In the primary visual cortex of the brain, neurons are organized into alternating columns that receive inputs from either the left or right eye. This organization is strongly dependent on early visual experience.
When one eye is deprived of visual inputs during a critical developmental period, the corresponding columns fail to develop properly, whereas those receiving inputs from the unaffected eye grow larger than normal.
The cortex consists primarily of two different types of neuron: excitatory neurons that synthesize and release the neurotransmitter glutamate, and inhibitory interneurons which use the transmitter ã-aminobutyric acid (GABA). How each of these cell types contributes to experience-dependent changes in the visual cortex is, however, unknown.
To investigate this, Tadaharu Tsumoto of the RIKEN Brain Science Institute, Wako, and his colleagues injected a calcium-sensitive dye, Fura-2, into the visual cortex of genetically engineered mice whose inhibitory interneurons express a fluorescent protein called Venus1. The intensity of Fura-2 fluorescence changes in response to the increase in calcium ion concentration that is characteristic of neuronal activity.
This approach enabled the researchers to both identify the interneurons in the visual cortex and monitor their activity. In animals reared normally, they first identified the ‘binocular’ regions of the primary visual cortex by visually stimulating each eye in turn, and using two-photon laser-scanning microscopy to locate the cells that responded to both. This revealed that inhibitory interneurons are more responsive to inputs from both eyes than excitatory neurons.
The responses in mice deprived of visual inputs to one eye for two days during the critical period were then examined. The change in the responses of both cell types was found to be similar—both had become more responsive to inputs from the open eye.
When mice were deprived of visual inputs to one eye after the critical period, however, the effect observed was far stronger on the inhibitory interneurons. They tended to receive inputs from the open eye, and their responses to inputs from the closed eye were also depressed, whereas those of the excitatory neurons remained almost stable. The interneurons normally act to inhibit the excitatory neurons, so their depressed responses may contribute to the stability of excitatory neuron responses to the deprived eye.
“Inhibitory interneurons are divided into several subtypes,” says Tsumoto. So, the next step is to determine which particular subtypes are involved in maintaining plasticity after the critical period.
The corresponding author for this highlight is based at the Laboratory for Cortical Circuit Plasticity, RIKEN Brain Science Institute
1. Kameyama, K., Sohya, K., Ebina, T., Fukuda, A., Yanagawa, Y. & Tsumoto, T. Difference in binocularity and ocular dominance plasticity between GABAergic and excitatory cortical neurons. Journal of Neuroscience 30, 1551–1559 (2010)
Saeko Okada | Research asia research news
Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology