Human subcortical pathways automatically detect collision trajectory without attention and awareness.

Detecting imminent collisions is essential for survival. Here, we used high-resolution fMRI at 7 Tesla to investigate the role of attention and consciousness for detecting collision trajectory in human subcortical pathways. Healthy participants can precisely discriminate collision from near-miss trajectory of an approaching object, with pupil size change reflecting collision sensitivity. Subcortical pathways from the superior colliculus (SC) to the ventromedial pulvinar (vmPul) and ventral tegmental area (VTA) exhibited collision-sensitive responses even when participants were not paying attention to the looming stimuli. For hemianopic patients with unilateral lesions of the geniculostriate pathway, the ipsilesional SC and VTA showed significant activation to collision stimuli in their scotoma. Furthermore, stronger SC responses predicted better behavioral performance in collision detection even in the absence of awareness. Therefore, human tectofugal pathways could automatically detect collision trajectories without the observers' attention to and awareness of looming stimuli, supporting "blindsight" detection of impending visual threats.

Functional connectivity between medial pulvinar and cortical networks as a predictor of arousal to noxious stimuli during sleep.

The interruption of sleep by a nociceptive stimulus is favoured by an increase in the pre-stimulus functional connectivity between sensory and higher level cortical areas. In addition, stimuli inducing arousal also trigger a widespread electroencephalographic (EEG) response reflecting the coordinated activation of a large cortical network. Because functional connectivity between distant cortical areas is thought to be underpinned by trans-thalamic connections involving associative thalamic nuclei, we investigated the possible involvement of one principal associative thalamic nucleus, the medial pulvinar (PuM), in the sleeper's responsiveness to nociceptive stimuli. Intra-cortical and intra-thalamic signals were analysed in 440 intracranial electroencephalographic (iEEG) segments during nocturnal sleep in eight epileptic patients receiving laser nociceptive stimuli. The spectral coherence between the PuM and 10 cortical regions grouped in networks was computed during 5 s before and 1 s after the nociceptive stimulus and contrasted according to the presence or absence of an arousal EEG response. Pre- and post-stimulus phase coherence between the PuM and all cortical networks was significantly increased in instances of arousal, both during N2 and paradoxical (rapid eye movement [REM]) sleep. Thalamo-cortical enhancement in coherence involved both sensory and higher level cortical networks and predominated in the pre-stimulus period. The association between pre-stimulus widespread increase in thalamo-cortical coherence and subsequent arousal suggests that the probability of sleep interruption by a noxious stimulus increases when it occurs during phases of enhanced trans-thalamic transfer of information between cortical areas.

The postnatal development of retinal projections in strepsirrhine galagos (Otolemur garnettii).

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.

The pulvinar as a hub of visual processing and cortical integration.

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.

Stimulation of the pulvinar nucleus of the thalamus in epilepsy: A systematic review and individual patient data (IPD) analysis.

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.

LSD-induced changes in the functional connectivity of distinct thalamic nuclei.

The role of the thalamus in mediating the effects of lysergic acid diethylamide (LSD) was recently proposed in a model of communication and corroborated by imaging studies. However, a detailed analysis of LSD effects on nuclei-resolved thalamocortical connectivity is still missing. Here, in a group of healthy volunteers, we evaluated whether LSD intake alters the thalamocortical coupling in a nucleus-specific manner. Structural and resting-state functional Magnetic Resonance Imaging (MRI) data were acquired in a placebo-controlled study on subjects exposed to acute LSD administration. Structural MRI was used to parcel the thalamus into its constituent nuclei based on individual anatomy. Nucleus-specific changes of resting-state functional MRI (rs-fMRI) connectivity were mapped using a seed-based approach. LSD intake selectively increased the thalamocortical functional connectivity (FC) of the ventral complex, pulvinar, and non-specific nuclei. Functional coupling was increased between these nuclei and sensory cortices that include the somatosensory and auditory networks. The ventral and pulvinar nuclei also exhibited increased FC with parts of the associative cortex that are dense in serotonin type 2A receptors. These areas are hyperactive and hyper-connected upon LSD intake. At subcortical levels, LSD increased the functional coupling among the thalamus's ventral, pulvinar, and non-specific nuclei, but decreased the striatal-thalamic connectivity. These findings unravel some LSD effects on the modulation of subcortical-cortical circuits and associated behavioral outputs.

[Simultanagnosia caused by cerebral infarction in the right temporal stem, right lateral thalamus, and right pulvinar regions].

A 76-year-old male patient was admitted to our hospital for the treatment of acute cerebral infarction in the right temporal stem, right lateral thalamus, and right pulvinar regions. Although his overall cognitive function was almost normal, he exhibited reduced visual sensitivity in the homonymous lower left quadrant of the visual field, left unilateral spatial neglect (USN), and simultanagnosia. Left USN improved 4 months after the onset of infarction; however, simultanagnosia persisted. To the best of our knowledge, this is the first case of simultanagnosia caused by cerebral infarction in the right temporal stem, right lateral thalamus, and right pulvinar regions.

Pulvinar quantitative susceptibility mapping predicts visual hallucinations post-deep brain stimulation in Parkinson's disease.

PURPOSE: We have reported the relationship between low pulvinar nuclei (PN) intensity in susceptibility-weighted imaging and the appearance of visual hallucinations and cognitive function. The aim of the study was to examine the changes in the quantitative susceptibility mapping (QSM) in patients with Parkinson's disease (PD) who underwent deep brain stimulation (DBS) and verify whether the PN susceptibility value (SV) on QSM can predict visual hallucination and cognitive changes after DBS. METHODS: This study examined 24 patients with PD who underwent DBS along with QSM imaging on magnetic resonance imaging (MRI). All MRIs were performed within 3 months before surgery. The PN SV was further assessed based on the QSM. Then, associations were examined among cognitive changes, hallucination, and PN SV. The cognitive function of the patient was compared immediately before surgery and at 1 year postoperatively. RESULTS: Visual hallucinations were observed in seven patients during the follow-up period. The PN SV was ≥0.045 ppm in nine patients with PD, and six of them had visual hallucinations, whereas only one of 15 patients with PD with SV of <0.045 ppm had visual hallucinations (Fisher's exact test, p = .0037). CONCLUSIONS: The SV of >0.045 ppm at the PN in QSM in patients with PD may provide useful information suggesting visual hallucination and cognitive deterioration after DBS treatment.

Role of endoscopic third ventriculostomy in patients undergoing resection of pulvinar area lesions: Preliminary clinical results.

BACKGROUND: Patients with pulvinar area lesions may develop hydrocephalus at any stage. The role of endoscopic third ventriculostomy (ETV) in this setting remains unclear. METHOD: We retrospectively enrolled 15 patients with a mean age of 43 years who underwent endoscopic resection of pulvinar area lesions using the supracerebellar infratentorial approach (SCITA). We compared the different modalities of hydrocephalus management and their outcomes. RESULTS: Nine of 15 patients (60.0%) had preoperative obstructive hydrocephalus. Five patients underwent ETV before tumor resection, and none developed postoperative hydrocephalus. Four patients underwent one-stage surgery for tumor removal, and one patient with a polymorphous low-grade neuroepithelial tumor of the young required postoperative ETV. Another patient with diffuse astrocytoma and hydrocephalus underwent concurrent lamina terminalis fenestration and endoscopic resection via the SCITA, which resulted in the resolution of hydrocephalus. The preoperative ETV group had no major postoperative complications, while the non-ETV group had three (0/5 vs. 3/4, P = 0.048). The ETV group also had a shorter intensive care unit stay; however, the difference was not significant (1.2 vs. 2.8; P = 0.188). ETV was effective in alleviating symptoms of postoperative hydrocephalus in patients with midbrain-invading tumors. CONCLUSION: Endoscopic surgery via the SCITA can address both tumor and hydrocephalus issues in some cases but has a higher surgical risk and postoperative hydrocephalus rate. Preoperative ETV can prevent these complications and improve postoperative outcomes.

Visual, delay, and oculomotor timing and tuning in macaque dorsal pulvinar during instructed and free choice memory saccades.

Causal perturbations suggest that primate dorsal pulvinar plays a crucial role in target selection and saccade planning, though its basic neuronal properties remain unclear. Some functional aspects of dorsal pulvinar and interconnected frontoparietal areas-e.g. ipsilesional choice bias after inactivation-are similar. But it is unknown if dorsal pulvinar shares oculomotor properties of cortical circuitry, in particular delay and choice-related activity. We investigated such properties in macaque dorsal pulvinar during instructed and free-choice memory saccades. Most recorded units showed visual (12%), saccade-related (30%), or both types of responses (22%). Visual responses were primarily contralateral; diverse saccade-related responses were predominantly post-saccadic with a weak contralateral bias. Memory delay and pre-saccadic enhancement was infrequent (11-9%)-instead, activity was often suppressed during saccade planning (25%) and further during execution (15%). Surprisingly, only few units exhibited classical visuomotor patterns combining cue and continuous delay activity or pre-saccadic ramping; moreover, most spatially-selective neurons did not encode the upcoming decision during free-choice delay. Thus, in absence of a visible goal, the dorsal pulvinar has a limited role in prospective saccade planning, with patterns partially complementing its frontoparietal partners. Conversely, prevalent visual and post-saccadic responses imply its participation in integrating spatial goals with processing across saccades.

Predictive role of pulvinar in social functional outcome of schizophrenia.

Identifying objective biological subtypes that predict long-term functional outcomes is crucial for understanding neurobiological mechanisms and identifying potential targets. Using resting-state functional magnetic resonance imaging data from 178 patients and 70 controls, we explored social function patterns using latent profile analysis. Long-term outcomes were compared among the biological subtypes using K-means clustering. Partial least squares regression (PLSR) was used to identify gene expression profiles associated with alterations in activity by leveraging transcriptional data from the Allen Human Brain Atlas. In patients with more functional impairment, left medial pulvinar (PM) exhibited significantly lower regional homogeneity of brain activity (ReHo, [95% CI (0.06-0.27), P = 0.002), a finding validated in the independent cohort. Functional connectivity between PM and secondary visual cortex displayed a suggestive decrease. Patients belonging to "higher pulvinar ReHo - better information processing" demonstrated better long-term outcomes and acute treatment response [95% CI (11.2-34.4), P < 0.001]. The PLSR component of imaging-transcriptomic associations partly explained the ReHo differences among patients with varying levels of functional impairment. It revealed enrichment of genes in the synaptic signaling pathway. Pathological changes in the pulvinar may affect social functioning. Higher pulvinar ReHo and better information processing, two objective biomarkers, have a predictive value for better long-term functional outcomes.

Context-dependent attentional spotlight in pulvinar-V1 interaction.

Spatial attention is often described as a mental spotlight that enhances information processing at the attended location. Using fMRI, we investigated background connectivity between the pulvinar and V1 in relation to focused versus diffused attention allocation, in weak and strong crowding contexts. Our findings revealed that focused attention led to enhanced correlations between the pulvinar and V1. Notably, this modulation was initiated by the pulvinar, and the strength of the modulation was dependent on the saliency of the target. These findings suggest that the pulvinar initiates information reweighting to V1, which underlies attentional selection in cluttered scenes.

The Collicular-Pulvinar-Amygdala Axis and Adult-Onset Idiopathic Focal Dystonias.

Adult-onset idiopathic focal dystonias (AOIFD) are the most common type of dystonia. It has varied expression including multiple motor (depending on body part affected) and non-motor symptoms (psychiatric, cognitive and sensory). The motor symptoms are usually the main reason for presentation and are most often treated with botulinum toxin. However, non-motor symptoms are the main predictors of quality of life and should be addressed appropriately, as well as treating the motor disorder. Rather than considering AOIFD as a movement disorder, a syndromic approach should be taken, one that accommodates all the symptoms. Dysfunction of the collicular-pulvinar-amygdala axis, with the superior colliculus as a central node, can explain the diverse expression of this syndrome.

A genetically defined tecto-thalamic pathway drives a system of superior-colliculus-dependent visual cortices.

Cortical responses to visual stimuli are believed to rely on the geniculo-striate pathway. However, recent work has challenged this notion by showing that responses in the postrhinal cortex (POR), a visual cortical area, instead depend on the tecto-thalamic pathway, which conveys visual information to the cortex via the superior colliculus (SC). Does POR's SC-dependence point to a wider system of tecto-thalamic cortical visual areas? What information might this system extract from the visual world? We discovered multiple mouse cortical areas whose visual responses rely on SC, with the most lateral showing the strongest SC-dependence. This system is driven by a genetically defined cell type that connects the SC to the pulvinar thalamic nucleus. Finally, we show that SC-dependent cortices distinguish self-generated from externally generated visual motion. Hence, lateral visual areas comprise a system that relies on the tecto-thalamic pathway and contributes to processing visual motion as animals move through the environment.

Pulvinar neuromodulation for seizure monitoring and network modulation in temporal plus epilepsy.

Deep brain stimulation (DBS) is a promising treatment for drug-refractory epilepsies (DRE) when targeting the anterior nuclei of thalamus (ANT). However, targeting other thalamic nuclei, such as the pulvinar, shows therapeutic promise. Our pioneering case study presents the application of ambulatory seizure monitoring using spectral fingerprinting (12.15-17.15 Hz) recorded through Medtronic Percept DBS implanted bilaterally in the medial pulvinar thalami. This technology offers unprecedented opportunities for real-time monitoring of seizure burden and thalamocortical network modulation for effective seizure reduction in patients with bilateral mesial temporal and temporal plus epilepsies that are not suitable for resection.

The anterior and pulvinar thalamic nuclei interactions in mesial temporal lobe seizure networks.

OBJECTIVE: To evaluate the respective roles of the anterior thalamic nucleus (ANT) and the medial pulvinar (PuM) during mesial temporal lobe seizures recorded by stereoelectroencephalography (SEEG). METHODS: We assessed functional connectivity (FC) in 15 SEEG recorded seizures from 6 patients using a non-linear correlation method. Functional interactions were explored between the mesial temporal region, the temporal neocortex, ANT and PuM. The node total-strength (the summed connectivity of the node with all other nodes) as well as the directionality of the links (IN and OUT strengths) were calculated to estimate drivers and receivers during the cortico-thalamic interactions. RESULTS: Significant increased thalamo-cortical FC during seizures was observed, with the node total-strength reaching a maximum at seizure end. There was no significant difference in global connectivity values between ANT and PuM. Regarding directionality, significantly higher thalamic IN strength values were observed. However, compared to ANT, PuM appeared to be the driver at the end of seizures with synchronous termination. CONCLUSIONS: This work demonstrates that during temporal seizures, both thalamic nuclei are highly connected with the mesial temporal region and that PuM could play a role in seizure termination. SIGNIFICANCE: Understanding functional connectivity between the mesial temporal and thalamic nuclei could contribute to the development of target-specific deep brain stimulation strategies for drug-resistant epilepsy.

Alterations of the thalamic nuclei volumes and intrinsic thalamic network in patients with restless legs syndrome.

We aimed to investigate the alterations of thalamic nuclei volumes and intrinsic thalamic network in patients with primary restless legs syndrome (RLS) compared to healthy controls. Seventy-one patients with primary RLS and 55 healthy controls were recruited. They underwent brain MRI using a three-tesla MRI scanner, including three-dimensional T1-weighted images. The intrinsic thalamic network was determined using graph theoretical analysis. The right and left whole thalamic volumes, and the right pulvinar inferior, left ventral posterolateral, left medial ventral, and left pulvinar inferior nuclei volumes in the patients with RLS were lower than those in healthy controls (0.433 vs. 0.447%, p = 0.034; 0.482 vs. 0.502%, p = 0.016; 0.013 vs. 0.015%, p = 0.031; 0.062 vs. 0.065%, p = 0.035; 0.001 vs. 0.001%, p = 0.034; 0.018 vs. 0.020%, p = 0.043; respectively). There was also a difference in the intrinsic thalamic network between the groups. The assortative coefficient in patients with RLS was higher than that in healthy controls (0.0318 vs. - 0.0358, p = 0.048). We demonstrated the alterations of thalamic nuclei volumes and intrinsic thalamic network in patients with RLS compared to healthy controls. These changes might be related to RLS pathophysiology and suggest the pivotal role of the thalamus in RLS symptoms.

Functional topography of pulvinar-visual cortex networks in macaques revealed by INS-fMRI.

The pulvinar in the macaque monkey contains three divisions: the medial pulvinar (PM), the lateral pulvinar (PL), and the inferior pulvinar (PI). Anatomical studies have shown that connections of PM are preferentially distributed to higher association areas, those of PL are biased toward the ventral visual pathway, and those of PI are biased with the dorsal visual pathway. To study functional connections of the pulvinar at mesoscale, we used a novel method called INS-fMRI (infrared neural stimulation and functional magnetic resonance imaging). This method permits studies and comparisons of multiple pulvinar networks within single animals. As previously revealed, stimulations of different sites in PL and PI produced topographically organized focal activations in visual areas V1, V2, and V3. In contrast, PM stimulation elicited little or diffuse response. The relative activations of areas V1, V2, V3A, V3d, V3v, V4, MT, and MST revealed that connections of PL are biased to ventral pathway areas, and those of PI are biased to dorsal areas. Different statistical values of activated blood-oxygen-level-dependent responses produced the same center of activation, indicating stability of connectivity; it also suggests possible dynamics of broad to focal responses from single stimulation sites. These results demonstrate that infrared neural stimulation-induced connectivity is largely consistent with previous anatomical connectivity studies, thereby demonstrating validity of our novel method. In addition, it suggests additional interpretations of functional connectivity to complement anatomical studies.