Top-Down Process

In unknown situations with unfamiliar objects human beings can use contextual information to assume what things are and what is going on around them. This is a process that we all use on a daily basis; we use it unconsciously but do not understand we are using it. Some researchers in the scientific community believe that this unconscious act is controlled in the area of the brain known as the pre-frontal cortex (PFC). The information that follows is an attempt to explain what top-down process is, explain the pre-frontal cortex and will discuss why researchers believe the two are connected.
Top-Down Process In simple terms top-down process could be described as large to small thinking.
Alleydog.com defines top-down process as: “large chink” processing and states that we form perceptions (or focus attention) by starting with the larger concept or idea (it can even be the concept or idea of an object) and then working our way down to the finer details or that concept or idea (n.d.). This definition leads to the question of where this processing could be taking place. Reasoning leads us to believe that top-down processing occurs in the prefrontal cortex.
Prefrontal Cortex According to Miller and Cohen, the prefrontal cortex, “is a collection of interconnected neocortical areas that sends and receives projections from virtually all the cortical sensory systems, motor systems and many subcortical structures” (p. 168, 2001). The prefrontal cortex is responsible processing large amounts of information. This area of the brain is used without instruction from subjects and processes information at speeds that we cannot comprehend. Miller and Cohen (2001) state that: The prefrontal cortex serves a specific function in cognitive control: the active maintenance of patterns of activity that represent goals and the means to achieve them. They provide bias signals throughout much of the rest of the brain, affecting no only visual processes but other sensory modalities. It is also responsible for response execution, memory retrieval, and emotional evaluation (p. 171). Given this information one could deduce the top-down process is controlled in the prefrontal cortex, and this is where perception is affected in the brain.
How Top-Down Processing and Prefrontal Cortex Relate
If indeed the prefrontal cortex is the area in which visual processes are managed and top-down processing is how we process what we see from large to small, the logic would tell us that the two are connected. Miller and Cohen state: The prefrontal cortex is important when “top-down” processing is needed that is, when behavior must be guided by internal states or intentions. The prefrontal cortex is critical in situations when the mappings between sensory inputs, thoughts, and actions either weakly established relative to other existing ones or are rapidly changing (p.168). When we walk in to our dark living room for example and we see a shadow above the television it is square and stationary. The likelihood that we will determine that it is a picture frame is 100%. Why would we not think that it was a pizza box for example? The prefrontal cortex processes the information from past experiences and determines what object best fits the current experience. Palmer (1975) calls this occurrence “context effects: effects of the environment of an object on the perception of that object” (p. 519). Palmer also says that “appropriate context should aid identification and that inappropriate context should hinder it” (p.519). It would not be appropriate for a pizza box to be hanging on the wall in a living room above a television, although it would be appropriate for a picture frame to be there. In this situation, it is a likely conclusion the prefrontal cortex processed the shape and location of the object (square on the wall above the television in the living room), compared it to past experiences with the same shape and location(seeing the picture frame above the television on a daily basis, or recently hanging the frame there), and came to an accurate conclusion as to what the object must obviously be- a picture frame hanging on the wall. The top-down process to the larger scale of the living room, worked down to the picture frame on the wall (Living room>wall>television>space above>dark square>picture frame). The prefrontal cortex discarded the option of the square being a pizza box because it was not in the kitchen and there was no evidence or precedence for a pizza box to be hanging there. Now it too the prefrontal cortex less time to process all of that information than it took me to type it.
Conclusion
Top-down processing and contextual information are processed in the prefrontal cortex area of the brain. As Bar would put it: “Our experience with the visual world dictates our predictions about what other objects to expect in a scene, and their special configuration” (p. 617, 2004). Visual perception affects the brain in the prefrontal cortex and according to Rossi, Pessoa, Desimone, and Ungerleider the prefrontal cortex is “involved in the top-down control of attention by means of descending feedback signals that bias sensory processing in favor of information that is behaviorally relevant” (p. 490, 2009).

References
Bar, M. (2004). Visual Objects in context. Nature Reviews. Neuroscience. 5(8), 617-629.
Doi:10.1038/nrn1476.
Miller, E. K. & Cohen, J. D. (2001). An Integrative Theory of prefrontal cortex Function. Annual Review of Neuroscience, 24, 167-202.
Palmer, S. E. (1975). The effect of contextual scenes on the identification of objects. Memory & Cognition, 3(5), 519-526
Rossi, A. F., Pessoa, L., Desimone, R., Ungerleider, L. G. (2009). The prefrontal cortex and the executive control of attention. Experimental Brain Research, 192(3), 489-497.
Doi:10-1007/s00221-008-1642-z.
Top-down processing. (n.d.). In alleydog online. Retrieved from
http://www.alleydog.com/glossary/definition.php?term=Top-Down%20Processing