AP Biology class blog for discussing current research in Biology

Tag: sight

Unlock the POV of Pups: How Dogs See the World Beyond Colors.

Madsen the dog, 001

Have you ever wondered how your furry friends recognize the world around them? This question was asked by a group of scientists who recently studied how canines “see” the world not only with their eyes, but also with their nose.

For a long time, the world believed that dogs could only see the world in black and white, or that dogs could only perceive color weakly, if at all. However, this myth was debunked in 1989 by ophthalmologist Jay Neitz and his colleagues, who discovered that dogs can indeed see colors, specifically blues and yellows. They cannot perceive reds and greens, similar to color-blind human.
Assorted Red and Green Apples (deuteranope view)

The reason why dogs can’t process light as well as most human is because they only have two types of color-sensing receptors, called cones, in their retinas, similar to many mammals: cats, pigs, and raccoons. This differentiates them from humans which have three cones. In addition, most dogs have 20/75 vision, meaning that they need to be 2o feet away to see as clear as a human would from 75 feet. Their world may be somewhat blurry compared to ours.

To truly understand how dogs see the world, we must look beyond their ability to process color, as highlighted by Sarah-Elizabeth Byosiere. Dogs rely on various other senses to help them “see,” or identify objects and movements around them. For example, unlike humans who have difficulty seeing in dark environments, dogs’ eyes are made to see in both daytime and nighttime. This is because of their abundance of rods, a type of photoreceptor cell in the retinas, which aids in night vision. Rods are 500-1000 times more sensitive to light than cones which allows dogs to see better in the dark. Dogs also have a unique structure in their eyes called the Tapetum Lucidum(Shown in diagram below), which acts like a mirror that reflects light back onto the retina. This enables them to see in conditions with six times less light than what human requires to see.

This is also the reason why dogs’ eyes will glow in photos in the dark, because their Tapetum Lucidum reflects the light back.

(Structure of eyes)

Mammal eye structure (tapetum lucidum)

Another significant aspect of dogs’ perception is their sense of smell, they are 10,000 to 100,000 times stronger than that of an average human. Dog’s mighty sense of smell plays a crucial role in how they perceive the world, they can even pick up odors from as far as 12 miles. Another study published recently in the Journal of Neuroscience revealed a direct connection between dogs’ olfactory bulb, which processes smell, and their occipital lobe, which processes vision. This integration of sight and smell was not observed to happen on any of other animal species.

While human are good at recognizing different colors, dogs are more into their sense of smell that humans can’t appreciate. Dogs aren’t missing out on anything; they just have their own unique way of exploring the world around them.

In AP Biology, we learned about how neurons transmit signal to the brain when we touch, hear, see, and smell. When vision and smell is received by optic nerve in eyes and olfactory sensory neurons in noses, they will pass the information of the sight and smell to the brain through neurons. Neurons transmit signals simply through a flow of ions across the axon membrane, which reverses the distribution of charges of the neuron compared to when it is at rest. This is how a neuron passes a signal to another neuron, they will repeat this process until they reach the occipital lobe and olfactory bulb in the brain where the information of the sight and smell will be processed and analyzed.

As a biology student, I have always wondered about how canines, mankind’s best friend, and how other animals see the world in their perspective. It is fascinating to find out that all animals have their unique way of sensing the world and collecting information from the area around them. Their “sensing” strategy are often different from ours’s; human primarily uses vision to receive information of the world, but our neighbors on earth could be using their sense of smell, sense of hearing, and even echoing to accomplish the same goal! Let me know in the comments below if you are also curious about how other animals recognize our world or if you are interested in this topic! Share your thoughts with me! If you want further information about this post or on this topic in general, please go to for more information and further research.

If You Give A Mouse…Sight!

In a recent study published in the Journal Of Experimental Medicine, researchers in China successfully used CRISPR Gene-Editing technology to restore sight to mice with retinitis pigmentosa.

That’s a lot of vocabulary all at once, so let’s establish some definitions first and foremost.  According to the National Eye Institute, retinitis pigmentosa is a “genetic disease that people [and animals] are born with…that [affects] the retina (the light-sensitive layer of tissue in the back of the eye)”. As for CRISPR Gene-Editing technology, YG Topics defines it as, “a unique technology that enables geneticists and medical researchers to edit parts of the genome by removing, adding or altering sections of the DNA sequence”.

Most inherent forms of blindness and loss-of-vision stem from genetic mutations, and thus retinitis pigmentosa is one of many forms of genetically caused blindness.  However, through CRISPR technology, the researchers in the study successfully edited the DNA of mice who had the mutation to eliminate retinitis pigmentosa and give them the ability to see.  The results of the study are very promising, as not only does retinitis pigmentosa affect mice, but human beings.  Thus, there is evidence that CRISPR could be used to cure blindness among everyday people.  Kai Yao, a professor from the Wuhan University of Science and Technology who contributed to the study said, “The ability to edit the genome of neural retinal cells, particularly unhealthy or dying photoreceptors, would provide much more convincing evidence for the potential applications of these genome-editing tools in treating diseases such as retinitis pigmentosa”.

In AP Biology, we discussed how DNA factors into the traits of a living being.  DNA is made up of 3 base codons that form up to 20 different amino acids.  These amino acids code for specific proteins.  Through a process of DNA transcription and translation, the DNA uses various forms of RNA to code for proteins, which help tell the cell what to do.  Thus, the way the cell acts is largely determined by its DNA.  Essentially, DNA codes certain traits through various amino acid sequences.  Mutations and alternations to amino acid sequences cause different traits, such as red hair, blue eyes, or blindness.

Thus, successfully altering the DNA of mice has huge implications for the human race.  CRISPR could potentially be used to edit the DNA of humans, and thus help limit and prevent certain genetic conditions.  Many diseases are based on genetic mutations, and if CRISPR Gene Editing technology is proven successful, we could potentially eliminate genetic diseases in a few decades.  While “much work still needs to be done to establish both the safety and efficacy” of CRISPR technology, some groundbreaking scientific treatments could be coming sooner than you think (Neuroscience News).

Мышь 2

Powered by WordPress & Theme by Anders Norén

Skip to toolbar