#thalamus

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Our brain constantly receives and processes information from the body and environment to keep us safe, balanced, and connected. Sensory data first passes through the thalamus and amygdala for danger detection, then moves to areas like the hippocampus and neocortex to form memories, make decisions, and create rational responses. The vagus nerve and parasympathetic nervous system help us regulate and return to calm, while the sympathetic system prepares us for action. This intricate network of pathways shows how body and brain work together, shifting between safety, alertness, and connection, to shape how we feel, think, and respond.

When your nervous system feels overloaded, don’t try to think your way out of it, change the input instead. Place one hand on your chest and one on your belly, and breathe slowly enough that your belly rises first. This pattern tells the brain that you are safe, reduces stress hormones, and gently shifts the body out of survival mode. Just 60 seconds can help tension, steady emotions, and bring your nervous system back into balance when life feels too much.

Informational diagram: How sensory information is processed by the brain

Sensory information is taken in by the occipital lobe, parietal lobe, temporal lobe, and/or the olfactory lobe.

The lobes send the sensory information to the somatosensory cortex.

The somatosensory cortex sends the information to the thalamus, which connects to the limbic system.

The information is sent to the amygdala, which gives initial/primal reactions to the stimuli.

The amygdala's reactions (including fight or flight response) are sent to the hippocampus, hypothalamus, and the frontal cortex.

The pituitary gland receives signals from the hypothalamus, then sends signals for the endocrine system to excrete hormones throughout the body. The frontal cortex sends rationalized information to the motor cortex, which controls voluntary actions.

Source linked below: "Meet Your Master - Getting to Know Your Brain: Crash Course Psychology #4" by Hank Green's Crash Course - February 24th, 2014

Every human has around 350 different types of these receptors, which are unique proteins on both the left and the right side of the upper nostrils. These receptors are the gateway to the complex dance of perception. They connect to the smell molecules upon arrival and then transfer signals toward the brain by chemical impulse. Every human has between six and eight million neurons in the nose to do just that. These signals are fired rapidly, by many neurons at a time, forming a pattern not unlike a line of musical notes, or the HTML coding of a webpage. When combined, the brain interprets the signals as a smell, an “odor image”.

These patterns are both complicated and minute. Scientists have found that if the chemical structure of two smells are identical except for just one carbon atom, the patterns sent in response are nonetheless distinguishably altered. Nonanoic acid, for example, is a nine-carbon chain that yields the salty smell of cheese. Decanoic acid, with only one carbon atom added to its structure, however, smells rancid, like sweat.

These patterned signals travel on pathways made by neurons, which snake from the nose through a thin sheet of bone called the cribriform plate, and are deposited in the olfactory bulb, which lies toward the bottom of the brain. The bulb takes these patterns, like reading the score of a piano concerto or lyrics to a lullaby, and sends them farther on to the olfactory cortex. The cortex, in turn, relays an interpretation to other parts of the brain like the thalamus, which deals in conscious perception, and the limbic areas, for emotional response.