By Nicholas P.W. Reeves, MD
In the words of famous neuroscientist Donald Hebb, “Neurons that fire together, wire together.” Thus, the conditioning that leads to abnormal neural circuit activity (in the brains of individuals with psychiatric disorders) can be recognized, and new patterns of thinking and behavior can be strengthened through conditioning that installs healthier patterns through the mechanisms of neural plasticity (e.g. changes in number of synapses for communication between neurons within a network and number/sensitivity of the neurotransmitter receptors on the postsynaptic neurons). These changes in neural circuit activity correlate with the changes in symptom intensity that a patient experiences when, for example, a therapist helps lead someone with PTSD through CPT or Prolonged Exposure, with a gradual reduction of trauma memory intensity, sensitivity to cues that trigger such trauma memories, and faulty beliefs based on feelings of hopelessness and helplessness.
How does neuroscience help us to better treat our patients or understand the etiology of their problems? The science itself does not tell us HOW the abnormalities in neural network activity (and the symptoms they correlate with) arose in the first place. The neuroscience also does not provide all the answers as to how best to treat these abnormalities in emotion/thinking/perception/behavior and the neural networks that underlie them. There are, however, some novel/emerging treatments such as Transcranial Magnetic Stimulation (TMS) and Deep Brain Stimulation (DBS), which were developed specifically with an understanding of neuroanatomy and the physiology of neural networks as a guide. Mind Therapy Clinic is proud to offer the cutting-edge treatment TMS to its clients, and this topic will be discussed later in the article.
What modern neuroscience tells us is that psychiatric disorders are associated with abnormal function in networks of neurons distributed throughout the brain. The phrenologists of the past went many leaps too far in the extrapolations they made from their core theory (to the point of preposterous notions of measuring skulls to determine personality), but there was a great deal of truth in the core theory, which postulated that the brain has a modular architecture, and that various regions of the brain serve specialized functions. We know that this is true today because studies of brain lesions (such as strokes or tumors) and using imaging or electrophysiologic methods that can capture real-time activity throughout the brain (e.g. fMRI, PET, EEG, MEG) have demonstrated that certain regions of the brain are critical for various different functions, such as movement (e.g. the motor cortex, basal ganglia), sensation/perception (e.g. the somatosensory, visual, auditory, and olfactory cortex regions, thalamus), and speech (Broca’s and Wernicke’s Areas of the cortex).
Furthermore, we know far more now than we ever did in the past about the areas of the brain that are important for emotional processing, such as the dorsolateral prefrontal cortex (DLPFC), involved in cognitive processing of emotion, social cognition, and many higher-order cognitive processes; the amygdala, involved in the generation of basic emotional experiences and a mediator of how emotion is expressed physiologically in the body, as well as the gatekeeper of the hippocampus, deciding whether a memory is worth storing based on its emotional salience; the orbitofrontal cortex, important for incorporating emotional information into the decision-making process, and for giving emotional experiences their subtle flavors; the anterior cingulate gyrus, critical for motivation, deciding where to allocate attention, suppression of impulsivity, and utilizing information about emotions and rewarding/punishing stimuli to motivate; the insula, with its role in mapping internal/visceral states with various emotions, and the awareness of emotional states, especially disgust, fear, and anger, as well as processing of physical pain, which causes emotional disturbances in so many who suffer from it. However, neuroscience-informed psychiatrists no longer hold the misguided reductionist view that these brain areas are responsible for each of these functions in isolation. Rather, they perform their various functions in coordination with many other brain areas, with brain circuits (aka neural networks) that connect the cortical areas with each other and with subcortical structures, such as the thalamus and striatum.
Perhaps the most extensively studied neural network relevant to psychiatry is called the Default Mode Network (DMN), which derived its name from the fact that there is prominent activity in this network when subjects are asked to sit quietly without any particular task at hand, when the brain is allowed to operate in its waking “default mode” when neither tasks nor sensory inputs are competing for its attention and processing capacity. This DMN is perhaps best thought of as a neurological correlate of mind wandering, and when our minds wander, we tend to have self-referential thoughts (about ourselves and other people in relation to our self), as well as reminiscences about the past and fantasies about potential futures. Not surprisingly, thinking about the self, how others relate to the self, imagining the thoughts/emotions of others, remembering the past, and imagining the future are all known and well-characterized functions of the DMN. The DMN has been demonstrated to have aberrant activity in various neuropsychiatric disorders, from depression (where excessive activity/connectivity is correlated with rumination and negative self-talk) to schizophrenia and autism (where disrupted activity/connectivity is associated with impaired social-emotional processing and cognition, as well as paranoid self-referential thinking in the case of schizophrenia).
An understanding of neural network architecture and of the abnormalities in emotion/thinking/perception/behavior that the neural networks produce in different psychiatric disorders was the basis upon which Transcranial Magnetic Stimulation (TMS) and Deep Brain Stimulation (DBS) were developed, with the neuroanatomy/physiology of neural networks as a guide. Mind Therapy Clinic is proud to offer TMS to its clients (including the new cost-saving but effectiveness-sparing 3 minute depression protocol iTBS!).
In summary, the field of psychiatry is undergoing exhilarating changes that are inspired by the principles of neuroscience, and several dramatically efficacious and neuroscience-informed treatments are emerging that may radically change the way psychiatry is practiced in the second half of the 21st century. There has never been a more fascinating time to be a scientifically savvy (read: nerdy) psychiatrist, and each successive generation of new psychiatrists will be able to truthfully say the same thing.