Researchers discover possible self-organizing mechanism of neural connections

January 10, 2017
Two opposite forms of spike timing-dependent plasticity (STDP) converge onto L2/3, spike timing-dependent long-term potentiation (t-LTP) from L4 and spike timing-dependent long-term depression (t-LTD) from the thalamus during the second postnatal week. Thalamic projection to L4 lost STDP at this age. Thalamic activity may facilitate L4-L2/3 synapse formation by t-LTP, while simultaneously weakening and retracting from direct innervation of L2/3 by t-LTD through CB1R, thus, reorganization of neural circuits may proceed in a self-organizing manner. Illustration adapted from Itami et al (2016) with modifications. Credit: Osaka University

Researchers have found that neural activity that retracts excessive early innervation in a certain pathway helps make late neural connections in a different pathway. This may provide a self-organizing mechanism of neural connections, and additionally, early excessive innervation may serve as a guide for making late neural connections.

The formation and refinement of is known to be often an activity-dependent process, but mechanisms and nature of activity are not yet clearly understood.

During neuronal circuit formation, afferent axons often make multiple, exuberant, or aberrant connections, which are later eliminated, sometimes in an activity-dependent manner. Such examples are widely seen throughout the central and peripheral nervous systems.

The finding made by a research group led by Fumitaka Kimura, associate professor at the Graduate School of Medicine, Osaka University indicates that such exuberant early thalamocortical connections are not useless, unnecessary connections but serve to help make L4-L2/3 connections. It will be intriguing to determine whether similar mechanisms might be operating in other systems. In addition, retraction of early thalamocortical connection was driven by cannabinoid type 1 receptor (CB1R). This suggests that external intake of cannabinoids (psychoactive ingredient of marijuana) will retract thalamocortical projection without . This may result in poor neural formation of L4-L2/3. Thus, intake of cannabinoids may result in a malformation of CB1R-free neurons.

This finding will lead to further understanding of neuronal circuit mechanism and contribute to raising awareness of prevention of cannabis and/or legal drug abuse.

Explore further: Adverse effects of cannabis scientifically verified

More information: Chiaki Itami et al. Concurrently induced plasticity due to convergence of distinct forms of spike timing-dependent plasticity in the developing barrel cortex, European Journal of Neuroscience (2016). DOI: 10.1111/ejn.13431

Related Stories

Adverse effects of cannabis scientifically verified

September 12, 2016
Researchers have clarified important mechanisms involved in the formation of neural circuits in the brain. This group also discovered that delta-9-tetrahydrocannabinol (THC), a psychoactive substance also found in cannabis, ...

Too much activity in certain areas of the brain is bad for memory and attention

August 23, 2016
Neurons in the brain interact by sending each other chemical messages, so-called neurotransmitters. Gamma-aminobutyric acid (GABA) is the most common inhibitory neurotransmitter, which is important to restrain neural activity, ...

Neural connections mapped with unprecedented detail

July 4, 2016
A team of neuroscientists at the Champalimaud Centre for the Unknown, in Lisbon, has been able to map single neural connections over long distances in the brain. "These are the first measurements of neural inputs between ...

Timing is key in the proper wiring of the brain: study

December 19, 2011
(Medical Xpress) -- After birth, the developing brain is largely shaped by experiences in the environment. However, neurobiologists at Yale and elsewhere have also shown that for many functions the successful wiring of neural ...

Recommended for you

The neural codes for body movements

July 21, 2017
A small patch of neurons in the brain can encode the movements of many body parts, according to researchers in the laboratory of Caltech's Richard Andersen, James G. Boswell Professor of Neuroscience, Tianqiao and Chrissy ...

Faulty support cells disrupt communication in brains of people with schizophrenia

July 20, 2017
New research has identified the culprit behind the wiring problems in the brains of people with schizophrenia. When researchers transplanted human brain cells generated from individuals diagnosed with childhood-onset schizophrenia ...

Scientists reveal how patterns of brain activity direct specific body movements

July 20, 2017
New research by Columbia scientists offers fresh insight into how the brain tells the body to move, from simple behaviors like walking, to trained movements that may take years to master. The discovery in mice advances knowledge ...

Scientists discover combined sensory map for heat, humidity in fly brain

July 20, 2017
Northwestern University neuroscientists now can visualize how fruit flies sense and process humidity and temperature together through a "sensory map" within their brains, according to new research.

Team traces masculinization in mice to estrogen receptor in inhibitory neurons

July 20, 2017
Researchers at Cold Spring Harbor Laboratory (CSHL) have opened a black box in the brain whose contents explain one of the remarkable yet mysterious facts of life.

Speech language therapy delivered through the Internet leads to similar improvements as in-person treatment

July 20, 2017
Telerehabilitation helps healthcare professionals reach more patients in need, but some worry it doesn't offer the same quality of care as in-person treatment. This isn't the case, according to recent research by Baycrest.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.