Thalamus and Neuropsychological Disorders

Dear Editor, We read the original article entitled "Thalamus – The Gateway to Cerebral Cortex" in the esteemed "Journal of the Scientific Society" with great interest. Hari et al. assessed the clinical and radiological characteristics of 83 individuals diagnosed with nontraumatic thalamic lesions.[1] They found that the most common isolated thalamic lesion is an ischemic infarct, which more commonly occurs in the male sex. The most common clinical presentation found was sensorimotor dysfunction. Scientists have long believed that the thalamus only acted as a "relay" between the cortex and hippocampus. Recent publications demonstrated that thalamic nuclei could provide a complex contribution to cognition and neuropsychological disorders, which some authors call as "cognitive thalamus." Herein, we would like to discuss the recent literature on the thalamus and neuropsychological disorders [Figure 1].Figure 1: Historical versus new hypothesis of thalamic functionYang et al. assessed the tactile decision in the mouse anterior lateral motor cortex about the underlying circuits. They observed that task selectivity was more strongly dependent on thalamic inputs than cortico-cortical inputs, suggesting that the thalamus drives subnetworks within the frontal cortex, coding distinct decision-making features.[2] This study can support further investigations about deep brain stimulation as therapeutic management in individuals with cognitive impairment. In a recent review of the literature by Steullet, thalamus abnormalities were identified as a biomarker of psychosis. The authors found that reduced thalamic volume, low N-acetylaspartate level, decreased alpha peak frequency in resting electroencephalogram, reduced spindles, and slow-wave during nonrapid eye movement sleep may be correlated with schizophrenia. Moreover, other specific abnormalities of the cortical-striatal-thalamic loop could be associated with the prediction to develop a psychotic episode.[3] The central dysfunctions may be caused by issues intrinsically related to the thalamus. Still, they could also be related to changes in other brain structures or networks involving the thalamus. Choi et al. studied the Pavlovian counterconditioning in male rats to establish the control of the paraventricular thalamus in motivational conflicts. They observed that the anterior–posterior axis of the paraventricular thalamus plays a significant role in conflict situations.[4] The idea of possible control of behavior based on the thalamus may make other types of management available, such as new drugs for anxiety disorders due to the behavioral inhibition system. It is worth mentioning that the anatomical location of paraventricular nuclei is adjacent to the third ventricle, which could be an essential approach for delivering new medications. Hubs are a vast number of connections that play a significant role in network functions. Hwang evaluated the significance of the thalamic hub in neuropsychological disorders. They observed that the number of thalamic connections is associated with neurological impairment. In this way, lesions to the thalamic subregions with stronger hub properties were related to widespread deficits in executive, language, and memory functions.[5] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.