Biology subjects

Ben-Shachar, M.

Publications and source records attributed to Ben-Shachar, M..

3 recordsLinked to original sources

bioRxiv2021

Interpreting sensory and cognitive signals in the cortical reading network

Voxels in the visual cortex contain neurons that are responsive to small regions of the visual field; these regions can be quantified using population receptive field (pRF) analysis. We measured pRFs using several types of patterns: words, visually matched false-fonts, and visually dissimilar checker patterns. In visual field maps pRF estimates using words and false-fonts are similar, but pRF estimates using checkers differ substantially. The pattern of results in the contiguous ventral occipito-temporal reading circuitry is different: word pRF estimates differ from false-fonts and checkers. These findings were replicated at two research sites. We explain these results with a qualitative model, where the response differences in the visual field maps arise from sensory signals, and the differences in the reading circuitry arise from the integration of sensory and cognitive signals.

neuroscience↗

bioRxiv2021

Attention to speech: Mapping distributed and selective attention systems

Daily life is full of situations where many people converse at the same time. Under these noisy circumstances, individuals can employ different listening strategies to deal with the abundance of sounds around them. In this fMRI study we investigated how applying two different listening strategies - Selective vs. Distributed attention - affects the pattern of neural activity. Specifically, in a simulated cocktail party paradigm, we compared brain activation patterns when listeners attend selectively to only one speaker and ignore all others, versus when they distribute their attention and attempt to follow two or four speakers at the same time. Results indicate that the two attention types activate a highly overlapping, bilateral fronto-temporal-parietal network of functionally connected regions. This network includes auditory association cortex (bilateral STG/STS) and higher-level regions related to speech processing and attention (bilateral IFG/insula, right MFG, left IPS). Within this network, responses in specific areas were modulated by the type of attention required. Specifically, auditory and speech-processing regions exhibited higher activity during Distributed attention, whereas fronto-parietal regions were activated more strongly during Selective attention. This pattern suggests that a common perceptual-attentional network is engaged when dealing with competing speech-inputs, regardless of the specific task at hand. At the same time, local activity within nodes of this network varies when implementing different listening strategies, reflecting the different cognitive demands they impose. These results nicely demonstrate the systems flexibility to adapt its internal computations to accommodate different task requirements and listener goals. Significance StatementHearing many people talk simultaneously poses substantial challenges for the human perceptual and cognitive systems. We compared neural activity when listeners applied two different listening strategy to deal with these competing inputs: attending selectively to one speaker vs. distributing attention among all speakers. A network of functionally connected brain regions, involved in auditory processing, language processing and attentional control was activated when applying both attention types. However, activity within this network was modulated by the type of attention required and the number of competing speakers. These results suggest a common attention to speech network, providing the computational infrastructure to deal effectively with multi-speaker input, but with sufficient flexibility to implement different prioritization strategies and to adapt to different listener goals.

neuroscience↗

bioRxiv2020

A general role for ventral white matter pathways in morphological processing: going beyond reading

The ability to recognize the structural components of words, known as morphological processing, was recently associated with the bilateral ventral white matter pathways, across different writing systems. However, it remains unclear whether these associations are specific to the context of reading. To shed light on this question, in the current study we investigated whether the ventral pathways are associated with morphological processing in an oral word production task that does not involve reading. Forty-five participants completed a morpheme-based fluency task in Hebrew, as well as diffusion MRI (dMRI) scans. We used probabilistic tractography to segment the major ventral and dorsal white matter pathways, and assessed the correlations between their microstructural properties and performance on the morpheme-based fluency task. We found significant correlations between morpheme-based fluency and properties of the bilateral ventral tracts, suggesting that the involvement of these tracts in morphological processing extends beyond the reading modality. In addition, significant correlations were found in the frontal aslant tract (FAT), a dorsal tract associated with oral fluency and speech production. Together, our findings emphasize that neurocognitive associations reflect both the cognitive construct under investigation as well as the task used for its assessment. Lastly, to elucidate the biological factors underlying these correlations, we incorporated the composite hindered and restricted model of diffusion (CHARMED) framework, measured in independent scans. We found that only some of our findings could be attributed to variation in a CHARMED-based estimate of fiber density. Further, we were able to uncover additional correlations that could not be detected using traditional dMRI indices. In sum, our results show that the involvement of the ventral tracts in morphological processing extends to the production domain, and demonstrate the added value of including sensitive structural measurements in neurocognitive investigations.

neuroscience↗