Songbird Neurons Reveals Building Block for Advance Cognition in Birds and Mammals

Neuroscientists from the University of Massachusetts Amherst examined the neurons in a songbird's forebrain and advanced insight into the fundamental operation of complex brain networks.

They discovered that ancient neurons in the outer regions of the brain, which includes the cortex and collectively known as the pallium, have most likely retained the features of the building blocks for advanced cognition in birds and mammals even after millions of years.

They published their study, "Genetically identified neurons in avian auditory pallium mirror core principles of their mammalian counterparts," in the journal Current Biology.

Excitatory vs. Inhibitory Neurons

Behavioral neuroscientist and senior author of the study Luke Remage-Healey said that neuroscientists like him have been catching birds doing sophisticated things and having sophisticated circuits that do those things, Science Daily reported.

But this is the first time that a study has been able to identify the excitatory and inhibitory neurons involved in these sophisticated bird behavior.

Together with a team of neuroscientists, including lead author Jeremy Spool who worked as a postdoctoral fellow in the NIH, the team used viral optogenetics to define the molecular identities of excitatory and inhibitory cell types in zebra finches (Taeniopygia guttata) and match them to the songbird's physiological properties.

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Co-author Yoko Yazaki-Sugiyama at the Okinawa Institute of Science and Technology in Japan curated a collection of viruses that the team used in conducting viral optogenetic experiments in the brain.

Optogenetics allowed the team of neuroscientists to use flashes of light to manipulate one cell from another cell. They targeted excitatory (CaMKII) and inhibitory (GAD1) cells in the auditory pallium of zebra finch to test predictions based on the mammalian pallium, the science news outlet reported.

"There's so much work out there on the physiology of these different cell types in the mammalian cortex that we were able to line up a series of predictions about what features birds may or may not have," Spool says.

Spool said that the CaMKII and GAD1 populations in songbirds were distinct in proportions that are expected from the mammalian brain. Then researchers examined whether the cell type populations would correspond to the physiology of their mammalian counterparts.

They found that a striking correspondence between the cortex and the molecules they were identifying in cell types in birds.

Building Blocks For Advanced Cognitive Functions

Spool said that their experiment showed that these excitatory and inhibitory neurons in both birds and mammals support advanced cognitive functions that were preserved for millions of years, Ash News reported.

Remage-Healey said that the NIH-grant study helps determine the basic units and bolts of how the brain works that build the foundation required to develop breakthroughs that could potentially help in developing neurological interventions for people with brain disorders.

"This can help us figure out what brain diversity is out there by unpacking these circuits and the ways they can go awry," Remage-Healey says.