Limits...
Keeping in touch with the visual system: spatial alignment and multisensory integration of visual-somatosensory inputs.

Mahoney JR, Molholm S, Butler JS, Sehatpour P, Gomez-Ramirez M, Ritter W, Foxe JJ - Front Psychol (2015)

Bottom Line: In support, electrophysiological results revealed significant differences between multisensory simultaneous VS and summed V + S responses, regardless of the spatial alignment of the constituent inputs.Nonetheless, multisensory effects were earlier in the aligned conditions, and were found to be particularly robust in the case of right-sided inputs (beginning at just 55 ms).In contrast to previous work on audio-visual and audio-somatosensory inputs, the current work suggests a degree of spatial specificity to the earliest detectable multisensory integrative effects in response to VS pairings.

View Article: PubMed Central - PubMed

Affiliation: The Cognitive Neurophysiology Laboratory, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg NY, USA ; Division of Cognitive and Motor Aging, Department of Neurology, Albert Einstein College of Medicine, New York NY, USA.

ABSTRACT
Correlated sensory inputs coursing along the individual sensory processing hierarchies arrive at multisensory convergence zones in cortex where inputs are processed in an integrative manner. The exact hierarchical level of multisensory convergence zones and the timing of their inputs are still under debate, although increasingly, evidence points to multisensory integration (MSI) at very early sensory processing levels. While MSI is said to be governed by stimulus properties including space, time, and magnitude, violations of these rules have been documented. The objective of the current study was to determine, both psychophysically and electrophysiologically, whether differential visual-somatosensory (VS) integration patterns exist for stimuli presented to the same versus opposite hemifields. Using high-density electrical mapping and complementary psychophysical data, we examined multisensory integrative processing for combinations of visual and somatosensory inputs presented to both left and right spatial locations. We assessed how early during sensory processing VS interactions were seen in the event-related potential and whether spatial alignment of the visual and somatosensory elements resulted in differential integration effects. Reaction times to all VS pairings were significantly faster than those to the unisensory conditions, regardless of spatial alignment, pointing to engagement of integrative multisensory processing in all conditions. In support, electrophysiological results revealed significant differences between multisensory simultaneous VS and summed V + S responses, regardless of the spatial alignment of the constituent inputs. Nonetheless, multisensory effects were earlier in the aligned conditions, and were found to be particularly robust in the case of right-sided inputs (beginning at just 55 ms). In contrast to previous work on audio-visual and audio-somatosensory inputs, the current work suggests a degree of spatial specificity to the earliest detectable multisensory integrative effects in response to VS pairings.

No MeSH data available.


Experimental Paradigm. (A) Unisensory visual, unisensory somatosensory, and multisensory VS conditions. LEDs were placed on both left and right thumbs and vibro-tactile stimulators were placed on both left and right index fingers. Mittens were used to hide vibro-tactile stimulators and headphones were used to mask the sound of the vibrators. Participants sat comfortably with their hands rested on a table and used a foot pedal located under their right foot to respond to any and all stimuli. Stimuli were 25° from the azimuth. (B) 168 electrode array and the four selected regions of interest (ROIs) used for statistical analyses.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4525670&req=5

Figure 1: Experimental Paradigm. (A) Unisensory visual, unisensory somatosensory, and multisensory VS conditions. LEDs were placed on both left and right thumbs and vibro-tactile stimulators were placed on both left and right index fingers. Mittens were used to hide vibro-tactile stimulators and headphones were used to mask the sound of the vibrators. Participants sat comfortably with their hands rested on a table and used a foot pedal located under their right foot to respond to any and all stimuli. Stimuli were 25° from the azimuth. (B) 168 electrode array and the four selected regions of interest (ROIs) used for statistical analyses.

Mentions: A TTL (transistor-transistor-logic, 5 volts, duration 60 ms) pulse was used to trigger the various stimuli through Presentation software. A total of eight stimulus conditions (four unisensory and four multisensory) were presented to the participants (see Figure 1A). The unisensory conditions included visual (V) and somatosensory (S) stimulation delivered to either the left or right hand. The multisensory conditions included spatially aligned simultaneous VS stimulation presented at the same location (e.g., left thumb and left index finger) and spatially misaligned simultaneous VS stimulation presented at different locations (e.g., left thumb and right index finger). The eight stimulus conditions were presented in random order with equal frequency in blocks of 200 trials. The average number of blocks that each participant completed was 24, permitting ∼600 trials of each of the eight stimulus conditions.


Keeping in touch with the visual system: spatial alignment and multisensory integration of visual-somatosensory inputs.

Mahoney JR, Molholm S, Butler JS, Sehatpour P, Gomez-Ramirez M, Ritter W, Foxe JJ - Front Psychol (2015)

Experimental Paradigm. (A) Unisensory visual, unisensory somatosensory, and multisensory VS conditions. LEDs were placed on both left and right thumbs and vibro-tactile stimulators were placed on both left and right index fingers. Mittens were used to hide vibro-tactile stimulators and headphones were used to mask the sound of the vibrators. Participants sat comfortably with their hands rested on a table and used a foot pedal located under their right foot to respond to any and all stimuli. Stimuli were 25° from the azimuth. (B) 168 electrode array and the four selected regions of interest (ROIs) used for statistical analyses.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525670&req=5

Figure 1: Experimental Paradigm. (A) Unisensory visual, unisensory somatosensory, and multisensory VS conditions. LEDs were placed on both left and right thumbs and vibro-tactile stimulators were placed on both left and right index fingers. Mittens were used to hide vibro-tactile stimulators and headphones were used to mask the sound of the vibrators. Participants sat comfortably with their hands rested on a table and used a foot pedal located under their right foot to respond to any and all stimuli. Stimuli were 25° from the azimuth. (B) 168 electrode array and the four selected regions of interest (ROIs) used for statistical analyses.
Mentions: A TTL (transistor-transistor-logic, 5 volts, duration 60 ms) pulse was used to trigger the various stimuli through Presentation software. A total of eight stimulus conditions (four unisensory and four multisensory) were presented to the participants (see Figure 1A). The unisensory conditions included visual (V) and somatosensory (S) stimulation delivered to either the left or right hand. The multisensory conditions included spatially aligned simultaneous VS stimulation presented at the same location (e.g., left thumb and left index finger) and spatially misaligned simultaneous VS stimulation presented at different locations (e.g., left thumb and right index finger). The eight stimulus conditions were presented in random order with equal frequency in blocks of 200 trials. The average number of blocks that each participant completed was 24, permitting ∼600 trials of each of the eight stimulus conditions.

Bottom Line: In support, electrophysiological results revealed significant differences between multisensory simultaneous VS and summed V + S responses, regardless of the spatial alignment of the constituent inputs.Nonetheless, multisensory effects were earlier in the aligned conditions, and were found to be particularly robust in the case of right-sided inputs (beginning at just 55 ms).In contrast to previous work on audio-visual and audio-somatosensory inputs, the current work suggests a degree of spatial specificity to the earliest detectable multisensory integrative effects in response to VS pairings.

View Article: PubMed Central - PubMed

Affiliation: The Cognitive Neurophysiology Laboratory, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg NY, USA ; Division of Cognitive and Motor Aging, Department of Neurology, Albert Einstein College of Medicine, New York NY, USA.

ABSTRACT
Correlated sensory inputs coursing along the individual sensory processing hierarchies arrive at multisensory convergence zones in cortex where inputs are processed in an integrative manner. The exact hierarchical level of multisensory convergence zones and the timing of their inputs are still under debate, although increasingly, evidence points to multisensory integration (MSI) at very early sensory processing levels. While MSI is said to be governed by stimulus properties including space, time, and magnitude, violations of these rules have been documented. The objective of the current study was to determine, both psychophysically and electrophysiologically, whether differential visual-somatosensory (VS) integration patterns exist for stimuli presented to the same versus opposite hemifields. Using high-density electrical mapping and complementary psychophysical data, we examined multisensory integrative processing for combinations of visual and somatosensory inputs presented to both left and right spatial locations. We assessed how early during sensory processing VS interactions were seen in the event-related potential and whether spatial alignment of the visual and somatosensory elements resulted in differential integration effects. Reaction times to all VS pairings were significantly faster than those to the unisensory conditions, regardless of spatial alignment, pointing to engagement of integrative multisensory processing in all conditions. In support, electrophysiological results revealed significant differences between multisensory simultaneous VS and summed V + S responses, regardless of the spatial alignment of the constituent inputs. Nonetheless, multisensory effects were earlier in the aligned conditions, and were found to be particularly robust in the case of right-sided inputs (beginning at just 55 ms). In contrast to previous work on audio-visual and audio-somatosensory inputs, the current work suggests a degree of spatial specificity to the earliest detectable multisensory integrative effects in response to VS pairings.

No MeSH data available.