Top left, Tim Bussey waiting to speak at the Japanese Neuroscience meeting in Yokohama. Top right, Tom McHugh, Satoshi Kida and Seung-Hee Lee on the train to Ikebukuro. Bottom right, Jaideep Bains and Andrew Holmes at a standing Izakaya in Yokohama. Bottom left, Andrew Holmes and Josh Johansen on the Ikebukuro train. Last week there were a series of neuroscience meetings and events in and around Tokyo featuring Paul, Andrew Holmes, Brian Wiltgen, Bernard Balleine, Tim Bussey and Seung-Hee Lee. A big thanks to our hosts Tom McHugh, Josh Johansen and Satoshi Kida. More pictures posted at conferences >> 2014.
There’s a rich history of studies trying to understand how neural circuits form during development. While a large number of molecules play key roles in shaping circuits in the developing brain, one kinase (α-CaMKII) appears to play an especially important role. Studies from Holly Cline‘s lab in Xenopus showed that CaMKII fine tunes the integration of new cells into circuits. Taking inspiration from these studies we asked whether the role of α-CaMKII is conserved in the adult brain as newly generated granule cells integrate into the adult hippocampus. Maithe Arruda-Carvalho generated mice in which α-CaMKII could be deleted from newborn cells, and found that α-CaMKII-deficient cells developed abnormal morphology and poorer connections. Consistent with this, she found that these mice were impaired in forming hippocampus-dependent memories. Image above shows α-CaMKII (green) expression is restricted to mainly mature dentate granule cells (NeuN, red). Blue = DAPI. The paper is published in Journal of Neuroscience.
In Washington this week telling the American Psychological Association all about Neurogenesis and Cognition were (from L to R): Tracey Shors, Liisa Galea, Paul, Mazen Kheirbek and Amar Sahay. Group selfie courtesy of Amar.
Memories are thought to be stored as enduring physical changes in ensembles of neurons, ensuring that activity patterns present at the time of encoding are recapitulated at the time of retrieval. But which neurons become part of this memory trace? Is allocation a random or non-random process? Our previous studies suggest the latter. In these studies we focused in particular on how fear memories are encoded in the amygdala. In our fear conditioning experiments, mice learn to associate a tone with a footshock and this association depends critically on neurons in the lateral amygdala (LA) . We found that manipulating the levels of the transcription factor cAMP responsive element binding (CREB) within this population of LA neurons influenced the likelihood of a neuron becoming part of a fear memory trace.
In this new study we explored the mechanisms underlying this CREB-mediated allocation. Previous studies had shown that one consequence of CREB over-expression is that cells become more excitable, and here we found that artificially increasing neuronal excitability produced exactly the same pattern of results as over-expressing CREB– more excitable neurons were more likely to become part of the memory trace. Moreover, co-expressing a factor that blocked these CREB-induced changes in excitability blocked these effects. Together these results suggest that relative levels of excitability determine which populations of cells encode the memory. The paper is published in Neuron, and Sheena and Adelaide explain all here:
A preview of our lab’s abstracts for this year’s SfN meeting in DC. Many of the usual suspects are there (neurogenesis, hippocampal, memories, forgetting) but there are also some newcomers (CLARITY and inhibitory) reflecting changes in our research-scape.
The Josselyn/Frankland lab is full of football sophisticates so, as the world cup begins, we surveyed the mood. First question, who do you want to win? Massive lab support for the Azzurri (7 out of 22)!
And second question, who is actually going to win it? There’s lots of obvious support for Spain, Germany, Brazil and Argentina. David picked England, proving that Americans know nothing about football. And some people don’t care (Gisella).
Congratulations to Afra who successfully defended her PhD yesterday. Her thesis explored how drug-associated memories reorganize over time (i.e., undergo systems consolidation). Above she is pictured post-defense with her PhD supervisory committee members Paul Fletcher and Sheena Josselyn.