A day in the life of a post-grad and a synapse

Starting with a quick day in the life of a post-grad. Wednesday, spoke with supervisor about asking neuroscientists to help with my research and was advised that if I am too formal it will put them off: Feeling slight tension now between reality and academic formality. Weekend, gardening and pretend there’s no issue. Monday, receive feedback on my Project Capability Claim (2000 words). What I have written is great; I’ve just missed a key point!! Work until 1am researching 360 feedback processes for comparison. Realise how awful some look and wonder if they’d get through an ethics committee. Tuesday, up early to complete paper and send in. Wednesday, receive email from Uni saying my student status is suspended because I haven’t paid my fees. “@*!!*@@!” translates to ‘is this worth it’. Easily sorted with a call to the Departmental head – no fees to pay. Thursday, my Claim paper is now good to submit; yeah J. Meeting with DProf colleagues so feeling energised. Work until late on my research method to resolve earlier issue and realise there are hundreds of variations. A definite ‘ah ha’ moment, as I can create a variation that works for me (relief). Another late night/ early morning to rewrite that section for the 3rd time! Week before Easter, now student member of the British Neuroscience Association and spent all week at their conference: Feel proud that I understood nearly everything. Easter, worked hard on finishing off Research Proposal (12500 words) and sent in on Monday. Tuesday, signed my publishing contract so now I have a publisher for my book J. Wednesday, my Research Proposal good to submit, yippee J. Thursday & Friday, proof read and corrected errors. Saturday, 7.30am – both papers submitted via the dreaded Turnitin system but it all went smoothly (Phew). Celebrated! Now preparing for the Panel interview in May which if I pass means that I will have to actually do what I have written about. Someone said this was a marathon and they’re right.

Now for brains and synapses. I feel that brains are similar and different, like a cake. Although you start with similar ingredients and the same method, each time you end up with a slightly different cake. Then the brain has areas and connections but as it is a ‘wet system’, I like the city analogy rather than the computer analogy. In a city, there are areas and roadways but the roads change, sometimes a little and sometimes a lot. With areas, you know when you’re definitely in it but are not certain where they start and end. Sometimes buildings work together, or have other branches, and sometimes they are autonomous. So a city, at one level, appears static and, at another level, is constantly changing. Sometimes it has major and obvious changes. For me in holistic terms, like a brain.

But how does this work at the synaptic level as that’s where the action seems to take place. This is a simplistic overview but I enjoyed understanding the basic principles of how synapses work. Basically, a sensory cell gets an input and passes it on to other cells which pass it on to other cells and so on until there is a response, by output cells.

Some cells pass on information so they excite other cells. But some cells try to stop information being passed on, so they inhibit other cells. All these cells are surrounded by fluid which contains, amongst other things, positive ions and negative ions. At rest a neuron is usually slightly more negatively charged than the fluid around it.

The axons from excitory cell A ‘connect’ to cell B’s dendrite synapse with a gap of a few ten-millionths of a millimetre. When Cell A’s axon ‘fires’ it releases Glutamate into the gap and this travels across and latches onto cell B’s receptors on the dendrite synapse. Where they latch on, an opening is created and positive ions from the fluid go into cell B.

Eventually the glutamate dissipates and the passage closes. If enough positive ions go into cell B they overcome the negative ions in cell B and surge wave-like down its axon. At the end, Cell B’s axon fires, releasing glutamate and the process repeats with the next cell. So the process is: positive wave surges down axon, glutamate released, build up positive ions in next cell, wave surges down that axon, etc, etc.

 

However, if cells fired all the time they’d get burnt out. So there are inhibitory cells. Their axons are on the cell body or on synapses close to the cell body. When GABA binds to these receptors they allow negative ions into cell B and making it more negative. Therefore it will take even more positive ions to neutralise them and cause a positive surge down Cell B’s axon.

Simplistically the brain uses surges of positive ions and blockades of negative ions to fire and inhibit cells. If there are more positive ions then a cell fires; too many negative ions and the cell does not fire.

 

This process can be affected in a number of ways: To increase the amount of positive ions getting into a cell, an axon can release glutamate for longer, faster or it makes more of it to be released. The Glutamate receptor can be enhanced so more positive ions flow in or there are more receptors that bind with glutamate. All of these increase the chance of firing the next cell. Also GABA can become less or more effective at allowing negative ions in the cell so it may fire easier or less easily.

Certain chemicals affect how much glutamate or GABA there is or how effective they are. Cortisol reduces the effect of GABA in the Amygdala so those cells fire more easily. Therefore the fight-flight response is easily triggered, which is why you view more things as threatening when stressed.

That’s the basics.