Cortical Networks for Ethologically Relevant Behaviors in Primates

Abstract

Parietal–frontal networks in primate brains are central to mediating actions. Physiological and anatomical investigations have shown that the parietal–frontal network is consistently organized across several branches of primate evolution that include prosimian galagos, New World owl and squirrel monkeys, and Old World macaque monkeys. Electrical stimulation with 0.5-sec trains of pulses delivered via microelectrodes evoked ethologically relevant actions from both posterior parietal cortex (PPC) and frontal motor cortex (FMC). Reaching, grasping, defensive, and other complex movement patterns were evoked from domains that had a characteristic organization in both FMC and PPC. Although a PPC domain (e.g. reaching) may be connected with other PPC domains (e.g. grasping and defensive), its connections with FMC are preferential for a matching domain (reaching). Similarly, electrical stimulation of a PPC domain and concurrent optical imaging of FMC, showed activation patterns consistent with the preferential connectivity of PPC and FMC domains. The evidence for similar arrangements of interconnected functional domains in PPC and FMC of members of three major branches of the primate radiation suggests that the parietal–frontal networks emerged early in the evolution of primates. The small size of PPC in the close relatives of primates including lagomorphs, rodents, and tree shrews, suggests a limited involvement of PPC in motor behavior before archaic primates emerged. However, functional domains may have evolved in motor cortex before the emergence of archaic primates.

Neural representations of ethologically relevant hand/mouth synergies in the human precentral gyrus

“…Finally, in apparent contrast with previous observations in monkey (2)(3)(4), in the present study, we did not identify complex neural representations for other ethologically relevant behaviors (e.g., defensive, manipulative) besides hand/mouth synergies. This could be taken as an indication that such representations do not exist in the human PrG, at least in the region we stimulated, but this hypothesis is unlikely.…”

“…However, the generality of this model was recently challenged in nonhuman primates, where reaching, grasping, defensive, and hand/mouth movements have been found to be represented as complex motor primitives in independent circumscribed territories of the precentral gyrus (PrG) (2)(3)(4). To account for this observation, it was suggested that complex motor primitives have emerged during primate evolution to optimize the production of ethologically relevant behaviors (4). However, to date, direct evidence is lacking that such integrated representations of ethologically relevant movements also exist in humans.…”

Large-scale signatures of unconsciousness are consistent with a departure from critical dynamics

“…Second, the effect we report was regionally localized to a set of frontal regions and the thalamus, as opposed to the global effect reported in [49]. This last distinction is very important, because the richness of anatomical connectivity varies throughout the brain, from the regular structure of the cerebellum and primary cortices to the highly complex, variable and phylogenetically advanced frontal and parietal associative cortices [50,51]. Indeed, we observed that the functional exploration of frontothalamic anatomical connectivity was hindered under propofol, highlighting its importance for the maintenance of conscious awareness.…”

Encoding of Both Reaching and Grasping Kinematics in Dorsal and Ventral Premotor Cortices

“…Reaching to grasp is a fundamental, ethologically relevant primate behavior (Kaas et al, 2013). Several cortical and subcortical structures are involved in the generation of these movements (Fattori et al, 2004;Grafton, 2010;Kaas et al, 2013).…”

“…Several cortical and subcortical structures are involved in the generation of these movements (Fattori et al, 2004;Grafton, 2010;Kaas et al, 2013). Recently, much emphasis has been placed on understanding the behavior of single cells in primary motor cortex (MI), one of the main sources of cortical output to the spinal cord during reach-tograsp movements (Saleh et al, 2010, Mollazadeh et al, 2011.…”