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Trends in Neurosciences Feb 2024The pulvinar nucleus of the thalamus is a crucial component of the visual system and plays significant roles in sensory processing and cognitive integration. The... (Review)
Review
The pulvinar nucleus of the thalamus is a crucial component of the visual system and plays significant roles in sensory processing and cognitive integration. The pulvinar's extensive connectivity with cortical regions allows for bidirectional communication, contributing to the integration of sensory information across the visual hierarchy. Recent findings underscore the pulvinar's involvement in attentional modulation, feature binding, and predictive coding. In this review, we highlight recent advances in clarifying the pulvinar's circuitry and function. We discuss the contributions of the pulvinar to signal modulation across the global cortical network and place these findings within theoretical frameworks of cortical processing, particularly the global neuronal workspace (GNW) theory and predictive coding.
Topics: Humans; Pulvinar; Thalamus; Visual Perception; Attention; Sensation
PubMed: 38143202
DOI: 10.1016/j.tins.2023.11.008 -
Psychiatry Research Jan 2024Rates of youth depression and suicide are rising worldwide and represent public health crises. The present study examined the relationship between trauma history and...
Rates of youth depression and suicide are rising worldwide and represent public health crises. The present study examined the relationship between trauma history and symptoms of depression, suicidal ideation, and anxiety among suicidal and depressed youth. A diverse group of 1000 8-20-year-olds enrolled in the statewide Texas Youth Depression and Suicide Research Network (TX-YDSRN) reported their trauma history (Traumatic Events Screening Inventory for Children) and symptoms of depression (Patient Health Questionnaire for adolescents; PHQ-A), anxiety (Generalized Anxiety Disorder scale; GAD-7), and suicidality (Concise Health Risk Tracking scale; CHRT-SR). Nearly half of the sample reported exposure to multiple categories of traumatic experiences. Number of trauma exposure categories significantly predicted PHQ-A and GAD-7 scores. Exposure to interpersonal trauma and to sexual trauma were significantly associated with PHQ-A, GAD-7, and CHRT-SR scores. The number of trauma exposure categories was associated with increased levels of anxiety and depression; however, only exposure to interpersonal or sexual trauma was associated with more suicidality. Clinicians should assess trauma exposure in patients seeking psychiatric care, especially for interpersonal and sexual trauma, which may be predictive of increased risk for suicidality in depressed youth. Future work should disentangle the effects of specific trauma types from multiple trauma exposure.
Topics: Child; Humans; Adolescent; Depression; Mental Health; Texas; Psychometrics; Suicide; Suicidal Ideation
PubMed: 38091894
DOI: 10.1016/j.psychres.2023.115620 -
Neurological Sciences : Official... May 2024This study aimed to examine the volumes of thalamic nuclei and the intrinsic thalamic network in patients with Wilson's disease (WDs), and to explore the correlation...
OBJECTIVE
This study aimed to examine the volumes of thalamic nuclei and the intrinsic thalamic network in patients with Wilson's disease (WDs), and to explore the correlation between these volumes and the severity of neurological symptoms.
METHODS
A total of 61 WDs and 33 healthy controls (HCs) were included in the study. The volumes of 25 bilateral thalamic nuclei were measured using structural imaging analysis with Freesurfer, and the intrinsic thalamic network was evaluated through structural covariance network (SCN) analysis.
RESULTS
The results indicated that multiple thalamic nuclei were smaller in WDs compared to HCs, including mediodorsal medial magnocellular (MDm), anterior ventral (AV), central median (CeM), centromedian (CM), lateral geniculate (LGN), limitans-suprageniculate (L-Sg), reuniens-medial ventral (MV), paracentral (Pc), parafascicular (Pf), paratenial (Pt), pulvinar anterior (PuA), pulvinar inferior (PuI), pulvinar medial (PuM), ventral anterior (VA), ventral anterior magnocellular (VAmc), ventral lateral anterior (VLa), ventral lateral posterior (VLp), ventromedial (VM), ventral posterolateral (VPL), and right middle dorsal intralaminar (MDI). The study also found a negative correlation between the UWDRS scores and the volume of the right MDm. The intrinsic thalamic network analysis showed abnormal topological properties in WDs, including increased mean local efficiency, modularity, normalized clustering coefficient, small-world index, and characteristic path length, and a corresponding decrease in mean node betweenness centrality. WDs with cerebral involvement had a lower modularity compared to HCs.
CONCLUSIONS
The findings suggest that the majority of thalamic nuclei in WDs exhibit significant volume reduction, and the atrophy of the right MDm is closely related to the severity of neurological symptoms. The intrinsic thalamic network in WDs demonstrated abnormal topological properties, indicating a close relationship with neurological impairment.
Topics: Humans; Hepatolenticular Degeneration; Thalamic Nuclei; Thalamus
PubMed: 38049551
DOI: 10.1007/s10072-023-07245-2 -
The Journal of Comparative Neurology Feb 2024Here, we describe the postnatal development of retinal projections in galagos. Galagos are of special interest as they represent the understudied strepsirrhine branch...
Here, we describe the postnatal development of retinal projections in galagos. Galagos are of special interest as they represent the understudied strepsirrhine branch (galagos, pottos, lorises, and lemurs) of the primate radiations. The projections of both eyes were revealed in each galago by injecting red or green cholera toxin subunit B (CTB) tracers into different eyes of galagos ranging from postnatal day 5 to adult. In the dorsal lateral geniculate nucleus, the magnocellular, parvocellular, and koniocellular layers were clearly labeled and identified by having inputs from the ipsilateral or contralateral eye at all ages. In the superficial layers of the superior colliculus, the terminations from the ipsilateral eye were just ventral to those from the contralateral eye at all ages. Other terminations at postnatal day 5 and later were in the pregeniculate nucleus, the accessory optic system, and the pretectum. As in other primates, a small retinal projection terminated in the posterior part of the pulvinar, which is known to project to the temporal visual cortex. This small projection from both eyes was most apparent on day 5 and absent in mature galagos. A similar reduction over postnatal maturation has been reported in marmosets, leading to the speculation that early retinal inputs to the pulvinar are responsible for the activation and early maturation of the middle temporal visual area, MT.
Topics: Animals; Galago; Visual Pathways; Superior Colliculi; Geniculate Bodies; Pulvinar
PubMed: 38047381
DOI: 10.1002/cne.25565 -
Current Research in Neurobiology 2023The role of thalamocortical circuits in memory has driven a recent burst of scholarship, especially in animal models. Investigating this circuitry in humans is more... (Review)
Review
The role of thalamocortical circuits in memory has driven a recent burst of scholarship, especially in animal models. Investigating this circuitry in humans is more challenging. And yet, the development of new recording and stimulation technologies deployed for clinical indications has created novel opportunities for data collection to elucidate the cognitive roles of thalamic structures. These technologies include stereoelectroencephalography (SEEG), deep brain stimulation (DBS), and responsive neurostimulation (RNS), all of which have been applied to memory-related thalamic regions, specifically for seizure localization and treatment. This review seeks to summarize the existing applications of neuromodulation of the anterior thalamic nuclei (ANT) and highlight several devices and their capabilities that can allow cognitive researchers to design experiments to assay its functionality. Our goal is to introduce to investigators, who may not be familiar with these clinical devices, the capabilities, and limitations of these tools for understanding the neurophysiology of the ANT as it pertains to memory and other behaviors. We also briefly cover the targeting of other thalamic regions including the centromedian (CM) nucleus, dorsomedial (DM) nucleus, and pulvinar, with associated potential avenues of experimentation.
PubMed: 38020810
DOI: 10.1016/j.crneur.2023.100109 -
Clinical Neurology and Neurosurgery Dec 2023Emerging neuromodulatory treatments, such as deep brain stimulation (DBS) and responsive neurostimulation (RNS), have shown promise in reducing drug-resistant seizures....
Emerging neuromodulatory treatments, such as deep brain stimulation (DBS) and responsive neurostimulation (RNS), have shown promise in reducing drug-resistant seizures. While centromedian thalamic nucleus and anterior thalamic nucleus stimulation have been effective in certain types of seizures, limited research has explored pulvinar nucleus stimulation for epilepsy. To address this gap, we conducted a systematic review and individual patient data analysis. Of 78 resultant articles, 5 studies with transient stimulation and chronic stimulation of the pulvinar nucleus were included. Of the 20 patients reviewed, 65% of patients had temporal lobe seizures, while 20% had temporooccipital/occipital lobe seizures. Transient stimulation studies via stereoelectroencephalography (SEEG) showed pulvinar evoked potential response rates of 80% in the mesial temporal region, 76% in the temporal neocortex, and 67% in the TP junction. Another study reported clinically less severe seizures in 62.5% of patients with pulvinar stimulation. In chronic stimulation studies, 80% of patients responded to RNS or DBS, and 2 of 4 patients experienced > 90% seizure reduction. The pulvinar nucleus of the thalamus emerges as a potential target for chronic stimulation in drug-resistant epilepsy. However, knowledge regarding pulvinar connectivity and chronic stimulation remains limited. Further research should investigate specific subregions of the pulvinar for epilepsy treatment. Understanding the role of pulvinar stimulation and its cortical connectivity will advance therapeutic interventions for epilepsy patients.
Topics: Humans; Pulvinar; Hippocampus; Deep Brain Stimulation; Epilepsy; Thalamus; Seizures; Drug Resistant Epilepsy; Anterior Thalamic Nuclei; Data Analysis
PubMed: 37979562
DOI: 10.1016/j.clineuro.2023.108041 -
Human Brain Mapping Dec 2023Congenital sensory deprivation induces significant changes in the structural and functional organisation of the brain. These are well-characterised by cross-modal...
Congenital sensory deprivation induces significant changes in the structural and functional organisation of the brain. These are well-characterised by cross-modal plasticity, in which deprived cortical areas are recruited to process information from non-affected sensory modalities, as well as by other neuroplastic alterations within regions dedicated to the remaining senses. Here, we analysed visual and auditory networks of congenitally deaf and hearing individuals during different visual tasks to assess changes in network community structure and connectivity patterns due to congenital deafness. In the hearing group, the nodes are clearly divided into three communities (visual, auditory and subcortical), whereas in the deaf group a fourth community consisting mainly of bilateral superior temporal sulcus and temporo-insular regions is present. Perhaps more importantly, the right lateral geniculate body, as well as bilateral thalamus and pulvinar joined the auditory community of the deaf. Moreover, there is stronger connectivity between bilateral thalamic and pulvinar and auditory areas in the deaf group, when compared to the hearing group. No differences were found in the number of connections of these nodes to visual areas. Our findings reveal substantial neuroplastic changes occurring within the auditory and visual networks caused by deafness, emphasising the dynamic nature of the sensory systems in response to congenital deafness. Specifically, these results indicate that in the deaf but not the hearing group, subcortical thalamic nuclei are highly connected to auditory areas during processing of visual information, suggesting that these relay areas may be responsible for rerouting visual information to the auditory cortex under congenital deafness.
Topics: Humans; Deafness; Hearing; Auditory Cortex; Brain; Hearing Loss, Sensorineural; Sense Organs; Neuronal Plasticity
PubMed: 37956260
DOI: 10.1002/hbm.26530 -
Frontiers in Neuroscience 2023Cortico-striato-thalamo-cortical (CSTC) loops are fundamental organizing units in mammalian brains. CSTCs process limbic, associative, and sensorimotor information in...
Cortico-striato-thalamo-cortical (CSTC) loops are fundamental organizing units in mammalian brains. CSTCs process limbic, associative, and sensorimotor information in largely separated but interacting networks. CTSC loops pass through paired striatal compartments, striosome (aka patch) and matrix, segregated pools of medium spiny projection neurons with distinct embryologic origins, cortical/subcortical structural connectivity, susceptibility to injury, and roles in behaviors and diseases. Similarly, striatal dopamine modulates activity in striosome and matrix in opposite directions. Routing CSTCs through one compartment may be an anatomical basis for regulating discrete functions. We used differential structural connectivity, identified through probabilistic diffusion tractography, to distinguish the striatal compartments (striosome-like and matrix-like voxels) in living humans. We then mapped compartment-specific projections and quantified structural connectivity between each striatal compartment, the globus pallidus interna (GPi), and 20 thalamic nuclei in 221 healthy adults. We found that striosome-originating and matrix-originating streamlines were segregated within the GPi: striosome-like connectivity was significantly more rostral, ventral, and medial. Striato-pallido-thalamic streamline bundles that were seeded from striosome-like and matrix-like voxels transited spatially distinct portions of the white matter. Matrix-like streamlines were 5.7-fold more likely to reach the GPi, replicating animal tract-tracing studies. Striosome-like connectivity dominated in six thalamic nuclei (anteroventral, central lateral, laterodorsal, lateral posterior, mediodorsal-medial, and medial geniculate). Matrix-like connectivity dominated in seven thalamic nuclei (centromedian, parafascicular, pulvinar-anterior, pulvinar-lateral, ventral lateral-anterior, ventral lateral-posterior, ventral posterolateral). Though we mapped all thalamic nuclei independently, functionally-related nuclei were matched for compartment-level bias. We validated these results with prior thalamostriate tract tracing studies in non-human primates and other species; where reliable data was available, all agreed with our measures of structural connectivity. Matrix-like connectivity was lateralized (left > right hemisphere) in 18 thalamic nuclei, independent of handedness, diffusion protocol, sex, or whether the nucleus was striosome-dominated or matrix-dominated. Compartment-specific biases in striato-pallido-thalamic structural connectivity suggest that routing CSTC loops through striosome-like or matrix-like voxels is a fundamental mechanism for organizing and regulating brain networks. Our MRI-based assessments of striato-thalamic connectivity in humans match and extend the results of prior tract tracing studies in animals. Compartment-level characterization may improve localization of human neuropathologies and improve neurosurgical targeting in the GPi and thalamus.
PubMed: 37954873
DOI: 10.3389/fnins.2023.1178473 -
Frontiers in Integrative Neuroscience 2023In the primate brain, the lateral prefrontal cortex (LPF) is a large, heterogeneous region critically involved in the cognitive control of behavior, consisting of...
In the primate brain, the lateral prefrontal cortex (LPF) is a large, heterogeneous region critically involved in the cognitive control of behavior, consisting of several connectionally and functionally distinct areas. Studies in macaques provided evidence for distinctive patterns of cortical connectivity between architectonic areas located at different dorsoventral levels and for rostrocaudal gradients of parietal and frontal connections in the three main architectonic LPF areas: 46d, 46v, and 12r. In the present study, based on tracer injections placed at different dorsoventral and rostrocaudal cortical levels, we have examined the thalamic projections to the LPF to examine to what extent fine-grained connectional gradients of cortical connectivity are reflected in the topography of thalamo-LPF projections. The results showed mapping onto the nucleus medialis dorsalis (MD), by far the major source of thalamic input to the LPF, of rostral-to-caudal LPF zones, in which MD zones projecting to more caudal LPF sectors are located more rostral than those projecting to intermediate LPF sectors. Furthermore, the MD zones projecting to the rostral LPF sectors tended to be much more extensive in the rostrocaudal direction. One rostrolateral MD sector appeared to be a common source of projections to caudal prefrontal areas involved in the oculomotor frontal domain, a more caudal and ventral MD sector to a large extent of the ventral LPF, and middle and dorsal MD sectors to most of the dorsal LPF. Additional topographically organized projections to LPF areas originated from the nucleus pulvinaris medialis and projections from the nucleus anterior medialis selectively targeted more rostral sectors of LPF. Thus, the present data suggest that the topography of the MD-LPF projections does not adhere to simple topological rules, but is mainly organized according to functional criteria.
PubMed: 37908780
DOI: 10.3389/fnint.2023.1239426 -
Journal of Neurosurgery Mar 2024Anatomical triangles provide neurosurgeons with the specificity required to access deep targets, supplementing more general instructions, such as craniotomy and...
OBJECTIVE
Anatomical triangles provide neurosurgeons with the specificity required to access deep targets, supplementing more general instructions, such as craniotomy and approach. The infragalenic triangle (IGT), bordered by the basal vein of Rosenthal (BVR), precentral cerebellar vein (PCV), and the quadrangular lobule of the cerebellum, is one of a system of anatomical triangles recently introduced to guide dissection to brainstem cavernous malformations and has not been described in detail. This study aimed to quantitatively analyze the anatomical parameters of the IGT and present key nuances for its microsurgical use.
METHODS
A midline supracerebellar infratentorial (SCIT) approach through a torcular craniotomy was performed on 5 cadaveric heads, and the IGT was identified in each specimen bilaterally. Anatomical measurements were obtained with point coordinates collected using neuronavigation. Three cadaveric brains were used to illustrate relevant brainstem anatomy, and 3D virtual modeling was used to simulate various perspectives of the IGT through different approach angles. In addition, 2 illustrative surgical cases are presented.
RESULTS
The longest edge of the IGT was the lateral edge formed by the BVR (mean ± SD length 19.1 ± 2.3 mm), and the shortest edge was the medial edge formed by the PCV (13.9 ± 3.6 mm). The mean surface area of the IGT was 110 ± 34.2 mm2 in the standard exposure. Full expansion of all 3 edges (arachnoid dissection, mobilization, and retraction) resulted in a mean area of 226.0 ± 48.8 mm2 and a 2.5-times increase in surface area exposure of deep structures (e.g., brainstem and thalamus). Thus, almost the entire tectal plate and its relevant safe entry zones can be exposed through an expanded unilateral IGT except for the contralateral inferior colliculus, access to which is usually hindered by PCV tributaries. Exposure of bilateral IGTs may be required to resect larger midline lesions to increase surgical maneuverability or to access the contralateral pulvinar.
CONCLUSIONS
The IGT provides a safe access route to the dorsal midbrain and reliable intraoperative guidance in the deep and complex anatomy of the posterior tentorial incisura. Its potential for expansion makes it a versatile anatomical corridor not only for intrinsic brainstem lesions but also for tumors and vascular malformations of the pineal region, dorsal midbrain, and posteromedial thalamus.
Topics: Humans; Neurosurgical Procedures; Craniotomy; Mesencephalon; Pineal Gland; Cadaver
PubMed: 37878005
DOI: 10.3171/2023.6.JNS222871