Normalization in human somatosensory cortex

Brouwer, Gijs Joost; Arnedo, Vanessa; Offen, Shani; Heeger, David J.; Grant, Arthur C.

doi:10.1152/jn.00939.2014

Cited by 33 publications

(28 citation statements)

References 111 publications

(121 reference statements)

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“…Another future direction would be to use encoding models to explicitly characterize pitch and timbre selectivity throughout the auditory cortex and thus explore in more depth how these populations are modulated by attention. These approaches have been successfully used to characterize suppressive stimulus interactions in the visual system (Brouwer and Heeger, 2011) and the somatosensory system (Brouwer et al, 2015) and could be similarly useful in understanding the interactions between representations of pitch and timbre.…”

Section: Discussionmentioning

confidence: 99%

Cortical Correlates of Attention to Auditory Features

et al. 2019

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Pitch and timbre are two primary features of auditory perception that are generally considered independent. However, an increase in pitch (produced by a change in fundamental frequency) can be confused with an increase in brightness (an attribute of timbre related to spectral centroid) and vice versa. Previous work indicates that pitch and timbre are processed in overlapping regions of the auditory cortex, but are separable to some extent via multivoxel pattern analysis. Here, we tested whether attention to one or other feature increases the spatial separation of their cortical representations and if attention can enhance the cortical representation of these features in the absence of any physical change in the stimulus. Ten human subjects (four female, six male) listened to pairs of tone triplets varying in pitch, timbre, or both and judged which tone triplet had the higher pitch or brighter timbre. Variations in each feature engaged common auditory regions with no clear distinctions at a univariate level. Attending to one did not improve the separability of the neural representations of pitch and timbre at the univariate level. At the multivariate level, the classifier performed above chance in distinguishing between conditions in which pitch or timbre was discriminated. The results confirm that the computations underlying pitch and timbre perception are subserved by strongly overlapping cortical regions, but reveal that attention to one or other feature leads to distinguishable activation patterns even in the absence of physical differences in the stimuli.Although pitch and timbre are generally thought of as independent auditory features of a sound, pitch height and timbral brightness can be confused for one another. This study shows that pitch and timbre variations are represented in overlapping regions of auditory cortex, but that they produce distinguishable patterns of activation. Most importantly, the patterns of activation can be distinguished based on whether subjects attended to pitch or timbre even when the stimuli remained physically identical. The results therefore show that variations in pitch and timbre are represented by overlapping neural networks, but that attention to different features of the same sound can lead to distinguishable patterns of activation.

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Section: Discussionmentioning

confidence: 99%

Cortical Correlates of Attention to Auditory Features

et al. 2019

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“…Divisive normalisation has proven to be a useful model to explain nonlinear responses in the visual (Heeger, 1991(Heeger, , 1992Albrecht, & Geisler, 1991), olfactory (Olsen, Bhandawat, & Wilson, 2010), and auditory system (Rabinowitz, Willmore, Schnupp, & King, 2011;David, Mesgarani, Fritz, & Shamma, 2009), as well as multisensory (Ohshiro, Angelaki, & DeAngelis, 2011) and even cognitive processes (Louie, Khaw, & Glimcher, 2013;Louie Grattan, & Glimcher, 2011;Reynolds & Heeger, 2009). Although the divisive normalisation model has been classically interpreted as a canonical mechanism for maximising sensitivity (Brouwer, Arnedo, Offen, Heeger, & Grant, 2015) and reducing redundancy (Sinz & Bethge, 2013), our results suggest it could also contribute to perceptual aggregation of multi-component stimuli. Figure 7.…”

Section: Mechanisms Underlying Overestimation Of Multiple Discrepant mentioning

confidence: 74%

“…Interestingly, a recent fMRI study used divisive normalisation models to explain the suppression of somatosensory responses during concurrent stimulations of different digits (Brouwer, Arnedo, Offen, Heeger, & Grant, 2015). In particular, Brouwer and colleagues (2015) speculated that interdigit suppression (i.e.…”

Section: Mechanisms Underlying Overestimation Of Multiple Discrepant mentioning

confidence: 99%

Why the whole is more than the sum of its parts: Salience-driven overestimation in aggregated tactile sensations

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Ferrè

Pellegrino

et al. 2019

Quarterly Journal of Experimental Psychology

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Experimental psychology often studies perception analytically, reducing its focus to minimal sensory units, such as thresholds or just noticeable differences in a single stimulus. Here, in contrast, we examine a synthetic aspect: how multiple inputs to a sensory system are aggregated into an overall percept. Participants in three experiments judged the total stimulus intensity for simultaneous electrical shocks to two digits. We tested whether the integration of component somatosensory stimuli into a total percept occurs automatically, or rather depends on the ability to consciously perceive discrepancy among components (Experiment 1), whether the discrepancy among these components influences sensitivity or/and perceptual bias in judging totals (Experiment 2), and whether the salience of each individual component stimulus affects perception of total intensity (Experiment 3). Perceptual aggregation of two simultaneous component events occurred both when participants could perceptually discriminate the two intensities, and also when they could not. Further, the actual discrepancy between the stimuli modulated both participants’ sensitivity and perceptual bias: increasing discrepancies produced a systematic and progressive overestimation of total intensity. The degree of this bias depended primarily on the salience of the stronger stimulus in the pair. Overall, our results suggest that important nonlinear mechanisms contribute to sensory aggregation. The mind aggregates component inputs into a coherent and synthetic perceptual experience in a salience-weighted fashion that is not based on simple summation of inputs.

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“…Using the LRBN task, we have also previously shown that bimanual processing may be more vulnerable to central perturbations compared to unimanual processing (Convento et al, 2018). These bimanual perceptual interactions, like other bimanual effects that operate in specific feature domains and with other task demands (Craig and Qian, 1997;Braun et al, 2005;Kuroki et al, 2017), are often understood as masking effects that may be explained by divisive normalization computations in the somatosensory system (Brouwer et al, 2015;Rahman and Yau, 2019).…”

Section: Discussionmentioning

confidence: 93%

Online and offline influences of vision on bimanual tactile spatial perception

Yr¹,

Convento²,

Jm³

2020

Preprint

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Vision and touch interact in spatial perception. How vision exerts online influences on tactile spatial perception is well-appreciated, but far less is known about how vision modulates tactile perception offline. Here, we investigated how visual cues exert both online and offline biases in bimanual tactile spatial perception. In a series of experiments, participants performed a 4-alternative forced-choice tactile detection task in which they reported the perception of peri-threshold taps on the left hand, right hand, both hands, or no touch (LRBN). Participants initially performed the LRBN task in the absence of visual cues. Subsequently, participants performed the LRBN task in blocks comprising non-informative visual cues that were presented on the left and right hands. To explore the effect of distractor salience on the visuo-tactile spatial interactions, we varied the brightness of the visual cues such that visual stimuli associated with one hand were consistently brighter than visual stimuli associated with the other hand. We found that participants performed the tactile detection task in an unbiased manner in the absence of visual distractors. Visual cues biased tactile performance, despite an instruction to ignore vision, and these online effects tended to be larger with brighter distractors. Moreover, tactile performance was biased toward the side of the brighter visual cues even on trials when no visual cues were presented during the visuo-tactile block. Using a modeling framework based on signal detection theory, we compared a number of alternative models to recapitulate the behavioral results and to link the visual influences on touch to sensitivity and criterion changes. Our collective results reveal the obligatory and systematic influences of vision on both online and offline tactile spatial perception. The nervous system appears to automatically leverage multiple sensory modalities to build representations and calibrate decision processes for bimanual tactile spatial perception.

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Normalization in human somatosensory cortex

Cited by 33 publications

References 111 publications

Cortical Correlates of Attention to Auditory Features

Cortical Correlates of Attention to Auditory Features

Why the whole is more than the sum of its parts: Salience-driven overestimation in aggregated tactile sensations

Online and offline influences of vision on bimanual tactile spatial perception

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