#olfactory system

Following Your Nose

Your nose can detect around a trillion smells, in part thanks to its olfactory sensory nerves. These nerves are also involved in clearing out waste that your brain produces, acting as a conduit for the drainage of waste-laden cerebrospinal fluid (CSF). Using mice, researchers dig deeper into the anatomy of CSF removal, focusing on the bone that separates the nasal cavity from the brain, the cribriform plate (pictured, captured using micro-CT imaging). They injected a dye into the brain to track the drainage of CSF via olfactory sensory nerves passing through holes in the cribriform plate. Chemically destroying these nerves significantly reduced CSF drainage via the cribriform plate without increasing pressure inside the skull. This suggests a compensatory change in CSF production or flow. Damage to these nerves in humans, such as by air pollution, could therefore disrupt CSF turnover, which is known to occur in certain brain diseases.

Written by Lux Fatimathas

Image from work by Jordan N. Norwood and colleagues

Pennsylvania State University, PA, USA

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

Published in eLife, May 2019

Magic Memory Mushrooms

These bright green structures are mushroom bodies – tightly-packed collections of nerve cells in the brain of an adult fruit fly. First described more than 150 years ago, they play an important role in learning, particularly around smells, and are often used as a model for human memory-making. Nerve cells in mushroom bodies communicate in two different ways – either through releasing and receiving chemical signals, or by direct electrical connections – but it’s not clear exactly which processes are at work in the mushroom body as memories are made. To find out, researchers removed one of the genes that builds electrical connections between mushroom body cells (known as gap junctions), finding that these flies could no longer learn to associate a particular smell with a mild electrical shock. This shows that direct electrical communication is a key part of memory formation and retrieval in flies, and might be important in human brains too.

Written by Kat Arney

Image from work by Wei-Huan Shyu and colleagues

Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan

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

Published in PLOS Genetics, May 2019

Organised Chaos

The brain’s nerve fibres can sometimes look a bit jumbled up, like a mesh of wires that badly needs tidying. In particular, the fibres that ultimately connect our nose to the part of the brain that interprets the smells we encounter (shown here as green, red-brown and white layers) have long been thought to be a bit disorganised. However, scientists have recently shown how this chaotic arrangement is actually what helps mice distinguish between similar odours. Rather than each ‘wire’ being responsible for a particular smell, the team found that they carry signals from many different smells. Mice can differentiate between odours because the pattern of signals carried in these nerves is distinctive for each smell, leaving a unique odour 'fingerprint' on this part of the brain. Perhaps there’s method in the madness of brain fibres after all, and that seemingly random connections may be more organised than we originally thought.

Written by Gaëlle Coullon

Image from work by Shyam Srinivasan and Charles F Stevens, The Salk Institute

Salk Institute for Biological Studies, La Jolla, CA, USA

Image copyright held by the original authors

Research published in the Journal of Comparative Neurology, July 2018

For most of us, the sense of smell is an integral part of everyday life; it plays a critical role in providing information about our surroundings, alerting us to potential dangers, enhancing our sense of taste, and evoking emotions and memories.  Yet from a scientific perspective, “olfaction is super-mysterious,” said Sandeep (Robert) Datta, professor of neurobiology in the Blavatnik Institute…

We often only realize how important our sense of smell is when it is no longer there: food hardly tastes good, or we no longer react to dangers such as the smell of smoke. Researchers at the University Hospital Bonn (UKB), the University of Bonn and the University of Aachen have investigated the neuronal mechanisms of human odor perception for the first time. Individual nerve cells in the brain…

Ever wonder why some scents can zap you into focus & others send you running? Explore the fascinating world of fragrance & the neurodivergent brain with Neatest Shapes!

Hey there, my magnificent olfactory adventurers! Neatest Shapes back again, this time to delve into the fascinating world of fragrance and neurodivergent brains. Scents are powerful things, capable of evoking memories, sparking emotions,and even influencing our mood. But for us neurodivergent folks, the world of perfume can be a bit of a paradox. On the one hand, certain scents can be incredibly…