My, how time has flown. This semester was truly a vacuum of time. The semester has given me much experience and growth as I have learned many new and interesting things. What I found to be the most interesting part of this term is how interoperable perceptive systems are. Every different perceptive function combines to create a full perceptive experience. Before this term, I considered perception only in terms of single systems, but after experiencing this class, I have learned that those who have the ability to perceive every available sense do so, it is truly an experience. I smell chicken… honestly, I smell chicken. There is a man in a seat behind me in the library eating a chicken sandwich. The volatile odorants from the delicious, savory, baked poultry have passed through the air and traveled up my nasal passages, these odorants get stuck in the mucous membrane of my olfactory epithelium and are picked up by the receptor cilia of the olfactory receptor cells, and coded to the olfactory bulb; this signal transduction to various cortical targets eliciting a number of responses. The sweet, sweet odor begins to go to work on my amygdala and thalamus, informing me it’s a pleasurable aroma. Feedback with my orbitofrontal cortex helps me decide I want to turn and see (and quite possibly snatch) the myriad of delicious foods my neighboring table is munching on. I turn, and the incredible edible meal comes into my field of vision. Certain wavelengths are absorbed in the chicken, while others are reflected. The wavelengths that are reflected enter through my pupil and hit my retina, travelling through the ventral stream, beyond V4 and into Area IT and to my temporal lobe where my memories are recalled. It’s things like this that amaze me about how the mind put things together.

Another example of putting it all together is synesthesia, the “mixing of the senses.” (Perception, 269). Synesthesia is the mixing of various sensations. One particular example is color graphemic synesthesia, a form in which people see colors when looking at letters or numbers; for instance, if a graphemic synesthetic saw the number 57, they may associate that number specifically with the color orange. Other synesthetic perceptions include sound to color synesthesia, which is find to be most interesting. The experience of synesthesia has been described as a concrete sensation rather than an emotive feeling which makes this experience markedly more phenomenal.

As a sound induces colors based on various sound spectra. I’ve always wondered what an experience such as that would be like, but I can merely speculate on the matter. The closest I’ve come is visualizations used in popular media players:

How is such interconnectivity possible? Do we attribute this to the plasticity of the brain? A possible neurological explanation for this is referred to as disinhibited feedback. When stimuli are conducted to areas of the brain that are signaled to from many different sensory pathways often receive some sort of feedback, to avoid sensory induction from multiple areas, feedback is implemented. In synesthetes, inhibition may not be occurring in particular pathways, thus allowing for sensory induction. Thus, the convergence of these pathways and their disinhibition could bring about the synesthetic experience.

This disinhibition could arise in developmental stages. It is possible that infants that have large, less differentiated connections between cortical areas could acquire synesthesia developmentally due to less differentiation (often mediated by the secretion of Nerve Growth Factor). This is only a theory, and experiencing this is something only a synesthete can understand (or someone on acid, as LSD can often invoke synesthetic effects, don’t do drugs by the way). Once again, how our mind interconnects our different perceptive pathways is truly amazing. This is the most important thing I learned during this semester.