scholarly journals Activation in Human MT/MST by Static Images with Implied Motion

2000 ◽  
Vol 12 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Zoe Kourtzi ◽  
Nancy Kanwisher
Keyword(s):  
Visual Motion ◽  
Visual Analysis ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Dynamic Information ◽  
Implied Motion ◽  
Medial Superior Temporal ◽  
Superior Temporal Cortex ◽  
Before And After ◽  
Static Images

A still photograph of an object in motion may convey dynamic information about the position of the object immediately before and after the photograph was taken (implied motion). Medial temporal/medial superior temporal cortex (MT/MST) is one of the main brain regions engaged in the perceptual analysis of visual motion. In two experiments we examined whether MT/MST is also involved in representing implied motion from static images. We found stronger functional magnetic resonance imaging (fMRI) activation within MT/MST during viewing of static photographs with implied motion compared to viewing of photographs without implied motion. These results suggest that brain regions involved in the visual analysis of motion are also engaged in processing implied dynamic information from static images.

scholarly journals Neural Correlates of Letter-String Length and Lexicality during Reading in a Regular Orthography

2003 ◽  
Vol 15 (7) ◽  
pp. 1052-1062 ◽  
Author(s):  
T. N. Wydell ◽  
T. Vuorinen ◽  
P. Helenius ◽  
R. Salmelin
Keyword(s):  
Letter String ◽  
Visual Analysis ◽  
Temporal Cortex ◽  
Occipital Cortex ◽  
String Length ◽  
Cortical Level ◽  
Behavioral Studies ◽  
Superior Temporal Cortex ◽  
Dual Route ◽  
Length Effects

Behavioral studies have shown that short letter strings are read faster than long letter-strings and words are read faster than nonwords. Here, we describe the dynamics of letter-string length and lexicality effects at the cortical level, using magnetoencephalography, during a reading task in Finnish with long (eight-letter) and short (four-letter) word/nonword stimuli. Length effects were observed in two spatially and temporally distinct cortical activations: (1) in the occipital cortex at about 100 msec by the strength of activation, regardless of the lexical status of the stimuli, and (2) in the left superior temporal cortex between 200 and 600 msec by the duration of activation, with words showing a smaller effect than nonwords. A significant lexicality effect was also evident in this later activation, with stronger activation and longer duration for nonwords than words. There seem to be no distinct cortical areas for reading words and nonwords. The early length effect is likely to be due to the low-level visual analysis common to all stimulus letter-strings. The later lexicality and length effects apparently reflect converging lexico-semantic and phonological influences, and are discussed in terms of dual-route and single-route connectionist models of reading.

scholarly journals Two Ways to Build a Thought: Distinct Forms of Compositional Semantic Representation Across Brain Regions

2019 ◽  
Author(s):  
Steven M Frankland ◽  
Joshua D. Greene
Keyword(s):  
Semantic Representation ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Human Mind ◽  
Separation Mechanism ◽  
Central Feature ◽  
Simple Sentence ◽  
Superior Temporal Cortex ◽  
Trial Basis ◽  
Broad Role

To understand a simple sentence such as “the woman chased the dog”, the human mind must dynamically organize the relevant concepts to represent who did what to whom. This structured re-combination of concepts (woman, dog, chased) enables the representation of novel events, and is thus a central feature of intelligence. Here, we use fMRI and encoding models to delineate the contributions of three brain regions to the representation of structured, relational combinations. We identify a region of rostral-medial prefrontal cortex (rmPFC) that shares representations of noun-verb conjunctions across sentences: for example, combining “woman” and “chased” to encode woman-as-chaser, distinct from woman-as-chasee. This PFC region differs from the left-mid superior temporal cortex (lmSTC) and hippocampus, two regions previously implicated in representing relations. lmSTC represents broad role combinations that are shared across verbs (e.g., woman-as-agent), rather than narrow roles, limited to specific actions (woman-as-chaser). By contrast, a hippocampal sub-region represents instances of recurring noun-verb conjunctions as dissimilar to one another, and is anti-correlated with rMPFC on a trial-by-trial basis, consistent with a pattern separation mechanism. These three regions appear to play distinct, but complementary, roles in encoding compositional event structure.

scholarly journals Theta-burst TMS of lateral occipital cortex reduces BOLD responses across category-selective areas in ventral temporal cortex

2020 ◽  
Author(s):  
Iris I A Groen ◽  
Edward H Silson ◽  
David Pitcher ◽  
Chris I Baker
Keyword(s):  
Temporal Cortex ◽  
Occipital Cortex ◽  
Brain Regions ◽  
Stimulus Category ◽  
Cortical Region ◽  
Face Area ◽  
Before And After ◽  
Ventral Temporal Cortex ◽  
Theta Burst ◽  
Lateral Occipital Cortex

AbstractHuman visual cortex contains three scene-selective regions in the lateral, medial and ventral cortex, termed the occipital place area (OPA), medial place area (MPA) and parahippocampal place area (PPA). Using functional magnetic resonance imaging (fMRI), all three regions respond more strongly when viewing visual scenes compared with isolated objects or faces. To determine how these regions are functionally and causally connected, we applied transcranial magnetic stimulation to OPA and measured fMRI responses before and after stimulation, using a theta-burst paradigm (TBS). To test for stimulus category-selectivity, we presented a range of visual categories (scenes, buildings, objects, faces). To test for specificity of any effects to TBS of OPA we employed two control conditions: Sham, with no TBS stimulation, and an active TBS-control with TBS to a proximal face-selective cortical region (occipital face area, or OFA). We predicted that TBS to OPA (but not OFA) would lead to decreased responses to scenes and buildings (but not other categories) in other scene-selective cortical regions. Across both ROI and whole-volume analyses, we observed decreased responses to scenes in PPA as a result of TBS. However, these effects were neither category specific, with decreased responses to all stimulus categories, nor limited to scene-selective regions, with decreases also observed in face-selective fusiform face area (FFA). Furthermore, similar effects were observed with TBS to OFA, thus effects were not specific to the stimulation site in the lateral occipital cortex. Whilst these data are suggestive of a causal, but non-specific relationship between lateral occipital and ventral temporal cortex, we discuss several factors that could have underpinned this result, such as the differences between TBS and online TMS, the role of anatomical distance between stimulated regions and how TMS effects are operationalised. Furthermore, our findings highlight the importance of active control conditions in brain stimulation experiments to accurately assess functional and causal connectivity between specific brain regions.

Paths of Apparent Human Motion Follow Motor Constraints

2017 ◽  
Author(s):  
Maggie Shiffrar ◽  
Christina Joseph
Keyword(s):  
Visual System ◽  
Apparent Motion ◽  
Visual Motion ◽  
Visual Analysis ◽  
Human Movement ◽  
Human Motion ◽  
Motion Cues ◽  
Illusory Perception ◽  
Static Images ◽  
Visual Motion Cues

The phenomenon of apparent motion, or the illusory perception of movement from rapidly displayed static images, provides an excellent platform for the study of how perceptual systems analyze input over time and space. Studies of the human body in apparent motion further suggest that the visual system is also influenced by an observer’s motor experience with his or her own body. As a result, the human visual system sometimes processes human movement differently from object movement. For example, under apparent motion conditions in which inanimate objects appear to traverse the shortest possible paths of motion, human motion instead appears to follow longer, biomechanically plausible paths of motion. Psychophysical and brain imaging studies converge in supporting the hypothesis that the visual analysis of human movement differs from the visual analysis of nonhuman movements whenever visual motion cues are consistent with an observer’s motor repertoire of possible human actions.

Task-relevant and Task-irrelevant Dimensions Are Modulated Independently at a Task-irrelevant Location

2012 ◽  
Vol 24 (9) ◽  
pp. 1884-1895 ◽  
Author(s):  
Audrey G. Lustig ◽  
Diane M. Beck
Keyword(s):  
Opposite Direction ◽  
Temporal Cortex ◽  
Medial Superior Temporal ◽  
Motion Signal ◽  
Superior Temporal Cortex ◽  
Feature Based ◽  
Opposite Color ◽  
Task Irrelevant ◽  
Direction Opposite ◽  
And Task

Single-cell and fMRI experiments indicate that task-relevant features are enhanced globally across the visual field (VF). Moreover, this global feature-based attention can spread to task-irrelevant features of the attended object. Here we ask whether a task-irrelevant feature, by virtue of being bound to a task-relevant feature, can also be enhanced at a task-irrelevant location. Specifically, we asked whether attending to the color of moving dots in one VF would influence the motion signal to colored moving dots in the other VF. Participants attended to either red or cyan dots, superimposed and moving in opposite directions. Critically, the color and motion of dots present in the opposite VF varied as a function of the attended dots such that they were either the same color/same direction, same color/opposite direction, opposite color/same direction, or opposite color/opposite direction as the attended dots. We found greater activity in ventral visual cortex when either the color or direction of motion matched the color or direction of motion at the attended location. Similar effects were found for direction of motion in human medial temporal/medial superior temporal cortex. Moreover, the color and motion effects did not interact in any region. Together, these results suggest that the coselection of an object's features modulates those features independently beyond the selected object.

scholarly journals Two Ways to Build a Thought: Distinct Forms of Compositional Semantic Representation across Brain Regions

2020 ◽  
Vol 30 (6) ◽  
pp. 3838-3855 ◽  
Author(s):  
Steven M Frankland ◽  
Joshua D Greene
Keyword(s):  
Semantic Representation ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Human Mind ◽  
Separation Mechanism ◽  
Central Feature ◽  
Simple Sentence ◽  
Superior Temporal Cortex ◽  
Trial Basis ◽  
Broad Role

Abstract To understand a simple sentence such as “the woman chased the dog”, the human mind must dynamically organize the relevant concepts to represent who did what to whom. This structured recombination of concepts (woman, dog, chased) enables the representation of novel events, and is thus a central feature of intelligence. Here, we use functional magnetic resonance (fMRI) and encoding models to delineate the contributions of three brain regions to the representation of relational combinations. We identify a region of anterior-medial prefrontal cortex (amPFC) that shares representations of noun-verb conjunctions across sentences: for example, a combination of “woman” and “chased” to encode woman-as-chaser, distinct from woman-as-chasee. This PFC region differs from the left-mid superior temporal cortex (lmSTC) and hippocampus, two regions previously implicated in representing relations. lmSTC represents broad role combinations that are shared across verbs (e.g., woman-as-agent), rather than narrow roles, limited to specific actions (woman-as-chaser). By contrast, a hippocampal sub-region represents events sharing narrow conjunctions as dissimilar. The success of the hippocampal conjunctive encoding model is anti-correlated with generalization performance in amPFC on a trial-by-trial basis, consistent with a pattern separation mechanism. Thus, these three regions appear to play distinct, but complementary, roles in encoding compositional event structure.

scholarly journals White matter deficits correlate with visual motion perception impairments in dyslexic carriers of the DCDC2 genetic risk variant

2021 ◽  
Author(s):  
Daniela Perani ◽  
Paola Scifo ◽  
Guido M. Cicchini ◽  
Pasquale Della Rosa ◽  
Chiara Banfi ◽  
...  
Keyword(s):  
White Matter ◽  
Motion Perception ◽  
Visual Motion ◽  
Visual Analysis ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Motion Processing ◽  
Motion Direction ◽  
Risk Variant ◽  
Visual Motion Processing

AbstractMotion perception deficits in dyslexia show a large intersubjective variability, partly reflecting genetic factors influencing brain architecture development. In previous work, we have demonstrated that dyslexic carriers of a mutation of the DCDC2 gene have a very strong impairment in motion perception. In the present study, we investigated structural white matter alterations associated with the poor motion perception in a cohort of twenty dyslexics with a subgroup carrying the DCDC2 gene deletion (DCDC2d+) and a subgroup without the risk variant (DCDC2d–). We observed significant deficits in motion contrast sensitivity and in motion direction discrimination accuracy at high contrast, stronger in the DCDC2d+ group. Both motion perception impairments correlated significantly with the fractional anisotropy in posterior ventral and dorsal tracts, including early visual pathways both along the optic radiation and in proximity of occipital cortex, MT and VWFA. However, the DCDC2d+ group showed stronger correlations between FA and motion perception impairments than the DCDC2d– group in early visual white matter bundles, including the optic radiations, and in ventral pathways located in the left inferior temporal cortex. Our results suggest that the DCDC2d+ group experiences higher vulnerability in visual motion processing even at early stages of visual analysis, which might represent a specific feature associated with the genotype and provide further neurobiological support to the visual-motion deficit account of dyslexia in a specific subpopulation.

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