Knowing how neurons communicate when the brain is carrying out a cognitive task is essential knowledge for the study of cerebral information processing. Despite this, it is an issue that has traditionally been little studied due to the difficulty of simultaneously recording the activity of single neurons during the different stages of the performance of the task.

In a study published recently in the journal  PNAS the temporal interaction between the electrical activity of neurons of five cortical areas  of two primates has been quantified: the sensory cortical (S1 and S2), premotor (MPC, DPC) and motor (M1) areas, while the specimens performed a somatosensory discrimination task in which they had to indicate with the movement of the hand which stimulus received had the highest intensity.

The research was led by Gustavo Deco, ICREA researcher of the Department of Information and Communication Technologies (DTIC) and director of the Center for Brain and Cognition (CBC) at UPF, jointly with Ranulfo Romo, a researcher at the UNAM in Mexico. Adrián Tauste and Marina Martínez-García, members of the CBC, co-author the paper.

The study involved the mathematical estimation of the interdependencies established between the action potential trains of each pair of neurons as a result of the different stages of cognitive task: perception, memory, decision-making and motor activity. 

Sensory and motor areas are correlated bidirectionally

As the respective director and lead author of the study, Deco and Tauste, point out "we have found that to carry out cognitive tasks, bidirectional dependencies are required between sensory and motor areas that are maintained even during intervals of the task in which neurons alone do not encode information about the stimulus and/or response".

"Interestingly, the results show that when the brain ceases to perform the task these neuronal correlations largely disappear, even in the presence of the same type of stimulus," they added.

These bidirectional dependencies between neurons are activated and deactivated depending on the values ​​of the stimulus and of the response, indicating that each piece of information related to the task travels through a differentiated neural pathway.

In addition, these neural interactions occur more quickly between somatosensory areas (S1 and S2), during periods of stimulation and memory than when they relate premotor and motor areas (MPC, DPC, M1) at the time of decision-making, suggesting that sensory and decision-making information is distributed at different speeds.

In conclusion, as Adrià Tauste, first author of the article states, "our work shows that there is neural communication in the brain activated specifically to perform a task and that the spatial and temporal characteristics of this communication depend on the type of information conveyed".

Reference work:

Adrià Tauste Campo, Marina Martínez Garcia, Verónica Nácher, Rogelio Luna, Ranulfo Romo and Gustavo Deco (2015), " Task-driven intra-and interarea communications in primate cerebral cortex",  PNAS, doi : 10.1073/pnas.1503937112.