Integration of Target and Effector Information in Human Posterior Parietal Cortex for the Planning of Action

2005 ◽  
Vol 93 (2) ◽  
pp. 954-962 ◽  
Author(s):  
W. Pieter Medendorp ◽  
Herbert C. Goltz ◽  
J. Douglas Crawford ◽  
Tutis Vilis
Keyword(s):  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Spatial Information ◽  
Target Location ◽  
Premotor Cortex ◽  
Target Selection ◽  
Right Hand ◽  
Pointing Movements ◽  
Posterior Parietal ◽  
The Right

Recently, using event-related functional MRI (fMRI), we located a bilateral region in the human posterior parietal cortex (retIPS) that topographically represents and updates targets for saccades and pointing movements in eye-centered coordinates. To generate movements, this spatial information must be integrated with the selected effector. We now tested whether the activation in retIPS is dependent on the hand selected. Using 4-T fMRI, we compared the activation produced by movements, using either eyes or the left or right hand, to targets presented either leftward or rightward of central fixation. The majority of the regions activated during saccades were also activated during pointing movements, including occipital, posterior parietal, and premotor cortex. The topographic retIPS region was activated more strongly for saccades than for pointing. The activation associated with pointing was significantly greater when pointing with the unseen hand to targets ipsilateral to the hand. For example, although there was activation in the left retIPS when pointing to targets on the right with the left hand, the activation was significantly greater when using the right hand. The mirror symmetric effect was observed in the right retIPS. Similar hand preferences were observed in a nearby anterior occipital region. This effector specificity is consistent with previous clinical and behavioral studies showing that each hand is more effective in directing movements to targets in ipsilateral visual space. We conclude that not only do these regions code target location, but they also appear to integrate target selection with effector selection.

Hemispheric Asymmetry in Memory-Guided Pointing During Single-Pulse Transcranial Magnetic Stimulation of Human Parietal Cortex

2006 ◽  
Vol 96 (6) ◽  
pp. 3016-3027 ◽  
Author(s):  
Michael Vesia ◽  
Jachin A. Monteon ◽  
Lauren E. Sergio ◽  
J. D. Crawford
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Parietal Cortex ◽  
Magnetic Stimulation ◽  
Hemispheric Asymmetry ◽  
Posterior Parietal Cortex ◽  
Single Pulse ◽  
Pointing Movements ◽  
Posterior Parietal ◽  
The Right ◽  
Stimulation Of

Dorsal posterior parietal cortex (PPC) has been implicated through single-unit recordings, neuroimaging data, and studies of brain-damaged humans in the spatial guidance of reaching and pointing movements. The present study examines the causal effect of single-pulse transcranial magnetic stimulation (TMS) over the left and right dorsal posterior parietal cortex during a memory-guided “reach-to-touch” movement task in six human subjects. Stimulation of the left parietal hemisphere significantly increased endpoint variability, independent of visual field, with no horizontal bias. In contrast, right parietal stimulation did not increase variability, but instead produced a significantly systematic leftward directional shift in pointing (contralateral to stimulation site) in both visual fields. Furthermore, the same lateralized pattern persisted with left-hand movement, suggesting that these aspects of parietal control of pointing movements are spatially fixed. To test whether the right parietal TMS shift occurs in visual or motor coordinates, we trained subjects to point correctly to optically reversed peripheral targets, viewed through a left–right Dove reversing prism. After prism adaptation, the horizontal pointing direction for a given visual target reversed, but the direction of shift during right parietal TMS did not reverse. Taken together, these data suggest that induction of a focal current reveals a hemispheric asymmetry in the early stages of the putative spatial processing in PPC. These results also suggest that a brief TMS pulse modifies the output of the right PPC in motor coordinates downstream from the adapted visuomotor reversal, rather than modifying the upstream visual coordinates of the memory representation.

Integration of Target and Effector Information in the Human Brain During Reach Planning

2007 ◽  
Vol 97 (1) ◽  
pp. 188-199 ◽  
Author(s):  
S. M. Beurze ◽  
F. P. de Lange ◽  
I. Toni ◽  
W. P. Medendorp
Keyword(s):  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Human Subjects ◽  
Premotor Cortex ◽  
Insular Cortex ◽  
Spatial Location ◽  
Posterior Parietal ◽  
The Right ◽  
Integrative Processing ◽  
Reach Planning

To plan a reaching movement, the brain must integrate information about the location of the target with information about the limb selected for the reach. Here, we applied rapid event-related 3-T fMRI to investigate this process in human subjects ( n = 16) preparing a reach following two successive visual instruction cues. One cue instructed which arm to use; the other cue instructed the location of the reach target. We hypothesized that regions involved in the integration of target and effector information should not only respond to each of the two instruction cues, but should respond more strongly to the second cue due to the added integrative processing to establish the reach plan. We found bilateral regions in the posterior parietal cortex, the premotor cortex, the medial frontal cortex, and the insular cortex to be involved in target–arm integration, as well as the left dorsolateral prefrontal cortex and an area in the right lateral occipital sulcus to respond in this manner. We further determined the functional properties of these regions in terms of spatial and effector specificity. This showed that the posterior parietal cortex and the dorsal premotor cortex specify both the spatial location of a target and the effector selected for the response. We therefore conclude that these regions are selectively engaged in the neural computations for reach planning, consistent with the results from physiological studies in nonhuman primates.

scholarly journals Effector selection precedes reach planning in the dorsal parietofrontal cortex

2012 ◽  
Vol 108 (1) ◽  
pp. 57-68 ◽  
Author(s):  
Pierre-Michel Bernier ◽  
Matthew Cieslak ◽  
Scott T. Grafton
Keyword(s):  
Posterior Parietal Cortex ◽  
Premotor Cortex ◽  
Target Selection ◽  
Movement Planning ◽  
Target Onset ◽  
Posterior Parietal ◽  
Full Knowledge ◽  
Selection For ◽  
The Right ◽  
Reach Planning

Experimental evidence and computational modeling suggest that target selection for reaching is associated with the parallel encoding of multiple movement plans in the dorsomedial posterior parietal cortex (dmPPC) and the caudal part of the dorsal premotor cortex (PMdc). We tested the hypothesis that a similar mechanism also accounts for arm selection for unimanual reaching, with simultaneous and separate motor goal representations for the left and right arms existing in the right and left parietofrontal cortex, respectively. We recorded simultaneous electroencephalograms and functional MRI and studied a condition in which subjects had to select the appropriate arm for reaching based on the color of an appearing visuospatial target, contrasting it to a condition in which they had full knowledge of the arm to be used before target onset. We showed that irrespective of whether subjects had to select the arm or not, activity in dmPPC and PMdc was only observed contralateral to the reaching arm after target onset. Furthermore, the latency of activation in these regions was significantly delayed when arm selection had to be achieved during movement planning. Together, these results demonstrate that effector selection is not achieved through the simultaneous specification of motor goals tied to the two arms in bilateral parietofrontal cortex, but suggest that a motor goal is formed in these regions only after an arm is selected for action.

scholarly journals Dynamical Latent State Computation in the Posterior Parietal Cortex

2022 ◽  
Author(s):  
Kaushik J Lakshminarasimhan ◽  
Eric Avila ◽  
Xaq Pitkow ◽  
Dora E Angelaki
Keyword(s):  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Target Location ◽  
Neural Representation ◽  
World Model ◽  
Population Activity ◽  
The World ◽  
Neural Interactions ◽  
Posterior Parietal ◽  
Hidden States

Success in many real-world tasks depends on our ability to dynamically track hidden states of the world. To understand the underlying neural computations, we recorded brain activity in posterior parietal cortex (PPC) of monkeys navigating by optic flow to a hidden target location within a virtual environment, without explicit position cues. In addition to sequential neural dynamics and strong interneuronal interactions, we found that the hidden state -- monkey's displacement from the goal -- was encoded in single neurons, and could be dynamically decoded from population activity. The decoded estimates predicted navigation performance on individual trials. Task manipulations that perturbed the world model induced substantial changes in neural interactions, and modified the neural representation of the hidden state, while representations of sensory and motor variables remained stable. The findings were recapitulated by a task-optimized recurrent neural network model, suggesting that neural interactions in PPC embody the world model to consolidate information and track task-relevant hidden states.

scholarly journals Attentional bias to threat and gray mater volume morphology in high anxious individuals

2020 ◽  
Author(s):  
Joshua M. Carlson ◽  
Lin Fang
Keyword(s):  
Attentional Bias ◽  
Parietal Cortex ◽  
Gray Matter ◽  
Posterior Parietal Cortex ◽  
Gray Matter Volume ◽  
Anterior Cingulate ◽  
Brain Morphology ◽  
Matter Volume ◽  
Posterior Parietal ◽  
The Right

AbstractIn a sample of highly anxious individuals, the relationship between gray matter volume brain morphology and attentional bias to threat was assessed. Participants performed a dot-probe task of attentional bias to threat and gray matter volume was acquired from whole brain structural T1-weighted MRI scans. The results replicate previous findings in unselected samples that elevated attentional bias to threat is linked to greater gray matter volume in the anterior cingulate cortex, middle frontal gyrus, and striatum. In addition, we provide novel evidence that elevated attentional bias to threat is associated with greater gray matter volume in the right posterior parietal cortex, cerebellum, and other distributed regions. Lastly, exploratory analyses provide initial evidence that distinct sub-regions of the right posterior parietal cortex may contribute to attentional bias in a sex-specific manner. Our results illuminate how differences in gray matter volume morphology relate to attentional bias to threat in anxious individuals. This knowledge could inform neurocognitive models of anxiety-related attentional bias to threat and targets of neuroplasticity in anxiety interventions such as attention bias modification.

scholarly journals Topographic Organization for Delayed Saccades in Human Posterior Parietal Cortex

2005 ◽  
Vol 94 (2) ◽  
pp. 1372-1384 ◽  
Author(s):  
Denis Schluppeck ◽  
Paul Glimcher ◽  
David J. Heeger
Keyword(s):  
Visual Field ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Target Location ◽  
Critical Role ◽  
Topographic Maps ◽  
Field Orientation ◽  
Topographic Organization ◽  
Motor Intention ◽  
Posterior Parietal

Posterior parietal cortex (PPC) is thought to play a critical role in decision making, sensory attention, motor intention, and/or working memory. Research on the PPC in non-human primates has focused on the lateral intraparietal area (LIP) in the intraparietal sulcus (IPS). Neurons in LIP respond after the onset of visual targets, just before saccades to those targets, and during the delay period in between. To study the function of posterior parietal cortex in humans, it will be crucial to have a routine and reliable method for localizing specific parietal areas in individual subjects. Here, we show that human PPC contains at least two topographically organized regions, which are candidates for the human homologue of LIP. We mapped the topographic organization of human PPC for delayed (memory guided) saccades using fMRI. Subjects were instructed to fixate centrally while a peripheral target was briefly presented. After a further 3-s delay, subjects made a saccade to the remembered target location followed by a saccade back to fixation and a 1-s inter-trial interval. Targets appeared at successive locations “around the clock” (same eccentricity, ≈30° angular steps), to produce a traveling wave of activity in areas that are topographically organized. PPC exhibited topographic organization for delayed saccades. We defined two areas in each hemisphere that contained topographic maps of the contra-lateral visual field. These two areas were immediately rostral to V7 as defined by standard retinotopic mapping. The two areas were separated from each other and from V7 by reversals in visual field orientation. However, we leave open the possibility that these two areas will be further subdivided in future studies. Our results demonstrate that topographic maps tile the cortex continuously from V1 well into PPC.

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