scholarly journals The Continuity Illusion Does Not Depend on Attentional State: fMRI Evidence from Illusory Vowels

2011 ◽  
Vol 23 (10) ◽  
pp. 2675-2689 ◽  
Author(s):  
Antje Heinrich ◽  
Robert P. Carlyon ◽  
Matthew H. Davis ◽  
Ingrid S. Johnsrude
Keyword(s):  
Primary Auditory Cortex ◽  
Neural Correlates ◽  
Middle Temporal Gyrus ◽  
Attentional State ◽  
Main Effect ◽  
Visual Distracter ◽  
Masking Noise ◽  
Illusory Percept ◽  
Left Middle Temporal Gyrus ◽  
Left Middle

We investigate whether the neural correlates of the continuity illusion, as measured using fMRI, are modulated by attention. As we have shown previously, when two formants of a synthetic vowel are presented in an alternating pattern, the vowel can be identified if the gaps in each formant are filled with bursts of plausible masking noise, causing the illusory percept of a continuous vowel (“Illusion” condition). When the formant-to-noise ratio is increased so that noise no longer plausibly masks the formants, the formants are heard as interrupted (“Illusion Break” condition) and vowels are not identifiable. A region of the left middle temporal gyrus (MTG) is sensitive both to intact synthetic vowels (two formants present simultaneously) and to Illusion stimuli, compared to Illusion Break stimuli. Here, we compared these conditions in the presence and absence of attention. We examined fMRI signal for different sound types under three attentional conditions: full attention to the vowels; attention to a visual distracter; or attention to an auditory distracter. Crucially, although a robust main effect of attentional state was observed in many regions, the effect of attention did not differ systematically for the illusory vowels compared to either intact vowels or to the Illusion Break stimuli in the left STG/MTG vowel-sensitive region. This result suggests that illusory continuity of vowels is an obligatory perceptual process, and operates independently of attentional state. An additional finding was that the sensitivity of primary auditory cortex to the number of sound onsets in the stimulus was modulated by attention.

scholarly journals Abnormal functional connectivity density in patients with dysthyroid optic neuropathy

2020 ◽  
Author(s):  
Yunhai Tu ◽  
Pingping Huang ◽  
Chuanwan Mao ◽  
Xiaozheng Liu ◽  
Jianlu Gao
Keyword(s):  
Visual Field ◽  
Functional Connectivity ◽  
Optic Neuropathy ◽  
Middle Temporal Gyrus ◽  
Functional Connectivity Density ◽  
Dysthyroid Optic Neuropathy ◽  
Middle Temporal ◽  
The Right ◽  
Left Middle Temporal Gyrus ◽  
Left Middle

[Objective] Functional connectivity density (FCD) mapping was used to investigate abnormalities and factors related to brain functional connectivity (F.C.) in cortical regions of patients with dysthyroid optic neuropathy (DON) and to analyze the pathogenesis of DON further. [Methods] Patients diagnosed with thyroid-associated ophthalmopathy (TAO) in the Eye Hospital were enrolled. All patients underwent comprehensive eye examinations and best-corrected visual acuity, visual field(V.F.) test. MRI data collection and analysis were completed in the 2nd Affiliated Hospital of Wenzhou Medical University. The patients were divided into two groups: the DON group, with an average visual field, mean deviation (M.D.) of both eyes < -5 dB, and the non-DON group (nDON group), with an average visual field M.D. of both eyes ≥ -2 dB. [Results] A total of 30 TAO patients (14 men, 16 women) with complete data who met the experimental requirements were enrolled. The average age was 48.79 (40~ 57) years. There were 16 patients in the DON group and 14 patients in the nDON group. No significant differences in age, gender, education level, and the maximum horizontal diameter of either medial rectus muscle were found between the two groups. The difference of brain FCD between the two groups showed significant abnormal connectivity in the right orbital gyri of the frontal lobe (Frontal_Inf_Orb_R) and the left precuneus in the DON group compared with the nDON group. As demonstrated by decreased FCD values in the right inferior frontal gyrus/orbital part, the relevant brain regions were the left middle temporal gyrus, left precuneus, left middle frontal gyrus, right postcentral gyrus, and brain gyri (excluding the supramarginal gyrus and angular gyrus) below the left parietal bone. The FCD associated with the left precuneus was increased, and the relevant brain areas were the left middle temporal gyrus, right cuneus, superior occipital gyrus, and right fusiform gyrus. A significant correlation was identified between the MD. of the binocular visual field and brain FCD. [Conclusion] The abnormal FCD in the cortex of DON patients suggests that a central nervous system mechanism may be related to the pathogenesis of the DON.

scholarly journals Aberrant functional connectivity density in patients with treatment-refractory obsessive-compulsive disorder: a pilot study

2019 ◽  
Vol 47 (6) ◽  
pp. 2434-2445
Author(s):  
Pei Wei Shan ◽  
Wei Liu ◽  
Caixing Liu ◽  
Yunyi Han ◽  
Lina Wang ◽  
...  
Keyword(s):  
Middle Temporal Gyrus ◽  
Obsessive Compulsive ◽  
Middle Temporal ◽  
Compulsive Disorder ◽  
Functional Connections ◽  
Processing Ability ◽  
Treatment Refractory ◽  
Left Middle Temporal Gyrus ◽  
Processing Circuit ◽  
Left Middle

Objective Functional connectivity (FC) is altered in patients with obsessive-compulsive disorder (OCD). Most previous studies have focused on the strength of FC in patients with OCD; few have examined the number of functional connections in these patients. The number of functional connections is an important index for assessing aberrant FC. In the present study, we used FC density (FCD) mapping to explore alterations in the number of functional connections in patients with treatment-refractory OCD (TROCD) using the FCD index. Methods Twenty patients with TROCD and 20 patients with OCD in clinical remission were enrolled in the study. Global FCD (gFCD) was adopted to compare the differences between the two groups of patients. Results The gFCD in the left middle temporal gyrus was lower in the patients with TROCD than in those with remitted OCD, suggesting that decreased information processing ability may play a significant role in TROCD. Conclusion The left middle temporal gyrus is a key component of the emotional processing circuit and attentional processing circuit. Decreased information processing ability in this brain region may play a significant role in TROCD; however, further well-designed follow-up studies are needed to support this hypothesis.

scholarly journals Lexical Influences on Categorical Speech Perception Are Driven by a Temporoparietal Circuit

2021 ◽  
pp. 1-13
Author(s):  
Gavin M. Bidelman ◽  
Claire Pearson ◽  
Ashleigh Harrison
Keyword(s):  
Parietal Lobe ◽  
Middle Temporal Gyrus ◽  
Brain Areas ◽  
Lexical Status ◽  
Inferior Parietal Lobe ◽  
Middle Temporal ◽  
Phonetic Perception ◽  
Speech Categorization ◽  
Left Middle Temporal Gyrus ◽  
Left Middle

Categorical judgments of otherwise identical phonemes are biased toward hearing words (i.e., “Ganong effect”) suggesting lexical context influences perception of even basic speech primitives. Lexical biasing could manifest via late stage postperceptual mechanisms related to decision or, alternatively, top–down linguistic inference that acts on early perceptual coding. Here, we exploited the temporal sensitivity of EEG to resolve the spatiotemporal dynamics of these context-related influences on speech categorization. Listeners rapidly classified sounds from a /gɪ/-/kɪ/ gradient presented in opposing word–nonword contexts ( GIFT–kift vs. giss–KISS), designed to bias perception toward lexical items. Phonetic perception shifted toward the direction of words, establishing a robust Ganong effect behaviorally. ERPs revealed a neural analog of lexical biasing emerging within ~200 msec. Source analyses uncovered a distributed neural network supporting the Ganong including middle temporal gyrus, inferior parietal lobe, and middle frontal cortex. Yet, among Ganong-sensitive regions, only left middle temporal gyrus and inferior parietal lobe predicted behavioral susceptibility to lexical influence. Our findings confirm lexical status rapidly constrains sublexical categorical representations for speech within several hundred milliseconds but likely does so outside the purview of canonical auditory-sensory brain areas.

A representational asymmetry for composition in the human left-middle temporal gyrus

2019 ◽  
Author(s):  
Steven M. Frankland ◽  
Joshua D. Greene
Keyword(s):  
Internal Structure ◽  
Argument Structure ◽  
Middle Temporal Gyrus ◽  
Middle Temporal ◽  
Sentence Level ◽  
Verb Argument Structure ◽  
Propositional Representation ◽  
The Rich ◽  
Left Middle Temporal Gyrus ◽  
Left Middle

AbstractNatural language is notable amongst representational systems for the rich internal structure of phrase and sentence-level expressions. Here, we provide evidence from two fMRI studies that a region of the left Middle Temporal Gyrus (MTG) exhibits a surprising representational asymmetry: verbs and patients (to whom was it done?) are bound to form a representation, but verbs and agents (who did it?) are not. Within MTG, BOLD signal to novel combinations of familiar components can be modeled by combining learned verb-patient conjunctive representations with more general agent representations, but not by the converse (verb-agent + patient). This asymmetry is not predicted by an abstract propositional representation of the event (e.g., chased(dog,cat), nor by a theory which derives conjunctions from the experienced statistical co-occurences between verbs and nouns. However, this asymmetry is predicted by various linguistic accounts of the internal structure of event descriptions (e.g., Williams, 1981; Marantz,1984; Grimshaw, 1990; Kratzer, 1996). These results provide evidence for the time-varying instantiation of re-usable representations of structure in MTG, consistent with the principle of compositionality, as well as accounts of verb-argument structure.

The Cortical Representation of Speech

1993 ◽  
Vol 5 (4) ◽  
pp. 467-479 ◽  
Author(s):  
B. M. Mazoyer ◽  
N. Tzourio ◽  
V. Frak ◽  
A. Syrota ◽  
N. Murayama ◽  
...  
Keyword(s):  
Middle Temporal Gyrus ◽  
Single Word ◽  
Regional Cerebral Blood ◽  
Word Comprehension ◽  
Left Frontal Lobe ◽  
Middle Temporal ◽  
Left And Right ◽  
French Words ◽  
Left Middle Temporal Gyrus ◽  
Left Middle

In this study, we compare regional cerebral blood flow (rCBF) while French monolingual subjects listen to continuous speech in an unknown language, to lists of French words, or to meaningful and distorted stories in French. Our results show that, in addition to regions devoted to single-word comprehension, processing of meaningful stories activates the left middle temporal gyrus, the left and right temporal poles, and a superior prefrontal area in the left frontal lobe. Among these regions, only the temporal poles remain activated whenever sentences with acceptable syntax and prosody are presented.

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