10 research outputs found
The representational dynamics of task and object processing in humans
Despite the importance of an observer’s goals in determining how a visual
object is categorized, surprisingly little is known about how humans process
the task context in which objects occur and how it may interact with the
processing of objects. Using magnetoencephalography (MEG), functional magnetic
resonance imaging (fMRI) and multivariate techniques, we studied the spatial
and temporal dynamics of task and object processing. Our results reveal a
sequence of separate but overlapping task-related processes spread across
frontoparietal and occipitotemporal cortex. Task exhibited late effects on
object processing by selectively enhancing task-relevant object features, with
limited impact on the overall pattern of object representations. Combining MEG
and fMRI data, we reveal a parallel rise in task-related signals throughout
the cerebral cortex, with an increasing dominance of task over object
representations from early to higher visual areas. Collectively, our results
reveal the complex dynamics underlying task and object representations
throughout human cortex
Decoding Brain Activity Associated with Literal and Metaphoric Sentence Comprehension Using Distributional Semantic Models
Recent years have seen a growing interest within the natural language processing (NLP)community in evaluating the ability of semantic models to capture human meaning representation in the brain. Existing research has mainly focused on applying semantic models to de-code brain activity patterns associated with the meaning of individual words, and, more recently, this approach has been extended to sentences and larger text fragments. Our work is the first to investigate metaphor process-ing in the brain in this context. We evaluate a range of semantic models (word embeddings, compositional, and visual models) in their ability to decode brain activity associated with reading of both literal and metaphoric sentences. Our results suggest that compositional models and word embeddings are able to capture differences in the processing of literal and metaphoric sentences, providing sup-port for the idea that the literal meaning is not fully accessible during familiar metaphor comprehension
A Probabilistic Functional Atlas of Human Occipito-Temporal Visual Cortex
Human visual cortex contains many retinotopic and category-specific regions. These brain regions have been the focus of a large body of functional magnetic resonance imaging research, significantly expanding our understanding of visual processing. As studying these regions requires accurate localization of their cortical location, researchers perform functional localizer scans to identify these regions in each individual. However, it is not always possible to conduct these localizer scans. Here, we developed and validated a functional region of interest (ROI) atlas of early visual and category-selective regions in human ventral and lateral occipito-temporal cortex. Results show that for the majority of functionally defined ROIs, cortex-based alignment results in lower between-subject variability compared to nonlinear volumetric alignment. Furthermore, we demonstrate that 1) the atlas accurately predicts the location of an independent dataset of ventral temporal cortex ROIs and other atlases of place selectivity, motion selectivity, and retinotopy. Next, 2) we show that the majority of voxel within our atlas is responding mostly to the labeled category in a left-out subject cross-validation, demonstrating the utility of this atlas. The functional atlas is publicly available (download.brainvoyager.com/data/visfAtlas.zip) and can help identify the location of these regions in healthy subjects as well as populations (e.g., blind people, infants) in which functional localizers cannot be run