First-rate first looks at behavior + neural circuits of ‘non-traditional’ species @ SfN17
Much like @salmont3’s recent post, I was interested in exploring posters that focused on “non-traditional” model organisms, especially in the realm of sensory processing (#theme_d), animal communication, neuroethology, and integrative behavior + physiology (#theme_f).
A lot has already been said about the invaluable contributions of non-traditional study species to neuroscience. I recently co-authored a paper with my lab mates earlier this year on the value of species diversity; Michael Yartsev dropped a paper a few weeks ago on a very similar topic, and those are just the papers related to neuroscience in 2017.
Other basic science advocates like Patricia Brennan continue to rally for the same cause. Namely, studying (neuro)science for the value of knowledge in it of itself (“basic” science; which often leads to pivotal incidental discoveries along the way, such as the Internet & PCR), and choosing an animal model that fits the research question rather than the other way around.
Below, I’ve highlighted a few of the many, extraordinary research posters presented at #SFN17 that showcases the power of species diversity that further enrich our wider understanding of how the nervous system develops, interprets its environment, and enables behavior.
First ever look at pinniped auditory circuits: On Monday morning, I was delighted to hear about some fantastic research from Juliane Krueger, PhD, a post-doc in the lab of Jon Kaas at Vanderbilt University. For the first time ever Juliane and colleagues explored the auditory system of pinnipeds, following up on their prior work exploring pinnipeds’ visual + somatosensory circuits. Pinnipeds are carneverous mammals, that include the likes of sea lions, seals, and walruses.
Northern elephant seal via NOAA
While comparative species work is interesting in it of itself, what excited me was the first look at a previously unstudied group of mammals that also happen to be one of the rarely found mammalian vocal learners (see my previous post on Birdsong 7 for more details on vocal learning rarity in the animal kingdom).
Jarvis ED (2007) J Ornithol
Overall, Krueger and colleagues traced the auditory circuit all the way from the auditory brain stem, to the midbrain, thalamic nuclei, and up to primary auditory cortex, and found they were pretty similar between a Northern elephant seal and a California sea lion (n = 1 per species), as well as similar to the distantly related cats (used as an anatomical reference). Therefore, this work provides further evidence for conserved sensory circuits within pinnipeds and across mammals.
Newly discovered blind, electric cavefish are distinct from their downstream relatives: Weakly electric fish use electric fields to communicate with one another. Recently, a new species of weakly electric blind cavefish were discovered in the Sao Vicente II Cave in Brazil. To ‘see’ how living in a dark cave affected the lives of these found fish relative to a closely related, and visually-dependent river fish, the researchers spent four days living in the cave and tracking the fish electric organ discharges around the clock.
Preliminary findings using microCT scans suggest that the electric organ was larger in cave fish, which might imply their electric field is stronger, and able to detect more distant features than surface fish.
Aside from anatomy, the researches took advantage of unique voltage signature each fish produces to follow their moves around their stomping grounds by recording electric fields of many fish at the same time underwater.
Behaviorally, the most stark finding was the blind cavefish couldn’t see eye-to-eye with their neighbors: compared to the surface fish, cavefish were much more territorial and solitary, with no overlapping foraging areas (compared to a criss-cross movement map seen in river fish). Interestingly, along with spatial divergence, cavefish also had more spaced out voltage frequencies compared to the relatively gregarious surface fish that had a smaller spread of frequencies.
Finally, for the first time outside of the lab, the researchers observed the classic jamming avoidance response in both species.
Measuring crocodile brain activity while they listen to classical music + watch a laser light show…for science!: I wrote more at length about this exciting (and terrifying) poster in my previous post, so be sure to check it out here
First ever investigation of tui (aka the R2D2 of birds) auditory circuits: The tui (Prosthemadera novaeseelandiae) is spectacular bird in both sound and plumage. Native to New Zealand, this kiwi puts NZ’s national bird to shame with its complex, mechanical, vocal repertoire that rivals R2D2 and parrots (as it can mimic human speech):
Bird? or Robot?
This poster happened to overlap with my own presentation, but I got quick look at the poster (sans presenter) before it was showtime for my own songbird science. Overall, the researchers tested whether its vocal mastery was matched by an equally enlarged/specialized auditory + song motor production regions, as has been found previously in specialized neural circuits for vocal learning in songbirds and auditory regions in owls.
Simplified song learning + production circuit; from Fee & Scharff (2010) ILAR
Overall, when compared to galliformes (e.g. chicken) and owls, tuis actually had a smaller cochlear nucleus than its feathered cousins, and a smaller midbrain auditory region MLd (nucleus mesencephalus pars dorsalis) and smaller HVC (sensory/sensorimotor region required for song learning and production; acronym as proper name) compared to songbirds, but a similarly sized Area X (similar to mammalian basal ganglia).
In the future, they’ll be looking at other brain regions such as RA (~laryngeal motor cortex) and Field L (~primary auditory cortex).
Untangling the complex web building behavior of orb-weavers : I made a quick stop at an intriguing poster on orb-weaving spiders (Uloborus diversus) presented by Andrew Gordus who’s just starting up his lab at Johns Hopkins. Essentially, he’s working out the neurobiology of web weaving in orb-weaver spiders.
For a brain biologist, there’s a lot of advantages to studying these guys (or gals…it turns out that only adult female orb-weavers knit webs). Namely, they aren’t cannibals, and lack venom glands, which makes it easier to access the brain.
The larger idea behind studying these spiders is that unlike birds that use found material to build nests on already existing structures, orb-weavers produce their webs using self-generated source material (silk), and manipulate their environment to establish a home, which takes an impress amount of spatial cognition and error correction, all being calculated in a fly-sized brain.
Gordus has some neat tools he’s developed to make things an itsy bitsy less difficult, including a spider GPS setup that allows him to automatically live-track direction, position, and orientation of individuals. In combination with technical tools, Gordus’ group is starting to unpack cellular and genetic mechanisms that enable web weaving in the future.
From the Gordus lab’s website
How honeybee neurons encode the waggle dance : Neuroscience has finally caught up with ethologist Karl von Frisch’s initial findings from the 1960s. For the first time, researchers were able to record from individual vibration-sensitive interneurons in honeybees in response to the waggle dance, which conveys information about pollen/food sources (see gif below). Honeybees detect vibration cues generated by the dancing compatriots,and calculate the direction of the food source.
While most the data presented was mainly from their recent tour de force paper in the Journal of Neuroscience, the group presented some exciting data from juvenile honeybees collected post-publication.
Honeybees only begin waggling after about the first week of life when they start foraging for food outside of the hive. As such, the researchers recorded from auditory neurons from one-day old and two-week old honeybees, and found both morphological (namely, different dendritic maturation) and electrophysiological changes across development (namely, increased inhibitory tone and resultant disinhibition, leadining to an overall enhanced excitation in response to the waggle dance in two-week old bees).
503.08 / KK25 - Interneurons in the primary auditory center of the honeybee brain responsive to air vibration pulses as elicited during waggle dance communication
What’s your favorite ‘outside of the box’ species found at #SfN17?
- Orb-weaver spiders
- Weakly electric cavefish