scholarly journals Decoding 3D spatial location across saccades in human visual cortex

2020 ◽  
Author(s):  
Xiaoli Zhang ◽  
Christopher M Jones ◽  
Julie D Golomb
Keyword(s):  
Visual Cortex ◽  
Eye Movements ◽  
Pattern Analysis ◽  
Critical Role ◽  
Visual Signals ◽  
Depth Information ◽  
Eye Position ◽  
Spatial Representations ◽  
Human Visual Cortex ◽  
Fixation Position

AbstractVisual signals are initially processed as two-dimensional images on our retina, but we live in a 3D world. Depth information needs to be reconstructed from the 2D retinal images, using cues such as binocular disparity. But in daily life, we also make frequent, rapid eye movements, which alter the 2D retinal input. How do we achieve stable 3D perception across saccades? Using fMRI pattern analysis, we investigated how 3D spatial representations in human visual cortex are influenced by saccades. Participants viewed stimuli in four possible 3D locations, defined by 2D vertical position (above or below screen center) and depth position (in front of or behind central screen plane). We compared the amount of 2D and depth information in visual cortical regions during no-saccade blocks (stationary fixation) with that during saccade blocks (series of guided saccades). On no-saccade blocks, decoding of stimulus location was highly dependent on fixation position: in later visual areas we could decode both vertical and depth information across blocks that shared the same fixation position (as previously reported), but little vertical or depth information could be decoded across blocks with different fixation positions. Strikingly, the neural similarity patterns appeared tolerant to changes in fixation position during saccade blocks: despite the saccade-induced retinal and fixation changes, we could reliably decode both vertical and depth information. The findings suggest that representations of 3D spatial locations may become more tolerant of fixation positions during dynamic saccades, perhaps due to active remapping which may encourage more stable representations of the world.SignificanceThis study investigates two fundamental challenges for visual perception: how to preserve spatial information across frequent eye movements, and how to integrate binocular depth location with 2D location to form coherent 3D percepts. Aspects of these challenges have been studied in isolation, but surprisingly no studies have investigated them jointly to ask how 3D spatial representations in human visual cortex are influenced by saccades. Our fMRI pattern analysis findings highlight a potentially critical role of active, dynamic saccades on stabilizing 3D spatial representations in the brain, revealing that representations of 3D space may be modulated by eye position during sustained fixation, but could become tolerant of changes in eye position during active, dynamic saccades.

scholarly journals Attentional Facilitation throughout Human Visual Cortex Lingers in Retinotopic Coordinates after Eye Movements

2010 ◽  
Vol 30 (31) ◽  
pp. 10493-10506 ◽  
Author(s):  
J. D. Golomb ◽  
A. Y. Nguyen-Phuc ◽  
J. A. Mazer ◽  
G. McCarthy ◽  
M. M. Chun
Keyword(s):  
Visual Cortex ◽  
Eye Movements ◽  
Human Visual Cortex

scholarly journals Distinct Narrow and Broadband Gamma Responses in Human Visual Cortex

2019 ◽  
Author(s):  
Eleonora Bartoli ◽  
William Bosking ◽  
Ye Li ◽  
Michael S. Beauchamp ◽  
Daniel Yoshor ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Critical Role ◽  
Visual Stimuli ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Systematic Change ◽  
Human Visual Cortex ◽  
Gamma Range ◽  
High Gamma ◽  
Differential Properties

AbstractHigh frequency activity (> 30 Hz) in the neocortical local field potential, typically referred to as the ‘gamma’ range, is thought to have a critical role in visual perception and cognition more broadly. Historically, animal studies recording from visual cortex documented clear narrowband gamma oscillations (NBG; ∼20-60 Hz) in response to visual stimuli. However, invasive measurements from human neocortex have highlighted a different broadband or ‘high’ gamma response (BBG; ∼70-150+ Hz). Growing evidence suggests these two forms of gamma response are distinct, but often conceptually or analytically conflated as the same ‘gamma’ response. Furthermore, recent debate has highlighted that both the occurrence and spectral properties of gamma band activity in visual cortex appears to be dependent on the attributes and class of presented visual stimuli. Using high-density intracranial recordings from human visual cortex, we integrate and extend these findings, dissociating the spectral, temporal and functional properties of NBG and BBG activity. We report results from two experiments, manipulating visual stimulus attributes (contrast-varying gratings) and class (object categories) dissecting the differential properties of NBG and BBG responses. NBG oscillations were only reliably recorded for grating stimuli, while their peak frequency varied with contrast level. Whereas BBG activity was observed in response to all stimulus classes tested, with no systematic change in its spectral features. Temporally, induced NBG was sustained throughout stimulus presentation, in opposition to a more transient response for the BBG. These findings challenge the ubiquity of ‘gamma’ activity in visual cortex, by clearly dissociating oscillatory and broadband effects.Significance StatementNeocortical narrowband gamma oscillations (∼20-60 Hz) have been implicated in vision and cognition as a mechanism for synchronizing brain regions. Efforts to study this phenomenon have revealed an additional ‘high-gamma’ range response (∼70-150+ Hz), which is broadband and non-oscillatory. These different gamma range activities are often conflated in support of the same functional role. Using invasive recordings from human visual cortex, we show that narrow and broadband gamma can be dissociated by spectral, temporal and functional response properties. While broadband gamma responses were more transient to the presentation of all stimuli, narrowband gamma responses were sustained and only occurred reliably to grating stimuli. These differences have important implications for the study, analysis and interpretation of neocortical gamma range activity.

Anatomy and Discharge Properties of Pre-Motor Neurons in the Goldfish Medulla That Have Eye-Position Signals During Fixations

2000 ◽  
Vol 84 (2) ◽  
pp. 1035-1049 ◽  
Author(s):  
E. Aksay ◽  
R. Baker ◽  
H. S. Seung ◽  
D. W. Tank
Keyword(s):  
Eye Movements ◽  
Firing Rate ◽  
Distinct Group ◽  
Eye Position ◽  
Temporal Position ◽  
Neural Integrator ◽  
Unit Recording ◽  
Fixation Position ◽  
Saccade Onset ◽  
Position Sensitivity

Previous work in goldfish has suggested that the oculomotor velocity-to-position neural integrator for horizontal eye movements may be confined bilaterally to a distinct group of medullary neurons that show an eye-position signal. To establish this localization, the anatomy and discharge properties of these position neurons were characterized with single-cell Neurobiotin labeling and extracellular recording in awake goldfish while monitoring eye movements with the scleral search-coil method. All labeled somata ( n = 9) were identified within a region of a medially located column of the inferior reticular formation that was ∼350 μm in length, ∼250 μm in depth, and ∼125 μm in width. The dendrites of position neurons arborized over a wide extent of the ventral half of the medulla with especially heavy ramification in the initial 500 μm rostral of cell somata ( n = 9). The axons either followed a well-defined ventral pathway toward the ipsilateral abducens ( n = 4) or crossed the midline ( n = 2) and projected toward the contralateral group of position neurons and the contralateral abducens. A mapping of the somatic region using extracellular single unit recording revealed that position neurons ( n > 120) were the dominant eye-movement-related cell type in this area. Position neurons did not discharge below a threshold value of horizontal fixation position of the ipsilateral eye. Above this threshold, firing rates increased linearly with increasing temporal position [mean position sensitivity = 2.8 (spikes/s)/°, n = 44]. For a given fixation position, average rates of firing were higher after a temporal saccade than a nasal one ( n = 19/19); the magnitude of this hysteresis increased with increasing position sensitivity. Transitions in firing rate accompanying temporal saccades were overshooting ( n = 43/44), beginning, on average, 17.2 ms before saccade onset ( n = 17). Peak firing rate change accompanying temporal saccades was correlated with eye velocity ( n = 36/41). The anatomical findings demonstrate that goldfish medullary position neurons have somata that are isolated from other parts of the oculomotor system, have dendritic fields overlapping with axonal terminations of neurons with velocity signals, and have axons that are capable of relaying commands to the abducens. The physiological findings demonstrate that the signals carried by position neurons could be used by motoneurons to set the fixation position of the eye. These results are consistent with a role for position neurons as elements of the velocity-to-position neural integrator for horizontal eye movements.

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