On oscillating neuronal responses in the visual cortex of the monkey

1992 ◽  
Vol 67 (6) ◽  
pp. 1464-1474 ◽  
Author(s):  
M. P. Young ◽  
K. Tanaka ◽  
S. Yamane
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Species Difference ◽  
Power Spectra ◽  
Field Potentials ◽  
Neuronal Responses ◽  
Temporal Area ◽  
Gabor Functions ◽  
Low Incidence ◽  
Behaving Monkeys

1. Recent studies of visual processing in the cat have shown stimulus-related oscillations in the 30- to 70-Hz range. We sought to replicate these findings in the monkey. 2. We recorded multiunit activity (MUA) and local field potentials (LFP) in areas V1 and middle-temporal area (MT), and MUA from the inferotemporal cortex (IT) of monkeys (Macaca fuscata). Recordings in all areas were made under conditions of anesthesia as close as possible to those in previous studies of oscillating responses in the cat. In addition, we recorded MUA in the IT of behaving monkeys while the monkeys performed a face discrimination task. 3. In areas V1 and MT, LFP power spectra showed broadband increases (1-100 Hz) in amplitude on stimulation by swept optimally oriented light bars, and not a shift in power from low to midfrequency, as has been reported in the cat. 4. MUA autocorrelograms (ACGs) classified by fitting Gabor functions, showed oscillations at approximately 10% of recording sites in V1 and MT, but these oscillations were in the alpha range (12-13 Hz). 5. MUA ACGs from IT in the anesthetized monkey showed no oscillations. 6. For MUA ACGs from IT in the behaving monkey, only two recording sites (out of 50) showed an oscillating response, with frequencies of 44 and 48 Hz. One oscillating response was associated with stimulation, and the other was associated with the absence of stimulation. 7. The very low incidence in the monkey of oscillating responses in the 30- to 70-Hz range (2 in 424 recordings made at 142 recording sites) and the absence of stimulus dependence suggest that such oscillations are unlikely to serve a function in the monkey, and that there may be a species difference between monkey and cat in the dynamics of neural activity in the visual cortex. 8. We found that methods of classifying responses as oscillating used in some of the studies of the cat may have led to overestimation of both the number of sites showing oscillation and the number of pairs of sites showing phase coherence. These problems arise from the failure to take account of badness of fit between Gabor functions and their corresponding ACGs, and from Gabor functions "ringing" in response to short phasic phenomena that could be consistent with nonoscillatory activity.

scholarly journals Feature-coding transitions to conjunction-coding with progression through human visual cortex

2017 ◽  
Vol 118 (6) ◽  
pp. 3194-3214 ◽  
Author(s):  
Rosemary A. Cowell ◽  
Krystal R. Leger ◽  
John T. Serences
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Temporal Cortex ◽  
Complex Stimulus ◽  
Imaging Data ◽  
Neuronal Responses ◽  
Human Visual Cortex ◽  
Early Visual Cortex ◽  
Parietal Cortices ◽  
Object Level

Identifying an object and distinguishing it from similar items depends upon the ability to perceive its component parts as conjoined into a cohesive whole, but the brain mechanisms underlying this ability remain elusive. The ventral visual processing pathway in primates is organized hierarchically: Neuronal responses in early stages are sensitive to the manipulation of simple visual features, whereas neuronal responses in subsequent stages are tuned to increasingly complex stimulus attributes. It is widely assumed that feature-coding dominates in early visual cortex whereas later visual regions employ conjunction-coding in which object representations are different from the sum of their simple feature parts. However, no study in humans has demonstrated that putative object-level codes in higher visual cortex cannot be accounted for by feature-coding and that putative feature codes in regions prior to ventral temporal cortex are not equally well characterized as object-level codes. Thus the existence of a transition from feature- to conjunction-coding in human visual cortex remains unconfirmed, and if a transition does occur its location remains unknown. By employing multivariate analysis of functional imaging data, we measure both feature-coding and conjunction-coding directly, using the same set of visual stimuli, and pit them against each other to reveal the relative dominance of one vs. the other throughout cortex. Our results reveal a transition from feature-coding in early visual cortex to conjunction-coding in both inferior temporal and posterior parietal cortices. This novel method enables the use of experimentally controlled stimulus features to investigate population-level feature and conjunction codes throughout human cortex. NEW & NOTEWORTHY We use a novel analysis of neuroimaging data to assess representations throughout visual cortex, revealing a transition from feature-coding to conjunction-coding along both ventral and dorsal pathways. Occipital cortex contains more information about spatial frequency and contour than about conjunctions of those features, whereas inferotemporal and parietal cortices contain conjunction coding sites in which there is more information about the whole stimulus than its component parts.

DENDRITIC BRANCHING PATTERNS OF PYRAMIDAL CELLS IN THE VISUAL CORTEX OF THE NEW WORLD MARMOSET MONKEY, WITH COMPARATIVE NOTES ON THE OLD WORLD MACAQUE MONKEY

Fractals ◽  
2001 ◽  
Vol 09 (03) ◽  
pp. 297-303 ◽  
Author(s):  
GUY N. ELSTON ◽  
HERBERT F. JELINEK
Keyword(s):  
Fractal Dimension ◽  
Visual Cortex ◽  
Visual Processing ◽  
Fractal Dimensions ◽  
Pyramidal Cells ◽  
Macaque Monkey ◽  
Temporal Area ◽  
Cortical Areas ◽  
Marmoset Monkey ◽  
Dendritic Arbors

The basal dendritic arbors of 442 supragranular pyramidal cells in visual cortex of the marmoset monkey were compared by fractal analyses. As detailed in a previous study,1 individual cells were injected with Lucifer Yellow and processed for a DAB reaction product. The basal dendritic arbors were drawn, in the tangential plane, and the fractal dimension (D) determined by the dilation method. The fractal dimensions were compared between cells in ten cortical areas containing cells involved in visual processing, including the primary visual area (V1), the second visual area (V2), the dorsoanterior area (DA), the dorsomedial area (DM), the dorsolateral area (DL), the middle temporal area (MT), the posterior parietal area (PP), the fundus of the superior temporal area (FST) and the caudal and rostral subdivisions of inferotemporal cortex (ITc and ITr, respectively). Of 45 pairwise interareal comparisons of the fractal dimension of neurones, 20 were significantly different. Moreover, comparison of data according to previously published visual processing pathways revealed a trend for cells with greater fractal dimensions in "higher" cortical areas. Comparison of the present results with those in homologous cortical areas in the macaque monkey2 revealed some similarities between the two species. The similarity in the trends of D values of cells in both species may reflect developmental features which result in different functional attributes.

scholarly journals Feature-coding transitions to conjunction-coding with progression through human visual cortex

2016 ◽  
Author(s):  
Rosemary A. Cowell ◽  
John T. Serences
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Temporal Cortex ◽  
Population Level ◽  
Complex Stimulus ◽  
Imaging Data ◽  
Neuronal Responses ◽  
Early Visual Cortex ◽  
Stimulus Features ◽  
Object Level

Identifying an object and distinguishing it from similar items depends upon the ability to perceive its component parts as conjoined into a cohesive whole, but the brain mechanisms underlying this ability remain elusive. The ventral visual processing pathway in primates is organized hierarchically: Neuronal responses in its early stages are sensitive to the manipulation of simple visual features whereas neuronal responses in subsequent stages are tuned to increasingly complex stimulus attributes. It is widely assumed that feature-coding dominates in early visual cortex whereas later visual regions employ conjunction-coding in which object representations are different from the sum of their simple-feature parts. However, no study has demonstrated that putative object-level codes in higher visual cortex cannot be accounted for by feature-coding and that putative feature-codes in regions prior to ventral temporal cortex are not equally well characterized as object-level codes. Thus the existence of a transition from feature- to conjunction-coding in visual cortex remains unconfirmed, and, if a transition does occur, its location remains unknown. By employing multivariate analysis of human functional imaging data, we measure both feature-coding and conjunction-coding directly, using the same set of visual stimuli, and pit them against each other to reveal the relative dominance of one versus the other throughout cortex. We provide the first demonstration of a transition from feature-coding in early visual cortex to conjunction-coding in both inferior temporal and posterior parietal cortices. This novel method enables the use of experimentally controlled stimulus features to investigate population-level feature- and conjunction-codes throughout human cortex.

scholarly journals Alzheimer’s Disease Progressively Reduces Visual Functional Network Connectivity

2021 ◽  
pp. 1-14
Author(s):  
Jie Huang ◽  
Paul Beach ◽  
Andrea Bozoki ◽  
David C. Zhu
Keyword(s):  
Visual Cortex ◽  
Lower Order ◽  
Resting State ◽  
Visual Processing ◽  
Network Connectivity ◽  
Higher Order ◽  
Functional Network ◽  
Functional Networks ◽  
The Face ◽  
Processing Network

Background: Postmortem studies of brains with Alzheimer’s disease (AD) not only find amyloid-beta (Aβ) and neurofibrillary tangles (NFT) in the visual cortex, but also reveal temporally sequential changes in AD pathology from higher-order association areas to lower-order areas and then primary visual area (V1) with disease progression. Objective: This study investigated the effect of AD severity on visual functional network. Methods: Eight severe AD (SAD) patients, 11 mild/moderate AD (MAD), and 26 healthy senior (HS) controls undertook a resting-state fMRI (rs-fMRI) and a task fMRI of viewing face photos. A resting-state visual functional connectivity (FC) network and a face-evoked visual-processing network were identified for each group. Results: For the HS, the identified group-mean face-evoked visual-processing network in the ventral pathway started from V1 and ended within the fusiform gyrus. In contrast, the resting-state visual FC network was mainly confined within the visual cortex. AD disrupted these two functional networks in a similar severity dependent manner: the more severe the cognitive impairment, the greater reduction in network connectivity. For the face-evoked visual-processing network, MAD disrupted and reduced activation mainly in the higher-order visual association areas, with SAD further disrupting and reducing activation in the lower-order areas. Conclusion: These findings provide a functional corollary to the canonical view of the temporally sequential advancement of AD pathology through visual cortical areas. The association of the disruption of functional networks, especially the face-evoked visual-processing network, with AD severity suggests a potential predictor or biomarker of AD progression.

Generalized signal-tuned Gabor approach for signal representation and analysis

2017 ◽  
Vol 28 (01) ◽  
pp. 1750001 ◽  
Author(s):  
José R. A. Torreão
Keyword(s):  
Fourier Transform ◽  
Visual Cortex ◽  
Fourier Transforms ◽  
Fractional Fourier Transform ◽  
Receptive Fields ◽  
Gabor Functions ◽  
Plausible Model ◽  
Spectral Signal ◽  
Potential Applications ◽  
Space Frequency

The signal-tuned Gabor approach is based on spatial or spectral Gabor functions whose parameters are determined, respectively, by the Fourier and inverse Fourier transforms of a given “tuning” signal. The sets of spatial and spectral signal-tuned functions, for all possible frequencies and positions, yield exact representations of the tuning signal. Moreover, such functions can be used as kernels for space-frequency transforms which are tuned to the specific features of their inputs, thus allowing analysis with high conjoint spatio-spectral resolution. Based on the signal-tuned Gabor functions and the associated transforms, a plausible model for the receptive fields and responses of cells in the primary visual cortex has been proposed. Here, we present a generalization of the signal-tuned Gabor approach which extends it to the representation and analysis of the tuning signal’s fractional Fourier transform of any order. This significantly broadens the scope and the potential applications of the approach.

scholarly journals The Neurophysiology of Backward Visual Masking: Information Analysis

1999 ◽  
Vol 11 (3) ◽  
pp. 300-311 ◽  
Author(s):  
Edmund T. Rolls ◽  
Martin J. Tovée ◽  
Stefano Panzeri
Keyword(s):  
Visual Processing ◽  
Visual Information ◽  
Computational Models ◽  
Direct Evidence ◽  
Visual Masking ◽  
Neuronal Response ◽  
Short Soas ◽  
Stimulus Onset ◽  
Backward Masking ◽  
Neuronal Responses

Backward masking can potentially provide evidence of the time needed for visual processing, a fundamental constraint that must be incorporated into computational models of vision. Although backward masking has been extensively used psychophysically, there is little direct evidence for the effects of visual masking on neuronal responses. To investigate the effects of a backward masking paradigm on the responses of neurons in the temporal visual cortex, we have shown that the response of the neurons is interrupted by the mask. Under conditions when humans can just identify the stimulus, with stimulus onset asynchronies (SOA) of 20 msec, neurons in macaques respond to their best stimulus for approximately 30 msec. We now quantify the information that is available from the responses of single neurons under backward masking conditions when two to six faces were shown. We show that the information available is greatly decreased as the mask is brought closer to the stimulus. The decrease is more marked than the decrease in firing rate because it is the selective part of the firing that is especially attenuated by the mask, not the spontaneous firing, and also because the neuronal response is more variable at short SOAs. However, even at the shortest SOA of 20 msec, the information available is on average 0.1 bits. This compares to 0.3 bits with only the 16-msec target stimulus shown and a typical value for such neurons of 0.4 to 0.5 bits with a 500-msec stimulus. The results thus show that considerable information is available from neuronal responses even under backward masking conditions that allow the neurons to have their main response in 30 msec. This provides evidence for how rapid the processing of visual information is in a cortical area and provides a fundamental constraint for understanding how cortical information processing operates.

fMRI-Guided TMS on Cortical Eye Fields: The Frontal But Not Intraparietal Eye Fields Regulate the Coupling Between Visuospatial Attention and Eye Movements

2009 ◽  
Vol 102 (6) ◽  
pp. 3469-3480 ◽  
Author(s):  
H. M. Van Ettinger-Veenstra ◽  
W. Huijbers ◽  
T. P. Gutteling ◽  
M. Vink ◽  
J. L. Kenemans ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Eye Movements ◽  
Visual Processing ◽  
Discrimination Performance ◽  
Visual Image ◽  
Single Pulse ◽  
Visuospatial Attention ◽  
Movement Direction ◽  
Key Factor ◽  
And Shifts

It is well known that parts of a visual scene are prioritized for visual processing, depending on the current situation. How the CNS moves this focus of attention across the visual image is largely unknown, although there is substantial evidence that preparation of an action is a key factor. Our results support the view that direct corticocortical feedback connections from frontal oculomotor areas to the visual cortex are responsible for the coupling between eye movements and shifts of visuospatial attention. Functional magnetic resonance imaging (fMRI)–guided transcranial magnetic stimulation (TMS) was applied to the frontal eye fields (FEFs) and intraparietal sulcus (IPS). A single pulse was delivered 60, 30, or 0 ms before a discrimination target was presented at, or next to, the target of a saccade in preparation. Results showed that the known enhancement of discrimination performance specific to locations to which eye movements are being prepared was enhanced by early TMS on the FEF contralateral to eye movement direction, whereas TMS on the IPS resulted in a general performance increase. The current findings indicate that the FEF affects selective visual processing within the visual cortex itself through direct feedback projections.

scholarly journals Spatiotemporal profiles of visual processing with and without primary visual cortex

NeuroImage ◽  
2012 ◽  
Vol 63 (3) ◽  
pp. 1464-1477 ◽  
Author(s):  
Andreas A. Ioannides ◽  
Vahe Poghosyan ◽  
Lichan Liu ◽  
George A. Saridis ◽  
Marco Tamietto ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing
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