Stokes, M. G. | bioRxiv Science

bioRxiv2017

Intrinsic neuronal dynamics predict distinct functional roles during working memory

Working memory (WM) is characterized by the ability to maintain stable representations over time; however, neural activity associated with WM maintenance can be highly dynamic. We explore whether complex population coding dynamics during WM relate to the intrinsic temporal properties of single neurons in lateral prefrontal cortex (lPFC), the frontal eye fields (FEF) and lateral intraparietal cortex (LIP) of two monkeys (Macaca mulatta). We found that cells with short timescales carried memory information relatively early during memory encoding in lPFC; whereas long timescale cells played a greater role later during processing, dominating coding in the delay period. We also observed a link between functional connectivity at rest and intrinsic timescale in FEF and LIP. Our results indicate that individual differences in the temporal processing capacity predicts complex neuronal dynamics during WM; ranging from rapid dynamic encoding of stimuli to slower, but stable, maintenance of mnemonic information.

neuroscience↗

bioRxiv2017

Decoding The Influence Of Anticipatory States On Visual Perception In The Presence Of Temporal Distractors

While it has long been recognised that anticipatory states amplify early EEG responses to visual targets in humans, it remains unclear how such modulations relate to the actual content of the neural representation, and help prioritise targets among temporally competing distractor stimuli. Using multivariate orientation decoding of high temporal resolution EEG recordings, we first demonstrate that anticipation also increases the amount of stimulus-identity information contained in these early brain responses. By characterising the influence of temporally adjacent distractors on target identity decoding, we additionally reveal that anticipation does not just attenuate distractor interference on target representations but, instead, delay it. Enhanced target decoding and distractor resistance are further predicted by the attenuation of posterior 8-14 Hz alpha oscillations. These findings offer several novel insights into how anticipatory states shape neural representations in service of resolving sensory competition in time, and they highlight the potential of non-invasive multivariate electrophysiology to track cognitive influences on perception in tasks with rapidly changing displays.\n\nHighlightsO_LIAnticipatory states help resolve visual competition in time\nC_LIO_LIAnticipation enhances early target coding and delays distractor interference\nC_LIO_LIAttenuated alpha oscillations also enhance target coding and distractor resistance\nC_LIO_LIEEG decoding is a powerful tool for tracking percepts in rapidly changing displays\nC_LI\n\nSignificance statementWhile the neural mechanisms by which anticipatory states help prioritise inputs that compete in space have received ample scientific investigation, the mechanisms by which the human brain accomplishes such prioritisation for inputs that compete in time remain less well understood. We used high temporal resolution EEG decoding to individuate (and track in time) neural information linked to visual target and distractors stimuli that were presented in close temporal proximity. This revealed that anticipatory states help resolve temporally competing percepts by a combination of enhanced target (but not distractor) coding as well as delayed interference on this target coding caused by temporally adjacent distractors - thus allocating a \"protective temporal window\" for high-fidelity target processing.

neuroscience↗