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Modulation of visual cortical excitability by working memory: effect of luminance contrast of mental imagery.

Cattaneo Z, Pisoni A, Papagno C, Silvanto J - Front Psychol (2011)

Bottom Line: We manipulated luminance contrast, a stimulus property known to strongly affect the magnitude of neuronal responses in early visual areas.These results point to a strong overlap in the neuronal processes underlying visual perception and mental imagery: not only does WM maintenance selectively engage neurons which are tuned to the maintained attribute (as has previously been shown), but the extent to which those neurons are activated depends on the image contrast (as is the case with visually evoked responses).From a methodological viewpoint, these results suggest that assessment of visual cortical excitability using TMS is affected by the TMS intensity used to probe the neuronal population.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Milano-Bicocca Milano, Italy.

ABSTRACT
Although much is known about the impact of stimulus properties such as luminance contrast, spatial frequency, and orientation on visually evoked neural activity, much less is known about how they modulate neural activity when they are properties of a mental image held in working memory (WM). Here we addressed this question by investigating how a parametric manipulation of an imagined stimulus attribute affects neuronal excitability in the early visual cortex. We manipulated luminance contrast, a stimulus property known to strongly affect the magnitude of neuronal responses in early visual areas. Luminance contrast modulated neuronal excitability, as assessed by the frequency of phosphenes induced by transcranial magnetic stimulation (TMS) with the exact nature of this modulation depending on TMS intensity. These results point to a strong overlap in the neuronal processes underlying visual perception and mental imagery: not only does WM maintenance selectively engage neurons which are tuned to the maintained attribute (as has previously been shown), but the extent to which those neurons are activated depends on the image contrast (as is the case with visually evoked responses). From a methodological viewpoint, these results suggest that assessment of visual cortical excitability using TMS is affected by the TMS intensity used to probe the neuronal population.

No MeSH data available.


Related in: MedlinePlus

Mean (n = 8) vividness rating for perceived phosphenes in the “Visual imagery condition” (A) and in the “Passive viewing” condition (B) of Experiment 1. Error bars represent ±1 SEM.
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Figure 3: Mean (n = 8) vividness rating for perceived phosphenes in the “Visual imagery condition” (A) and in the “Passive viewing” condition (B) of Experiment 1. Error bars represent ±1 SEM.

Mentions: Figure 2 shows the proportion of “Phosphene present” judgments as a function of stimulus contrast (0.1, 0.5, or 0.9) and task condition (imagery or passive viewing). In this analysis, the three response types which indicate phosphene presence (i.e., “weak”; “almost clear,” “absolutely clear”) are combined. A 2 × 3 ANOVA, with task condition (imagery or passive viewing), and contrast level (0.1, 0.5, 0.9) as within-subjects factors revealed a main effect of task condition [F(1,7) = 6.56, p = 0.038] but no main effect of contrast [F(2,14) = 0.72, p = 0.50] and no interaction [F(2,41) = 0.5, p = 0.62]. This analysis thus indicates that there was a general increase in “phosphene present” judgments associated with visual imagery which was not affected by stimulus contrast. Figure 3 shows the vividness ratings for the “Phosphene present” judgments for the Imagery and Passive viewing conditions. As can be seen in the figure, the vast majority of phosphenes were classified as “weak.”


Modulation of visual cortical excitability by working memory: effect of luminance contrast of mental imagery.

Cattaneo Z, Pisoni A, Papagno C, Silvanto J - Front Psychol (2011)

Mean (n = 8) vividness rating for perceived phosphenes in the “Visual imagery condition” (A) and in the “Passive viewing” condition (B) of Experiment 1. Error bars represent ±1 SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3111229&req=5

Figure 3: Mean (n = 8) vividness rating for perceived phosphenes in the “Visual imagery condition” (A) and in the “Passive viewing” condition (B) of Experiment 1. Error bars represent ±1 SEM.
Mentions: Figure 2 shows the proportion of “Phosphene present” judgments as a function of stimulus contrast (0.1, 0.5, or 0.9) and task condition (imagery or passive viewing). In this analysis, the three response types which indicate phosphene presence (i.e., “weak”; “almost clear,” “absolutely clear”) are combined. A 2 × 3 ANOVA, with task condition (imagery or passive viewing), and contrast level (0.1, 0.5, 0.9) as within-subjects factors revealed a main effect of task condition [F(1,7) = 6.56, p = 0.038] but no main effect of contrast [F(2,14) = 0.72, p = 0.50] and no interaction [F(2,41) = 0.5, p = 0.62]. This analysis thus indicates that there was a general increase in “phosphene present” judgments associated with visual imagery which was not affected by stimulus contrast. Figure 3 shows the vividness ratings for the “Phosphene present” judgments for the Imagery and Passive viewing conditions. As can be seen in the figure, the vast majority of phosphenes were classified as “weak.”

Bottom Line: We manipulated luminance contrast, a stimulus property known to strongly affect the magnitude of neuronal responses in early visual areas.These results point to a strong overlap in the neuronal processes underlying visual perception and mental imagery: not only does WM maintenance selectively engage neurons which are tuned to the maintained attribute (as has previously been shown), but the extent to which those neurons are activated depends on the image contrast (as is the case with visually evoked responses).From a methodological viewpoint, these results suggest that assessment of visual cortical excitability using TMS is affected by the TMS intensity used to probe the neuronal population.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Milano-Bicocca Milano, Italy.

ABSTRACT
Although much is known about the impact of stimulus properties such as luminance contrast, spatial frequency, and orientation on visually evoked neural activity, much less is known about how they modulate neural activity when they are properties of a mental image held in working memory (WM). Here we addressed this question by investigating how a parametric manipulation of an imagined stimulus attribute affects neuronal excitability in the early visual cortex. We manipulated luminance contrast, a stimulus property known to strongly affect the magnitude of neuronal responses in early visual areas. Luminance contrast modulated neuronal excitability, as assessed by the frequency of phosphenes induced by transcranial magnetic stimulation (TMS) with the exact nature of this modulation depending on TMS intensity. These results point to a strong overlap in the neuronal processes underlying visual perception and mental imagery: not only does WM maintenance selectively engage neurons which are tuned to the maintained attribute (as has previously been shown), but the extent to which those neurons are activated depends on the image contrast (as is the case with visually evoked responses). From a methodological viewpoint, these results suggest that assessment of visual cortical excitability using TMS is affected by the TMS intensity used to probe the neuronal population.

No MeSH data available.


Related in: MedlinePlus