Saccade direction encoding in the primate entorhinal cortex during visual exploration

Killian, Nathaniel J.; Potter, Steve M.; Buffalo, Elizabeth A.

doi:10.1073/pnas.1417059112

Cited by 70 publications

(80 citation statements)

References 51 publications

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“…Congruent with a neural spatial map of where the a primate is looking, entorhinal cells have been identified that provide a grid-like representation of fixation locations on a computer monitor as monkeys freely viewed images (Killian et al, 2012; Meister et al). In addition, similar to heading direction cells in rodents (Taube, Muller, and Ranck, 1990), entorhinal neurons were recently found to be selective for the direction of the upcoming or previously-completed saccade regardless of where the monkey was currently looking (Killian et al, 2015). Although the details regarding these different reference frames across species and brain structures remain to be resolved, a more central remaining mystery is how MTL neurons with spatial representation potentially influence orienting behavior guided by memory.…”

Section: Why Study the Neurophysiology Of Memory Through Eye Movemmentioning

confidence: 94%

“…By recording and stimulating in two brain structures at different time points relative to an eye movement, MTL connectivity with the inferotemporal cortex, known for visual object processing, was shown to peak 100 ms after fixation even for saccades made in darkness (Sobotka, Zuo, and Ringo, 2002). Additionally, neurons coding for the direction of a saccade have recently been reported in the entorhinal cortex (Killian, Potter, and Buffalo, 2015). Taken together, these findings demonstrate the relevance of eye movement itself to MTL processing.…”

Section: Why Study the Neurophysiology Of Memory Through Eye Movemmentioning

confidence: 99%

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Getting directions from the hippocampus: The neural connection between looking and memory

Meister

Buffalo

2016

Neurobiology of Learning and Memory

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Investigations into the neural basis of memory in human and non-human primates have focused on the hippocampus and associated medial temporal lobe (MTL) structures. However, how memory signals from the hippocampus affect motor actions is unknown. We propose that approaching this question through eye movement, especially by assessing the changes in looking behavior that occur with experience, is a promising method for exposing neural computations within the hippocampus. Here, we review how looking behavior is guided by memory in several ways, some of which have been shown to depend on the hippocampus, and how hippocampal neural signals are modulated by eye movements. Taken together, these findings highlight the need for future research on how MTL structures interact with the oculomotor system. Probing how the hippocampus reflects and impacts motor output during looking behavior renders a practical path to advance our understanding of the hippocampal memory system.

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Section: Why Study the Neurophysiology Of Memory Through Eye Movemmentioning

confidence: 94%

Section: Why Study the Neurophysiology Of Memory Through Eye Movemmentioning

confidence: 99%

Getting directions from the hippocampus: The neural connection between looking and memory

Meister

Buffalo

2016

Neurobiology of Learning and Memory

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“…Despite the overall similarity between the anatomies of the rat and human EC, primate data suggest that the human EC receives a larger contribution from higher visual cortical areas (25). In primates, behavior as restricted as eye movements over static visual displays is sufficient to elicit spatially periodic ("grid-like") patterns of neuronal activity that correlate with saccade direction (26,27). Interspecies differences in sensory processing make the spatial representations of place cells display marked variability.…”

Section: Significancementioning

confidence: 99%

Context-dependent spatially periodic activity in the human entorhinal cortex

Nádasdy

Nguyen

Török

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The spatially periodic activity of grid cells in the entorhinal cortex (EC) of the rodent, primate, and human provides a coordinate system that, together with the hippocampus, informs an individual of its location relative to the environment and encodes the memory of that location. Among the most defining features of grid-cell activity are the 60°rotational symmetry of grids and preservation of grid scale across environments. Grid cells, however, do display a limited degree of adaptation to environments. It remains unclear if this level of environment invariance generalizes to human grid-cell analogs, where the relative contribution of visual input to the multimodal sensory input of the EC is significantly larger than in rodents. Patients diagnosed with nontractable epilepsy who were implanted with entorhinal cortical electrodes performing virtual navigation tasks to memorized locations enabled us to investigate associations between grid-like patterns and environment. Here, we report that the activity of human entorhinal cortical neurons exhibits adaptive scaling in grid period, grid orientation, and rotational symmetry in close association with changes in environment size, shape, and visual cues, suggesting scale invariance of the frequency, rather than the wavelength, of spatially periodic activity. Our results demonstrate that neurons in the human EC represent space with an enhanced flexibility relative to neurons in rodents because they are endowed with adaptive scalability and context dependency.grid cell | spatial memory | entorhinal cortex | single unit | human

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“…Research regarding the functional significance of the distinct regions of the ERC in human and non-human primates is just emerging; however, in primates, cells in posterior ERC code for saccade direction during visual exploration (Killian, Potter, Buffalo, 2015).…”

Section: Cc-by-nc-ndmentioning

confidence: 99%

Modelling the influence of the hippocampal memory system on the oculomotor system

Ryan

Shen

Kacollja

et al. 2018

Preprint

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Visual exploration is influenced by what we remember. Amnesic cases, who have damage to the hippocampus (HC) and/or extended medial temporal lobe (MTL), show alterations in their gaze patterns relative to neurologically intact adults on tasks of memory. Recent work has revealed an extensive set of polysynaptic connections between the hippocampus and oculomotor system. However, little is known about how activation within the HC may impact the oculomotor system. In the present work, we conducted simulations of the functional interactions between the two systems by leveraging a computational modeling platform (The Virtual Brain; thevirtualbrain.org) with structural connectivity as defined through the CoCoMac database and tractography data from macaques. We examined how activity dissipated throughout the pre-identified polysynaptic pathways when subregions of the HC, and regions of the broader MTL, were stimulated. Stimulation of CA1, pre-and para-subiculum, and entorhinal, perirhinal, and parahippocampal cortices each resulted in observable responses in regions of the oculomotor system, including the frontal eye fields. Stimulation of the subiculum and CA3 did not culminate in responses in the frontal eye fields, and in such instances, activity was also not observed in parietal areas, posterior cingulate, and V4, suggesting that these regions may be important for transmitting information from the HC to regions within the oculomotor system. These findings provide novel evidence that activity originating within the HC and/or MTL may travel through specific nodes and pathways to influence the oculomotor system.. CC-BY-NC-ND 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/303511 doi: bioRxiv preprint first posted online Apr. 18, 2018; Significance StatementNo major account of oculomotor (eye movement) guidance considers the influence of the hippocampus and broader medial temporal lobe system, yet it is clear that information is exchanged between the two systems. Prior experience influences current viewing, and cases of amnesia due to compromised hippocampal/medial temporal lobe function show specific alterations in viewing behaviour. Using computational modeling, we show that stimulation of subregions of the hippocampus and regions of the medial temporal lobe results in observable responses in brain regions that are involved in the control of eye movements. These findings suggest that information from memory may be readily provided to the oculomotor system, and calls for a reconsideration of the neural circuitry involved in oculomotor guidance.

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Saccade direction encoding in the primate entorhinal cortex during visual exploration

Cited by 70 publications

References 51 publications

Getting directions from the hippocampus: The neural connection between looking and memory

Getting directions from the hippocampus: The neural connection between looking and memory

Context-dependent spatially periodic activity in the human entorhinal cortex

Modelling the influence of the hippocampal memory system on the oculomotor system

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