Browsing by Subject "sound localization"
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Item Open Access Sounds and beyond: multisensory and other non-auditory signals in the inferior colliculus.(Frontiers in neural circuits, 2012-01) Gruters, Kurtis G; Groh, Jennifer MThe inferior colliculus (IC) is a major processing center situated mid-way along both the ascending and descending auditory pathways of the brain stem. Although it is fundamentally an auditory area, the IC also receives anatomical input from non-auditory sources. Neurophysiological studies corroborate that non-auditory stimuli can modulate auditory processing in the IC and even elicit responses independent of coincident auditory stimulation. In this article, we review anatomical and physiological evidence for multisensory and other non-auditory processing in the IC. Specifically, the contributions of signals related to vision, eye movements and position, somatosensation, and behavioral context to neural activity in the IC will be described. These signals are potentially important for localizing sound sources, attending to salient stimuli, distinguishing environmental from self-generated sounds, and perceiving and generating communication sounds. They suggest that the IC should be thought of as a node in a highly interconnected sensory, motor, and cognitive network dedicated to synthesizing a higher-order auditory percept rather than simply reporting patterns of air pressure detected by the cochlea. We highlight some of the potential pitfalls that can arise from experimental manipulations that may disrupt the normal function of this network, such as the use of anesthesia or the severing of connections from cortical structures that project to the IC. Finally, we note that the presence of these signals in the IC has implications for our understanding not just of the IC but also of the multitude of other regions within and beyond the auditory system that are dependent on signals that pass through the IC. Whatever the IC "hears" would seem to be passed both "upward" to thalamus and thence to auditory cortex and beyond, as well as "downward" via centrifugal connections to earlier areas of the auditory pathway such as the cochlear nucleus.Item Embargo Visual Cues Modulate Auditory Responses in the Macaque Inferior Colliculus(2024) Schmehl, Meredith NicoleHow the brain uses multisensory cues to process complex sensory environments remains a key question in neuroscience. Of particular interest is whether relatively early sensory areas, which are commonly considered to be unisensory in function, might take in information from other sensory modalities to inform the representation of the primary modality of interest. We explored how visual cues might inform the representation of sounds in the macaque inferior colliculus, a subcortical auditory region that receives visual input and has visual and eye movement-related responses. Using in vivo single-unit extracellular recordings, we observed neuronal responses in the inferior colliculus while two monkeys performed a localization task involving both auditory and visual stimuli. We found that pairing a visual cue with a sound can change a neuron’s response to that sound, even if the neuron is unresponsive to visual input alone. Visual cues also enhance localization behavior in both spatial precision and temporal latency. Finally, when two simultaneous sounds are present and one sound is accompanied by a visual cue, neurons’ responses to the two stimuli on individual trials may correlate with each monkey’s behavior during the task. Together, these results suggest that the inferior colliculus uses visual cues to alter its sound responsiveness and inform perceptual behavior, providing insight into how the brain combines multisensory information into a single perceptual object at a relatively early stage of the auditory pathway.