A neuromorphic VLSI grid cell system

2012 ◽  
Author(s):  
Tarek M. Massoud ◽  
Timothy K. Horiuchi
Keyword(s):  
Grid Cell ◽  
Cell System ◽  
Neuromorphic Vlsi

scholarly journals Modulation of human intracranial theta oscillations during freely moving spatial navigation and memory

2019 ◽  
Author(s):  
Zahra M. Aghajan ◽  
Diane Villaroman ◽  
Sonja Hiller ◽  
Tyler J. Wishard ◽  
Uros Topalovic ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Spatial Memory ◽  
High Frequency ◽  
Medial Temporal Lobe ◽  
Spatial Navigation ◽  
Grid Cell ◽  
Cell System ◽  
Theta Oscillations ◽  
Neural Basis ◽  
Freely Moving

SummaryHow the human brain supports accurate navigation of a learned environment has been an active topic of research for nearly a century1–5. In rodents, the theta rhythm within the medial temporal lobe (MTL) has been proposed as a neural basis for fragmenting incoming information and temporally organizing experiences and is thus widely implicated in spatial and episodic memory6. In addition, high-frequency theta (~8Hz) is associated with navigation, and loss of theta results in spatial memory deficits in rats 7. Recently, high-frequency theta oscillations during ambulatory movement have been identified in humans8,9, though their relationship to spatial memory remains unexplored. Here, we were able to record MTL activity during spatial memory and navigation in freely moving humans immersed in a room-scale virtual reality (VR) environment. Naturalistic movements were captured using motion tracking combined with wireless VR in participants implanted with an intracranial electroencephalographic (iEEG) recording system for the treatment of epilepsy. We found that prevalence of theta oscillations across brain sites during both learning and recall of spatial locations during ambulatory navigation is critically linked to memory performance. This finding supports the reinstatement hypothesis of episodic memory—thought to underlie our ability to recreate a prior experience10–12—and suggests that theta prevalence within the MTL may act as a potential representational state for memory reinstatement during spatial navigation. Additionally, we found that theta power is hexadirectionally modulated13–15 as a function of the direction of physical movement, most prominently after learning has occurred. This effect bears a resemblance to the rodent grid cell system16 and suggests an analog in human navigation. Taken together, our results provide the first characterization of neural oscillations in the human MTL during ambulatory spatial memory tasks and provide a platform for future investigations of neural mechanisms underlying freely moving navigation in humans.

scholarly journals Path integration in place cells of developing rats

2018 ◽  
Vol 115 (7) ◽  
pp. E1637-E1646 ◽  
Author(s):  
Tale L. Bjerknes ◽  
Nenitha C. Dagslott ◽  
Edvard I. Moser ◽  
May-Britt Moser
Keyword(s):  
Path Integration ◽  
Grid Cell ◽  
Cell System ◽  
Place Cells ◽  
Postnatal Life ◽  
Motion Information ◽  
Grid Cells ◽  
Adult Rats ◽  
Self Motion ◽  
Made In

Place cells in the hippocampus and grid cells in the medial entorhinal cortex rely on self-motion information and path integration for spatially confined firing. Place cells can be observed in young rats as soon as they leave their nest at around 2.5 wk of postnatal life. In contrast, the regularly spaced firing of grid cells develops only after weaning, during the fourth week. In the present study, we sought to determine whether place cells are able to integrate self-motion information before maturation of the grid-cell system. Place cells were recorded on a 200-cm linear track while preweaning, postweaning, and adult rats ran on successive trials from a start wall to a box at the end of a linear track. The position of the start wall was altered in the middle of the trial sequence. When recordings were made in complete darkness, place cells maintained fields at a fixed distance from the start wall regardless of the age of the animal. When lights were on, place fields were determined primarily by external landmarks, except at the very beginning of the track. This shift was observed in both young and adult animals. The results suggest that preweaning rats are able to calculate distances based on information from self-motion before the grid-cell system has matured to its full extent.

scholarly journals Inferring circuit mechanisms from sparse neural recording and global perturbation in grid cells

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
John Widloski ◽  
Michael P Marder ◽  
Ila R Fiete
Keyword(s):  
Grid Cell ◽  
Neural Recording ◽  
Cell System ◽  
Network Activity ◽  
Connectivity Matrix ◽  
Neural Recordings ◽  
Systems Neuroscience ◽  
Global Circuit ◽  
Full Knowledge ◽  
Cortical Circuit

A goal of systems neuroscience is to discover the circuit mechanisms underlying brain function. Despite experimental advances that enable circuit-wide neural recording, the problem remains open in part because solving the ‘inverse problem’ of inferring circuity and mechanism by merely observing activity is hard. In the grid cell system, we show through modeling that a technique based on global circuit perturbation and examination of a novel theoretical object called the distribution of relative phase shifts (DRPS) could reveal the mechanisms of a cortical circuit at unprecedented detail using extremely sparse neural recordings. We establish feasibility, showing that the method can discriminate between recurrent versus feedforward mechanisms and amongst various recurrent mechanisms using recordings from a handful of cells. The proposed strategy demonstrates that sparse recording coupled with simple perturbation can reveal more about circuit mechanism than can full knowledge of network activity or the synaptic connectivity matrix.

Distance coding strategies based on the entorhinal grid cell system

2009 ◽  
Vol 22 (5-6) ◽  
pp. 536-543 ◽  
Author(s):  
Zsófia Huhn ◽  
Zoltán Somogyvári ◽  
Tamás Kiss ◽  
Péter Érdi
Keyword(s):  
Grid Cell ◽  
Cell System ◽  
Coding Strategies ◽  
Distance Coding

Using the extended quarter degree grid cell system to unify mapping and sharing of biodiversity data

2009 ◽  
Vol 47 (3) ◽  
pp. 382-392 ◽  
Author(s):  
R. Larsen ◽  
T. Holmern ◽  
S. D. Prager ◽  
H. Maliti ◽  
E. Røskaft
Keyword(s):  
Grid Cell ◽  
Cell System ◽  
Biodiversity Data

Robust path integration in the entorhinal grid cell system with hippocampal feed-back

2009 ◽  
Vol 101 (1) ◽  
pp. 19-34 ◽  
Author(s):  
Dávid Samu ◽  
Péter Erős ◽  
Balázs Ujfalussy ◽  
Tamás Kiss
Keyword(s):  
Path Integration ◽  
Grid Cell ◽  
Cell System

scholarly journals Environmental anchoring of grid-like representations minimizes spatial uncertainty during navigation

2017 ◽  
Author(s):  
Tobias Navarro Schröder ◽  
Benjamin W. Towse ◽  
Matthias Nau ◽  
Neil Burgess ◽  
Caswell Barry ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Motion Parallax ◽  
Grid Cell ◽  
Cell System ◽  
Neural Mechanisms ◽  
Spatial Uncertainty ◽  
Grid System ◽  
Virtual Navigation ◽  
Human Participants

SummaryMinimizing spatial uncertainty is essential for navigation, but the neural mechanisms remain elusive. Here we combine predictions of a simulated grid cell system with behavioural and fMRI measures in humans during virtual navigation. First, we showed that polarising cues produce anisotropy in motion parallax. Secondly, we simulated entorhinal grid cells in an environment with anisotropic information and found that self-location is decoded best when grid-patterns are aligned with the axis of greatest information. Thirdly, when exposing human participants to polarised virtual reality environments, we found that navigation performance is anisotropic, in line with the use of parallax. Eye movements showed that participants preferentially viewed polarising cues, which correlated with navigation performance. Finally, using fMRI we found that the orientation of grid-cell-like representations in entorhinal cortex anchored to the environmental axis of greatest parallax information, orthogonal to the polarisation axis. In sum, we demonstrate a crucial role of the entorhinal grid system in reducing uncertainty in representations of self-location and find evidence for adaptive spatial computations underlying entorhinal representations in service of optimal navigation.

scholarly journals Cortical microcircuit determination through global perturbation and sparse sampling in grid cells

2015 ◽  
Author(s):  
John Widloski ◽  
Ila R Fiete
Keyword(s):  
Grid Cell ◽  
Recurrent Network ◽  
Cell System ◽  
Network Activity ◽  
Orientation Tuning ◽  
Connectivity Matrix ◽  
Grid Cells ◽  
Neural Recordings ◽  
Global Circuit ◽  
Full Knowledge

Under modern interrogation, famously well-studied neural circuits such as that for orientation tuning in V1 are steadily giving up their secrets, but quite basic questions about connectivity and dynamics, including whether most computation is done by lateral processing or by selective feedforward summation, remain unresolved. We show here that grid cells offer a particularly rich opportunity for dissecting the mechanistic underpinnings of a cortical circuit, through a strategy based on global circuit perturbation combined with sparse neural recordings. The strategy is based on the theoretical insight that small perturbations of circuit activity will result in characteristic quantal shifts in the spatial tuning relationships between grid cells, which should be observable from multi-single unit recordings of a small subsample of the population. The predicted shifts differ qualitatively across candidate recurrent network mechanisms, and also distinguish between recurrent versus feedforward mechanisms. More generally, the proposed strategy demonstrates how sparse neu- ral recordings coupled with global perturbation in the grid cell system can reveal much more about circuit mechanism as it relates to function than can full knowledge of network activity or of the synaptic connectivity matrix.

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