Biology subjects

Vetter, P.

Publications and source records attributed to Vetter, P..

3 recordsLinked to original sources

bioRxiv2026

Decoding the ''bouba-kiki'' effect in early visual cortex

The "bouba-kiki" effect, or sound symbolism, is the non-arbitrary mapping between speech sounds and visual shapes, in which words like "bouba" are consistently associated with round shapes, and "kiki" with spiky shapes. Despite robust behavioral evidence for sound symbolic associations, it is still unclear whether they are a linguistic epiphenomenon or manifest themselves as distinct sensory representations in the human brain. Using fMRI and multivariate pattern analyses, we show that, in the absence of visual input, round and spiky sound symbolic words elicit distinct neural representations, not only in auditory and speech processing regions, but also in parietal and even early visual cortex including V1. These neural representations correlate with behavioural shape judgements of sound-symbolic words, as revealed by representational similarity analyses. Our findings suggest a potential functional mechanism for sound symbolism: phonological features of sound symbolic words are represented in auditory and speech processing regions and linked to cross-modal shape representations in parietal and early visual regions, which in turn lead to sound symbolic perceptual judgements. Thus, our results provide evidence for a neural mechanism underlying the "bouba-kiki" effect in the human brain.

neuroscience↗

bioRxiv2024

Immune escape of Omicron lineages BA.1, BA.2, BA.5.1, BQ.1, XBB.1.5, EG.5.1 and JN.1.1 after vaccination, infection and hybrid immunity

In the 5th year after the emergence of SARS-CoV-2, Omicron lineages continue to evolve and cause infections. Here, we used eight authentic SARS-CoV-2 isolates to assess their capacity to escape immunity of different exposure histories and their replicative capacity in polarized human airway epithelial cells (HAE) derived from the nasal and bronchial epithelium. Using live-virus neutralization assays of 108 human sera or plasma of different immunological backgrounds, progressive immune escape was observed from B.1 (ancestral virus) to EG.5.1, but no significant difference between EG.5.1 and JN.1.1. Vaccinated individuals without natural infection and individuals with a single infection, but no vaccination showed markedly reduced or completely lost neutralization against the latest variants, while in those with hybrid immunity almost all sera showed some neutralization capacity. Furthermore, although absolute titers differed between groups, the pattern of immune escape between the variants remains comparable with strongest loss of neutralization observed for the latest variants. In vitro studies with HAE at 33{degrees}C and 37{degrees}C showed some, but minor differences in virus replication and innate immune responses upon infection. Notably, infection with XBB.1.5, EG.5.1 and JN.1.1 showed slightly increased viral growth in nasal HAE at 33{degrees}C. Altogether, these data underscore increasing immune escape across heterogeneous immunological backgrounds with gradually increasing antibody escape of evolving Omicron lineages until variant EG.5.1, but not any further for the latest dominant lineage JN.1.1. They also suggest that viral dynamics within Omicron lineages are driven by a combination of immune evasion and increase in viral replication.

microbiology↗

bioRxiv2017

Predictive feedback to V1 dynamically updates with sensory input

Predictive coding theories propose that the brain creates internal models of the environment to predict upcoming sensory input. Hierarchical predictive coding models of vision postulate that higher visual areas generate predictions of sensory inputs and feed them back to early visual cortex. In V1, sensory inputs that do not match the predictions lead to amplified brain activation, but does this amplification process dynamically update to new retinotopic locations with eye-movements? We investigated the effect of eye-movements in predictive feedback using functional brain imaging and eye-tracking whilst presenting an apparent motion illusion. Apparent motion induces an internal model of motion, during which sensory predictions of the illusory motion feed back to V1. We observed attenuated BOLD responses to predicted stimuli at the new post-saccadic location in V1. Therefore, pre-saccadic predictions update their retinotopic location in time for post-saccadic input, validating dynamic predictive coding theories in V1.

neuroscience↗