Correlated variability modifies working memory fidelity in primate prefrontal neuronal ensembles

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Computational Neuroscience

Background:

• Neurons in the primate lateral prefrontal cortex (LPFC) sustain firing to encode working memory (WM) representations.
• This sustained activity is hypothesized to result from recurrent dynamics within neuronal ensembles.

Purpose of the Study:

• To test the hypothesis that recurrent dynamics underlie WM representations in LPFC.
• To investigate how spike count correlations (rSC) within LPFC neuronal ensembles impact WM coding during a spatial WM task.

Main Methods:

• Utilized microelectrode arrays to record neuronal activity in the LPFC during a spatial WM task.
• Analyzed pairwise spike count correlations (rSC) between neurons.
• Employed linear decoding to assess the influence of rSC structure on information coding.

Main Results:

• Observed rSC patterns indicating stronger coupling between similarly tuned neurons and increased inhibition between dissimilar neurons.
• Demonstrated that rSC structure can facilitate or impair WM coding based on ensemble size and neuron tuning.
• Showed that optimized subensembles, even with poorly selective neurons, enhanced coding fidelity via rSC structure modulation.

Conclusions:

• Recurrent dynamics, reflected in rSC patterns, are crucial for WM-related activity in LPFC.
• The ensemble-level rSC structure significantly contributes to the fidelity of WM representations.
• WM coding in LPFC emerges from a synergy between individual neuron properties and multidimensional ensemble dynamics.