#visual system

Today's paper is an old one (for neuro, at least) hailing from 1979. The authors explored the visual system in the brains of echolocating and non-echolocating bats-- if you didn't know that some bats don't echolocate, now you do.

They tried a couple different methods, including removing one eye and looking for the destruction of downstream neurons and injecting the eye with an early form of anterograde tracers (psst: these are just chemicals that travel down neurons the same way information does, depositing chemical along the way, so you can see what neurons are connected).

They found that, generally, the echolocating bats had a "less developed" visual processing pathway. Some areas were smaller, some seemed less connected to the eye, and some didn't have the cellular complexity of the same areas in non-echolocating bats. This all makes sense: a bat that navigates more with sound doesn't need to process visual information as thoroughly. Better to leave more of the brain for hearing.

Just for fun, here is one of the echolocating bats (Myotis lucifugus, or little brown bat, photo from Bat Conservation International):

And here is one of the non-echolocating bats (in the paper it is called Pteropus giganteus, but the modern nomenclature is Pteropus medius; regardless, it's an Indian flying fox and I got this photo from Wikipedia):

Thanks for appreciating bats with me today!

After a short break, keep working again!

I won't be taking classes because I'm in an internship this semester, but I'm still working in two labs and the obligation to do so is increasing :')

Be prepared to see posts full of articles, even though I'm still not ready to read..

For music: Hakim Bey

Surprise Discovery Reveals Second Visual System in Cerebral Cortex: Mouse Study

"This undermines the whole concept of the visual system in mammalian cortex as a perfect hierarchy with V1 as the gatekeeper and raises a multitude of questions, including how these two parallel visual systems evolved and how they cooperate to produce a unified visual experience."

Scene Seen

We may think of our eyes as cameras, faithfully photographing the things we see and projecting them directly into the brain. In fact, the visual system works more like a sketch artist, piecing together the most likely representation of reality with plenty of interpretation and improvisation. Scientists used to think that specific nerve cells in the brain created ‘maps’ of information about objects, such as how big and which way up they are, by detecting their edges. But what seem like definite shapes and structures may be tricks of the light – for example, strong shadows can fool us into thinking they are edges too. Researchers are now using sophisticated techniques to measure brain activity while volunteers watch images like these, zooming in from big picture to tiny detail or zooming out in the opposite direction, to understand more about how the brain constructs our view of the world around us.

Written by Kat Arney

Image from work by Peter Neri, Sensory Processing and Computation, Laboratoire des Systèmes Perceptifs

Laboratoire des Systèmes Perceptifs, Département d'études cognitives, Ecole Normale Supérieure, PSL Research University, CNRS, Paris, France

Image originally published under a Creative Commons Licence (BY 4.0)

Published in PLOS Biology, August 2017