Thursday, August 22, 2019

Nose - The Tip of the Smelling Story

Researchers at Cold Spring Harbor Laboratory (CSHL) and Harvard have found that smell is based on more than the neuronal networks that receive various stimuli. Different from vision (that pays attention to edges, shading, brightness, and color), smell is affected by odor molecules and a lot of other intriguing unknowns. 

Odors, good or bad, enter the nose as the front door of the smelling (olfactory) mechanism. Some smells like your breath and sweat are identified as "self" and mostly ignored. (Unless you have been on the tennis court or football field for a heavy workout. Then the usual monitoring gets kicked up a notch and even YOU notice you stink.) 

Other smells set off different neural activity patterns across the brain. 

In mammals, the olfactory bulb has neuronal circuits that process information via receptors. It sends information to higher processing brain areas, including the cerebral cortex. There, smell messages are analyzed thoroughly and sent across the brain (i.e. chocolate=yum or skunk spray=yuck) before they return to the bulb in a feedback loop.

The latest research shows that signaling is linear and is further analyzed in the brain with respect to intensity, known characteristics, and past experience (i.e., banana or mountain lion). Go Science!

Wednesday, March 20, 2019

Nanoparticles and Near Infrared Vision

Last month an article was published in Cell describing how researchers had injected the retinas of mice with nanoparticles that attached to retinal photoreceptor cells and changed near-infrared light (IR) to green light the animals could see in the dark. Like a mouse version of night vision goggles without the goggles.

To see if the treated mice could actually see in the IR range (700 nanometers to 1 millimeter), they checked the pupils of the injected mice and noted that the test animals' eyes constricted when shown 900 nm light, while the controls (not treated) mice did not.  

Then, researchers gave the mice a choice of two boxes: one that was completely dark and one illuminated by near-infrared light. Control mice spent time in both boxes, but mice with nanoparticle treated retinas chose the dark box, suggesting that they could see the near-IR light and preferred the dark. 

This research has tons of applications. All of which are fascinating. I plan to keep an eye on developments in mammalian night vision. Who knows? Maybe someday everyone will have excellent night vision and no one will stub a toe in the dark. Go science!