The brain is one of the most profound networks we can study and implements information cascading in a unique framework. The brain is a network of many neurons that provide one-way signals to each other, similar to the linear model presented in class. Neurons signal other neurons to fire by releasing neurotransmitters at synapses to other neurons upon reaching an action potential, causing affected neurons to repeat this procedure to continuing neurons. Brain activation occurs in groups rather than in a straight line as presented in class. Therefore the first neuron activated in a cascade may activate several neurons and continue to activate other proximate neurons. As the cascade continues the growth of activated neurons may slow down as less neurons in a particular group are left to activate. The brain’s cascading is similar to the linear cascade in class in the sense that the longer the cascade lasts, the more number of nuerons become active. Our cerebral cascading explains how a certain smell or song may cascade into a larger population of neurons that encode for a larger concept or memory. For instance the smell of our first date’s perfume or the music playing during that car ride can invoke that experience long after its completed.

The Neural Cascade of Attentional Control provides some interesting evidence for cerebral cascading. The experimenters told the subject to focus on a computer screen in which the subject was presented with a left, right, or neutral signal (used as a control). Then a dot is then presented on either the left, right, or not presented according to the respective signals. This separated the subject’s spatial queue processing (expecting the dot to the left or right) from general queue processing (waiting for the left, right, or neutral signal to appear). The left and right signals created a spatial orienting signal in the brain, which the research has confirmed to be located in the more medial portions of the frontal cortex. The lateral parts of the frontal cortex first activate in response to the general queue processing with the subject waiting for the signal. Research then found that about 400ms later the medial parts of the brain would become more active with the subject utilizing spatial attention to expect the dot to the left or right. The brain imaging data reveals that after repeated trials the activations become stronger, suggesting there is some pathway in between the two brain activities that utilizes a cascade. This research illustrates a cascading principle not outlined by the linear model. The more often a cascade is used, the stronger it becomes. Professor Easley presents a framework for this idea with the umbrella example in class. If the people are only correct part of the time then we may not bring an umbrella every time we see people with umbrellas. This parallels the idea that if the subjects do not see a left, right, or neutral signal when expecting to, then the entire cascade may fall apart. However if the people with umbrellas are reliable then the cascade becomes very strong and we would be inclined to follow it more often.

Traumatic Brain Injury illustrates the necessity of cascading activation in the brain. Neurons need to fire and interact to maintain their cascading exchange of resources within the brain. Physical damage to the brain often kills several brain cells that may release toxic chemicals and kill surrounding cells, causing a negative cascade and severe brain damage. At the same time the loss of neurons in previous cascades hurts further neurons dependant on these intermediaries. This illustrates one implementation of The Tipping Point, where a certain selection or number of influential neurons may cause systemic brain damage if destroyed through physical damage. On a lighter note, researchers have recently found a potential treatment for the destructive cascading of brain damage: progesterone. The hormone prevents further propagation of toxic chemicals released from brain damage, and also develops new circuits and fixes old connections to repair the previous cascading paths in the brain needed to maintain a healthy level of activation.