How your synaptic network develops

Given that all human brains, like human bodies, are remarkably similar, it is surprising that thoughts, ideas, like and dislikes can be so different.  The reason is that it is not our brain regions per se that create the difference, but rather the ways in which those regions are connected.

Each human brain consists of something in excess of 85 billion specialist cells called neurons, and each neuron will establish an average of around 15,000 connections with other cells in your body.

Amazingly, brain cells do not touch one another but instead communicate with other cells by converting the electrical impulse from within the cell to a chemical message that then passes to other cells across gaps between the cells called synapses.

These tiny gaps, around one ten-millionth of a millimetre in size, form what is known as your synaptic network.  As a result of the DNA you inherited from your parents and your lifetime experiences, it is this network of connections that makes you the person you are.  Everything you think, know and feel is as a result of the way in which this network operates.  In the words of the American neuroscientist and NYU Professor Joseph LeDoux, "You are your synapses.  They are who you are."

In order to explain how your synaptic network develops we often use the analogy of the way in which a road network develops and evolves over time, but we recently came across a brilliant video clip from a BBC series featuring the British doctor and Professor Robert Winston.  In the video clip he describes the way in which the synaptic network develops as we learn something new by drawing an analogy with crossing a deep ravine.  Have a look at the video and see what you think:  https://www.youtube.com/watch?v=AGieqH2tl8M

Do you allow pets in your bed?

Hygiene debates aside, a new survey published in journal Mayo Clinic Proceedings (Krahn et al., 2015) suggests having a pet in bed may benefit some people’s sleep. Of the 150 pet owners interviewed, over half allowed their pets into the bedroom with 41% of that group saying there was no disruption to sleep. Indeed some people claimed it to aid sleep, providing relaxation, security, companionship and even bed warming.

Recognising the potential for bias in positive responses, the researchers state that sleep is dependent on a state of physical and mental relaxation, so indeed it must be true that some pet owners sleep better with their beloved animal next to them. Many pet owners view companion animals as family members that they wish to bring into as many aspects of their life as possible.

It is long known that animals can tap into calm and well-being in people. Pet therapy has a huge impact in elderly care homes and tactile stimulation can enable some memories, however fleeting, to return to previous pet owners now suffering from neurological disorders. We should encourage more interaction with animals and the elderly – maybe not for a sleepover, but certainly to stimulate and build relationships with.

Sleep Cleans the Brain

Sleep continues to be of great interest to scientists as we look to discover why it is so important for human survival. Sleep is not an inactive state, rather it is a period of time when strengthening and rejuvenation takes place. We know it matters for our bodies to restore and regenerate, to grow muscle, repair tissue and to synthesise hormones. We also know sleep matters for our brains and for optimal cognitive functioning. It is required for storage of memories and lack of it impedes attention, decision making, reasoning and focus.

Some new research led by Danish Neuroscientist Dr Maiken Nedergaard and her colleagues at the University of Rochester Medical Centre have now started to unlock some of the mysteries around the mechanisms behind sleep benefits for the brain. She is interested in the glial cells – a group found uniquely in the brain – and their purpose, believing them to be part of what keeps the brain “healthy”.

Given the fact that brain tissue has a significantly higher energy demand than other human tissues Nedergaard’s team were interested in the lack of a lymphatic system in the brain and spinal cord to “drain away” excess molecules such as proteins. The lymphatic system plays a critical role in the human immune system enabling the disposal of waste to the liver – so why does this process not apply to the brain?  Her team have found that cerebrospinal (CSF) fluid, a clear liquid surrounding the brain and spinal cord, moves through the brain along a series of channels – managed by the glial cells. It is as if the CSF acts as a “sink” for waste and the brain actually can export molecules to the liver. Rodent studies show that the glia are the start of a transport network that end up in the lymph nodes in the neck. The team have termed this process the glymphatic system.

The team reported that this glymphatic system helps remove a toxic protein called beta-amyloid from brain tissue and their most recent research shows that sleep helps to clear these proteins. This has a huge implication for a number of neurological conditions such as Alzheimer’s and other dementias as they are characterised by an accumulation of proteins. Dr Nedergaard also points out in the journal Science that medical teams should allow patients with traumatic brain injury to sleep and not to keep waking them up every 10 minutes to take vital measurements.

The glymphatic system paves the way for more understanding of brain health. And the message is, as Dr. Nedergaard says, “…we need sleep. It cleans up the brain.”


The work was funded in the USA by the National Institute of Health’s specialist group – The National Institute of Neurological Disorders and Stroke (NINDS).