It is widely thought that the volitional focusing of attention on a sensory input depends on top-down influences from the prefrontal cortex (PFC) acting on sensory cortex. However, much of the evidence for this is circumstantial. Halassa et al now provide direct evidence using optogenetic manipulation in mice. When they temporarily disrupted the PFC, mice had trouble focusing on a visual input in the face of an auditory distraction and vice-versa. Moreover, they went on to show that the PFC acts on sensory cortex, not directly but, through the thalamic reticular nucleus (TRN). Manipulation of thalamocortical circuits showed that behavior depended on PFC interactions with the thalamus, not on PFC interactions with sensory cortex. Further, thalamic activity was correlated with behavioral performance and its manipulation was causal to performance. This all suggests that attention is focused when the PFC acts on sensory cortex via the thalamus.
Wimmer, R. D., Schmitt, L. I., Davidson, T. J., Nakajima, M., Deisseroth, K., & Halassa, M. M. (2015). Thalamic control of sensory selection in divided attention. Nature.
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The Miller Lab uses experimental and theoretical approaches to study the neural basis of the high-level cognitive functions that underlie complex goal-directed behavior. ekmillerlab.mit.edu