Abstract

Please join us for our fortnightly journal club online via zoom where two presenters will jointly present a topic together. The next topic is ‘Structured vs random mixed selectivity in frontal cortex’ presented by Jake Stroud and Michal Wojcik.

Zoom information: https://us02web.zoom.us/j/84958321096?pwd=dFpsYnpJYWVNeHlJbEFKbW1OTzFiQT09 Meeting ID: 849 5832 1096 Passcode: 506576

Summary: Historically, neuroscientists have focused on analysing what single neurons represent (ie what a neuron is selective to). This has been a fruitful approach for understanding several brain areas (such primary visual cortex), however, more recent studies suggest that this approach may not apply so readily to frontal cortices. This is mainly because neurons in frontal cortex have been shown to be selective to multiple task features (they display mixed selectivity). Theoretical studies suggest that if neurons display random mixed selectivity, this allows a brain area to perform many complex tasks. Following this, empirical studies have found evidence of such random mixed selectivity in frontal cortex, however several recent papers (both theoretical and empirical) suggest the opposite: that non-random (ie more classical structured) selectivity is actually expected for certain tasks. In this journal club we will review these studies and we’ll offer some theoretical justification as to why some studies find evidence for random mixed selectivity and why others find evidence for structured selectivity.

Key papers:

The importance of mixed selectivity in complex cognitive tasks, Rigotti et al., Nature, 2013, https://www.nature.com/articles/nature12160

A category-free neural population supports evolving demands during decision-making, Raposo et al., Nature Neurosi., 2014, https://www.nature.com/articles/nn.3865

Frontal cortex neuron types categorically encode single decision variables, Hirokawa et al., Nature, 2019, https://www.nature.com/articles/s41586-019-1816-9

The role of population structure in computations through neural dynamics, Dubreuil et al., bioRxiv, 2021, https://www.biorxiv.org/content/10.1101/2020.07.03.185942v2.full