Christian Ruff pays tribute to the late, great, Jon Driver by reviewing neural mechanisms of top-down control of attention and memory.
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Jutras et al find a relationship between hippocampal theta and visual exploration via saccadic eye movements. Saccades caused a theta reset that was predictive of subsequent recognition of visual images. Enhanced theta power before stimulus onset was also predictive of recognition.
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Eldar et al show that neural gain influences learning style. Subjects learned associations between pictures and reward. The association could be based on different stimulus dimensions and different people had different predispositions for one dimension or the other. Eldar et al assessed neural gain by pupil dilation (which is correlated with locus coeruleus norepinephrine activity) and found that the higher the gain, the more likely subjects were to follow their predispositions. The increase in gain was thought to boost the asymmetry of strength between different functional networks which are responsible for the predisposition in learning style.
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Miller Lab graduate student Simon Kornblith publishes a paper in Neuron from work in his old lab. By combining FMRI with electrode recording and stimulation, they found an area in the occipitotemporal cortex that has many scene-selective neurons, the lateral place patch (LPP). By stimulating it, they discover connections to several other cortical areas, including a medial place patch (MPP) in the parahippocampal gyrus. Elegant and important work, Simon, congratulations! Now, get back to work. ?
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Shenhav, Botvinick, and Cohen tie together a number of observations and notions into a new theory of ACC function: allocation of control based on an evaluation of the expected value of control (EVC).
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Pinto et al, despite enough statistical power, fail to see any correlation between performance of a top-down attention task (search) and a bottom-up attention task (singleton capture). They argue that top-down and bottom-up attention systems operate independently.
They cite our work, which suggests that top-down vs bottom up attention signals originate from prefrontal vs parietal cortex:
Buschman, T.J. and Miller, E.K. (2007) Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices. Science. 315: 1860-1862 The Scientist’s “Hot Paper” for October 2009. View PDF » -
Dipoppa and Gutkin propose a model of working memory in which gamma-beta oscillations gates access, theta oscillations protects working memory from distractions, and alpha oscillations clears out old memories.
This is consistent with our observations that beta helps from ensembles for rules held in working memory while alpha clears out a dominant ensemble so that a weaker one can be used:
Buschman, T.J., Denovellis, E.L., Diogo, C., Bullock, D. and Miller, E.K. (2012) Synchronous oscillatory neural ensembles for rules in the prefrontal cortex. Neuron, 76: 838-846. View PDF -
Zhang et al studied rule-based behavior by either having human subjects choose the rule themselves or by instructing them to the rule. They found context-dependent and context-independent (chosen vs instructed) rule representations in frontal and parietal cortex. This gives insight into the architecture of cognitive control.
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Cowell and Cottrell trained a computational model on images used in fMRI studies of object and face processing. They used multivariate pattern analysis and were able to replicate evidence for a specialized face area even though the model had no specialized processing for faces. The authors suggest that fMRI evidence for a specialized face area should be interpreted with caution.
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Excellent review of an important topic: Working memory capacity. The limitation in working memory capacity is the most objective, easily measured, and tractable property of conscious thought..
Luck and Vogel (2013)Miller Lab work cited:
Siegel, M., Warden, M.R., and Miller, E.K. (2009) Phase-dependent neuronal coding of objects in short-term memory. Proceedings of the National Academy of Sciences, 106: 21341-21346. View PDF »