A Neuropsychoanalytic Model of Brain Function
Mark Solms, a neuropsychologist in Cape Town, South Africa, has for the last two decades been at the center the movement to enrich both psychoanalysis and neuroscience by bringing their perspectives together. He and his colleagues around the world call this "neuropsychoanalysis." The use findings from neuroimaging, psychopharmacology, findings from animal research, as well as what they call the “clinical-pathological” method, which draws on observations from psychotherapy of brain-damaged patients. In 2002, Solms and his colleague Oliver Turnbull published The Brain and the Inner World: An Introduction to the Neuroscience of Subjective Experience. In it they examine neuroscientific findings from the perspective of Freud’s ideas to generate a neuroscience-based picture of conscious experience. The result is the clearest explication of higher-level brain functions I have found so far.
Solms and Turnbull begin with basic concepts of brain organization, some of which were new to me. The posterior portions of the cortex are mainly concerned with receiving and processing sensory information from the outer world. Information about the body emerges through the hypothalamus, which they view as the center of the limbic system. The prefrontal cortex, among other functions, provides control over limbic functions, mainly by inhibition. The motor output of the cortex is through the motor strip on the posterior edge of the frontal lobe. The brainstem and limbic system have their own output through the autonomic nervous system and hormones, but also through emotions and instinctual behaviors.
Solms and Turnbull distinguish “channel” functions which operate through narrow pathways, using glutamate and aspartate as excitatory neurotransmitters and gamma-aminobutyric acid (GABA) as their inhibitory neurotransmitter. “State” functions, on the other hand, use small numbers of neurons in discrete nuclei which project widely to other parts of the brain, using neuromodulators like acetylcholine, serotonin, norepinephrine, dopamine, and histamine. Also, hormonal neuromodulators circulate through the bloodstream and cerebrospinal fluid (CSF), acting globally on the whole brain. And peptide neuromodulators diffuse locally and exert more specific actions.
The external senses use channel functions to perceive and analyze the external world. Solms and Turnbull view emotions as another sensory modality, of the state of the body. Emotional systems are not only channel-dependent, but also state-dependent, using small molecule neuromodulators, hormones, and peptides. The anatomic regions involved in emotions are the same as for the “background state of consciousness”—the hypothalamus, ventral tegmental area, parabrachial nuclei, periaqueductal gray, raphe nuclei, nucleus locus coeruleus, and reticular formation.
The authors identify several approaches to the famous “binding problem” of neuroscience—how all this information is brought together and processed so that consciousness emerges. The anatomic approach identifies sites in the brain where channel pathways come together: one is the junction of the temporal, parietal, and occipital lobes, where several sensory pathways converge; another is the prefrontal cortex. A different approach approach is temporal, looking at which cells in the brain fire together in synchronized rhythms.
A third, which Solms and Turnbull discuss in detail, has external perceptions grounded in internal perceptions. A “virtual body” is thought to be created in the limbic system using projections from internal senses (though it does not appear to be spatially organized). This is derived Antonio Damasio’s idea that internal self-monitoring gives value to external perceptions, for example, that a perception of food is evaluated by the body’s state of hunger. This gives rise to core consciousness—our in-the-moment awareness of self and environment. Extended consciousness includes this self-awareness along with awareness of the past and future and involves association cortices and the prefrontal lobes.
Solms and Turnbull draw on an earlier version of Jaak Panksepp’s basic emotional systems—seeking, rage, fear, lust, care, panic/grief, and play—each of which Panksepp has associated with specific brain regions and neurotransmitters.
Solms and Turnbull note that the psychoanalytic concept of the ego to some extent parallels our neuroscientific understanding of ventromedial prefrontal lobe function. Both portray inhibitory emotional systems that are operate for the most part outside conscious awareness. Patients with ventromedial prefrontal damage, like as the famous case of Phineas Gage, show exemption from mutual contradiction, inattention to time, replacement of external reality by psychic reality, and “mobility of cathexis,” that is, the less edited stream of consciousness of free-associated thinking.
After consciousness, Solms and Turnbull go on to discuss memory and fantasy, dreams and hallucinations, and language. Toward the end of the book they summarize their picture of the mind/brain function in something like these terms: 1) Core awareness is grounded in the brainstem nuclei which regulate visceral life. 2) Upper brainstem nuclei govern “activational tone”, which is perceived subjectively as the “background medium of our conscious awareness.” It reflects the momentary state of bodily needs and is experienced as “quality of feeling.” 3) The posterior forebrain sensory systems are the external sources of awareness. “A unit of consciousness—a moment of awareness—is the coupling of the momentary state of core consciousness with the “concurrent surround of objects” derived from sensation. 4) Panksepp’s basic emotions of seeking, rage, fear, lust, care, panic/grief, and play are built on this foundation of core consciousness. Found in all mammals, they are inherited and develop differently in each individual. 5) Most memory is nonconscious. Conscious memory, most importantly “episodic” memory of personal experiences, links the memory of an external event with what was felt. The hippocampus is central to this. 6) Prefrontal executive functions are primarily inhibitory. They use, among other processes, “imaginary acting”, i.e. “running the envisaged action programs while motor output is precluded.” The prefrontal lobes mature in childhood and are heavily dependent on experience. 7) Mirror neurons in cortical action systems likely participate in children’s internalization of their parents’ behavior. Inner speech is how children transform parental prohibitions into inhibitions.
This is a compelling synthesis. Though it is fifteen years old; the basic information about internal and external perception, the limbic system, and the role of the prefrontal lobes is still valid. Solms’s and Turnbull’s ideas about the synthesis of these perceptions with basic emotions to form momentary self-awareness, and with memory and rehearsal of future actions to form extended conscious, have almost certainly been critiqued and extended, but for now this model is the best I have found.
Mark Solms and Oliver Turnbull. The Brain and the Inner World: An Introduction to the Neuroscience of Subjective Experience. Other Press, 2002.