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Neuroscience

The Science Behind Déjà Vu

Have you ever looked at something and have had an eerie thought of familiarity? “Wait, I feel like I have already been here before..”, “This is so weird, I swear I met you somewhere..”, or even something as simple as, “I felt like I already bought the groceries for this week.” So, what is this feeling? Will science be able to explain it? 

Carrie-Ann Moss, as “trinity in the matrix trilogy”, describes déjà vu as “a glitch in the matrix”. Is it really? Does this mean we, as humans, live in a simulation? Are we a video game? What even is this? This explanation is perfect for those late night thoughts and science fiction fans, as it doesn’t give a solid understanding of what it actually is! The sensation of déjà vu is brief and frequently unexpected, which is why we equate it with mystery and even the otherworldly. déjà vu intrigues us for the same exact reasons that make studying difficult. This oddity occurs in about 60% of the population. Because it is a transient sensation and there isn’t a definite trigger for it, déjà vu is challenging to investigate in the lab. Nevertheless, depending on their proposed assumptions, academics have employed a variety of methods to explore the phenomenon. Researchers may conduct participant surveys, research potentially associated processes, particularly those connected to memory, or develop additional experiments to test the phenomenon of déjà vu.

Regarding memory, most of the explanations surrounding this theory are built off the idea that you have experienced a situation in the past, or something very similar to it. You remember this situation with your unconscious mind, but forget it through your conscious mind. Therefore, giving that feeling of familiarity even though you don’t know why. For example, the single element familiarity hypothesis. The single element familiarity hypothesis proposes that if one aspect of the situation is familiar to you but you aren’t cognizant of it since it’s in a different location, such as if you see your doctor on the street, you will feel a sense of déjà vu. Even if you don’t recognize your doctor, your brain still associates that sensation of familiarity with the entire setting. This theory has also been expanded by other academics to include several components. The gestalt familiarity hypothesis concentrates on the arrangement of objects in a scene and how déjà vu happens when you see something with a similar layout. For instance, even if you haven’t seen your friend’s sofa in their living room previously, you may have seen a room with the same sofa in a different house. Having no memory of the other house, you have a sense of déjà vu. The gestalt similarity hypothesis has the benefit of being more easily verified. In one study, participants viewed virtual reality images of rooms before being asked how familiar a new space seemed and whether they felt like they were having déjà vu.  The researchers discovered that when the new room resembled the old ones, study participants who couldn’t remember the old ones tended to assume it was familiar and that they were having déjà vu. Additionally, these scores were higher the more similar the new space was to the old room.

According to some theories, déjà vu occurs when there is spontaneous brain activity unrelated to the current situation. You may experience a false sense of familiarity if that occurs in the area of your brain responsible for remembering. Some of the data comes from people who have temporal lobe epilepsy, which is characterized by aberrant electrical activity in the area of the brain that controls memory. These patients may have déjà vu when their brains are electronically stimulated as part of a pre-surgery examination. According to one study, déjà vu occurs when the parahippocampal system, which aids in recognizing familiar objects, inadvertently malfunctions and leads you to mistakenly believe that something is familiar when it isn’t. Others have argued that déjà vu cannot be attributed to a single system of familiarity, but rather incorporates a variety of memory structures as well as the relationships among them. 

Other theories are based on the speed at which information moves through the brain. Your brain’s many “lower order” areas send information to “higher order” areas, which combine data to help you make sense of the outside world. Your brain perceives your environment inaccurately if this intricate process is somehow interfered with—for example, if one component delivers something slower or faster than usual.

Despite the fact that all of the aforementioned theories seem to share one element in common, an explanation for déjà vu has yet to be found. In order to be more certain of the proper explanation, scientists might continue to create tests that more directly examine the nature of déjà vu.

Aamuktha Yalamanchili , Youth Medical Journal 2022

References

https://www.scientificamerican.com/article/can-science-explain-deja-vu/

https://www.sciencefocus.com/the-human-body/deja-vu/

https://www.bustle.com/wellness/how-does-deja-vu-work-theres-a-scientific-explanation-for-this-bizarre-phenomenon-2920454

https://www.discovermagazine.com/mind/whats-really-happening-when-you-experience-deja-vu

Categories
Neuroscience

The Brain: How does it actually work?

The brain, arguably it’s the human body’s most unexplored organ. That’s because it’s a very complicated organ that controls every possible aspect of our life. The way we think, how we feel, touch, see, and even something as simple as breathing, letting us stay alive every second. 

The brain is made of about 60% fat and the rest is water, protein, carbohydrates, and salts. Before understanding the way the brain works, understanding the anatomy of the brain is important. The most common misconception of the brain is that it is a muscle. However the brain is an organ made up of nerves. The brain appears to the untrained eye as a pink glob. If you simply look up the structure of a brain, you’ll see a pink glob with portions that are color coded and each of which is accountable for a specific function. That being, there are three main structures that make up the brain, the cerebellum, cerebrum, and brain stem. 

The cerebral cortex is a part of the cerebrum, which is the front of the brain. This section accounts for thinking, emotion, problem-solving, and personality. The folds of the cerebral cortex completely enclose the cerebrum. Additionally, this region of the brain accounts for 50% of the weight of the entire brain due to its huge surface area.

 The cerebral cortex covers the cerebrum and has four lobes. The frontal, temporal, parietal, and occipital lobe. These lobes are in charge of their own activities in the brain. For example the frontal lobe is responsible for language, and other cognitive functions, the temporal lobe (which contains the wernicke area, helping humans understand language) plays a major part in visual perception and hearing, the parietal lobe porches what they see or hear, leaving the occipital lobe to interpret visual information as it also contains the visual cortex. The cerebral cortex’s right hemisphere, also referred to as the right side, governs the left side of the body, while the left side (or left hemisphere) governs the right side. The corpus callosum, a bridge of white matter, connects the two hemispheres (or sides) of the brain. The cerebrum and spinal cord are linked via the brainstem. The brainstem is made up of the midbrain, pons, and medulla. The midbrain aids in awareness and helps you respond to environmental changes, such as potential threats.

The pons have multiple functions, including blinking, facial expressions, and focusing vision. Ten cranial nerves arise from the pons which connect to the face, neck, and trunk. 

The medulla regulated the biological functions which are key for survival such as heartbeat, blood flow, and breathing. This part of the brain detects changes in blood oxygen and CO2 levels. Swallowing, coughing, and vomiting also originate from the medulla. 

Lastly, there’s another section of the brain called the cerebellum, also known as the “little brain”. It’s stuffed underneath the cerebrum at the back of the head. It regulates balance, and movements we’ve learned, like fastening buttons. However, it cannot initiate the movements, it just manages them. The cerebral cortex developed on top of the cerebellum, an ancient portion of the brain, as humans developed. 

There is no single “centerpiece” for the brain. No particular part of the brain acts as a control system that merges signals from various regions. However, instead, multiple connections form a dense network that overlaps between the different regions. Your brain contains billions of nerve cells that are arranged in patterns that coordinate actions and thoughts. Nerves work similar to an electrical circuit, if the brain is considered a big computer. The brain processes information that it receives from the senses and body and sends messages back to the body through the help of nerves. However, in biology, electricity is the movement of charged particles (ions) through a cell’s membrane, also known as the surface layer. An electrical wave travels the entire length of a neuron, also known as a nerve cell, due to the movement of ions. This neuron has longer branches that send messages and shorter branches that receive signals, resembling a tree (called an axon). And at the ends of axons known as synapses, electrical messages leap from one neuron to another. This results in the generation of a fresh electrical wave in that neuron via the release of chemical signals called neurotransmitters. The little chemical neurotransmitters are then released by the neuron in response to the electrical wave at the synapses, where they travel to other cells to connect proteins on their membrane-like cell surfaces. Our muscles receive instructions from our neurons about when to move in this way.

References: 

https://www.hopkinsmedicine.org/health/conditions-and-diseases/anatomy-of-the-brain

https://www.webmd.com/brain/picture-of-the-brain

https://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Anatomy-of-the-Brain

https://nida.nih.gov/videos/human-brain-major-structures-functions

https://www.mayoclinic.org/brain/sls-20077047?s=3

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7725213/