Nice demo showing that cues that automatically draw attention can modulate activity in primary visual cortex.
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Stoianov et al show how two mechanisms interact in the prefrontal cortex to support goal-directed behavior. Categorization extracts behavioral abstractions (states) and reward-driven processes assign value to these categories
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Ranganath and Jacob walk us through the role that prefrontal cortex dopamine plays in cognition.
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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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Ester et al use human imaging to show that the parietal and frontal cortices maintain information about specific visual stimuli held in memory. This shows that top-down control of working memory and storage functions are not so separate. We kind of knew that from the neuron level, but very nice demo in humans.
Ester, Edward F., Thomas C. Sprague, and John T. Serences. “Parietal and Frontal Cortex Encode Stimulus-Specific Mnemonic Representations during Visual Working Memory.” Neuron (2015).
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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. -
Advance copy of our new paper:
Kornblith, S. Buschman, T.J., and Miller, E.K. (2015) Stimulus Load and Oscillatory Activity in Higher Cortex. Cerebral Cortex. doi: 10.1093/cercor/bhv182 Journal linkAbstract:
Exploring and exploiting a rich visual environment requires perceiving, attending, and remembering multiple objects simultaneously. Recent studies have suggested that this mental “juggling” of multiple objects may depend on oscillatory neural dynamics. We recorded local field potentials from the lateral intraparietal area, frontal eye fields, and lateral prefrontal cortex while monkeys maintained variable numbers of visual stimuli in working memory. Behavior suggested independent processing of stimuli in each hemifield. During stimulus presentation, higher-frequency power (50–100 Hz) increased with the number of stimuli (load) in the contralateral hemifield, whereas lower-frequency power (8–50 Hz) decreased with the total number of stimuli in both hemifields. During the memory delay, lower-frequency power increased with contralateral load. Load effects on higher frequencies during stimulus encoding and lower frequencies during the memory delay were stronger when neural activity also signaled the location of the stimuli. Like power, higher-frequency synchrony increased with load, but beta synchrony (16–30 Hz) showed the opposite effect, increasing when power decreased (stimulus presentation) and decreasing when power increased (memory delay). Our results suggest roles for lower-frequency oscillations in top-down processing and higher-frequency oscillations in bottom-up processing. -
Fries and colleagues report that coupling between theta and gamma rhythms support attention. The 4 Hz phase of gamma oscillations predicted the accuracy of the subject’s ability to detect stimulus dimming.
Landau, Ayelet Nina, et al. “Distributed Attention Is Implemented through Theta-Rhythmic Gamma Modulation.” Current Biology (2015).
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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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Voytek et al provide more evidence that oscillatory dynamics play a critical role in neural communication and cognitive control. As humans performed tasks that required greater abstraction, there was an increase in theta synchrony between anterior and posterior frontal cortex. This may allow more anterior frontal cortex is communicate the higher level goals to motor cortex.