Representation of comparison signals in cortical area MT during a delayed direction discrimination task

Lui, Leo; Pasternak, Tatiana

doi:10.1152/jn.00016.2011

Cited by 43 publications

(61 citation statements)

References 35 publications

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“…MT neurons can show a direction-selective response to coherent motion far outside of the classic RF-even when the motion is located in the ipsilateral hemifield (Zaksas and Pasternak 2005). It is thought that this information arrives in MT through feedback connections, likely from prefrontal cortex (Hussar and Pasternak 2010;Lui and Pasternak 2011;Zaksas and Pasternak 2006). The same mechanism could explain why LFP power was correlated with the subject's detection performance when there was no coherent motion pulse in the RF.…”

Section: Discussionmentioning

confidence: 99%

Dynamics of the functional link between area MT LFPs and motion detection

Smith

Beliveau

Schoen

et al. 2015

Journal of Neurophysiology

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-The evolution of a visually guided perceptual decision results from multiple neural processes, and recent work suggests that signals with different neural origins are reflected in separate frequency bands of the cortical local field potential (LFP). Spike activity and LFPs in the middle temporal area (MT) have a functional link with the perception of motion stimuli (referred to as neural-behavioral correlation). To cast light on the different neural origins that underlie this functional link, we compared the temporal dynamics of the neural-behavioral correlations of MT spikes and LFPs. Wide-band activity was simultaneously recorded from two locations of MT from monkeys performing a threshold, two-stimuli, motion pulse detection task. Shortly after the motion pulse occurred, we found that high-gamma (100 -200 Hz) LFPs had a fast, positive correlation with detection performance that was similar to that of the spike response. Beta (10 -30 Hz) LFPs were negatively correlated with detection performance, but their dynamics were much slower, peaked late, and did not depend on stimulus configuration or reaction time. A late change in the correlation of all LFPs across the two recording electrodes suggests that a common input arrived at both MT locations prior to the behavioral response. Our results support a framework in which early high-gamma LFPs likely reflected fast, bottom-up, sensory processing that was causally linked to perception of the motion pulse. In comparison, late-arriving beta and highgamma LFPs likely reflected slower, top-down, sources of neuralbehavioral correlation that originated after the perception of the motion pulse.behavior; cortex; local field potential; MT; vision VISUALLY GUIDED DECISIONS involve multiple neural components, such as sensory and evaluative stages (Gold and Shadlen 2007). But when and how do different neural components make their contribution? This question is typically studied by measuring the trial-by-trial correlation between cortical spiking and perceptual behavior (Parker and Newsome 1998). Interpreting these neural-behavioral correlations, however, is difficult because they do not tell us whether fluctuations in neural activity directly produced fluctuations in perception. Thus additional data are needed to better understand and model the causality behind observed neural-behavioral correlations.Recent efforts have focused on the local field potential (LFP) and suggest that distinct neurophysiological processes can be measured from different LFP frequency bands (Bastos et al. 2015;Katzner et al. 2009;Kopell et al. 2010;Siegel et al. 2012). Gamma-band LFPs are thought to carry stimulus information (Belitski et al. 2010) and reflect the synaptic inputs from earlier stages (Khawaja et al. 2009) and the activity of local neurons (Ray and Maunsell 2011a), while beta-band LFPs may reflect intercortical feedback (Saalmann et al. 2007). Correspondingly, attention increases gamma LFP power in a manner similar to that of local spiking activity, while beta power is attenuated (Khaya...

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Section: Discussionmentioning

confidence: 99%

Dynamics of the functional link between area MT LFPs and motion detection

Smith

Beliveau

Schoen

et al. 2015

Journal of Neurophysiology

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“…At the same time, however, sustained and content-specific patterns of spiking persist in lPFC, and this persistent spiking in PFC may provide important top-down feedback to MT that induces a locally spike-silent but content-specific change in LFPs (Figure 8). Finally, under this coding scheme, the presentation of a matching test stimulus at the end of the delay period may more easily trigger the re-emergence of the same spiking pattern that was present in MT during the encoding of the sample stimulus, as this pattern is held in a ‘primed’ state during the STM delay period via the continuous top-down modulation of LFPs (see also: Lui & Pasternak, 2011 for conceptually related ideas). Importantly, because this tonic top-down input to MT is generated via sustained spiking activity in distal lPFC, the content-specific patterns of sub-threshold membrane potentials in MT could co-exist with and persevere through bouts of local spiking in MT that are evoked by other distracting stimuli presented during the delay period.…”

Section: Alternate Mechanisms Of Storage – Dynamic and Activity (Spikmentioning

confidence: 99%

Neural mechanisms of information storage in visual short-term memory

2016

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The capacity to briefly memorize fleeting sensory information supports visual search and behavioral interactions with relevant stimuli in the environment. Traditionally, studies investigating the neural basis of visual short term memory (STM) have focused on the role of prefrontal cortex (PFC) in exerting executive control over what information is stored and how it is adaptively used to guide behavior. However, the neural substrates that support the actual storage of content-specific information in STM are more controversial, with some attributing this function to PFC and others to the specialized areas of early visual cortex that initially encode incoming sensory stimuli. In contrast to these traditional views, I will review evidence suggesting that content-specific information can be flexibly maintained in areas across the cortical hierarchy ranging from early visual cortex to PFC. While the factors that determine exactly where content-specific information is represented are not yet entirely clear, recognizing the importance of task-demands and better understanding the operation of non-spiking neural codes may help to constrain new theories about how memories are maintained at different resolutions, across different timescales, and in the presence of distracting information.

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“…Two reciprocally interconnected cortical regions relevant to these tasks are motion-processing area MT and the dorsolateral region of the prefrontal cortex (PFC) associated with sensory maintenance and executive control (Barbas, 1988; Miller and Cohen, 2001; Petrides and Pandya, 2006). Our recent work showed that MT neurons, in addition to exhibiting direction selective (DS) responses to motion, carried some stimulus-related activity during the delay and their responses during the comparison phase of the task reflected the previously presented direction (Zaksas and Pasternak, 2006; Lui and Pasternak, 2011). …”

Section: Introductionmentioning

confidence: 99%

Memory-Guided Sensory Comparisons in the Prefrontal Cortex: Contribution of Putative Pyramidal Cells and Interneurons

Hussar¹,

Pasternak²

2012

J. Neurosci.

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Comparing two stimuli that occur at different times demands the coordination of bottom-up and top-down processes. It has been hypothesized that the dorsolateral prefrontal (PFC) cortex, the likely source of top-down cortical influences, plays a key role in such tasks, contributing to both maintenance and sensory comparisons. We examined this hypothesis by recording from the PFC of monkeys comparing directions of two moving stimuli, S1 and S2, separated by a memory delay. We determined the contribution of the two principal cell types to these processes, by classifying neurons into broad-spiking (BS) putative pyramidal cells and narrow-spiking (NS) putative local interneurons. During the delay, BS cells were more likely to exhibit anticipatory modulation and to represent the remembered direction. While this representation was transient, appearing at different times in different neurons, it weakened when direction was not task-relevant, suggesting its utility. During S2, both putative cell types showed comparison-related activity modulations. These modulations were of two types, each carried by different neurons, which either preferred trials with stimuli moving in the same direction or trials with stimuli of different directions. These comparison effects were strongly correlated with choice, suggesting their role in circuitry underlying decision-making. These results provide the first demonstration of distinct contributions made by principal cell types to memory-guided perceptual decisions. During sensory stimulation both cell types represent behaviorally relevant stimulus features, contributing to comparison and decision-related activity. However in the absence of sensory stimulation, putative pyramidal cells dominated, carrying information about the elapsed time and the preceding direction.

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Representation of comparison signals in cortical area MT during a delayed direction discrimination task

Cited by 43 publications

References 35 publications

Dynamics of the functional link between area MT LFPs and motion detection

Dynamics of the functional link between area MT LFPs and motion detection

Neural mechanisms of information storage in visual short-term memory

Memory-Guided Sensory Comparisons in the Prefrontal Cortex: Contribution of Putative Pyramidal Cells and Interneurons

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