Adjunct Professor of Biology
dlizarraga@palomar.edu
Palomar College
1140 West Mission Road
San Marcos, CA 92069
Dr. David Lizarraga
Biology Department
Category: Some Interesting Stuff from the World of Biology
Neuroscientists Say They’ve Found an Entirely New Form of Neural Communication
Scientists think they’ve identified a previously unknown form of neural communication that self-propagates across brain tissue, and can leap wirelessly from neurons in one section of brain tissue to another – even if they’ve been surgically severed.
The discovery offers some radical new insights about the way neurons might be talking to one another, via a mysterious process unrelated to conventionally understood mechanisms, such as synaptic transmission, axonal transport, and gap junction connections.
“We don’t know yet the ‘So what?’ part of this discovery entirely,” says neural and biomedical engineer Dominique Durand from Case Western Reserve University.
“But we do know that this seems to be an entirely new form of communication in the brain, so we are very excited about this.”
Before this, scientists already knew there was more to neural communication than the above-mentioned connections that have been studied in detail, such as synaptic transmission.
For example, researchers have been aware for decades that the brain exhibits slow waves of neural oscillations whose purpose we don’t understand, but which appear in the cortex and hippocampus when we sleep, and so are hypothesised to play a part in memory consolidation.
“The functional relevance of this input‐ and output‐decoupled slow network rhythm remains a mystery,” explains neuroscientist Clayton Dickinson from the University of Alberta, who wasn’t involved in the new research but has discussed it in a perspective article.
“But [it’s] one that will probably be solved by an elucidation of both the cellular and the inter‐cellular mechanisms giving rise to it in the first place.”
To that end, Durand and his team investigated slow periodic activity in vitro, studying the brain waves in hippocampal slices extracted from decapitated mice. What they found was that slow periodic activity can generate electric fields which in turn activate neighbouring cells, constituting a form of neural communication without chemical synaptic transmission or gap junctions.
“We’ve known about these waves for a long time, but no one knows their exact function and no one believed they could spontaneously propagate,” Durand says.
“I’ve been studying the hippocampus, itself just one small part of the brain, for 40 years and it keeps surprising me.”
This neural activity can actually be modulated – strengthened or blocked – by applying weak electrical fields and could be an analogue form of another cell communication method, called ephaptic coupling.
The team’s most radical finding was that these electrical fields can activate neurons through a complete gap in severed brain tissue, when the two pieces remain in close physical proximity.
“To ensure that the slice was completely cut, the two pieces of tissue were separated and then rejoined while a clear gap was observed under the surgical microscope,” the authors explain in their paper. “The slow hippocampal periodic activity could indeed generate an event on the other side of a complete cut through the whole slice.”
If you think that sounds freaky, you’re not the only one. The review committee at The Journal of Physiology – in which the research has been published – insisted the experiments be completed again before agreeing to print the study.
Durand et al. dutifully complied, but sound pretty understanding of the cautiousness, all things considered, given the unprecedented weirdness of the observation they’re reporting. “It was a jaw-dropping moment,” Durand says, “for us and for every scientist we told about this so far.” “But every experiment we’ve done since to test it has confirmed it so far.”
It’ll take a lot more research to figure out if this bizarre form of neural communication is taking place in human brains – let alone decoding what exact function it performs – but for now, we’ve got new science that’s shocking in all kinds of ways, as Dickson adroitly observes.
“While it remains to be seen if the [findings] are relevant to spontaneous slow rhythms that occur in both cortical and hippocampal tissue in situ during sleep and sleep‐like states,” Dickson writes, “they should probably (and quite literally) electrify the field.”
The findings are reported in The Journal of Physiology.
Skin Cells Directly Converted into Motor Neurons
http://bit.ly/2w4XTUJ
Cool! That this is even possible, I figured, is related to the fact that skin epithelium and neural tissue both arise from the ectoderm, but it turns out that dermal fibroblasts (mesodermal in origin) are being converted. Even cooler?
Bugged: The Insects Who Rule the World and the People Obsessed with Them
Excellent read!
Bugged: The Insects Who Rule the World and the People Obsessed with Them
by David MacNeal.
St. Martin’s Press, 2017 ($25.99)
Review from Scientific American:
During the steamy summer months many people dream of a world without mosquitoes, ants and other pesky bugs. But remove all the insects, which comprise about 75 percent of species in the animal kingdom, and the world as we know it could not exist. Insects bind together nearly every ecosystem by pollinating 80 percent of food plants and recycling dead organic matter. Science writer MacNeal travels the globe documenting the science and culture of all things “bug.” There is the painstaking work of taxonomists who continue to catalogue the earth’s estimated 10 quintillion insects; the Greek island beekeepers; and the Zika-fighting mosquitoes in Brazil. The world is surprisingly full of insect lovers, one of whom tells MacNeal that “bugs are more interesting than people.” Interesting or not, insects provide “beneficial, multibillion-dollar services keeping life on this planet humming along.”
Histology Guide – A Virtual Histology Laboratory
Histology Guide – a virtual histology laboratory with zoomable images of microscope slides and electron micrographs.
Desert people evolve to drink water poisoned with deadly arsenic | New Scientist
People living in the Atacama desert of Chile evolved specific gene mutations over the past 7000 years that make them better at detoxifying the heavy metal
Source: Desert people evolve to drink water poisoned with deadly arsenic | New Scientist
The length of human pregnancy may be limited by the mother’s metabolism, not the size of the birth canal.
The research challenges the long-held notion of an evolutionary trade-off between childbirth and a pelvis adapted for walking upright.
Source: ScienceDaily
Octopus Eyes Are Crazier Than We Imagined
As if we needed more evidence that cephalopods are on the verge of a global uprising that will end in humanity’s destruction, our favorite tentacled invertebrates appear to have an insane visual system that allows them to perceive color despite being technically colorblind. This, along with distributed brains and the ability to bust out of jars from the inside? We’re screwed.
A single-celled organism discovered that is the only known eukaryotic organism that lacks mitochondria.
A single-celled organism discovered in chinchilla droppings is the only known eukaryotic organism that lacks mitochondria-like organelles. Christopher Intagliata reports.
Source: Microbe Breaks the Powerhouse Rules – Scientific American