We discuss the concept of colimitation of primary productivity in aquatic environments, with an emphasis on reconciling this concept with recent advances in marine bioinorganic chemistry. Colimitations are divided into three categories on the basis of their mathematical formulations and visualizations: type I, independent nutrient colimitation (e.g., N and P); type II, biochemical substitution colimitation (e.g., Co and Zn); and type III, biochemically dependent colimitation (e.g., Zn and C), where the ability to acquire one nutrient is dependent upon sufficient supply of another. The potential for colimitation occurring in the marine environment and the critical importance of understanding nutrient bioavailability are discussed.

The thalamic reticular nucleus (TRN) is hypothesized to regulate neocortical rhythms and behavioral state. Using optogenetics and multi-electrode recording in behaving mice, we found that brief selective drive of TRN switched thalamocortical firing mode from tonic to bursting and generated state-dependent neocortical spindles. These findings provide causal support for the TRN in state-regulation in vivo and introduce a new model for addressing the role of this structure in behavior.

Peripheral sensory organs provide the first transformation of sensory information, and understanding how their physical embodiment shapes transduction is central to understanding perception. We report the characterization of surface transduction during active sensing in the rodent vibrissa sensory system, a widely used model. Employing high-speed videography, we tracked vibrissae while rats sampled rough and smooth textures. Variation in vibrissa length predicted motion mean frequencies, including for the highest velocity events, indicating that biomechanics, such as vibrissa resonance, shape signals most likely to drive neural activity. Rough surface contact generated large amplitude, high-velocity "stick-slip-ring" events, while smooth surfaces generated smaller and more regular stick-slip oscillations. Both surfaces produced velocities exceeding those applied in reduced preparations, indicating active sensation of surfaces generates more robust drive than previously predicted. These findings demonstrate a key role for embodiment in vibrissal sensing and the importance of input transformations in sensory representation.