Neural substrates for allocentric‐to‐egocentric conversion of remembered reach targets in humans

Chen, Ying; Monaco, Simona; Crawford, J. Douglas

doi:10.1111/ejn.13885

Cited by 22 publications

(31 citation statements)

References 86 publications

(159 reference statements)

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“…Figure B provides a flow diagram of transformations carried out on allocentric and egocentric representations of reach targets in order to generate reach movements. As indicated in our recent fMRI study, allocentric coding of remembered reach targets was converted into egocentric representations at the first possible opportunity, which then goes through internal egocentric transformations—as egocentric represented targets do—until motor output is sent to the effector (hand) for reaching execution. In this proposed model, there could be some processing related to the further use of allocentric cues during reach execution, because behavioral studies suggest that allocentric landmarks continue to have an influence during the movement .…”

Section: Functional Overview Of Allocentric Egocentric and Allo‐to‐mentioning

confidence: 98%

“…), at least three processing stages are involved: early target representation in egocentric and/or allocentric frames of reference, transformation of these visuospatial codes into egocentric plans for reach, and finally the motor execution of the reach movement. We have also found memory delays to be useful in dissociating these stages in both behavioral and neuroimaging studies …”

Section: Introductionmentioning

confidence: 94%

“…The fMRI study described above confirmed that egocentric cortical coding of reaches occurred only after a cue was used to specify reach direction, but could not specify where and how this is done. To address this question, we designed another fMRI study to identify the neural substrates of allo‐to‐ego conversion, by prompting this conversion at different times and using different sensory cues …”

Section: Neural Mechanisms For Allo‐to‐ego Conversion Of Remembered Rmentioning

confidence: 99%

“…We have also found memory delays to be useful in dissociating these stages in both behavioral and neuroimaging studies. [7][8][9][10][11][12][13][14][15][16][17][18][19] The focus of our review will be on the neural mechanisms of allocentric versus egocentric representations of reach targets in memory in humans. Specifically, we will consider cortical substrates for visual memory of reach targets encoded in the two types of reference frames, and those for converting allocentric representations into egocentric representations in order to execute reaching motions.…”

Section: (C) An Example Of the Original Target Location (T Solid Yelmentioning

confidence: 99%

“…To address this question, we designed another fMRI study to identify the neural substrates of allo-to-ego conversion, by prompting this conversion at different times and using different sensory cues. 12 As illustrated in Figure 4A, a reach target was originally represented (phase 2: target + landmark presentation) and maintained in memory (phase 3: first delay) relative to an allocentric landmark, regardless of the type of upcoming reach tasks. After the first delay, a verbal instruction (phase 4) provided participants with a cue of whether the landmark would reappear at the same location (same cue), or at a different location (different cue) after a second delay (phase 5).…”

Section: Neural Mechanisms For Allo-to-ego Conversion Of Remembered Rmentioning

confidence: 99%

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Allocentric representations for target memory and reaching in human cortex

Chen

Crawford

2019

Annals of the New York Academy of Sciences

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The use of allocentric cues for movement guidance is complex because it involves the integration of visual targets and independent landmarks and the conversion of this information into egocentric commands for action. Here, we focus on the mechanisms for encoding reach targets relative to visual landmarks in humans. First, we consider the behavioral results suggesting that both of these cues influence target memory, but are then transformed—at the first opportunity—into egocentric commands for action. We then consider the cortical mechanisms for these behaviors. We discuss different allocentric versus egocentric mechanisms for coding of target directional selectivity in memory (inferior temporal gyrus versus superior occipital gyrus) and distinguish these mechanisms from parieto‐frontal activation for planning egocentric direction of actual reach movements. Then, we consider where and how the former allocentric representations of remembered reach targets are converted into the latter egocentric plans. In particular, our recent neuroimaging study suggests that four areas in the parietal and frontal cortex (right precuneus, bilateral dorsal premotor cortex, and right presupplementary area) participate in this allo‐to‐ego conversion. Finally, we provide a functional overview describing how and why egocentric and landmark‐centered representations are segregated early in the visual system, but then reintegrated in the parieto‐frontal cortex for action.

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Section: Functional Overview Of Allocentric Egocentric and Allo‐to‐mentioning

confidence: 98%

Section: Introductionmentioning

confidence: 94%

Section: Neural Mechanisms For Allo‐to‐ego Conversion Of Remembered Rmentioning

confidence: 99%

Section: (C) An Example Of the Original Target Location (T Solid Yelmentioning

confidence: 99%

Section: Neural Mechanisms For Allo-to-ego Conversion Of Remembered Rmentioning

confidence: 99%

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Allocentric representations for target memory and reaching in human cortex

Chen

Crawford

2019

Annals of the New York Academy of Sciences

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The role of perception and action on the use of allocentric information in a large-scale virtual environment

2020

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In everyday life, our brain constantly builds spatial representations of the objects surrounding us. Many studies have investigated the nature of these spatial representations. It is well established that we use allocentric information in real-time and memory-guided movements. Most studies relied on small-scale and static experiments, leaving it unclear whether similar paradigms yield the same results on a larger scale using dynamic objects. We created a virtual reality task that required participants to encode the landing position of a virtual ball thrown by an avatar. Encoding differed in the nature of the task in that it was either purely perceptual (“view where the ball landed while standing still”—Experiment 1) or involved an action (“intercept the ball with the foot just before it lands”—Experiment 2). After encoding, participants were asked to place a real ball at the remembered landing position in the virtual scene. In some trials, we subtly shifted either the thrower or the midfield line on a soccer field to manipulate allocentric coding of the ball’s landing position. In both experiments, we were able to replicate classic findings from small-scale experiments and to generalize these results to different encoding tasks (perception vs. action) and response modes (reaching vs. walking-and-placing). Moreover, we found that participants preferably encoded the ball relative to the thrower when they had to intercept the ball, suggesting that the use of allocentric information is determined by the encoding task by enhancing task-relevant allocentric information. Our findings indicate that results previously obtained from memory-guided reaching are not restricted to small-scale movements, but generalize to whole-body movements in large-scale dynamic scenes.

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