Neuroscience Experiments I Want to Do
First, an intro to Neuroscience
I have just had this eureka moment relating to the mechanisms underlying human cognition. I’ll articulate my idea by fusing together smaller details over the course of a few posts, and hope that I am not reinventing the wheel, or even worse, building a square one!
Our wondrous brains are constituted by an enormously complex network of interconnected neurons. The fields of science trying to understand the brain are fascinating, and I’m so glad that I’m getting interested at a time when there is lots to be discovered(so hopefully I will one day I can contribute). Before discussing my ideas comes a refresher on elementary neuroscience(summarizing the first chapter of an excellent neuroscience textbook at http://neuroscience.uth.tmc.edu/s1/introduction.html).
I’ll do this in increments, beginning with this post: a quick intro to how neurons work.
Ready? Lets think!
Neurons are a specialized type of cell characterized by the axons and dendrites protruding from it’s central body. Neurons can both receive signals through dendrites and transmit signals through axons.
The transmission of a signal between two neurons occurs across a minute junction between the two neurons called a synapse. Neurons on the transmitting ends are “upstream” from the synapse and are called presynaptic neurons, and neurons “downstream” from the synapse are….wait for it….postsynaptic neurons. Transmission of a signal across the synapse is mediated by a neurotransmitter(small signaling protein that bonds to receptors on dendrite of postsynaptic neuron).
The transmission of a signal through axons to other neuron’s dendrites is effectuated by an action potential, the result of the neuron’s membrane potential reaching a certain threshold of depolarization(+).
Consider Neuron N. The frequency of action potentials in N is positively related to the intensity of the depolarization from from its presynaptic neurons. A presynaptic neuron when triggered, depolarizes N in what is called an excitatory postsynaptic potential(EPSP). When an EPSP is of a certain intensity, or EPSPs from multiple presynaptic neurons are together of a certain intensity, an action potential is triggered.
The opposite of an EPSP is an inhibitory postsynaptic potential(IPSP), where a presynaptic neuron releases a transmitter that hyper-polarizes(-) postsynaptic neurons. Hyper-polarizing a neuron means pulling down its membrane potential farther from the threshold needed for an action potential.
The action potential threshold is binary. Either it is not reached, in which case the neuron remains silent, or it is reached or exceeded, and the action potential fire. To review:
- An action potential is reached when a neuron has reached a certain level of depolarization across the membrane, caused by the intensity of EPSPs. IPSPs polarize the neuron, inhibiting the likelihood of an action potential.
- Each neuron can transmit signals to about 10,000 peers, and receive a signal from the same number.
This simple behavior of neurons allows for very complex behavior, which we will discuss in the next post.
