Executive control: Balancing stability and flexibility via the duality of evolutionary neuroanatomical trends

Department of Psychiatry and Biobehavioral Sciences, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, USA.
Dialogues in clinical neuroscience 03/2012; 14(1):39-47.
Source: PubMed


The concept of executive functions has a rich history and remains current despite increased use of other terms, including working memory and cognitive control. Executive functions have sometimes been equated with functions subserved by the frontal cortex, but this adds little clarity, given that we so far lack a comprehensive theory of frontal function. Pending a more complete mechanistic understanding, clinically useful generalizations can help characterize both healthy cognition and multiple varieties of cognitive impairment. This article surveys several hierarchical and autoregulatory control theories, and suggests that the evolutionary cytoarchitectonic trends theory provides a valuable neuroanatomical framework to help organize research on frontal structure-function relations. The theory suggests that paleocortical/ventrolateral and archicortical/dorsomedial trends are associated with neural network flexibility and stability respectively, which comports well with multiple other conceptual distinctions that have been proposed to characterize ventral and dorsal frontal functions, including the "initiation/inhibition," "what/where," and "classification/expectation" hypotheses.

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    • "Since cognitive control impairments are major treatment targets, understanding their biological underpinnings is of great clinical interest. In exploring these biological mechanisms, it is important to consider that cognitive control is a multifaceted construct (Bilder, 2012; Braver, 2012; Miyake et al., 2000). One pragmatic way of dissecting cognitive control is to separate proactive and reactive control. "
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    • "A similar conceptual approach was used to distinguish " rigidity, " " chaos, " and " integration " to characterize semantic network states in people with Asperger's syndrome, schizophrenia, and healthy semantic processing , respectively (see Faust and Kenett, 2014 for good graphical models; see also Siegel, 2010; Kaufman, 2014 for additional examples). The theory of evolutionary cytoarchitectonic trends may provide an anatomic and neuropsychopharmacologic substrate for these cognitive dimensions, with complementary systems that increase the stability or flexibility of cognitive states via the archicortical and paleocortical trends, respectively (Christensen and Bilder, 2000; Bilder, 2012). Local cortical networks employ the complementary actions of tonic and phasic dopamine signaling, which putatively mediate stability and flexibility, respectively (Bilder et al., 2004); similarly, D1-and D2-like dopamine transmission may mediate persistence or updating within cell assemblies (Durstewitz and Seamans, 2002). "
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    ABSTRACT: Complexity theorists have suggested that production "on the edge of chaos" is important to self organization and evolutionary change in thermodynamic systems, biology, and economics. We apply this heuristic to cognitive systems and neural network activation states, which can vary from an ordered (predictable) regime, to a chaotic (unpredictable) regime. Evolutionary cytoarchitectonic theory specifies complementary anatomical systems governing stability and flexibility. Psychopathology is associated with shifts in the regulation of stability and flexibility, and may yield both increased redundancy and increased entropy within the same individual. We suggest this fits existing literature showing: (a) examples of exceptional creativity in individuals with mental illness, without an overall increase in creative achievement associated with "madness" (b) increases in creative achievement among relatives of people with mental illness, or people with milder syndromes, for whom increased flexibility or stability is less disabling; and (c) effects of pharmacological manipulations, suggesting an inverted-U function resembling the Yerkes-Dodson Law, possibly linked to tonic and phasic dopaminergic transmission.
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    • "Specifically, we examined the different mechanisms called upon to rapidly switch between tasks vs. those needed to maintain strong representations that support all EF tasks. We discuss these distinctions primarily in the context of the Unity/Diversity model of EF (Friedman et al., 2008; Miyake & Friedman, 2012); however, this idea of a flexibility/stability tradeoff in goal-directed behavior has been discussed by a number of researchers (e.g., Bilder, 2012; Cools, 2012; Goschke, 2000; Tunbridge, Harrison, & Weinberger, 2006). The Common EF vs. Shifting-Specific constructs map relatively well to particular components of the PBWM model (although that mapping is not perfectly one-to-one, as addressed in the discussion ). "
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