Anterior Intraparietal Area: a Hub in the Observed Manipulative Action Network.

Current knowledge regarding the processing of observed manipulative actions (OMAs) (e.g., grasping, dragging, or dropping) is limited to grasping and underlying neural circuitry remains controversial. Here, we addressed these issues by combining chronic neuronal recordings along the anteroposterior extent of monkeys\u2019 anterior intraparietal (AIP) area with tracer injections into the recorded sites. We found robust neural selectivity for 7 distinct OMAs, particularly in the posterior part of AIP (pAIP), where it was associated with motor coding of grip type and own-hand visual feedback. This cluster of functional properties appears to be specifically grounded in stronger direct connections of pAIP with the temporal regions of the ventral visual stream and the prefrontal cortex, as connections with skeletomotor related areas and regions of the dorsal visual stream exhibited opposite or no rostrocaudal gradients. Temporal and prefrontal areas may provide visual and contextual information relevant for manipulative action processing. These results revise existing models of the action observation network, suggesting that pAIP constitutes a parietal hub for routing information about OMA identity to the other nodes of the network

Proprietà sensoriali e motorie in classi neuronali fisiologicamente identificate in diverse aree dei circuiti parieto-frontali per afferramento.

I meccanismi neurali che sottendono i processi sensoriali e motori nel cervello dei primati non sono ancora stati chiariti. Decenni di letteratura neurofisiologica evidenziano la presenza di distinte proprietà neuronali in molti nodi dei circuiti corticali per l’afferramento, dai neuroni puramente motori che codificano lo scopo a quelli sensori-motori che rispondono alla presentazione visiva di oggetti, azioni o entrambi. L’attribuzione di queste proprietà funzionali a specifiche classi neuronali, come agli interneuroni inibitori o ai neuroni piramidali, sarebbe fondamentale per comprendere al meglio le funzioni cognitive e percettive che emergono dalla organizzazione intrinseca del sistema motorio. Ad oggi, molti studi mostrano che i neuroni corticali possono essere identificati prendendo in considerazione le diverse caratteristiche della loro forma d’onda e delle loro proprietà di scarica. Tuttavia, la specifica relazione tra classi neuronali identificate fisiologicamente e le loro proprietà di codifica resta ancora da chiarire, specialmente nelle aree appartenenti al sistema motorio dei primati. Per indagare questo problema abbiamo studiato le caratteristiche dei potenziali d’azione di 355 singoli neuroni ben isolati registrati extracellularmente. I neuroni sono stati registrati in 5 emisferi di tre scimmie macaco mentre svolgevano un compito di raggiungimento e afferramento di tipo go/nogo con tre differenti oggetti bersaglio, e mentre osservavano uno sperimentatore svolgere lo stesso compito. L’attività dei singoli neuroni è stata registrata dall’area intraparietale anteriore AIP (n=86), dall’area premotoria ventrale F5 (n=106) e dall’area pre-supplementare motoria F6 (n=163). Inizialmente abbiamo suddiviso tutte le forme d’onda registrate nelle tre aree in 3 gruppi attraverso una procedura di clustering non supervisionato. Queste tre classi di neuroni presentavano caratteristiche fisiologiche diverse e non si distribuivano uniformemente tra le aree. Nell’ area F6 prevalevano cellule con forma d’onda ampia e il numero di neuroni facilitati e inibiti era bilanciato sia durante il compito di esecuzione sia durante quello di osservazione. Al contrario, i neuroni con forma d’onda stretta risultavano più facilitati dai segnali visivi e dotati di una maggiore modulazione visuo-motoria congiunta sia quando l’azione veniva compiuta sia quando veniva osservata, soprattutto nelle are AIP e F5. Questi risultati chiariscono i meccanismi cellulari alla base dell'elaborazione locale delle informazioni sensori-motorie per la pianificazione, l'esecuzione e l’osservazione di azioni di prensione. Ulteriori studi potrebbero rilevare il contributo di reti cortico-sottocorticali più ampie ai meccanismi chiariti nel presente lavoro.The neural machinery underlying sensory and motor processes in the primate brain remain largely unclear. Decades of neurophysiological literature evidenced the presence of distinct neuronal properties in many nodes of the cortical grasping network, from purely motor neurons encoding motor goals to sensorimotor neurons responsive to visually presented objects, observed actions or both. The attribution of these functional properties to specific neuronal classes, such as inhibitory interneurons or pyramidal neurons, would be crucial to achieve a better understanding of the motor-based perceptual and cognitive functions stemming from the inner organization of the motor system. To date, several studies showed that cortical neurons can be identified by jointly considering a variety of features of their spike waveform and firing properties, but the specific relation between physiologically characterized neuronal classes and their coding properties remains unclear, especially in areas of the primates’ motor system. To address this issue, here we studied the features of extracellularly recorded spikes of 355 well-isolated single neurons. Neurons were sampled from 5 hemispheres of 3 macaque monkeys while they performed or observed an experimenter performing, a reaching-grasping go/no-go task with three different objects as targets. Single neuron activity was recorded from anterior intraparietal area AIP (n=86), ventral premotor area F5 (n=106) and pre-supplementary motor area F6 (n=163). First, we performed an unsupervised clustering of spike waveforms that reliably dissociated 3 clusters. We found that physiologically-identified classes of cells, unevenly distributed across the investigated areas, carry distinct visuomotor signals. Broadly spiking neurons are prevalent in area F6 and exhibit a balanced amount of facilitated and suppressed activity during action execution and observation. In contrast, narrow spiking neurons are mostly facilitated by visual signals and show greater mutual modulation of their motor and visual response during one’s own and others’ action, particularly in areas AIP and F5. These findings shed light on the cellular mechanisms underlying local processing of sensorimotor information for planning and executing grasping actions and for processing others’ observed action. Further studies may unravel the contribution of larger cortico-subcortical brain network to the mechanisms elucidated by the present work

Stable readout of observed actions from format-dependent activity of monkey's anterior intraparietal neurons

Humans accurately identify observed actions despite large dynamic changes in their retinal images and a variety of visual presentation formats. A large network of brain regions in primates participates in the processing of others' actions, with the anterior intraparietal area (AIP) playing a major role in routing information about observed manipulative actions (OMAs) to the other nodes of the network. This study investigated whether the AIP also contributes to invariant coding of OMAs across different visual formats. We recorded AIP neuronal activity from two macaques while they observed videos portraying seven manipulative actions (drag, drop, grasp, push, roll, rotate, squeeze) in four visual formats. Each format resulted from the combination of two actor's body postures (standing, sitting) and two viewpoints (lateral, frontal). Out of 297 recorded units, 38% were OMA-selective in at least one format. Robust population code for viewpoint and actor's body posture emerged shortly after stimulus presentation, followed by OMA selectivity. Although we found no fully invariant OMA-selective neuron, we discovered a population code that allowed us to classify action exemplars irrespective of the visual format. This code depends on a multiplicative mixing of signals about OMA identity and visual format, particularly evidenced by a set of units maintaining a relatively stable OMA selectivity across formats despite considerable rescaling of their firing rate depending on the visual specificities of each format. These findings suggest that the AIP integrates format-dependent information and the visual features of others' actions, leading to a stable readout of observed manipulative action identity.status: publishe

Anterior Intraparietal Area: A Hub in the Observed Manipulative Action Network

Current knowledge regarding the processing of observed manipulative actions (OMAs) (e.g., grasping, dragging, or dropping) is limited to grasping and underlying neural circuitry remains controversial. Here, we addressed these issues by combining chronic neuronal recordings along the anteroposterior extent of monkeys' anterior intraparietal (AIP) area with tracer injections into the recorded sites. We found robust neural selectivity for 7 distinct OMAs, particularly in the posterior part of AIP (pAIP), where it was associated with motor coding of grip type and own-hand visual feedback. This cluster of functional properties appears to be specifically grounded in stronger direct connections of pAIP with the temporal regions of the ventral visual stream and the prefrontal cortex, as connections with skeletomotor related areas and regions of the dorsal visual stream exhibited opposite or no rostrocaudal gradients. Temporal and prefrontal areas may provide visual and contextual information relevant for manipulative action processing. These results revise existing models of the action observation network, suggesting that pAIP constitutes a parietal hub for routing information about OMA identity to the other nodes of the network.status: publishe

Anterior Intraparietal Area: A Hub in the Observed Manipulative Action Network

Current knowledge regarding the processing of observed manipulative actions (OMAs) (e.g., grasping, dragging, or dropping) is limited to grasping and underlying neural circuitry remains controversial. Here, we addressed these issues by combining chronic neuronal recordings along the anteroposterior extent of monkeys' anterior intraparietal (AIP) area with tracer injections into the recorded sites. We found robust neural selectivity for 7 distinct OMAs, particularly in the posterior part of AIP (pAIP), where it was associated with motor coding of grip type and own-hand visual feedback. This cluster of functional properties appears to be specifically grounded in stronger direct connections of pAIP with the temporal regions of the ventral visual stream and the prefrontal cortex, as connections with skeletomotor related areas and regions of the dorsal visual stream exhibited opposite or no rostrocaudal gradients. Temporal and prefrontal areas may provide visual and contextual information relevant for manipulative action processing. These results revise existing models of the action observation network, suggesting that pAIP constitutes a parietal hub for routing information about OMA identity to the other nodes of the network

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)