The incredible detail of the brain Micron-scale synaptic clusters underlie learning and memory
Assistant Professor Yuji Ikegaya and his group at the University of Tokyo’s Graduate School of Pharmaceutical Sciences have described an important aspect of the synaptic organization of the brain that underlies learning, and settled a long-running argument in the process.
Each neuron in the brain may have one or more dendrites, which connect to many others at synapses to transmit signals or receive them at dendritic spines. Two models for the distribution of these synapses have been debated for many years, one that the arrangement of dendritic spines was random, and the other that they were arranged in localized clusters.
Professor Ikegaya’s group in the Laboratory of Chemical Pharmacology developed a new large-scale spine imaging method to observe simultaneously the activity of hundreds of dendritic spines, and found that spines within 8 μm of each other often received clustered inputs simultaneously. Additionally, the group showed that these localized clusters form as a result of long-term potentiation (LTP), a process that takes place in the brain during learning and memory formation.
Even if the initial network of synapses is random, connections are determined to be necessary or unnecessary through learning and the localized effect of LTP. The latter are removed, giving rise to synaptic cluster input.
This research is a huge step forward in our understanding of learning and memory formation on the synaptic level and opens up a new approach to neurological problems impacting memory such as Alzheimer’s disease and depression.
(Public Relations Division: Euan McKay, Azusa Minamizaki)
Department release/press release (Japanese)
Naoya Takahashi, Kazuo Kitamura, Naoki Matsuo, Mark Mayford, Masanobu Kano, Norio Matsuki, Yuji Ikegaya
“Locally Synchronized Synaptic Inputs”
Science 20 January 2012: Vol. 335 no. 6066 pp. 353-356, doi:10.1126/science.1210362