Conditioned Audio-Visual Targeting Reflexes in Split Brain Cats

Brunk, R; Czihak, E; Oppermann, B; Santibáñez, G

doi:10.1007/978-94-009-8225-3_5

Cited by 2 publications

(2 citation statements)

References 6 publications

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“…By contrast, neurobehavioural experiments carried out in animals suggest that callosal section has little or no effect on auditory localization behaviour (Moore et al, 1974;Casseday and Neff, 1975;Brunk et al, 1979). The absence of an effect may result from the use of experimental paradigms that do not provide an accurate assessment of sound localization.…”

Section: Introductionmentioning

confidence: 96%

“…Other factors which could have masked the presence of de®cits include small sample size (Moore et al, 1974), the type of stimulus (i.e. pure tones, which are mainly treated subcortically) and long stimulus duration, which would allow scanning by movement of the head (Moore et al, 1974;Casseday and Neff, 1975;Brunk et al, 1979). In fact, using a multiple-sound source paradigm and binaural presentation, Poirier et al (1993) found that acallosal individuals displayed a de®cit throughout the auditory ®eld.…”

Section: Introductionmentioning

confidence: 99%

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Sound localization in callosal agenesis and early callosotomy subjects: brain reorganization and/or compensatory strategies

Lessard¹,

Leporé²,

Villemagne³

et al. 2002

Brain

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In order to evaluate the callosal involvement in sound localization, the present study examined the response accuracy of acallosal and early callosotomized subjects to monaural and binaural auditory targets presented in three-dimensional space. In these subjects, bilateral localization cues, such as interaural time and level differences, are integrated at the cortical and subcortical levels without the additional support of the callosal commissure. Because acallosal and early-callosotomized subjects have developed with this reduced source of binaural activation of cortical cells, they might have perfected their ability to use monaural sound localization cues. This hypothesis was tested by assessing localization performance under both binaural and monaural listening conditions. Five subjects with callosal agenesis, one callosotomized subject operated early in life and 19 control subjects were asked to localize broad-band noise bursts (BBNBs) of fixed intensity in the horizontal plane in an anechoic chamber. BBNBs were delivered through randomly selected loudspeakers. Two conditions were tested: (i) localization of a stationary sound source; and (ii) localization of a moving sound source. Listeners had to report the apparent stimulus location by pointing to its perceived position on a graduated perimeter. The results indicated that the acallosal subjects were less accurate than controls, but only in the binaural moving sound condition. More interestingly, in the monaural testing conditions, some of the acallosal subjects and the early-callosotomized subject performed significantly better than control subjects. This suggests that, because of the absence of the corpus callosum, these subjects compensate for their reduced access to cortically determined binaural cues by making more efficient use of monaural cues.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Sound localization in callosal agenesis and early callosotomy subjects: brain reorganization and/or compensatory strategies

Lessard¹,

Leporé²,

Villemagne³

et al. 2002

Brain

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Binaural noise stimulation of auditory callosal fibers of the cat: responses to interaural time delays

et al. 1995

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The corpus callosum, the principal neocortical commissure, allows for the interhemispheric transfer of lateralized information between the hemispheres. The aim of the present experiment was to study callosal transfer of auditory information in the cat, with particular reference to its contribution to sound localization. The corpus callosum was approached under direct visual control, and axonic responses were recorded under light anesthesia using glass micro-pipettes. Results showed that auditory information is transmitted in the posterior portion of the callosum. Diotic presentations, in which interaural time delay was manipulated, indicated that, for a large number of fibers, the largest excitatory or inhibitory interactions were obtained at null interaural time delay, a condition which supports the notion of a callosal contribution to auditory midline fusion. However, an important number of callosal fibers was also found to be excited maximally at specific, non-zero interaural time delays, suggesting that they preferred sounds situated at spatial locations other than the midline. The results are discussed in relation to those obtained electrophysiologically for the visual and somesthesic modalities and in terms of results obtained in human and animal behavioral experiments.

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Conditioned Audio-Visual Targeting Reflexes in Split Brain Cats

Cited by 2 publications

References 6 publications

Sound localization in callosal agenesis and early callosotomy subjects: brain reorganization and/or compensatory strategies

Sound localization in callosal agenesis and early callosotomy subjects: brain reorganization and/or compensatory strategies

Binaural noise stimulation of auditory callosal fibers of the cat: responses to interaural time delays

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