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Lack of multisensory integration in hemianopia: no influence of visual stimuli on aurally guided saccades to the blind hemifield.

Ten Brink AF, Nijboer TC, Bergsma DP, Barton JJ, Van der Stigchel S - PLoS ONE (2015)

Bottom Line: The superior colliculus (SC) is part of the spared pathway that is considered to be responsible for this phenomenon.In one patient with a more limited quadrantano-pia, a facilitation effect of the spatially coincident visual stimulus was observed.We conclude that our results show that multisensory integration is infrequent in the blind field of patients with hemianopia.

View Article: PubMed Central - PubMed

Affiliation: Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, The Netherlands; Brain Center Rudolf Magnus Institute of Neuroscience and Centre of Excellence for Rehabilitation Medicine, University Medical Centre Utrecht and Rehabilitation Centre De Hoogstraat, Utrecht, The Netherlands.

ABSTRACT
In patients with visual hemifield defects residual visual functions may be present, a phenomenon called blindsight. The superior colliculus (SC) is part of the spared pathway that is considered to be responsible for this phenomenon. Given that the SC processes input from different modalities and is involved in the programming of saccadic eye movements, the aim of the present study was to examine whether multimodal integration can modulate oculomotor competition in the damaged hemifield. We conducted two experiments with eight patients who had visual field defects due to lesions that affected the retinogeniculate pathway but spared the retinotectal direct SC pathway. They had to make saccades to an auditory target that was presented alone or in combination with a visual stimulus. The visual stimulus could either be spatially coincident with the auditory target (possibly enhancing the auditory target signal), or spatially disparate to the auditory target (possibly competing with the auditory tar-get signal). For each patient we compared the saccade endpoint deviation in these two bi-modal conditions with the endpoint deviation in the unimodal condition (auditory target alone). In all seven hemianopic patients, saccade accuracy was affected only by visual stimuli in the intact, but not in the blind visual field. In one patient with a more limited quadrantano-pia, a facilitation effect of the spatially coincident visual stimulus was observed. We conclude that our results show that multisensory integration is infrequent in the blind field of patients with hemianopia.

No MeSH data available.


Related in: MedlinePlus

Experimental set-up.The eight speaker symbols (black and grey) depict the locations of both auditory and visual stimuli that were used in the experiment. Four of these locations (the black speaker symbols) were used for the sound selection.
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pone.0122054.g003: Experimental set-up.The eight speaker symbols (black and grey) depict the locations of both auditory and visual stimuli that were used in the experiment. Four of these locations (the black speaker symbols) were used for the sound selection.

Mentions: Sound selection: The auditory stimuli consisted of 500 ms bursts of broadband noise. Each auditory stimulus was presented against a constant background noise (57 dB) generated by the projector. We determined for each participant the lowest intensity at which they could coarsely localize the sound stimulus in order to obtain subjectively hard-to-localize stimuli for each participant. Five sounds with a different intensity (31, 36, 41, 47 and 52 dB) were presented each 16 times randomly at 4 of the 8 used locations (Fig. 3). Participants indicated verbally in which of the four quadrants they thought the sound originated. For the experiment, the lowest intensity that was localized correctly in all trials was used. If none of the sounds were localized correctly in all trials, the highest intensity of 57 dB was used. The sound with the highest intensity had to be localized correctly in at least 75% of the trials for the patient to be included. By this criterion, six patients were excluded. Their maximum success rate varied from 38% to 69% correct localizations for one of the sounds.


Lack of multisensory integration in hemianopia: no influence of visual stimuli on aurally guided saccades to the blind hemifield.

Ten Brink AF, Nijboer TC, Bergsma DP, Barton JJ, Van der Stigchel S - PLoS ONE (2015)

Experimental set-up.The eight speaker symbols (black and grey) depict the locations of both auditory and visual stimuli that were used in the experiment. Four of these locations (the black speaker symbols) were used for the sound selection.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383622&req=5

pone.0122054.g003: Experimental set-up.The eight speaker symbols (black and grey) depict the locations of both auditory and visual stimuli that were used in the experiment. Four of these locations (the black speaker symbols) were used for the sound selection.
Mentions: Sound selection: The auditory stimuli consisted of 500 ms bursts of broadband noise. Each auditory stimulus was presented against a constant background noise (57 dB) generated by the projector. We determined for each participant the lowest intensity at which they could coarsely localize the sound stimulus in order to obtain subjectively hard-to-localize stimuli for each participant. Five sounds with a different intensity (31, 36, 41, 47 and 52 dB) were presented each 16 times randomly at 4 of the 8 used locations (Fig. 3). Participants indicated verbally in which of the four quadrants they thought the sound originated. For the experiment, the lowest intensity that was localized correctly in all trials was used. If none of the sounds were localized correctly in all trials, the highest intensity of 57 dB was used. The sound with the highest intensity had to be localized correctly in at least 75% of the trials for the patient to be included. By this criterion, six patients were excluded. Their maximum success rate varied from 38% to 69% correct localizations for one of the sounds.

Bottom Line: The superior colliculus (SC) is part of the spared pathway that is considered to be responsible for this phenomenon.In one patient with a more limited quadrantano-pia, a facilitation effect of the spatially coincident visual stimulus was observed.We conclude that our results show that multisensory integration is infrequent in the blind field of patients with hemianopia.

View Article: PubMed Central - PubMed

Affiliation: Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, The Netherlands; Brain Center Rudolf Magnus Institute of Neuroscience and Centre of Excellence for Rehabilitation Medicine, University Medical Centre Utrecht and Rehabilitation Centre De Hoogstraat, Utrecht, The Netherlands.

ABSTRACT
In patients with visual hemifield defects residual visual functions may be present, a phenomenon called blindsight. The superior colliculus (SC) is part of the spared pathway that is considered to be responsible for this phenomenon. Given that the SC processes input from different modalities and is involved in the programming of saccadic eye movements, the aim of the present study was to examine whether multimodal integration can modulate oculomotor competition in the damaged hemifield. We conducted two experiments with eight patients who had visual field defects due to lesions that affected the retinogeniculate pathway but spared the retinotectal direct SC pathway. They had to make saccades to an auditory target that was presented alone or in combination with a visual stimulus. The visual stimulus could either be spatially coincident with the auditory target (possibly enhancing the auditory target signal), or spatially disparate to the auditory target (possibly competing with the auditory tar-get signal). For each patient we compared the saccade endpoint deviation in these two bi-modal conditions with the endpoint deviation in the unimodal condition (auditory target alone). In all seven hemianopic patients, saccade accuracy was affected only by visual stimuli in the intact, but not in the blind visual field. In one patient with a more limited quadrantano-pia, a facilitation effect of the spatially coincident visual stimulus was observed. We conclude that our results show that multisensory integration is infrequent in the blind field of patients with hemianopia.

No MeSH data available.


Related in: MedlinePlus