Big-ass survey of cortex by Gray and crew:

Dotson, N. M., Hoffman, S. J., Goodell, B., & Gray, C. M. (2018). Feature-Based Visual Short-Term Memory Is Widely Distributed and Hierarchically OrganizedNeuron.

Gradual progression from sensory to task-related processing in cerebral cortex
Scott L. Brincat*, Markus Siegel*, Constantin von Nicolai, Earl K. Miller


Somewhere along the cortical hierarchy, behaviorally relevant information is distilled from raw sensory inputs. We examined how this transformation progresses along multiple levels of the hierarchy by comparing neural representations in visual, temporal, parietal, and frontal cortices in monkeys categorizing across three visual domains (shape, motion direction, color). Representations in visual areas MT and V4 were tightly linked to external sensory inputs. In contrast, prefrontal cortex (PFC) largely represented the abstracted behavioral relevance of stimuli (task rule, motion category, color category). Intermediate-level areas — posterior inferotemporal (PIT), lateral intraparietal (LIP), and frontal eye fields (FEF) — exhibited mixed representations. While the distribution of sensory information across areas aligned well with classical functional divisions — MT carried stronger motion information, V4 and PIT carried stronger color and shape information — categorical abstraction did not, suggesting these areas may participate in different networks for stimulus-driven and cognitive functions. Paralleling these representational differences, the dimensionality of neural population activity decreased progressively from sensory to intermediate to frontal cortex. This shows how raw sensory representations are transformed into behaviorally relevant abstractions and suggests that the dimensionality of neural activity in higher cortical regions may be specific to their current task.

Nice review and test of a hypothesis about the role of transient beta oscillations in cortical processing.

Sherman et al (2016) Neural mechanisms of transient neocortical beta rhythms: Converging evidence from humans, computational modeling, monkeys, and mice

Wang and colleagues present a model of the whole cortex (almost).  A gradient of synaptic excitation results in sensory areas show fast responses while cognitive areas show slow integrative activity.  Different temporal hierarchies/dynamics coexist in the same networks.

A Large-Scale Circuit Mechanism for Hierarchical Dynamical Processing in the Primate Cortex
Rishidev Chaudhuri, Kenneth Knoblauch, Marie-Alice Gariel,  Henry Kennedy, Xiao-Jing Wang
Neuron, Volume 88, Issue 2, 21 October 2015, Pages 419–431

In general, this fits pretty well with our recent study of actual neural dynamics across the cortex:
Siegel, M., Buschman, T.J., and Miller, E.K. (2015) Cortical information flow during flexible sensorimotor decisions.  Science. 19 June 2015: 1352-1355.  View PDF

Kozma et al report brief periods of de-synchronization followed by intense synchronization.  They speculate that this may correspond to an “aha!” moment when things “fall into place”.  Interesting.

Kozma, Robert, Jeffery Jonathan Davis, and Walter J. Freeman. “Synchronized minima in ECoG power at frequencies between beta-gamma oscillations disclose cortical singularities in cognition.” Journal of Neuroscience and Neuroengineering 1.1 (2012): 13-23.

Siegel, M., Buschman, T.J., and Miller, E.K. (2015) Cortical information flow during flexible sensorimotor decisions.  Science19 June 2015: 1352-1355.

During flexible behavior, multiple brain regions encode sensory inputs, the current task, and choices.  It remains unclear how these signals evolve. We simultaneously recorded neuronal activity from six cortical regions (MT, V4, IT, LIP, PFC and FEF) of monkeys reporting the color or motion of stimuli. Following a transient bottom-up sweep, there was a top-down flow of sustained task information from frontoparietal to visual cortex.  Sensory information flowed from visual to parietal and prefrontal cortex. Choice signals developed simultaneously in frontoparietal regions and travelled to FEF and sensory cortex. This suggests that flexible sensorimotor choices emerge in a frontoparietal network from the integration of opposite flows of sensory and task information.

From the MIT News Office:
Uncovering a dynamic cortex
Neuroscientists show that multiple cortical regions are needed to process information.

Markov et al provide an excellent review and analysis of the anatomy of visual cortex and beyond.  The show that supragranular layers contain highly segregated feedforward and feedback pathways.  Their analysis of the detailed anatomy revealed that feedback connections are more numerous and have more levels than feedforward connections.  By contrast, infragranular layers are less hierarchical and may be more involved in point-to-point cross-talk than feedforward or feedback processing.  Markov et al map the feedforward and feedback pathways to recent observations that feedforward vs feedback communication is supported by gamma vs beta cortical oscillations.

For more on the role of oscillations in feedforward and feedback cortical communication, see our review:
Miller, E.K. and Buschman, T.J. (2013) Cortical circuits for the control of attention.  Current Opinion in Neurobiology.  23:216–222  View PDF »