Multisensory top down templates and multi sensory integration
Multisensory top down templates and multi sensory integration
2023 has had a number of articles released on multi sensory integration with some important findings including:
· Multisensory functional brain networks
· Multisensory templates as a top down process
· Multisensory processing occurring at earliest stages of information processing.
Some of the important points from these articles have been included but they are worth reading in their entirety if you are interested in this area.
Scheliga et al (2023) completed a meta-analysis with multiple sensory modalities to identify a common brain network.
· supports different functional roles for multisensory integration.
· The perception of environmental stimuli mostly occurs on many sites in the nervous system addressing multiple sensory channels at once.
· information in one sense can shape information processing in the other.
· multisensory stimuli evoke a response of the organism that is different from the sum of the unisensory stimuli presented separately.
· the insula may coordinate attention to the information from multiple senses.
· Meanwhile, many studies have shown that MSI takes place at various subcortical levels and that structures like the thalamus integrate different senses even before higher cortical regions are involved
· the insula may coordinate attention to the information from multiple senses.
· Within this network, the thalamus may be the first subcortical relay station projecting multisensory information to a higher cortical integration center, the STG/STS. (STG: superior temporal gyrus, STS: superior temporal sulcus)
Newell et al’s (2023 ) research was on multisensory top–down templates controlling responses in “sensory-specific” cortices and they found that:
“Multisensory objects are selected involuntarily, independently of unisensory task demands,
co-occurring crossmodal stimuli are often easier to:
o detect,
o perceive,
o attend to,
compared with unisensory stimuli, irrespective of the observer's goals
Thus, in multisensory environments, attentional selection is controlled
via integrated top-down object representations, and so not only by
separate sensory-specific top-down feature templates “.
· “To date, processes such as causal inference or predictive coding have mainly been proposed to explain cross-sensory interactions for perception and have not adequately been considered in models of the formation of multisensory object categories in memory, despite the relevance. Given the increasing knowledge of multisensory interactions in the brain, we argue that there is a timely need for an extension of these models. For example, traditionally it was assumed that multisensory integration occurred late in information processing, underpinned by activations in association cortex or beyond in neural structures supporting associative learning and memory. However, evidence for crossmodal interactions in primary sensory regions of the brain, revealing plasticity changes to multisensory inputs at all stages of brain processing, is now overwhelming . Indeed, the past few decades have witnessed growing evidence for multisensory interactions within primary sensory regions of the brain, including activations in the visual cortex to auditory and somatosensory inputs and responses in primary auditory cortex to visual inputs , suggesting that cross-sensory inputs moderate early stages of information processing. “
Choi et al (2023) article describes multiple areas of the brain involved in multi sensory integration. This article is part of a theme issue: ‘Decision and control processes in multisensory perception’.
· prior experience would be one of the major factors that can cause flexible Multisensory integration.
· Therefore, the attention recruited by stimuli in a bottom-up fashion can modulate Multi Sensory Integration, and it is a mechanism that can selectively integrate important and relevant stimuli for the survival of an animal in a complicated environment with numerous sensory inputs.
· Multisensory integration (MSI) occurs in a variety of brain areas, spanning cortical and subcortical regions. In traditional studies on sensory processing, the sensory cortices have been considered for processing sensory information in a modality-specific manner. The sensory cortices, however, send the information to other cortical and subcortical areas, including the higher association cortices and the other sensory cortices, where the multiple modality inputs converge and integrate to generate a meaningful percept. This integration process is neither simple nor fixed because these brain areas interact with each other via complicated circuits, which can be modulated by numerous internal and external conditions. As a result, dynamic MSI makes multisensory decisions flexible and adaptive in behaving animals. Impairments in MSI occur in many psychiatric disorders, which may result in an altered perception of the multisensory stimuli and an abnormal reaction to them. This review discusses the diversity and flexibility of MSI in mammals, including humans, primates and rodents, as well as the brain areas involved. It further explains how such flexibility influences perceptual experiences in behaving animals in both health and disease. This article is part of the theme issue
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References:
Choi I, Demir I, Oh S, Lee S-H. 2023 Multisensory integration in the mammalian brain: diversity and flexibility in health and disease. Phil. Trans. R. Soc. B 378: 20220338. https://doi.org/10.1098/rstb.2022.0338
Newell, F. N., McKenna, E., Seveso, M. A., Devine, I., Alahmad, F., & Hirst, R. J. (2023). Multisensory perception constrains the formation of object categories: A review of evidence from sensory-driven and predictive processes on categorical decisions. Philosophical Transactions of the Royal Society B: Biological Sciences, 378(1886). https://doi.org/10.1098/rstb.2022.0342
Scheliga, Sebastian, Kellermann, Thilo, Lampert, Angelika, Rolke, Roman, Spehr, Marc and Habel, Ute. "Neural correlates of multisensory integration in the human brain: an ALE meta-analysis" Reviews in the Neurosciences, vol. 34, no. 2, 2023, pp. 223-245. https://doi.org/10.1515/revneuro-2022-0065