Erez and Duncan elegantly show that the prefrontal cortex only cares about behavioral (goal) relevance. Human subjects detected whether images from one of two visual categories were present in a scene. The prefrontal cortex did not distinguish between the two categories but did distinguish whether an image was one the two categories (i.e., a target) or not (a non-target).
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Abstract context representations are not just in the prefrontal cortex, they are also in the amygdala. The authors also report that errors were associated with reduced context encoding. Cool.
Saez, A., et al. “Abstract Context Representations in Primate Amygdala and Prefrontal Cortex.” Neuron 87.4 (2015): 869-881.
Preview by Cohen and Paz:
Cohen, Yarden, and Rony Paz. “It All Depends on the Context, but Also on the Amygdala.” Neuron 87.4 (2015): 678-680. -
Genovesio et al show that neurons in the prefrontal cortex can encode stimulus duration and distance. Importantly, neural selectivity was highly context dependent. Neurons seemed to have different, unrelated, selectivity in different behavioral contexts This adds to growing evidence that PFC neurons are not simple filters or have single “triggers”. Instead, PFC neurons are non-linear multitaskers that participate in many different neural ensembles.
Further reading:
Yuste, Rafael. “From the neuron doctrine to neural networks.” Nature Reviews Neuroscience (2015).Rigotti, M., Barak, O., Warden, M.R., Wang, X., Daw, N.D., Miller, E.K., & Fusi, S. (2013) The importance of mixed selectivity in complex cognitive tasks. Nature, 497, 585-590, doi:10.1038/nature12160. View PDF
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Pinto and Dan use Ca2+ imaging to identify different subtypes of inhibitory neurons in the mouse prefrontal cortex. They found that different subtypes encode different aspects of the task. By contrast, excitatory neurons are diverse and their task-related activity by cortical layer.
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Micheli et al find that during sustained attention, successful near-threshold visual detection is predicted by increased phase synchrony between the frontal and temporal/parietal cortex. They suggest that beta coherent states in the prefrontal cortex regulate top-down expectancy and coupling with posterior cortex facilitates the gating of that information.
Evidence for the role of beta in top-down selection continues to mount.
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As the authors pun, the claustrum is worthy of attention given its extensive connections with the cortex. Goll, Atlan, and Citri propose a new hypothesis for the role of inputs from the prefrontal cortex to the claustrum in top-down attentional selection. The claustrum acts to control the output of selected cortical representations at the expense of others.
Goll, Yael, Gal Atlan, and Ami Citri. “Attention: the claustrum.” Trends in Neurosciences (2015).
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Nice review of the mechanisms and role of dopamine receptors in the prefrontal cortex.
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The title says it all (almost). Voloh et al found increased theta-gamma cross-frequency coupling between the anterior cingulate and prefrontal cortex during covert shifts of attention.
Theta–gamma coordination between anterior cingulate and prefrontal cortex indexes correct attention shifts
Benjamin Voloh, Taufik A. Valiante, Stefan Everling, and Thilo Womelsdorf
PNAS 2015 ; published ahead of print June 22, 2015, doi:10.1073/pnas.1500438112 -
Tremblay et al decode the allocation of attention, stimulus location, and saccade from local field potentials in a frequency-dependent matter. Decoding from LFPs was more stable across time than decoding from spikes.
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Working memory has long been thought to depend on sustained firing of cortical neurons. However, single neurons showing unbroken sustained activity is rare and average population activity is often only strong near the end of a memory delay. Mark Stokes presents the intriguing hypothesis for activity-silent working memory. He suggests that working memory depends on patterns of functional connectivity between neurons, not sustained activity.