Biology subjects

Korczyk, M.

Publications and source records attributed to Korczyk, M..

3 recordsLinked to original sources

bioRxiv2024

Repetition suppression for mirror images of objects and not Braille letters in the ventral visual stream of congenitally blind individuals

Mirror-invariance effect describes the cognitive tendency to perceive mirror-image objects as identical. Mirrored letters, however, are distinct orthographic units and must be identified as different. Mirror-invariance must be broken to enable efficient reading. Consistent with this phenomenon, a small, localized region in the ventral visual stream, the Visual Word Form Area (VWFA), exhibits repetition suppression to identical and mirror pairs of objects but only to identical pairs of letters. The ability of congenitally blind individuals to break mirror invariance for pairs of mirrored Braille letters has been demonstrated behaviorally. However, its neural underpinnings have not yet been investigated. Here, in an fMRI repetition suppression paradigm, congenially blind individuals (both sexes) recognized pairs of everyday objects and Braille letters in identical (p & p), mirror (p & q), and different (p & z) orientations. We found repetition suppression for identical and mirror pairs of everyday objects in the parietal and ventral-lateral occipital cortex, indicating that mirror-invariant object recognition engages the ventral visual stream in tactile modality as well. However, repetition suppression for identical but not mirrored pairs of Braille letters was found in the left parietal cortex and the lateral occipital cortex but not in the VWFA. These results suggest notable differences in reading-related orthographic processes between sighted and blind individuals, with the LOC region in the latter being a potential hub for letter-shape processing. Significance StatementMirror invariance is a tendency to recognize rotated objects as identical. Letters are unique shapes as people learn to recognize mirrored letters (e.g., b and d) as distinct objects. In our study, we investigated the neural underpinnings of tactile mirror invariance in congenitally blind individuals. We demonstrated engagement of the parietal, occipital, and ventral visual regions in mirror-invariant tactile object recognition, indicating that this perceptual bias extends beyond the visual modality. Moreover, we found that unlike in the sighted, it was the parietal and lateral occipital cortex that showed neural signatures of breaking mirror invariance for Braille letters in congenitally blind individuals, suggesting substantial differences between visual and tactile reading.

neuroscience↗

bioRxiv2024

Blind individuals' enhanced ability to sense their own heartbeat is related to the thickness of their occipital cortex

Blindness is associated with heightened sensory abilities, such as improved hearing and tactile acuity. Moreover, recent evidence suggests that blind individuals are better than sighted individuals at perceiving their own heartbeat, suggesting enhanced interoceptive accuracy. Structural changes in the occipital cortex have been hypothesized as the basis of these behavioral enhancements. Indeed, several studies have shown that congenitally blind individuals have increased cortical thickness within occipital areas compared to sighted individuals, but how these structural differences relate to behavioral enhancements is unclear. This study investigated the relationship between cardiac interoceptive accuracy and cortical thickness in 23 congenitally blind individuals and 23 matched sighted controls. Our results show a significant positive correlation between performance in a heartbeat counting task and cortical thickness only in the blind group, indicating a connection between structural changes in occipital areas and blind individuals better ability to perceive heartbeats.

neuroscience↗

bioRxiv2022

Cardiac interoception is enhanced in blind individuals

Blind individuals have superior abilities to perform perceptual tasks that rely on exteroceptive information, since visual deprivation is associated with massive cross-modal plasticity. However, it is unknown whether neuroplasticity after visual loss also affects interoception, i.e., the sensations arising from ones inner organs that convey information about the physiological state of the body. Herein, we examine the influence of blindness on cardiac interoception, which is an interoceptive submodality that has important links to emotional processing and bodily self-awareness. We tested 36 blind and 36 age-and sex-matched sighted volunteers and examined their cardiac interoceptive ability using a well-established heartbeat counting task. The results showed that blind individuals had significantly higher accuracy in perceiving their heartbeat than did individuals in a matched sighted control group. In contrast, there were no significant differences between the groups in the metacognitive dimensions of cardiac interception or the purely physiological measurement of heart rate, thereby underscoring that the improved accuracy likely reflects a superior perceptual sensitivity to cardiac interoceptive signals in blind individuals. We conclude that visual deprivation leads to enhanced interoception, which has important implications for the study of the extent of massive cross-modal plasticity after visual loss, understanding emotional processing in blind individuals, and learning how bodily self-awareness can develop and be sustained in the absence of visual experience.

neuroscience↗