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Spatio-temporal low-level neural networks account for visual masking.

Polat U, Sterkin A, Yehezkel O - Adv Cogn Psychol (2008)

Bottom Line: When a mask is presented, typically within less than 100 msec before or after the target, the response to the target is reduced.Thus, the masking effect depends on the spatial-temporal combination of these factors.We propose that masking effects, either suppression or facilitation, reflect integration into the spatial and the temporal domains of the feedforward response to the target and the lateral inputs evoked by the mask (excitatory and/or inhibitory).

View Article: PubMed Central - PubMed

Affiliation: Goldschleger Eye Research Institute, Tel-Aviv University, Sheba Medical Center, 52621 Tel-Hashomer, Israel.

ABSTRACT
T emporal masking is a paradigm that is widely used to study visual information processing. When a mask is presented, typically within less than 100 msec before or after the target, the response to the target is reduced. The results of our psychophysical and visual evoked potential (VEP) experiments show that the masking effect critically depends on a combination of several factors: (1) the processing time of the target, (2) the order of presentation of the target and the mask, and (3) the spatial arrangement of the target and the mask. Thus, the masking effect depends on the spatial-temporal combination of these factors. Suppression was observed when the mask was positioned within a spatial range that was found to evoke inhibition, and when the temporal separation between the target and the mask was short. In contrast, lateral facilitation was observed when the mask was presented at a spatial separation that did not evoke inhibition from the target's vicinity and with a temporal sequence that preceded the target, or when it was presented simultaneously with it, but not when the target preceded the mask. We propose that masking effects, either suppression or facilitation, reflect integration into the spatial and the temporal domains of the feedforward response to the target and the lateral inputs evoked by the mask (excitatory and/or inhibitory). Because the excitation evoked by the mask develops and propagates slowly from the mask's location to the target's location, it lags behind the response to the target. On the other hand, inhibition that is produced in the vicinity of the target evolves more rapidly and follows the onset and offset of the stimulus more closely. Thus, lateral excitation that overcomes the inhibition may facilitate the grouping of local elements into a global percept by increasing the survivability of the object and its accessibility for perceptual awareness.

No MeSH data available.


Related in: MedlinePlus

Waveforms of visual evoked potentials under BM-on-T and BM-on-SM. The							average waveforms (time courses of 1000 ms, 5 subjects) of the visual							evoked potentials (VEP) in a single subject under the two BM conditions,							BM-on-T (left panel) and BM-on-SM (central panel) are shown. These							waveforms are compared with the responses evoked by M presented alone at							different delays relative to the beginning of the trial, corresponding							to the different ISIs tested under BM conditions (right panel). The							different ISIs tested under the BM conditions (0, 50, 150, or 250 ms)							and the corresponding delays of M (50, 100, 200, or 300 ms) are coded							with different colors.
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Figure 7: Waveforms of visual evoked potentials under BM-on-T and BM-on-SM. The average waveforms (time courses of 1000 ms, 5 subjects) of the visual evoked potentials (VEP) in a single subject under the two BM conditions, BM-on-T (left panel) and BM-on-SM (central panel) are shown. These waveforms are compared with the responses evoked by M presented alone at different delays relative to the beginning of the trial, corresponding to the different ISIs tested under BM conditions (right panel). The different ISIs tested under the BM conditions (0, 50, 150, or 250 ms) and the corresponding delays of M (50, 100, 200, or 300 ms) are coded with different colors.

Mentions: Figure 7 depicts the time course evoked under the two BM conditions, BM-on-T and BM-on-SM, at different ISIs, in comparison with the responses evoked by M presented at different delays, corresponding to the different ISIs tested under the BM conditions. Figure 8 summarizes the P1 values under the two BM conditions, both for the target and mask stimuli.


Spatio-temporal low-level neural networks account for visual masking.

Polat U, Sterkin A, Yehezkel O - Adv Cogn Psychol (2008)

Waveforms of visual evoked potentials under BM-on-T and BM-on-SM. The							average waveforms (time courses of 1000 ms, 5 subjects) of the visual							evoked potentials (VEP) in a single subject under the two BM conditions,							BM-on-T (left panel) and BM-on-SM (central panel) are shown. These							waveforms are compared with the responses evoked by M presented alone at							different delays relative to the beginning of the trial, corresponding							to the different ISIs tested under BM conditions (right panel). The							different ISIs tested under the BM conditions (0, 50, 150, or 250 ms)							and the corresponding delays of M (50, 100, 200, or 300 ms) are coded							with different colors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2864984&req=5

Figure 7: Waveforms of visual evoked potentials under BM-on-T and BM-on-SM. The average waveforms (time courses of 1000 ms, 5 subjects) of the visual evoked potentials (VEP) in a single subject under the two BM conditions, BM-on-T (left panel) and BM-on-SM (central panel) are shown. These waveforms are compared with the responses evoked by M presented alone at different delays relative to the beginning of the trial, corresponding to the different ISIs tested under BM conditions (right panel). The different ISIs tested under the BM conditions (0, 50, 150, or 250 ms) and the corresponding delays of M (50, 100, 200, or 300 ms) are coded with different colors.
Mentions: Figure 7 depicts the time course evoked under the two BM conditions, BM-on-T and BM-on-SM, at different ISIs, in comparison with the responses evoked by M presented at different delays, corresponding to the different ISIs tested under the BM conditions. Figure 8 summarizes the P1 values under the two BM conditions, both for the target and mask stimuli.

Bottom Line: When a mask is presented, typically within less than 100 msec before or after the target, the response to the target is reduced.Thus, the masking effect depends on the spatial-temporal combination of these factors.We propose that masking effects, either suppression or facilitation, reflect integration into the spatial and the temporal domains of the feedforward response to the target and the lateral inputs evoked by the mask (excitatory and/or inhibitory).

View Article: PubMed Central - PubMed

Affiliation: Goldschleger Eye Research Institute, Tel-Aviv University, Sheba Medical Center, 52621 Tel-Hashomer, Israel.

ABSTRACT
T emporal masking is a paradigm that is widely used to study visual information processing. When a mask is presented, typically within less than 100 msec before or after the target, the response to the target is reduced. The results of our psychophysical and visual evoked potential (VEP) experiments show that the masking effect critically depends on a combination of several factors: (1) the processing time of the target, (2) the order of presentation of the target and the mask, and (3) the spatial arrangement of the target and the mask. Thus, the masking effect depends on the spatial-temporal combination of these factors. Suppression was observed when the mask was positioned within a spatial range that was found to evoke inhibition, and when the temporal separation between the target and the mask was short. In contrast, lateral facilitation was observed when the mask was presented at a spatial separation that did not evoke inhibition from the target's vicinity and with a temporal sequence that preceded the target, or when it was presented simultaneously with it, but not when the target preceded the mask. We propose that masking effects, either suppression or facilitation, reflect integration into the spatial and the temporal domains of the feedforward response to the target and the lateral inputs evoked by the mask (excitatory and/or inhibitory). Because the excitation evoked by the mask develops and propagates slowly from the mask's location to the target's location, it lags behind the response to the target. On the other hand, inhibition that is produced in the vicinity of the target evolves more rapidly and follows the onset and offset of the stimulus more closely. Thus, lateral excitation that overcomes the inhibition may facilitate the grouping of local elements into a global percept by increasing the survivability of the object and its accessibility for perceptual awareness.

No MeSH data available.


Related in: MedlinePlus