Neuroplasticity and the brain connectome: what can Jean Talairach’s reflections bring to modern psychosurgery?

Abstract

<jats:p>Contrary to common psychosurgical practice in the 1950s, Dr. Jean Talairach had the intuition, based on clinical experience, that the brain connectome and neuroplasticity had a role to play in psychosurgery. Due to the remarkable progress of pharmacology at that time and to the technical limits of neurosurgery, these concepts were not put into practice. Currently, these concepts are being confirmed by modern techniques such as neuroimaging and computational neurosciences, and could pave the way for therapeutic innovation in psychiatry.</jats:p><jats:p>Psychosurgery commonly uses a localizationist approach, based on the idea that a lesion to a specific area is responsible for a deficit opposite to its function. To psychosurgeons such as Walter Freeman, who performed extensive lesions causing apparently inevitable deficit, Talairach answered with clinical data: complex psychic functions cannot be described that simply, because the same lesion does not provoke the same deficit in different patients. Moreover, cognitive impairment did not always follow efficacious psychosurgery. Talairach suggested that selectively destructing part of a network could open the door to a new organization, and that early psychotherapy could encourage this psychoplasticity. Talairach did not have the opportunity to put these concepts into practice in psychiatric diseases because of the sudden availability of neuroleptics, but connectomics and neuroplasticity gave rise to major advances in intraparenchymal neurosurgery, from epilepsy to low-grade glioma. In psychiatry, alongside long-standing theories implicating focal lesions and diffuse pathological processes, neuroimaging techniques are currently being developed. In mentally healthy individuals, combining diffusion tensor imaging with functional MRI, magnetoencephalography, and electroencephalography allows the determination of a comprehensive map of neural connections in the brain on many spatial scales, the so-called connectome. Ultimately, global neurocomputational models could predict physiological activity, behavior, and subjective feeling, and describe neuropsychiatric disorders.</jats:p><jats:p>Connectomic studies comparing psychiatric patients with controls have already confirmed the early intuitions of Talairach. As a striking example, massive dysconnectivity has been found in schizophrenia, leading some authors to propose a “dysconnection hypothesis.” Alterations of the connectome have also been demonstrated in obsessive-compulsive disorder and depression. Furthermore, normalization of the functional dysconnectivity has been observed following clinical improvement in several therapeutic interventions, from psychotherapy to pharmacological treatments. Provided that mental disorders result from abnormal structural or functional wiring, targeted psychosurgery would require that one be able: 1) to identify the pathological network involved in a given patient; 2) to use neurostimulation to safely create a reversible and durable alteration, mimicking a lesion, in a network compatible with neuroplasticity; and 3) to predict which functional lesion would result in adapted neuronal plasticity and/or to guide neuronal plasticity to promote recovery. All these conditions, already suggested by Talairach, could now be achievable considering modern biomarkers and surgical progress.</jats:p>

Electromagnetic Brain Stimulation in Patients With Disorders of Consciousness

“…Stereotactic surgical methodology was first described in the late 19th century (Apra et al, 2016), but applications in neurological diseases on the basis of neurophysiological principles started only in the second half of the 20th century (Giller et al, 2017; Bourdillon et al, 2018). Performing a lesion on deep mesencephalic or diencephalic small structures with wide projections on large cortical areas was exciting perspectives in psychiatric and neurological fields and drastically reduced the morbidity of the surgical procedures (Miocinovic et al, 2013; Bourdillon et al, 2017). These lesional procedures were indicated in pathologies producing positive signs (like tremor or dystonia) but were useless in pathologies in which negative signs were preponderant, such as disorder of consciousness (DoC).…”

Effective accuracy of stereoelectroencephalography: robotic 3D versus Talairach orthogonal approaches

“…developed a strong interest in the mapping of brain networks through his primary interest in psychiatry. 3 Therefore, when Talairach got involved in epilepsy research, he imagined a stereotactic methodology allowing prolonged intracranial electroencephalography (EEG) for recording epileptic networks, namely stereoelectroencephalography (SEEG). He developed this procedure with Gabor Szikla, and the use of angiography to maximize vascular safety by preventing damage to blood vessels was an obsession.…”

Neurosurgery for Refractory Schizophrenia: A Systematic Literature Review

“…Currently, another technique has been designed to improve the accuracy of DBS, called closedloop deep brain stimulation (CL-DBS), which uses studies of the complete connection that occurs from one point to another point in the brain through neural pathways, called a connectome. [49][50][51] One of the advantages of DBS, when compared to other surgical procedures, is its reversibility. 12 Studies have also reported its benefit in reducing recurrence rates, decreasing the intensity of residual psychosis, and improving cognitive impairment by reducing the negative symptoms.…”