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Fear - light at the end of the tunnel

The Vagus Nerve – Anxiety, Un-learning Fear and PTSD

The vagus nerve has multiple branches that innervate many of our organs, including the heart, lungs and stomach, and much more. However, a new Swiss study by Melanie Klarer et al published in May this year in the Journal of Neuroscience, has shown how afferent vagus pathways are able to modulate our fear and anxiety response, and also affect our ability to ‘un-learn’ previously conditioned fear responses.

Around 80% or more of the vagus nerve fibres are dedicated to sending signals to the brain about the state of the viscera and it is known that healthy vagus nerve communication from gut to brain helps to slow down the fear response, by using neurotransmitters such as acetylcholine and GABA – lowering heart rate and blood pressure and encouraging the parasympathetic response of ‘rest and digest’.

So, for this study, the team at ETH Zurich dissected these afferent nerve fibres to the stomach, to study how interrupting this feedback loop might affect brain and cognitive function.

The researchers were especially interested in the link between innate anxiety and ‘learned’ or ‘conditioned’ fear – in the tests the brain was still able to send signals to the stomach but the brain could not ‘hear’ the stomach’s vagal response.

In anxiety-behaviour experiments, rats without vagal feedback from the gut demonstrated two main findings – a reduced innate fear (e.g. to bright lights, open spaces etc) but also a longer retention of previously learned fears. This confirms the importance of healthy vagal tone to overcome fear conditioning.

Furthermore, the loss of the gut vagus signal altered the production of adrenaline and GABA in the brain, meaning that the rats took much longer to re-associate sounds previously associated with a negative stimulus with a new ‘safe’ or neutral situation.

The Implications for PTSD

Hence these new findings may eventually shine a light on developing new treatments for PTSD (post-traumatic stress disorder) – stimulation or normalisation of the vagus nerve may help people to reassociate non-threatening stimuli which became traumatically associated with triggering fear/anxiety, with a new neutral or non-traumatic experience/response. Vagus nerve stimulation (VNS) is currently used to treat epilepsy and depression, but its efficacy remains controversial.

In a press release Urs Meyer stated:

“We were able to show for the first time that the selective interruption of the signal path from the stomach to the brain changed complex behavioural patterns. This has traditionally been attributed to the brain alone. The study shows clearly that the stomach also has a say in how we respond to fear; however, what it says, i.e. precisely what it signals, is not yet clear.”

This short video from 2011 also discusses the possible use of VNS for patients with PTSD:

 

Read here, from half way down the page ‘Activating the Vagus Nerve Without Machinery‘ for a quick run-down of some ways to improve vagus function or to stimulate the vagus pathway:
Insightful Nutrition – Orthomolecular Health and Nutrition – ‘Activating the Vagus Pathway’

REFERENCES

1. Klarer, M. et al. Gut Vagal Afferents Differentially Modulate Innate Anxiety and Learned Fear. J. Neurosci. 34 , 7067–7076 (2014).

Brain in a drop of water

Brain Anatomy 101

Grab a cup of coffee, and in just under 20 minutes you will have completed a basic primer in brain anatomy, provided by these two videos from Anatomy Zone on YouTube.

Once you’re done, you can test yourself at this site run by the University of Utah (part of the Visible Human Project), which challenges you with a labelled dissections quiz.

Basic Parts of the Brain – Part 1

Basic Parts of the Brain – Part 2

 

REFERENCES:

Videos by Anatomy Zone on YouTube

Leaf-Brain photo by Vancanjay on freeimages.com

neurons in the brain

Adult Brain Repair Pathway And New Cell-Type Discovered

Researchers have discovered a previously unknown brain cell-type that directly instructs stem cells to produce new neurons. Although the work is still in it’s early stages, the research implies that the adult brain is capable of restoring itself following injury.

The new cells have been found in the subventricular zone of the adult (mouse) brain, and they release an enzyme called choline acetyltransferase (ChAT), which eventually goes on to help make acetylcholine.

By ‘accelerating’ and ‘decelerating’ the impulse frequency of these newly discovered neurons, they observed clear changes in the production of neural stem cells in the brain.

“We have been working to determine how neurogenesis is sustained in the adult brain. It is very unexpected and exciting to uncover this hidden gateway, a neural circuit that can directly instruct the stem cells to make more immature neurons,”
Chay Kuo M.D. – Lead Researcher, Duke University, Durham, NC

It is hoped that by understanding these repair pathways, it will eventually become possible to rebuild the brain following damage.

The work was published in Nature Neuroscience at the beginning of June this year.

 

 

REFERENCES:

1. Paez-Gonzalez, P., Asrican, B., Rodriguez, E. & Kuo, C. T. Identification of distinct ChAT+ neurons and activity-dependent control of postnatal SVZ neurogenesis. Nat Neurosci advance online publication, (2014).

 

 

Twirl image - plasticity

The Power Of Neuroplasticity

This film is an amazing and moving example of paediatric neuroplasticity. The autoimmune syndrome Rasmussen’s Syndrome was causing this girl multiple daily seizures, and cognitive impairment, so to halt the progress of the neural destruction neurosurgeons performed a hemispherectomy.

The outcome was a total cessation of seizure activity, and after much rehabilitation, a greatly improved quality of life.
(caution – some possibly disturbing scenes)

 

 

REFERENCES

1. Neuroplasticity. (2014, May 2). In Wikipedia, The Free Encyclopedia. Retrieved 20:08, June 3, 2014, from http://en.wikipedia.org/w/index.php?title=Neuroplasticity&oldid=606755191

sleeping for glymphatic outflow

Sleep Accelerates Glymphatic Outflow – Drives Out Brain Toxins

Further research on the importance of sleep to glymphatic clearance was published in October 2013 by Maiken Nedergaard et al, the team involved in the original discovery of the glymphatic pathway. The more recent work shows that the clearance of brain metabolites is most efficient during sleep.

It is hoped this new understanding of the importance of sleep may pave the way for new treatments for Alzheimer’s, Parkinson’s and other diseases of the brain caused by the build up of neurotoxic metabolites, such as Amyloid β.

The glymphatic system is formed by glial cells creating tubes around blood vessels in the brain, and the new research (in mice) showed that the calibre of these drainage pathways enlarged up to 60% during sleep, compared with when the mice were kept awake.

Here is a short video from the University of Rochester where the research is being carried out:

In particular, beta amyloid protein which is known to form damaging plaques in Alzheimer’s disease, was shown to be excreted from the brain twice as quickly during sleep.

So it seems that sleep is absolutely essential to long-term neurological health, as well as its day-to-day housekeeping.

More in the video below.

Our upcoming 5-day course provides more information on the anatomy and function of the brain, neurocranium and CSF, and their integration within the OCF concept

 

REFERENCES

Sleep Drives Metabolite Clearance from the Adult Brain
Lulu Xie, Hongyi Kang, Qiwu Xu, Michael J. Chen, Yonghong Liao, Meenakshisundaram Thiyagarajan, John O’Donnell, Daniel J. Christensen, Charles Nicholson, Jeffrey J. Iliff, Takahiro Takano, Rashid Deane, and Maiken Nedergaard
Science 18 October 2013: 342 (6156), 373-377. [DOI:10.1126/science.1241224]

intracranial dural membranes side view showing falx and tentorium

We Have Got You Covered – how the meninges control brain development

Meningeal layers

A little revision of the meningeal and periosteal layers of the brain and skull

As osteopaths working with OCF, we are already aware of the importance of the ‘reciprocal tension membrane‘ as Sutherland referred to it.

However, according to this research from 2011, the meninges also seem to have an important role in foetal brain development:

“Through the release of diffusible factors, the meninges influence the proliferative and migratory behaviour of neural progenitors and neurons in the forebrain and hindbrain. Meningeal cells also secrete and organize the pial basement membrane, a critical anchor point for the radially-oriented fibers of neuroepithelial stem cells”.

Seeing as much brain development occurs in the first year of life outside the womb, it seems possible that brain development could be affected by continuing deformity or strain within the membrane system, left over from the birth/perinatal process (study anyone?). The authors conclude with this:

“It is also clear that disruption of meningeal function either generally or focally can lead to significant disruption of (foetal) brain development. Future work will inevitably expand our understanding of the human syndromes where brain malformations are caused primarily by defects in meningeal development”.

Check out the PDF below for the full text.

PDF: we have got you covered – how the meninges control brain development

 

Our upcoming 5-day course provides more information on the anatomy and function of the Reciprocal Tension Membrane, and it’s integration within the OCF concept

 

References:
“We’ve got you “covered”: how the meninges control brain development”
Julie A. Siegenthaler and Samuel J. Pleasure
Curr Opin Genet Dev. 2011 June ; 21(3): 249–255. doi:10.1016/j.gde.2010.12.005.

‘Meninges’ image By SVG by Mysid, original by SEER Development Team [1] [Public domain], via Wikimedia Commons

memory research chemicals being stored as memory

Finding the Messenger – memory research visualises neural pathway

When I first read this article I thought it was an April Fool. It put me in mind of previous studies by Karl S. Lashley where researchers tried to find the ‘Engram’ – a physical structure representative of a single memory – and failed. It seems that the storage of memory is non-local, i.e. distributed among a neural network involving many different regions of the brain, which is probably why Lashley’s attempt to ‘splice out’ the memory region of the cortex was unsuccessful.

The Molecular Basis of Memory Function: Tracking mRNA in Brain Cells

However, this research published in ‘Science’ has utilised up-to-date visualisation technology and builds on our understanding that Messenger RNA (mRNA) seems to be involved in the memory pathway, both in formation and retrieval.

On a personal level, this pie chart best illustrates the fickle nature of the every-day reality of memory function…still, check out the video below to see those little brain-messengers at work: