When seeing is behaving

Visual behavior is a study of how the things we see translate to how we behave. Many neuroscientists across the world are working on this problem which is quite intuitive to us all. If you see a lurking shadow of a large man in a dark alley, you would most probably feel scared and start to walk faster. In this case your visual system is processing information that is driving your behavior which gives rise to questions like what part of the visual pathway- from eye to brain is processing the information and how is it getting communicated to our emotions? Study of visual behavior seeks to understand these questions.

Recently, I got the opportunity to attend two talks delivered by professors in this field. The interesting thing about these talks was they approached the question of visual behavior from two directions. While Dr. Marcus Meister of Caltech studied the retina in the eye, Dr.Mark Bear of MIT explored the visual cortex in the brain.

The retina in our eyes contain more than 50 types of neurons most of whose function is unknown. Some of these neurons have been identified to modulate our innate behaviors (behavior that is shown by all humans) like the pupil reflex or the visual cliff reflex. The lab of Dr. Meister seeks to find the neuron in the retina responsible for one such innate behavior – the looming response. The looming response is the fear response that an animal shows when something is approaching from above. This is easily recreated in the lab where mice are shown a black dot getting bigger in size on a screen attached to the top of the cage. This lab has already isolated a cell type that is believed to modulate this behavior. This is a very cool story because it tells us that at our eye is capable of eliciting some of the innate behaviors without any help from the brain (mice without cortex also show looming response).

Now lets take a look at how the region of the brain called the visual cortex is involved in behavior. One of  our superpowers is recognition. We are very adept at remembering things that we have seen just once. So how do we do that? Intuitively you would think that our eye will carry the information about the thing to the visual cortex from there it will go somewhere else to be matched with the other similar things stored in our memory. Turns out that we don’t go through that long route. According to the lab of Dr. Mark Bear, there are cells in our visual cortex that form a “memory” of items in that they increase their firing rate. When the same item is shown again the firing rate of the cells remain elevated which helps us to recognize it. This is an interesting find in its own right but since I had heard Dr. Meister before, I couldn’t help but wonder if this “memory” starts even earlier in the retina.

Another unrelated but entertaining thing about these two talks was how cute all the mice looked in their experiments. This is quite something coming from me because I have a deeply instilled fear of animals after I was chased by a dog for two miles when I was about ten. I wanted to end this post with some of those cute videos but it turns out that they aren’t available in either of the lab websites. So I am dedicating this post to all mice – the rock stars of experimental research:

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