scholarly journals Beyond Fixation: detailed characterization of neural selectivity in free-viewing primates

2021 ◽  
Author(s):  
Jacob L Yates ◽  
Shanna H Coop ◽  
Gabriel H Sarch ◽  
Ruei-Jr Wu ◽  
Daniel A Butts ◽  
...  
Keyword(s):  
Eye Movements ◽  
Receptive Fields ◽  
Natural Behavior ◽  
Visual Neurons ◽  
Trained Subjects ◽  
V1 Neurons ◽  
Fixational Eye Movements ◽  
Neural Selectivity

Virtually all vision studies use a fixation point to stabilize gaze, rendering stimuli on video screens fixed to retinal coordinates. This approach requires trained subjects, is limited by the accuracy of fixational eye movements, and ignores the role of eye movements in shaping visual input. To overcome these limitations, we developed a suite of hardware and software tools to study vision during natural behavior in untrained subjects. We show this approach recovers receptive fields and tuning properties of visual neurons from multiple cortical areas of marmoset monkeys. Combined with high-precision eye-tracking, it achieves sufficient resolution to recover the receptive fields of foveal V1 neurons. These findings demonstrate the power of this approach for characterizing neural response while simultaneously studying the dynamics of natural behavior.

Spatial Organization of Receptive Fields of V1 Neurons of Alert Monkeys: Comparison With Responses to Gratings

2002 ◽  
Vol 88 (5) ◽  
pp. 2557-2574 ◽  
Author(s):  
Igor Kagan ◽  
Moshe Gur ◽  
D. Max Snodderly
Keyword(s):  
Eye Movements ◽  
Spatial Organization ◽  
Receptive Fields ◽  
Window Size ◽  
Group 14 ◽  
Simple Cells ◽  
Complex Cells ◽  
V1 Neurons ◽  
Fixational Eye Movements ◽  
Spatial Frequencies

We studied the spatial organization of receptive fields and the responses to gratings of neurons in parafoveal V1 of alert monkeys. Activating regions (ARs) of 228 cells were mapped with increment and decrement bars while compensating for fixational eye movements. For cells with two or more ARs, the overlap between ARs responsive to increments (INC) and ARs responsive to decrements (DEC) was characterized by a quantitative overlap index (OI). The distribution of overlap indices was bimodal. The larger group (78% of cells) was composed of complex cells with strongly overlapping ARs (OI ≥ 0.5). The smaller group (14%) was composed of simple cells with minimal spatial overlap of ARs (OI ≤ 0.3). Simple cells were preferentially located in layers dominated by the magnocellular pathway. A third group of neurons, the monocontrast cells (8%), responded only to one sign of contrast and had more sustained responses to flashed stimuli than other cells. One hundred fourteen neurons were also studied with drifting sinusoidal gratings of various spatial frequencies and window widths. For complex cells, the relative modulation (RM, the ratio of the 1st harmonic to the mean firing rate), ranged from 0.6 ± 0.4 to 1.1 ± 0.5 (mean ± SD), depending on the stimulus conditions and the mode of correction for eye movements. RM was not correlated with the degree of overlap of ARs, indicating that the spatial organization of receptive fields cannot reliably be predicted from RM values. In fact, a subset of complex cells had RM > 1, the traditional criterion for identifying simple cells. However, unlike simple cells, even those complex cells with high RM could exhibit diverse nonlinear responses when the spatial frequency or window size was changed. Furthermore, the responses of complex cells to counterphase gratings were predominantly nonlinear even harmonics. These results show that RM is not a robust test of linearity. Our results indicate that complex cells are the most frequently encountered neurons in primate V1, and their behavior needs to receive more emphasis in models of visual function.

Eye Position Compensation Improves Estimates of Response Magnitude and Receptive Field Geometry in Alert Monkeys

2007 ◽  
Vol 97 (5) ◽  
pp. 3439-3448 ◽  
Author(s):  
Yamei Tang ◽  
Alan Saul ◽  
Moshe Gur ◽  
Stephanie Goei ◽  
Elsie Wong ◽  
...  
Keyword(s):  
Eye Movements ◽  
Receptive Field ◽  
Receptive Fields ◽  
Eye Position ◽  
Stimulus Position ◽  
Fixational Eye Movements ◽  
Field Geometry ◽  
Receptive Field Subregions ◽  
Movement Compensation ◽  
Definition Of

Studies of visual function in behaving subjects require that stimuli be positioned reliably on the retina in the presence of eye movements. Fixational eye movements scatter stimuli about the retina, inflating estimates of receptive field dimensions, reducing estimates of peak responses, and blurring maps of receptive field subregions. Scleral search coils are frequently used to measure eye position, but their utility for correcting the effects of fixational eye movements on receptive field maps has been questioned. Using eye coils sutured to the sclera and preamplifiers configured to minimize cable artifacts, we reexamined this issue in two rhesus monkeys. During repeated fixation trials, the eye position signal was used to adjust the stimulus position, compensating for eye movements and correcting the stimulus position to place it at the desired location on the retina. Estimates of response magnitudes and receptive field characteristics in V1 and in LGN were obtained in both compensated and uncompensated conditions. Receptive fields were narrower, with steeper borders, and response amplitudes were higher when eye movement compensation was used. In sum, compensating for eye movements facilitated more precise definition of the receptive field. We also monitored horizontal vergence over long sequences of fixation trials and found the variability to be low, as expected for this precise behavior. Our results imply that eye coil signals can be highly accurate and useful for optimizing visual physiology when rigorous precautions are observed.

Role of Eye Movements in the Retinal Code for a Size Discrimination Task

2007 ◽  
Vol 98 (3) ◽  
pp. 1380-1391 ◽  
Author(s):  
Ronen Segev ◽  
Elad Schneidman ◽  
Joe Goodhouse ◽  
Michael J. Berry
Keyword(s):  
Eye Movements ◽  
Visual Information ◽  
Ganglion Cells ◽  
Multielectrode Array ◽  
Retinal Ganglion ◽  
Size Discrimination ◽  
Fixational Eye Movements ◽  
Stationary Objects ◽  
A Minor

The concerted action of saccades and fixational eye movements are crucial for seeing stationary objects in the visual world. We studied how these eye movements contribute to retinal coding of visual information using the archer fish as a model system. We quantified the animal's ability to distinguish among objects of different sizes and measured its eye movements. We recorded from populations of retinal ganglion cells with a multielectrode array, while presenting visual stimuli matched to the behavioral task. We found that the beginning of fixation, namely the time immediately after the saccade, provided the most visual information about object size, with fixational eye movements, which consist of tremor and drift in the archer fish, yielding only a minor contribution. A simple decoder that combined information from ≤15 ganglion cells could account for the behavior. Our results support the view that saccades impose not just difficulties for the visual system, but also an opportunity for the retina to encode high quality “snapshots” of the environment.

A model of the dynamics of retinal activity during natural visual fixation

2007 ◽  
Vol 24 (2) ◽  
pp. 217-230 ◽  
Author(s):  
GAËLLE DESBORDES ◽  
MICHELE RUCCI
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Ganglion Cells ◽  
Receptive Fields ◽  
Visual Fixation ◽  
Natural Scenes ◽  
M Cells ◽  
Retinal Activity ◽  
Cell Responses ◽  
Fixational Eye Movements

During visual fixation, small eye movements keep the retinal image continuously in motion. It is known that neurons in the visual system are sensitive to the spatiotemporal modulations of luminance resulting from this motion. In this study, we examined the influence of fixational eye movements on the statistics of neural activity in the macaque's retina during the brief intersaccadic periods of natural visual fixation. The responses of parvocellular (P) and magnocellular (M) ganglion cells in different regions of the visual field were modeled while their receptive fields scanned natural images following recorded traces of eye movements. Immediately after the onset of fixation, wide ensembles of coactive ganglion cells extended over several degrees of visual angle, both in the central and peripheral regions of the visual field. Following this initial pattern of activity, the covariance between the responses of pairs of P and M cells and the correlation between the responses of pairs of M cells dropped drastically during the course of fixation. Cell responses were completely uncorrelated by the end of a typical 300-ms fixation. This dynamic spatial decorrelation of retinal activity is a robust phenomenon independent of the specifics of the model. We show that it originates from the interaction of three factors: the statistics of natural scenes, the small amplitudes of fixational eye movements, and the temporal sensitivities of ganglion cells. These results support the hypothesis that fixational eye movements, by shaping the statistics of retinal activity, are an integral component of early visual representations.

scholarly journals Modeling the role of fixational eye movements in real-world scenes

2015 ◽  
Vol 151 ◽  
pp. 78-84 ◽  
Author(s):  
Andrés Olmedo-Payá ◽  
Antonio Martínez-Álvarez ◽  
Sergio Cuenca-Asensi ◽  
J.M. Ferrández ◽  
E. Fernández
Keyword(s):  
Eye Movements ◽  
Real World ◽  
Fixational Eye Movements

scholarly journals Rhythmic neural spiking and attentional sampling arising from cortical receptive field interactions

2018 ◽  
Author(s):  
Ricardo Kienitz ◽  
Joscha T. Schmiedt ◽  
Katharine A. Shapcott ◽  
Kleopatra Kouroupaki ◽  
Richard C. Saunders ◽  
...  
Keyword(s):  
Eye Movements ◽  
Receptive Field ◽  
Spatial Attention ◽  
Receptive Fields ◽  
Reaction Times ◽  
List Type ◽  
Attention Task ◽  
Area V4 ◽  
Fixational Eye Movements ◽  
Visual Cortical Area

SummaryGrowing evidence suggests that distributed spatial attention may invoke theta (3-9 Hz) rhythmic sampling processes. The neuronal basis of such attentional sampling is however not fully understood. Here we show using array recordings in visual cortical area V4 of two awake macaques that presenting separate visual stimuli to the excitatory center and suppressive surround of neuronal receptive fields elicits rhythmic multi-unit activity (MUA) at 3-6 Hz. This neuronal rhythm did not depend on small fixational eye movements. In the context of a distributed spatial attention task, during which the monkeys detected a spatially and temporally uncertain target, reaction times (RT) exhibited similar rhythmic fluctuations. RTs were fast or slow depending on the target occurrence during high or low MUA, resulting in rhythmic MUA-RT cross-correlations at at theta frequencies. These findings suggest that theta-rhythmic neuronal activity arises from competitive receptive field interactions and that this rhythm may subserve attentional sampling.HighlightsCenter-surround interactions induce theta-rhythmic MUA of visual cortex neuronsThe MUA rhythm does not depend on small fixational eye movementsReaction time fluctuations lock to the neuronal rhythm under distributed attention

The Role of Subcortical Visual Structures in Target Foveation Control

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 291-291
Author(s):  
G I Novikov
Keyword(s):  
Eye Movements ◽  
Visual Target ◽  
Receptive Fields ◽  
Movement Control ◽  
Lateral Geniculate Body ◽  
Electrophysiological Data ◽  
Electrical Microstimulation ◽  
Neuronal Populations

The role of subcortical levels—the lateral geniculate body (LGB) and superior colliculus (SC) of cat—in the control of foveation eye movements is described by a model based on our own electrophysiological data. These data include the characteristics of eye movements elicited by local electrical microstimulation of neuronal structures in the LGB and the SC. The model represents a multilevel system forming the program of foveation eye movements by performing the following actions in temporal sequence: determination of the position of the visual target in retinotopic coordinates, determination of its craniotopic coordinates and determination of the direction and calculation of the velocity of the moving visual target. I discuss algorithms and neuronal mechanisms (including electrophysiological data on single neurons and neuronal populations) of subcortical levels of the cat visual system taking part in foveation eye-movement control for stationary and moving visual objects, as well as the role of directional and orientation properties of receptive fields of subcortical neurons in this control.

scholarly journals IDENTIFYING TRENDS IN MICROSACCADE RATE ON OCULOMOTOR TRACKER IN EARLY VS LATE STAGE PEDIATRIC CASES WITH PERSISTENT POST-CONCUSSION SYMPTOMS (PPCS)

2021 ◽  
Vol 9 (7_suppl3) ◽  
pp. 2325967121S0016
Author(s):  
Prem Kumar Thirunagari ◽  
Nancy Phu ◽  
David Tramutolo ◽  
Hector Rieiro ◽  
Tanya Polec ◽  
...  
Keyword(s):  
Eye Movements ◽  
Late Stage ◽  
Visual Processing ◽  
Pediatric Patients ◽  
Early Stage ◽  
Statistical Significance ◽  
Small Sample ◽  
T Test ◽  
Fixational Eye Movements

Background: Oculomotor and visual processing deficits occur commonly after brain injury in young athletes. A subset of these concussed athletes do experience prolonged recoveries or PPCS with ongoing oculomotor deficits and visual symptoms. There have been limited studies conducted to determine the significance of oculomotor tracking (OMT) testing in the pediatric population, and even less investigating the role of microsaccades. Hence, investigations on microsaccades(MS), physiological adjustive micro eye movements critical in visual processing and central/peripheral visual integration, may provide insight on the role of visual dysfunction in PPCS course, prognosis, and management. Purpose: The purpose of this study is to identify possible MS rate trends and differences between early and late stage PPCS pediatric patients. Methods: A retrospective cohort study of 41 pediatric patients with PPCS or symptoms greater than one month from injury. Data was collected from 7/1/2018 to 12/1/2019 and the age group ranged from 8 to 21 years. For each participant, using the OMT device we measured the number of saccades generated, the size and speed of the microsaccades, the area covered and the ratio of vertical-to-horizontal direction component of the fixational eye movements, using a 250 Hz video-eye tracker mounted inside a HTC Vive VR headset. Participants were instructed to fixate on a central dot for 140 seconds, in 20-second intervals. Patients were classified into early or late stages of PPCS (early stage: 1-6 months; late stage: >6 months) to compare MS rate between stages. Exclusion criteria included history of visual disorders, learning disorders, seizure disorder, or intracranial hemorrhage. Results: 27 patients were in the early stage while 14 patients were in the late stage. The early stage group had a mean MS rate of 125 beats/min while the late stage group had a mean MS rate of 116 beats/min. A two sample t-test assuming no difference between early and late stage patients resulted in a p value of 0.51. Conclusion: There is a potential trend in declining MS numbers with progressive PPCS stage. Although the t-test didn’t show statistical significance, this could be due to the small sample size of our study. Future studies are needed to validate this initial finding and to identify the significance of microsaccade patterns in concussion prognosis and management. [Figure: see text]

scholarly journals Prevalence of multiple subtypes of binocularly-modulated visual neurons in the mouse superior colliculus

2020 ◽  
Author(s):  
Ashley Lynn Russell ◽  
Jason W Triplett
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Visual Processing ◽  
Spatial Summation ◽  
Stimulus Presentation ◽  
Visual Neurons ◽  
Evoked Activity ◽  
Multiple Species ◽  
Binocular Perception

A central role of the visual system is to integrate inputs from both eyes to form one coherent visual perception. The superior colliculus (SC) plays a central role in visual processing, gaze orientation and vergence eye movements necessary for binocular vision. Indeed, the SC receives direct inputs from both the contralateral and ipsilateral eye and binocularly-modulated neurons have been identified in the SC of multiple species. However, evidence for binocular processing in rodents, particularly mice, has not been functionally confirmed. In this study we recorded visually-evoked activity in the mouse SC while presenting visual stimuli to each eye individually or both together and reveal a surprising diversity of binocularly-modulated responses. Strikingly, we found that ~2/3 of all identified neurons in the anteromedial SC were binocularly-modulated. Furthermore, we identified four binocular subtypes based on their differential responses under varying ocularities of stimulus presentation. Interestingly, we found both orientation- and direction- selective (OS and DS, respectively) neurons in all four binocular subtypes. And, tuning properties of binocular neurons were distinct from neighboring monocular neurons, exhibiting more linear spatial summation. Together, these data suggest that binocular neurons are prevalent in the anteromedial SC of the mouse. Additionally, the distinct tuning properties of binocular neurons suggest a previously unappreciated complexity of visual processing in the SC, which may contribute to binocular perception.

scholarly journals Coding of chromatic spatial contrast by macaque V1 neurons

2021 ◽  
Author(s):  
Abhishek De ◽  
Gregory D. Horwitz
Keyword(s):  
Color Image ◽  
Receptive Fields ◽  
Luminance Contrast ◽  
Chromatic Contrast ◽  
Simple Cells ◽  
Complex Cells ◽  
V1 Neurons ◽  
Full Color ◽  
Common Principle ◽  
Neural Selectivity

ABSTRACTColor perception relies on spatial comparisons of chromatic signals, but how the brain performs these comparisons is poorly understood. Here, we show that many V1 neurons compare signals across their receptive fields (RF) using a common principle. We estimated the spatial-chromatic RFs of each neuron, and then measured neural selectivity to customized colored edges that were sampled using a novel closed-loop technique. We found that many double-opponent (DO) cells, which have spatially and chromatically opponent RFs, responded to chromatic contrast as a weighted sum, akin to how simple cells respond to luminance contrast. Other neurons integrated chromatic signals non-linearly, confirming that linear signal integration is not an obligate property of V1 neurons. The functional similarity of DO and simple cells suggests a common underlying neural circuitry, promotes the construction of image-computable models for full-color image representation, and sheds new light on V1 complex cells.

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