WIDE ANGLE

A tiny slit of light through the darkness is one of my earliest memories. Disoriented and intimidated by all the bustle around me, I tried to move my head to look around--my only thoughts: What is going on? Where am I? My insides were in a whirl as if things had not yet settled down deep in my gut. Next, I tried to move my appendage but was not entirely successful. Just then, a hushed but rushed voice whispered: Hold still, little one, lest you drown in the vast ocean below. 

I do not remember what I noticed first: the wise-looking gentle being, who was also very old and had her appendage wrapped around mine, or the never-ending stream running right below my head. I do remember being awed by my reflection, though. A star-shaped head with a long leg reaching for the zenith--I looked different from the old nana next to me--and I was glad. However, I turned to look for my other appendage, like the one old nana had, the one that had her stuck to the ocean. Oh! Why do I not have that? Perhaps then I could have moved around. Dismayed and confused, I looked at the wise one for answers, but she had already dozed off! 

Just then came another voice, very authoritative and not soothing like old nana’s, and what it said blew my mind: Welcome to the brain, new neurons! You will be assigned to your respective layers shortly. You will also be given a number, which you will report to your fellow layer-mates who have already reached their destination and are eagerly waiting for you. Now pay attention!- and so began the ceremony. I was in a daze the entire time; you see, the movement in my gut had not ceased. It made me anxious, and I could not see very clearly, but I think I saw some of my neighbors disappear. 

L4-S1-N304-20! L4-S1-N304-20! Hey you! The one with the sleeping mother. P7889-5N! Wake up!

Suddenly, old nana stirred vigorously and blinked a few times; Then apologized to the voice and looked at me. I did not pay attention to all of that; my mind was reeling from the fact that old nana was my mother? I realized she was saying something, and the mean, number-calling voice was not interested in us anymore as well. I broke from my trance and asked in what I hope was a stern voice: Mother? Are you my mother? The gall of the old nana, she dared to bring tears in her eyes. In a shivering and hushed voice, she wrapped her appendage tighter around me and said: Oh! I did not realize I had fallen asleep. Five rounds of dividing your body had exhausted me, I believe. I am so sorry. I would have explained more to you, my little one, but there is no time. Do not worry! One of your siblings is in L4--that is where you are going, yes? Your sibling will assist you, I am sure, and everyone in L4 is very welcoming. After saying this, old nana loosened her grip and pushed me up. I did not move. My anger and confusion had morphed into something else, and I asked: Will I see you again? I could not bring myself to call her mother yet. She gasped once, and then with great determination in her eyes said: On you go! My limb will guide you. Do not be scared. Go on! Chop! Chop! With these words, she gave me a shove, and I started to journey onward into the unknown. 

At some point, there were many similar-looking neurons cheering me on as I climbed past them. I remember seeing some of my fellow traveling neurons be received by their layer-mates. I was still drowned in the thoughts of my mother, the old nana, with a shroud of apprehension wrapped around me, and the chaos in my gut did not help at all. Soon, I saw a bunch of neurons rush towards me and disentangle me from the only belonging of my mother. 

Some time passed before I found my sibling--L4-S1-N299-20. My sibling was indeed very kind and told stories, some of them about our mother. We often laid waiting for our siblings to pass by and even waved to them.

One day, we discovered our mother’s limb was gone. Our layer-mates told us not to be disheartened. 

It has been a long time since then. One of the things my layer-mates and my sibling would tell me after our mother was gone was: Do not worry. You will soon meet your partner, and you will form a bond that will define your existence. They are on their way from the thalamus, quite far away, actually. Nevertheless, be patient. 

That, my friends, is a story for another time. Till then, hold on to your parents as long as you can, and do not forget to visit them from time to time.

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Tuli Pramanik

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Author's Note:

My entry revolves around the life of a neuron called L4-S1-N304-20, from its birth till the time it reaches layer IV of the neocortex. L4 stands for the destination layer, S1 signifies the region of the brain that this neuron occupies, which is, primary somatosensory area(S1), and 304-20 is a number tag, it is also the room number where Tole lab in DBS- TIFR is based (B-304), who celebrated 20th anniversary last year. 

Since, it is a later-born layer IV neuron, the first wave of layer IV neurons has already reached their destination, a group that also includes the sibling neuron. The progenitor/mother cell here is an old progenitor. As we know from literature, each progenitor can give rise to approximately 8-9 neurons, occupying various layers in the cortex, in its lifetime. The newborn neurons wriggle outward/upward using the process of its progenitor cell as a scaffold. Layer IV neurons also form functional synapses with the thalamocortical axons, originating in the thalamus, and form the foundation of the somatosensory processing unit of the mammals.