Language processing in the occipital cortex of congenitally blind adults

Bedny, Marina; Pascual‐Leone, Álvaro; Dodell-Feder, David; Fedorenko, Evelina; Saxe, Rebecca

doi:10.1073/pnas.1014818108

Cited by 366 publications

(446 citation statements)

References 58 publications

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“…In recent years, the occipital cortex, as well as adjacent ventral areas such as the fusiform gyrus (16,17), have been the main regions of interest in the study of cross-modal phenomena in blindness. Multiple studies have shown that the occipital cortex takes over multiple sensory abilities traditionally belonging to other unimodal cortices, such as auditory (18,19), tactile (20), or higher cognitive functions, including language processing (21). However, in light of our results, neuroplastic reorganization in blindness is centralized-in network and graph theory sense-beyond the visual cortex or its direct functional connections.…”

Section: Discussioncontrasting

confidence: 42%

Brain circuit–gene expression relationships and neuroplasticity of multisensory cortices in blind children

Ortiz-Terán

Diez

Ortiz

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Sensory deprivation reorganizes neurocircuits in the human brain. The biological basis of such neuroplastic adaptations remains elusive. In this study, we applied two complementary graph theory-based functional connectivity analyses, one to evaluate whole-brain functional connectivity relationships and the second to specifically delineate distributed network connectivity profiles downstream of primary sensory cortices, to investigate neural reorganization in blind children compared with sighted controls. We also examined the relationship between connectivity changes and neuroplasticity-related gene expression profiles in the cerebral cortex. We observed that multisensory integration areas exhibited enhanced functional connectivity in blind children and that this reorganization was spatially associated with the transcription levels of specific members of the cAMP Response Element Binding protein gene family. Using systems-level analyses, this study advances our understanding of human neuroplasticity and its genetic underpinnings following sensory deprivation.blindness | children | neuroplasticity | functional connectivity | CREB family N europlasticity is an intrinsic ability of the brain to modify and rewire itself following experiences (1). The study of neuroplastic reorganization in blind individuals offers a model through which neuroadaptive processes can be identified. For instance, cross-modal neuroplasticity is a mechanism by which blind individuals recruit visual-related cortices to process sensory information from other perceptual modalities (2-5). In addition to occipital regions, parietal and frontal multimodal integration regions of blind adults are capable of functional connectivity reorganization (6). These brain areas are part of a multimodal integration network that acts as a bridge integrating multisensory functions across cortical regions (7). Our group has previously characterized the hierarchical structure and central position of the multimodal integration network in adult blind subjects (6). Although this finding advances our understanding of how information from primary unimodal cortices is adaptively integrated into higher-order associative areas, it remains unclear if neuroplastic changes within multimodal integration areas also occur in blind children. Furthermore, in addition to clarifying the sites of prominent neuroplastic changes, the biological mechanisms through which neuroplastic alterations occur have yet to be fully elucidated in blind individuals.Concurrent advances in cellular and molecular biology and neuroimaging provide a unique opportunity to explore the interlinked relationships between genes and neural circuits (8). A neuroimaging endophenotype is informative because it is more closely related to the genetic end product than clinical or behavioral phenotypes (9). Thus, examining properties of systemslevel brain organization and cortical gene expression has great potential to expand our understanding of neuroplastic mechanisms, particularly if specific gene expression patt...

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Section: Discussioncontrasting

confidence: 42%

Brain circuit–gene expression relationships and neuroplasticity of multisensory cortices in blind children

Ortiz-Terán

Diez

Ortiz

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Averaging across word positions, responses are highest for sentences, weaker for word-lists and Jabberwocky, and weakest for nonword-lists ( Fig. 2A and Table 2), a pattern similar to the one observed previously in fMRI (28,51). It is worth noting that unlike in fMRI, where the responses to word-lists and Jabberwocky are similar in magnitude (28), the ECoG response to word-lists is generally higher than the response to Jabberwocky ( Fig.…”

Section: Resultsmentioning

confidence: 47%

Neural correlate of the construction of sentence meaning

Fedorenko

Scott

Brunner

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The neural processes that underlie your ability to read and understand this sentence are unknown. Sentence comprehension occurs very rapidly, and can only be understood at a mechanistic level by discovering the precise sequence of underlying computational and neural events. However, we have no continuous and online neural measure of sentence processing with high spatial and temporal resolution. Here we report just such a measure: intracranial recordings from the surface of the human brain show that neural activity, indexed by γ-power, increases monotonically over the course of a sentence as people read it. This steady increase in activity is absent when people read and remember nonword-lists, despite the higher cognitive demand entailed, ruling out accounts in terms of generic attention, working memory, and cognitive load. Response increases are lower for sentence structure without meaning ("Jabberwocky" sentences) and word meaning without sentence structure (word-lists), showing that this effect is not explained by responses to syntax or word meaning alone. Instead, the full effect is found only for sentences, implicating compositional processes of sentence understanding, a striking and unique feature of human language not shared with animal communication systems. This work opens up new avenues for investigating the sequence of neural events that underlie the construction of linguistic meaning.ow does a sequence of sounds emerging from one person's mouth create a complex meaning in another person's mind? Although we have long known where language is processed in the brain (1-3), we still know almost nothing about how neural circuits extract and represent the meaning of a sentence. A powerful method for addressing this question is intracranial recording of neural activity directly from the cortical surface in neurosurgery patients (i.e., electrocorticography or ECoG) (4, 5). Although opportunities for ECoG data collection are rare, determined by clinical-not scientific-priorities, they nonetheless offer an unparalleled combination of spatial and temporal resolution, and further provide direct measures of actual neural activity, rather than indirect measures via blood flow (as in PET, fMRI, and near infrared spectroscopy/optical imaging). ECoG data are particularly valuable for the study of uniquely human functions like language, where animal models are inadequate. Here we used ECoG to identify the neural events that occur online as the meaning of a sentence is extracted and represented.Prior intracranial recording studies of language have largely focused on speech perception and production (e.g., refs. 6-11) and word-level processes (e.g., refs. 12-26). However, the most distinctive feature of human language is its compositionality: the ability to create and understand complex meanings from novel combinations of words structured into phrases and sentences (27). As a first step toward understanding the neural basis of sentence comprehension, we recorded intracranial responses while participants read sentences and...

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“…We have already discussed Broca's area and the ATL; other language-related areas that are typically activated by this contrast include the left posterior temporal lobe and the angular gyrus (Bedny et al, 2011;Pallier et al, 2011;Fedorenko et al, 2012c). The difference between our results and previous studies cannot be attributed solely to the differences between production and comprehension; several production studies have revealed effects in these areas (Menenti et al, 2011Segaert et al, 2012Segaert et al, , 2013.…”

Section: Whole-brain Contrasts Of Complexity and Structurecontrasting

confidence: 56%

“…The sentence > list contrast in comprehension occasionally activates Broca's area (Bedny et al, 2011;Fedorenko et al, 2011;Pallier et al, 2011), but these effects are much less consistent than for the ATL . This suggests that this activation reflects the contribution of working memory resources or cognitive control mechanisms needed to parse difficult input rather than fundamental syntactic operations (Novick et al, 2005;Rogalsky et al, 2008).…”

Section: Introductionmentioning

confidence: 89%