October 14, 2015

van Rheede JJ, Richards BA, Akerman CJ, “Sensory-Evoked Spiking Behavior Emerges via an Experience-Dependent Plasticity Mechanism”, Neuron, 87(5), 1050-1062

The ability to generate action potentials (spikes) in response to synaptic input determines whether a neuron participates in information processing. How a developing neuron becomes an active participant in a circuit or whether this process is activity dependent is not known, especially as spike-dependent plasticity mechanisms would not be available to non-spiking neurons. Here we use the optic tectum of awake Xenopus laevis tadpoles to determine how a neuron becomes able to generate sensory-driven spikes in vivo. At the onset of vision, many tectal neurons do not exhibit visual spiking behavior, despite being intrinsically excitable and receiving visuotopically organized synaptic […]
June 24, 2015

Yiu AP, Mercaldo V, Yan C, Richards BA, Rashid AJ, Hsiang HL, Pressey J, Mahadevan V, Tran MM, Kushner SA, Woodin MA, Frankland PW and Josselyn SA, “Neurons are recruited to a memory trace based on relative neuronal excitability at the time of training”, Neuron, 83(3), 722-735

Memories are thought to be sparsely encoded in neuronal networks, but little is known about why a given neuron is recruited or allocated to a particular memory trace. Previous research shows that in the lateral amygdala (LA), neurons with increased CREB are selectively recruited to a fear memory trace. CREB is a ubiquitous transcription factor implicated in many cellular processes. Which process mediates neuronal memory allocation? One hypothesis is that CREB increases neuronal excitability to bias neuronal recruitment, although this has not been shown experimentally. Here we use several methods to increase neuronal excitability and show this both biases recruitment into […]
June 24, 2015

Muldal AM, Lillicrap TP, Richards BA and Akerman CJ, “Clonal relationships impact neuronal tuning within a phylogenetically ancient vertebrate brain structure”, Current Biology, 24(16), 1929-1933

Understanding how neurons acquire specific response properties is a major goal in neuroscience. Recent studies in mouse neocortex have shown that “sister neurons” derived from the same cortical progenitor cell have a greater probability of forming synaptic connections with one another [1 and 2] and are biased to respond to similar sensory stimuli [3 and 4]. However, it is unknown whether such lineage-based rules contribute to functional circuit organization across different species and brain regions [5]. To address this question, we examined the influence of lineage on the response properties of neurons within the optic tectum, a visual brain area found in all vertebrates [6]. […]
June 24, 2015

Richards BA, Xia F, Santoro A, Husse J, Woodin MA, Josselyn SA, Frankland PW, “Patterns across multiple memories are identified over time”, Nature Neuroscience, 17(7), 981-986

Memories are not static but continue to be processed after encoding. This is thought to allow the integration of related episodes via the identification of patterns. Although this idea lies at the heart of contemporary theories of systems consolidation, it has yet to be demonstrated experimentally. Using a modified water-maze paradigm in which platforms are drawn stochastically from a spatial distribution, we found that mice were better at matching platform distributions 30 d compared to 1 d after training. Post-training time-dependent improvements in pattern matching were associated with increased sensitivity to new platforms that conflicted with the pattern. Increased sensitivity […]