The Brain.
The brain is a natural starting point for the Integrative Psychiatry Matrix (IPM). We are usually first encountered with what the brain EMITS (Emotions, Memories, Images, Thoughts, and Sensations). Psychological symptoms reflect communication on a microscopic (subcellular) and macroscopic (regional) scale.
Neurobiological networking abnormalities underly the experiences and symptoms we encounter in psychiatric practice. In light of this, it is difficult for the practicing clinician to conceptualize networking abnormalities in a way that translates well into clinical practice. If our goal is neural integration, then having an understanding of the major brain networks is key. At the risk of being overly simplistic, I use the following image to help me conceptualize neural networks.
The arousal network is the starting point for central nervous system arousal and activation. This is where the individual is aroused, and the attentional networks are jump-started. The arousal network includes the locus coeruleus (LC) and associated norepinephrine activity, the ventral tegmental area (VTA) and associated dopaminergic activity, and the reticular activating system (RAS).
The frontoparietal network captures the “who” behind the experience. This large network includes four subnetworks: the default mode network (DMN), central executive network (CEN), sensorimotor network (SMN), and salience network (SN). The DMN is responsible for internally oriented cognition (Li, Mai, & Liu, 2014). When at rest, driving on autopilot, or daydreaming, the DMN is highly active. It involves self-concept, social evaluations, and narrative or life story comprehension. The DMN includes the medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), angular gyrus (AG), and lateral parietal cortex (LPC). The CEN is responsible for externally oriented cognition and behavior (Bremer et al., 2022). The CEN is the executive that converts thought into action. It involves goal-oriented tasks, reasoning, problem-solving, and top-down control of negative thoughts and emotions. The CEN includes the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), and posterior parietal cortex (PPC). The SMN Governs psychomotricity. It is activated during motor tasks and prepares the brain when planning and executing coordinated motor movements (Zhu et al., 2022). The SMN includes the pre- and post-central gyrus and supplementary motor areas (SMA). The SN is involved in switching between internally oriented states (e.g., DMN) and externally oriented states (e.g., CEN, SMN) (Bremer et al., 2022). It includes the anterior insula (AI) and anterior cingulate cortex (ACC). The arousal network, limbic system, and temporal lobe activate the SN.
The frontostriatal network aids in predicting “what” outcome may occur in a given context. This network determines and controls the responses we give to a stimulus in a given situation. It is made up of the dorsal striatum with frontal projections. The dorsal striatum can be divided into two key regions: the caudate and putamen. The caudate drives automatic thought, and the putamen drives automatic movement. With this in mind, this network becomes an area where habitual activities are of concern. This network becomes a key player in the cortico-striato-thamao-cortical (CSTC) loop, which I call the preoccupation loop. Impairments in this loop have been associated with anxiety, obsessions, and compulsions (Peters, Dunlop, & Downar, 2016). The functions of the CSTC loop are integrated with the SN.
The frontocerebellar network predicts “when” an outcome may occur. This network provides the context for the frontostriatal network. The cerebellum is the neural learning machine and is critical in the development and execution of procedural learning by creation and error-driven modification of internal behavior models (Molinari et al., 1997). This system is essentially responsible for the storage and operation of three-term contingencies (antecedent, behavior, consequence) as a part of operant conditioning.
The autonomic network is “where” an individual experiences the things the brain EMITS (emotions, memories, images, thoughts, and sensations). The central autonomic network (CAN) controls the activity along the autonomic nervous system and includes the insula, anterior cingulate cortex, amygdala, hypothalamus, periaqueductal gray, and locus coeruleus (Lamotte et al., 2021). The autonomic nervous system is divided into the sympathetic and parasympathetic nervous systems. The sympathetic nervous system (sANS) is predominantly responsible for the “fight and flight” responses and presents as mobilization and hyperarousal. Through the lens of polyvagal theory, we now understand that the parasympathetic nervous system is divided into two complexes: the ventral vagal and dorsal vagal complexes (VVC and DVC, respectively) (Porges, 2022). With the autonomic nervous system, you find a nested hierarchy corresponding with evolutionary history. The VVC is activated first, prompting social engagement for co-regulation. This is the most recent system in our evolutionary history and captures the “rest and digest” activity. If this fails, then the sympathetic nervous system is activated. If this fails or the system is overwhelmed, then the evolutionarily oldest system, the DVC, is activated, leading to a freeze, submission, or immobilization response (Porges, 2022). This is clinically recognizable as a hypoaroused presentation.
The frontolimbic network informs the “why” behind an experience, adding emotional content to the aforementioned systems. This system conditions behavior, adding a degree of reinforcement or avoidance to a given behavioral sequence. It is also a transdiagnostic correlate of emotion regulation (Kebets et al., 2021). Two key subsystems include the emotional and reward networks. The emotional network is involved in emotional thinking and affective bias. It includes the anterior cingulate cortex, orbitofrontal prefrontal cortex, amygdala, hippocampus, and insula. The reward network is involved in interest, motivation, and pleasure. It includes the prefrontal cortex, caudate, and nucleus accumbens. These two networks are interrelated (Yankouskaya et al., 2022).
The frontotemporal network informs “how” information is processed. The temporal lobe processes speech, language, auditory, and visual information (Crinion et al., 2003). It is also involved in memory formation. The activities of the temporal lobe are implicated in salience network modulation as inputs to direct switching between the default mode and central executive networks (Zhou et al., 2021). This has implications for psychosis, sensory overload, and attention deficits (Allen et al., 2019; Zhou et al., 2021).
As you can see, this networking model provides a general location for the who, what, when, where, why, and how associated with a given experience. This networking perspective provides a more practical view that readily translates to the plan of care.
We can focus on the arousal network through interventions targeting the circadian sleep and activity balance.
Psychedelics, mindfulness, insight-oriented approaches, and behavioral activation quiet the DMN and engage the CEN and SMN to modify the frontoparietal network. We can additionally target the frontoparietal network top-down with cognitive therapy techniques.
We can focus on the frontostriatal and frontocerebellar networks through behavioral interventions.
The autonomic network can be modified by somatic, polyvagal, and biofeedback approaches.
We can target the frontolimbic network using depth and bottom-up psychology approaches, such as psychoanalysis, hypnotherapy, eye movement desensitization and reprocessing, and internal family systems.
Finally, we can target the frontotemporal network through sensory processing modalities.
I apply this conceptualization by addressing the who, what, when, where, why, and how in each clinical encounter to expand upon my understanding of the phenotypic expression of psychiatric illness. This guides my workup and treatment considerations.
I expand upon this conceptualization in detail in my book “A New Way Forward” and my Integrative Psychiatry Program.
