The default-mode, ego-functions and free-energy: a neurobiological account of Freudian ideas

Abstract

This article explores the notion that Freudian constructs may have neurobiological substrates. Specifically, we propose that Freud's descriptions of the primary and secondary processes are consistent with self-organized activity in hierarchical cortical systems and that his descriptions of the ego are consistent with the functions of the default-mode and its reciprocal exchanges with subordinate brain systems. This neurobiological account rests on a view of the brain as a hierarchical inference or Helmholtz machine. In this view, large-scale intrinsic networks occupy supraordinate levels of hierarchical brain systems that try to optimize their representation of the sensorium. This optimization has been formulated as minimizing a free-energy; a process that is formally similar to the treatment of energy in Freudian formulations. We substantiate this synthesis by showing that Freud's descriptions of the primary process are consistent with the phenomenology and neurophysiology of rapid eye movement sleep, the early and acute psychotic state, the aura of temporal lobe epilepsy and hallucinogenic drug states.

Figure 1

The DMN (yellow/orange) and attention system (blue): resting state functional connectivity of three seed regions: the dorsal medial prefrontal cortex, ventral medial prefrontal cortex and hippocampal formation (medial temporal lobes). Positive correlations (yellow–orange) with all seeds were evident in the posterior cingulate (PCC), posterior inferior parietal lobule (pIPL) and medial prefrontal cortex (mPFC). Regions negatively correlated with these seeds constitute the attention system and include the superior parietal lobule (SPL), intraparietal sulcus (IPS), the motion-sensitive middle temporal area (MT+), the frontal eye fields (FEF) the dorsal anterior cingulate (dACC), the dorsolateral prefrontal cortex (DLPFC), the ventral premotor cortex and the frontal operculum. Image reproduced from Buckner et al. (2008), with permission.

Figure 2

Resting state functional connectivity in three cortical networks: (i) dorsal attention system (DAS, blue) using voxels in the middle temporal area and superior parietal lobule as regions of interest; (ii) the salience system (light green) using voxels in the anterior PFC and anterior inferior parietal lobule as regions of interest; and (iii) the default mode network (orange) using the hippocampal formation and posterior inferior parietal lobule as regions of interest. Overlap between the networks is shown in dark green (salience system and DMN) and red (dorsal attention systems and salience system). Image used with permission from Justin Vincent and Randy Buckner.