scholarly journals Efficient Visual Object and Word Recognition Relies on High Spatial Frequency Coding in the Left Posterior Fusiform Gyrus: Evidence from a Case-Series of Patients with Ventral Occipito-Temporal Cortex Damage

2012 ◽  
Vol 23 (11) ◽  
pp. 2568-2580 ◽  
Author(s):  
Daniel J. Roberts ◽  
Anna M. Woollams ◽  
Esther Kim ◽  
Pelagie M. Beeson ◽  
Steven Z. Rapcsak ◽  
...  
Keyword(s):  
Word Recognition ◽  
Spatial Frequency ◽  
Temporal Cortex ◽  
Case Series ◽  
High Spatial Frequency ◽  
Fusiform Gyrus ◽  
Visual Object ◽  
Frequency Coding ◽  
Left Posterior

Natural scenes have matched amplitude-modulated sounds that systematically influence visual scanning

2012 ◽  
Vol 25 (0) ◽  
pp. 121
Author(s):  
Marcia Grabowecky ◽  
Aleksandra Sherman ◽  
Satoru Suzuki
Keyword(s):  
Eye Movements ◽  
Spatial Frequency ◽  
Memory Task ◽  
High Spatial Frequency ◽  
Visual Object ◽  
Natural Scenes ◽  
Scale Invariant ◽  
Visual Coding ◽  
Visual Spatial ◽  
Spatial Frequencies

We have previously demonstrated a linear perceptual relationship between auditory amplitude-modulation (AM) rate and visual spatial-frequency using gabors as the visual stimuli. Can this frequency-based auditory–visual association influence perception of natural scenes? Participants consistently matched specific auditory AM rates to diverse visual scenes (nature, urban, and indoor). A correlation analysis indicated that higher subjective density ratings were associated with faster AM-rate matches. Furthermore, both the density ratings and AM-rate matches were relatively scale invariant, suggesting that the underlying crossmodal association is between visual coding of object-based density and auditory coding of AM rate. Based on these results, we hypothesized that concurrently presented fast (7 Hz) or slow (2 Hz) AM-rates might influence how visual attention is allocated to dense or sparse regions within a scene. We tested this hypothesis by monitoring eye movements while participants examined scenes for a subsequent memory task. To determine whether fast or slow sounds guided eye movements to specific spatial frequencies, we computed the maximum contrast energy at each fixation across 12 spatial frequency bands ranging from 0.06–10.16 cycles/degree. We found that the fast sound significantly guided eye movements toward regions of high spatial frequency, whereas the slow sound guided eye movements away from regions of high spatial frequency. This suggests that faster sounds may promote a local scene scanning strategy, acting as a ‘filter’ to individuate objects within dense regions. Our results suggest that auditory AM rate and visual object density are crossmodally associated, and that this association can modulate visual inspection of scenes.

Delineating the low and high spatial frequency inputs to face perception using transcranial random noise stimulation

2020 ◽  
Author(s):  
Bhuvanesh Awasthi
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Response Times ◽  
Random Noise ◽  
Temporal Cortex ◽  
High Spatial Frequency ◽  
Bayesian Approaches ◽  
Frequency Information ◽  
Transcranial Random Noise Stimulation ◽  
The Right

This study used high frequency transcranial Random Noise Stimulation (tRNS) to examine how low and high spatial frequency filtered faces are processed. In a response time behavioral task, healthy young adults categorized male and female faces, presented at fovea and periphery in alternate blocks, while sham and high frequency random noise was applied to occipito-parietal location on their scalp. Both the frequentist and bayesian approaches show that stimulation at the right occipito-temporal cortex significantly reduced response times to peripherally presented low spatial frequency information. This finding points to a possible plasticity in targeted regions induced by non-invasive neuromodulation of spatial frequency information in rapid perception of faces.

Spatial Frequency Tolerant Visual Object Representations in the Human Ventral and Dorsal Visual Processing Pathways

2019 ◽  
Vol 31 (1) ◽  
pp. 49-63 ◽  
Author(s):  
Maryam Vaziri-Pashkam ◽  
JohnMark Taylor ◽  
Yaoda Xu
Keyword(s):  
Spatial Frequency ◽  
Visual Processing ◽  
Spatial Scales ◽  
High Spatial Frequency ◽  
Visual Input ◽  
Differential Sensitivity ◽  
Visual Object ◽  
Object Representations ◽  
Object Category ◽  
Object Categories

Primate ventral and dorsal visual pathways both contain visual object representations. Dorsal regions receive more input from magnocellular system while ventral regions receive inputs from both magnocellular and parvocellular systems. Due to potential differences in the spatial sensitivites of manocellular and parvocellular systems, object representations in ventral and dorsal regions may differ in how they represent visual input from different spatial scales. To test this prediction, we asked observers to view blocks of images from six object categories, shown in full spectrum, high spatial frequency (SF), or low SF. We found robust object category decoding in all SF conditions as well as SF decoding in nearly all the early visual, ventral, and dorsal regions examined. Cross-SF decoding further revealed that object category representations in all regions exhibited substantial tolerance across the SF components. No difference between ventral and dorsal regions was found in their preference for the different SF components. Further comparisons revealed that, whereas differences in the SF component separated object category representations in early visual areas, such a separation was much smaller in downstream ventral and dorsal regions. In those regions, variations among the object categories played a more significant role in shaping the visual representational structures. Our findings show that ventral and dorsal regions are similar in how they represent visual input from different spatial scales and argue against a dissociation of these regions based on differential sensitivity to different SFs.

Organization of local horizontal functional interactions between neurons in the inferior temporal cortex of macaque monkeys

2014 ◽  
Vol 111 (12) ◽  
pp. 2589-2602 ◽  
Author(s):  
Hiroshi Tamura ◽  
Yoshiya Mori ◽  
Hidekazu Kaneko
Keyword(s):  
Neuronal Activity ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Visual Object ◽  
Detailed Knowledge ◽  
Visual Response ◽  
Stimulus Preference ◽  
Macaque Monkeys ◽  
Functional Interactions ◽  
Cross Correlation Analysis

Detailed knowledge of neuronal circuitry is necessary for understanding the mechanisms underlying information processing in the brain. We investigated the organization of horizontal functional interactions in the inferior temporal cortex of macaque monkeys, which plays important roles in visual object recognition. Neuronal activity was recorded from the inferior temporal cortex using an array of eight tetrodes, with spatial separation between paired neurons up to 1.4 mm. We evaluated functional interactions on a time scale of milliseconds using cross-correlation analysis of neuronal activity of the paired neurons. Visual response properties of neurons were evaluated using responses to a set of 100 visual stimuli. Adjacent neuron pairs tended to show strong functional interactions compared with more distant neuron pairs, and neurons with similar stimulus preferences tended to show stronger functional interactions than neurons with different stimulus preferences. Thus horizontal functional interactions in the inferior temporal cortex appear to be organized according to both cortical distances and similarity in stimulus preference between neurons. Furthermore, the relationship between strength of functional interactions and similarity in stimulus preference observed in distant neuron pairs was more prominent than in adjacent pairs. The results suggest that functional circuitry is specifically organized, depending on the horizontal distances between neurons. Such specificity endows each circuit with unique functions.

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