“Understanding Human Vision: A Comprehensive Discussion”

QUESTION

Read it

1. The human eye can only perceive electromagnetic energy in the form of visible light (Betts et al., 2013). Humans lack ultraviolet light sensors, but bees’ eyes have photoreceptors for it. Both humans and bees are trichromatic, meaning that we both have three photoreceptors, but the colors are different (Riddle, 2016). We both have blue and green receptors, but humans also have red, whereas bees don’t. In place of red, they have the ultraviolet light sensors. This means that bees cannot see red, although they can see orange and yellow. We cannot see “bee’s purple,” which is a mixture of yellow and ultraviolet light. “Even though humans can see more colors, bees have a much broader range of color vision. Their ability to see ultraviolet light gives them an advantage when seeking nectar,” (Riddle, 2016, para. 2).

2. Most color blind people are born with the condition, which means it is congenital (Turbert, 2022). They may have defects in their retinas’ cones, which are the parts of the eye that discriminates between reds, greens, and blues. Other people may have acquired color deficiency, which results from aging, trauma, medications, chemicals, or diseases like glaucoma, diabetes, and Alzheimer’s.

People with normal vision have trichromacy, which means that all three of their cones work properly (Colour Blind Awareness, n.d.). Those with anomalous trichromacy have all three of their cones working, but one cone perceives light differently. Protanomaly has a minimized responsivity to red light (red looks green), deuteranomaly for green light (green looks red), and tritanomaly for blue light (hard to tell the difference between blue and green, and yellow and red). Dichromacy is when two cones work to recognize color properly, but one cone cannot perceive parts of the light spectrum. Protanopia does not perceive red lights, deuteranopia does not perceive green lights (both unable to tell difference between red and green at all), and tritanopia does not perceive blue lights (unable to tell difference between blue and green, purple and red, and yellow and pink). Monochromacy describes people who cannot see color at all. They see the world in different shades of grey.

3. Transduction occurs when environmental stimuli, such as a light or chemical, is converted into a neural signal by sensory receptor cells (Betts et al., 2013). Sensation/transduction can be internal or external. Exteroceptors are external, such as somatosensory receptors in the skin. Interoceptors are internal, such as receptors in organs or tissues. Proprioceptors are “located near a moving part of the body, such as a muscle, that interprets the positions of the tissues as they move,” (Betts et al., 2013, para. 5). The type of receptor cell also depends on what kind of stimuli needs to be interpreted. For example, chemoreceptors are responsible for the chemical stimuli in taste and smell, while mechanoreceptors can sense physical stimuli like pressure, vibration, and balance.

Perception is the interpretation of neural signals from transduction into something meaningful (Betts et al., 2013). Once transduction turns stimuli into signals, the action potential is sent to the thalamus, which sends the signal to the appropriate part of the brain (The Human Memory, 2022). The sensory cortex is part of the cerebral cortex, which is composed of the visual, auditory, primary olfactory, gustatory, and primary somatosensory cortices. The area of the brain that the signal is sent to depends on what kind of stimuli is being interpreted.

For example, photoreceptors in the eyes’ retinas (cones and rods) begin to process visual information by transducing light energy into electrical signals (Betts et al., 2013). This changes the amount of neurotransmitters that the cones and rods are distributing onto the bipolar cells, which connects to retinal ganglion cells (RGC). “The axons of RGCs… collect at the optic disc and leave the eye as the optic nerve,” (Betts et al., 2013, para. 59). The signal is then sent from the optic nerve to the lateral geniculate nucleus in the thalamus, the brain’s relay station, to be sent to the primary visual cortex in the occipital lobe for processing (The Human Memory, 2022). The visual information is then sent back to the thalamus, then to the association cortices, where it is given meaning (Purves, 2001b).

4. Stimuli is first sent from the sensory receptors to the thalamus, then to the primary sensory and motor cortices of the cerebral cortex to be processed (Purves, 2001a). The primary cortices are more responsible for interpreting the sensations themselves. The signals are then sent back into the thalamus, where it is directed to the association cortices. These association cortices are in charge of complex processing that results in cognition, where the sensory information is given meaning (Purves, 2001b). Other functions in cognition include remembering, thinking, learning, and speaking, such as attributing the stimuli to memories. After perception is when the body can produce an appropriate response in behavior to the stimuli.

References

Betts, J. G., Young, K. A., Wise, J. A., Johnson, E., Poe, B., Kruse, D. H., Korol, O., Johnson, J. E., Womble, M., & DeSaix, P. (2013, April 25). Anatomy and physiology. OpenStax. https://philschatz.com/anatomy-book/contents/m46577.html

Colour Blind Awareness (n.d.). Types of colour blindness. Retrieved March 28, 2023 from https://www.colourblindawareness.org/colour-blindness/types-of-colour-blindness/

National Eye Institute (2019, June 26). Types of color blindness. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/color-blindness/types-color-blindness

Purves, D., Augustine, G. J., Fitzpatrick, D., et al. (2001a). Neuroscience 2nd edition. Sunderland (MA): Sinauer Associates. https://www.ncbi.nlm.nih.gov/books/NBK10952/

Purves, D., Augustine, G. J., Fitzpatrick, D., et al. (2001b). Neuroscience 2nd edition. Sunderland (MA): Sinauer Associates. https://www.ncbi.nlm.nih.gov/books/NBK11109/

Riddle, S. (2016, May 20). How bees see and why it matters. Bee Culture. https://www.beeculture.com/bees-see-matters/#:~:text=Like%20us%2C%20bees%20are%20trichromatic,ultraviolet%20light%2C%20blue%20and%20green.

The Human Memory (2022, May 20). Sensory cortex. https://human-memory.net/sensory-cortex/

Turbert, D. (2022, Sept 26). What is color blindness? American Academy of Ophthalmology. https://www.aao.org/eye-health/diseases/what-is-color-blindness

Answer this question

1. In seven or more sentences, provide constructive feedback, ask a question, or share a resource you discovered related to the week’s lessons.  Explore additional thoughts on the topic. What did you discover when reading your classmate’s post?   This is our space to share experiences with the activity and the week’s content.

ANSWER

“Understanding Human Vision: A Comprehensive Discussion”

In the provided post, the author delves into various aspects of human vision, covering topics such as the differences between human and bee vision, color blindness, sensory processing, and the journey of sensory stimuli from receptors to cognition. The post is rich in content and provides valuable information. Here are some constructive feedback, questions, and additional insights on the topic:

Human and Bee Vision: The comparison between human and bee vision is fascinating. It’s interesting to note that both are trichromatic, but their sensitivity to different colors varies. A question to consider is how the differences in color perception between humans and bees affect their daily activities and survival strategies. For example, how does the ability to see ultraviolet light benefit bees in seeking nectar, and what implications does this have for their pollination role?

Color Blindness: The explanation of color blindness is clear and informative. It’s essential to understand the various types of color deficiency. It would be valuable to explore how color blindness can impact individuals in their daily lives, such as career choices, art appreciation, and safety concerns. Additionally, discussing potential assistive technologies or solutions for those with color blindness could be enlightening.

Sensory Processing: The explanation of transduction and the role of sensory receptors is well-structured. One aspect to further explore is the concept of adaptation, where sensory receptors adjust to prolonged exposure to a stimulus. How does adaptation influence our perception, and are there real-world examples of its effects on our senses?

Perception and Cognition: The journey of sensory information from receptors to cognition is elucidated effectively. The role of the association cortices in giving sensory information meaning is intriguing. It might be beneficial to explore case studies or examples of how the brain’s interpretation of sensory data can differ between individuals and cultures, shedding light on the subjectivity of perception.

Resources: The inclusion of resources, including academic references, adds credibility to the post. It would be helpful to provide more context on how these resources contributed to the understanding of the topics discussed and whether there are any ongoing research trends in the field of sensory perception.

In conclusion, the post offers a comprehensive exploration of human vision, color perception, sensory processing, and cognition. To enhance the discussion, further exploration of the real-world implications of these concepts and the potential for technological solutions would be valuable. Additionally, providing more context on the role of the included resources can aid in understanding the depth of the topic. Overall, this is a well-structured and informative post on the intricacies of human vision and sensory perception.