When we drift into deep slow-wave sleep (SWS), waves of neuronal activity wash across our neocortex.
Birds also engage in SWS, but they lack this particular brain structure. Researchers from the Max Planck Institute for Ornithology in Seewiesen, Germany have gained deeper insight into the sleeping avian brain.
They found complex 3D plumes of brain activity propagating through the brain that clearly differed from the two-dimensional activity found in mammals. These findings show that the layered neuronal organization of the neocortex is not required for waves to propagate, and raise the intriguing possibility that the 3D plumes of activity perform computations not found in mammals.
Mammals, including humans, depend upon the processing power of the neocortex to solve complex cognitive tasks. This part of the brain also plays an important role in sleep. During SWS, slow neuronal oscillations propagate across the neocortex as a traveling wave, much like sports fans performing the wave in a stadium.
It is thought that this wave might be involved in coordinating the processing of information in distant brain regions. Birds have mammalian-like cognitive abilities, but yet different neuronal organization. They lack the elegant layered arrangement of neurons characteristic of the neocortex. Instead, homologous neurons are packaged in unlayered, seemingly poorly structured nuclear masses of neurons.
Researchers from the Max Planck Institute for Ornithology in Seewiesen together with colleagues from the Netherlands and Australia now investigated in female zebra finches how brain activity changed over space and time during sleep.
"When we first looked at the recordings, it appeared that the slow waves were occurring simultaneously in all recording sites. However, when we visualized the data as a movie and slowed it down, a fascinating picture emerged!" says Gabriël Beckers from Utrecht University, who developed the high-resolution recording method at the Max Planck Institute for Ornithology in Seewiesen.
The waves were moving across the two-dimensional recording array as rapidly changing arcs of activity. Rotating the orientation of the array by 90 degrees revealed similar patterns, and thereby established the 3D nature of the plumes propagating through the brain. The researchers found similar patterns in distant brain regions involved in processing different types of information, suggesting that this type of activity is a general feature of the sleeping avian brain.
In addition to revealing how neurons in the avian brain behave during sleep, this research also adds to our understanding of the sleeping neocortex. "Our findings demonstrate that the traveling nature of slow waves is not dependent upon the layered organization of neurons found in the neocortex, and is unlikely to be involved in functions unique to this pattern of neuronal organization," says Niels Rattenborg, head of the Avian Sleep Group in Seewiesen. "In this respect, research on birds refines our understanding of what is and is not special about the neocortex."
Finally, the researchers wonder whether the 3D geometry of wave propagation in the avian brain reflects computational properties not found in the neocortex. While this idea is clearly speculative, the authors note that during the course of evolution, birds replaced the three-layered cortex present in their reptilian ancestors with nuclear brain structures. "Presumably, there are benefits to the seemingly disorganized, nuclear arrangement of neurons in the avian brain that we are far from understanding. Whether this relates to what we have observed in the sleeping bird brain is a wide open question," says Rattenborg.
Dr. Stefan Leitner | Max-Planck-Institut für Ornithologie
Cnidarians remotely control bacteria
21.09.2017 | Christian-Albrechts-Universität zu Kiel
Immune cells may heal bleeding brain after strokes
21.09.2017 | NIH/National Institute of Neurological Disorders and Stroke
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
21.09.2017 | Physics and Astronomy
21.09.2017 | Life Sciences
21.09.2017 | Health and Medicine