The central nervous system consists of one’s brain and spinal and is involved in various tasks, such as controlling reflexes. Reflexes are a prime example of bottom-up processing, where the signal begins with sensory information or stimuli observed from the surrounding environment, such as the heat from the candle, which is then relayed to the spinal cord and the brain. However, one difference between bottom-up processing and reflexes is that even before the signal reaches the brain to be processed, the spinal cord has already sent out a response signal, which in the figure shown below is a stimulation of the motor neuron that causes the person to move their hand away from the candle. While the response signal is being sent from the spinal cord, the sensory signal from the sensory neuron is being passed on from the spinal cord to the brain, where it can be processed. When the brain processes this sensory information, it first reaches the thalamus, which acts as a switchboard mechanism and relays this sensory information to the correct part of the brain to be processed. For instance, in the case below, the sensory information from the skin is sent from the thalamus to the sensory cortex, where the brain can comprehend what has happened. However, the brain doesn’t necessarily need to send a return signal because the spinal cord reflex has already sent out a response signal.
My personal experience with reflexes and bottom-up processing has occurred in many different areas of my life. For instance, when I am working with a Bunsen burner in lab, it is not common for me to touch the flame. During these instances, similar to the figure shown above, my reflexes move my hand away from the Bunsen burner just as I start to feel the pain.
Sources
“Chapter 3 – Neuron and the Brain.” Psychology, by Josh Wede,
psu.pb.unizin.org/intropsych/chapter/neuron-and-the-brain/.