An Integrative Model of Effortful Control

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  Figure 1. Schematic representation of the integrative model of effortful control. The construct of effort involves the following three aspects: (1) the mechanism of effort, which is a neural network including a finite number of processing units (PU); (2) an effort signal generated by these processing units; and (3) a feeling of effort raising consciousness once the signal of effort is generated. The mechanism of effort fulfills the main function of making decisions regarding the intensity and the direction of the engagement in effort in ongoing or future tasks. Decisions are determined by the integration of miscellaneous input signals related to the task constraints (e.g., number of alternatives), immediate and delayed rewards (e.g., financial gain, social approval, or satisfaction of biological urge) or punishments (e.g., financial loss, social disapproval, or painful experience), and the current state of the organism (e.g., level of arousal or level of blood glucose). The mechanism of effort produces two main outputs: the effort signal and the autonomic signal. The strength of the effort signal depends on the number of processing units recruited to achieve the goal of the task. As the…

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  Figure 2. Schematic illustration of the key structures and pathways of the Salience Network that underlie the mechanism of effort. The illustration depicts and emphasizes certain direct pathways between structures or networks based on anatomical evidence of the main functions of the model presented in this article. The two main nodes of the salience network are the anterior insula and the dorsal anterior cingulate cortex(ACC). These two areas of the neocortex participate in the limbic system and are reciprocally interconnected. The Salience Network is represented by a gray rectangle. Once an individual is engaged in the realization of an effortful cognitive task or physical exercise, the Salience Network activates the Central Executive Network (CEN) and deactivates the default mode network through the effort signal sent by the pyramidal neurons in layer 5 of the cortical columns in the anterior insula (brown arrow). During the task, the Salience Network controls the activity of the CEN through the effort signal, which oscillates according to a theta rhythm. The pyramidal neurons located in layers 2–3 of the cortical columns in the anterior insula and dorsal ACC compute the effort signal.…

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  Figure 3. Connections between agranular and eulaminate cortical columns. (A) Feedback pathway from layer 5–6 pyramidal neurons in agranular columns to layers 1–3 in eulaminate columns. (B) Feedforward pathway from layer 1–3 pyramidal neurons to layers 5–6 in agranular columns.

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  Figure 4. The Salience Network as a slow-wave generator. The processing units in the Salience Network are the cortical columns of the dorsal ACC and the anterior insula. Layer 2–3 pyramidal neurons of these cortical columns generate a theta rhythm (4–8 Hz) under the control of cholinergic input. Tangential connections between cortical columns allow processing units to pulse synchronously. Layer 5 pyramidal neurons transmit this slow-wave inhibitory control signal to eulaminate brain regions to focus their processing on relevant task features.