Midbrain learning

August 5, 2017

Richards BA, Frankland PW, “The Persistence and Transience of Memory”, Neuron, 94 (6), 1071-1074

The predominant focus in the neurobiological study of memory has been on remembering (persistence). However, recent studies have considered the neurobiology of forgetting (transience). Here we draw parallels between neurobiological and computational mechanisms underlying transience. We propose that it is the interaction between persistence and transience that allows for intelligent decision-making in dynamic, noisy environments. Specifically, we argue that transience (1) enhances flexibility, by reducing the influence of outdated information on memory-guided decision-making, and (2) prevents overfitting to specific past events, thereby promoting generalization. According to this view, the goal of memory is not the transmission of information through time, […]
January 31, 2017

Raimondo JV, Richards BA, Woodin MA, “Neuronal chloride and excitability — the big impact of small changes”, Current Opinion in Neurobiology, 43, 35-42

Synaptic inhibition is a critical regulator of neuronal excitability, and in the mature brain the majority of synaptic inhibition is mediated by Cl−-permeable GABAA receptors. Unlike other physiologically relevant ions, Cl− is dynamically regulated, and alterations in the Cl−gradient can have significant impact on neuronal excitability. Due to changes in the neuronal Cl− concentration, GABAergic transmission can bidirectionally regulate the induction of excitatory synaptic plasticity and gate the closing of the critical period for monocular deprivation in visual cortex. GABAergic circuitry can also provide a powerful restraining mechanism for the spread of excitation, however Cl− extrusion mechanisms can become overwhelmed […]
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

Multisensory integration and learning in the superior colliculus

Deep in an evolutionarily ancient region of our brains, called the superior colliculus, neurons combine visual, auditory and tactile information to generate a map of important objects in the world and orient our bodies towards or away from them. This is critical for our ability to rapidly, and unconsciously respond to things around us. However, the capabilities of the superior colliculus are not hardwired. Rather, they develop in early life through a process of sensory-driven learning. We are interested in understanding what different genetic sub-types of neurons exist in the colliculus and what their functional roles are in multisensory integration. […]