critical role for VMH in fear and carries implications for the selective intervention in pathological fear in humans.

Source Article
Silva, B.A., Mattucci, C., Illarionova, A., Grinevich, V., Canteras, N.S. & Gross, C. Independent hypothalamic circuits for social and predator fear. Published online in Nature Neuroscience on 10 November 2013. DOI: 10.1038/nn.3573.

Original press release:http://www.embl.de/aboutus/communication_outreach/media_
relations/2013/131110_Monterotondo/