Landmark study on neural circuits shows that “cells that fire together wire together,” refining the popular “Use it or lose it”

– A net­work of neu­rons recon­struct­ed with large-scale elec­tron microscopy. Cred­it: Clay Reid, Allen Insti­tute; Wei-Chung Lee, Har­vard Med­ical School; Sam Inger­soll, graph­ic artist.

Research on largest net­work of cor­ti­cal neu­rons to date pro­filed (Med­ical Xpress):

“Even the sim­plest net­works of neu­rons in the brain are com­posed of mil­lions of con­nec­tions, and exam­in­ing these vast net­works is crit­i­cal to under­stand­ing how the brain works. An inter­na­tion­al team of researchers, led by R. Clay Reid, Wei Chung Allen Lee and Vin­cent Bonin from the Allen Insti­tute for Brain Sci­ence, Har­vard Med­ical School and Neu­ro-Elec­tron­ics Research Flan­ders (NERF), respec­tive­ly, has pub­lished the largest net­work to date of con­nec­tions between neu­rons in the cor­tex, where high-lev­el pro­cess­ing occurs, and have revealed sev­er­al cru­cial ele­ments of how net­works in the brain are organized.

“For decades, researchers have stud­ied brain activ­i­ty and wiring in iso­la­tion, unable to link the two,” says Vin­cent Bonin, Prin­ci­pal Inves­ti­ga­tor at Neu­ro-Elec­tron­ics Research Flan­ders. “What we have achieved is to bridge these two realms with unprece­dent­ed detail, link­ing elec­tri­cal activ­i­ty in neu­rons with the nanoscale synap­tic con­nec­tions they make with one another.”

Ana­lyz­ing this wealth of data yield­ed sev­er­al results, includ­ing the first direct struc­tur­al evi­dence to sup­port the idea that neu­rons that do sim­i­lar tasks are more like­ly to be con­nect­ed to each oth­er than neu­rons that car­ry out dif­fer­ent tasks. Fur­ther­more, those con­nec­tions are larg­er, despite the fact that they are tan­gled with many oth­er neu­rons that per­form entire­ly dif­fer­ent func­tions.” (bold­ed by editor)

Study: Anato­my and func­tion of an exci­ta­to­ry net­work in the visu­al cor­tex (Nature)

• Abstract: Cir­cuits in the cere­bral cor­tex con­sist of thou­sands of neu­rons con­nect­ed by mil­lions of synaps­es. A pre­cise under­stand­ing of these local net­works requires relat­ing cir­cuit activ­i­ty with the under­ly­ing net­work struc­ture. …we found that pyra­mi­dal neu­rons with sim­i­lar ori­en­ta­tion selec­tiv­i­ty pref­er­en­tial­ly formed synaps­es with each oth­er, despite the fact that axons and den­drites of all ori­en­ta­tion selec­tiv­i­ties pass near each oth­er with rough­ly equal prob­a­bil­i­ty. There­fore, we pre­dict that mech­a­nisms of func­tion­al­ly spe­cif­ic con­nec­tiv­i­ty take place at the length scale of spines. Neu­rons with sim­i­lar ori­en­ta­tion tun­ing formed larg­er synaps­es, poten­tial­ly enhanc­ing the net effect of synap­tic speci­fici­ty. With the abil­i­ty to study thou­sands of con­nec­tions in a sin­gle cir­cuit, func­tion­al con­nec­tomics is prov­ing a pow­er­ful method to uncov­er the orga­ni­za­tion­al log­ic of cor­ti­cal networks.

To learn more:

• To Be (Your Con­nec­tome), or Not to Be (Your Genome)
• Use It or Lose It, and Cells that Fire togeth­er Wire together