-
The Journal of Comparative Neurology Dec 2023In this study, thalamic connections of the caudal part of the posterior parietal cortex (PPCc) are described and compared to connections of the rostral part of PPC...
In this study, thalamic connections of the caudal part of the posterior parietal cortex (PPCc) are described and compared to connections of the rostral part of PPC (PPCr) in strepsirrhine galagos. PPC of galagos is divided into two parts, PPCr and PPCc, based on the responsiveness to electrical stimulation. Stimulation of PPC with long trains of electrical pulses evokes different types of ethologically relevant movements from different subregions ("domains") of PPCr, while it fails to evoke any movements from PPCc. Anatomical tracers were placed in both dorsal and ventral divisions of PPCc to reveal thalamic origins and targets of PPCc connections. We found major thalamic connections of PPCc with the lateral posterior and lateral pulvinar nuclei, distinct from those of PPCr that were mainly with the ventral lateral, anterior pulvinar, and posterior nuclei. The anterior, medial, and inferior pulvinar, ventral anterior, ventral lateral, and intralaminar nuclei had fewer connections with PPCc. Dominant connections of PPCc with lateral posterior and lateral pulvinar nuclei provide evidence that unlike the sensorimotor-orientated PPCr, PPCc is more involved in visual-related functions.
Topics: Animals; Galago; Neural Pathways; Parietal Lobe; Thalamus; Movement; Thalamic Nuclei
PubMed: 37702312
DOI: 10.1002/cne.25537 -
Journal of Neurology Jan 2024To investigate brain MRI abnormalities in a cohort of patients with rapidly progressive dementia (RPD) with and without a diagnosis of Creutzfeldt-Jakob disease (CJD).
OBJECTIVE
To investigate brain MRI abnormalities in a cohort of patients with rapidly progressive dementia (RPD) with and without a diagnosis of Creutzfeldt-Jakob disease (CJD).
METHODS
One hundred and seven patients with diagnosis of prion disease (60 with definite sCJD, 33 with probable sCJD and 14 with genetic prion disease) and 40 non-prion related RPD patients (npRPD) underwent brain MRI including DWI and FLAIR. MRIs were evaluated with a semiquantitative rating score, which separately considered abnormal signal extent and intensity in 22 brain regions. Clinical findings at onset, disease duration, cerebrospinal-fluid 14-3-3 and t-tau protein levels, and EEG data were recorded.
RESULTS
Among patients with definite/probable diagnosis of CJD or genetic prion disease, 2/107 had normal DWI-MRI: in one patient a 2-months follow-up DWI-MRI showed CJD-related changes while the other had autopsy-proven CJD despite no DWI abnormalities 282 days after clinical onset. CJD-related cortical changes were detected in all lobes and involvement of thalamus was common. In the npRPD groups, 6/40 patients showed DWI alterations that clustered in three different patterns: (1) minimal/doubtful signal alterations (limbic encephalitis, dementia with Lewy bodies); (2) clearly suggestive of alternative diagnoses (status epilepticus, Wernicke or metabolic encephalopathy); (3) highly suggestive of CJD (mitochondrial disease), though cortical swelling let exclude CJD.
CONCLUSIONS
In the diagnostic work-up of RPD, negative/doubtful DWI makes CJD diagnosis rather unlikely, while specific DWI patterns help differentiating CJD from alternative diagnoses. The pulvinar sign is not exclusive of the variant form.
Topics: Humans; Creutzfeldt-Jakob Syndrome; Magnetic Resonance Imaging; Brain; Prion Diseases; Thalamus
PubMed: 37698615
DOI: 10.1007/s00415-023-11962-1 -
Epilepsy Research Oct 2023The thalamus is a key structure that plays a crucial role in initiating and propagating seizures. Recent advancements in neuroimaging and neurophysiology have identified... (Review)
Review
The thalamus is a key structure that plays a crucial role in initiating and propagating seizures. Recent advancements in neuroimaging and neurophysiology have identified the thalamus as a promising target for neuromodulation in drug-resistant epilepsies. This review article presents the latest innovations in thalamic targets and neuromodulation paradigms being explored in pilot or pivotal clinical trials. Multifocal temporal plus or posterior quadrant epilepsies are evaluated with pulvinar thalamus neuromodulation, while centromedian thalamus is explored in generalized epilepsies and Lennox Gastaut syndrome. Multinodal thalamocortical neuromodulation with novel stimulation paradigms such as long bursting or low-frequency stimulation is being investigated to quench the epileptic network excitability. Beyond seizure control, thalamic neuromodulation to restore consciousness is being studied. This review highlights the promising potential of thalamic neuromodulation in epilepsy treatment, offering hope to patients who have not responded to conventional medical therapies. However, it also emphasizes the need for larger randomized controlled trials and personalized stimulation paradigms to improve patient outcomes further.
Topics: Humans; Thalamus; Epilepsy, Generalized; Seizures; Drug Resistant Epilepsy; Lennox Gastaut Syndrome
PubMed: 37660585
DOI: 10.1016/j.eplepsyres.2023.107219 -
NeuroImage Oct 2023Spatial attention is often described as a mental spotlight that enhances information processing at the attended location. Using fMRI, we investigated background...
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.
Topics: Humans; Pulvinar; Cognition; Diffusion
PubMed: 37619793
DOI: 10.1016/j.neuroimage.2023.120341 -
Human Brain Mapping Dec 2023Conscious visual motion information follows a cortical pathway from the retina to the lateral geniculate nucleus (LGN) and on to the primary visual cortex (V1) before...
Conscious visual motion information follows a cortical pathway from the retina to the lateral geniculate nucleus (LGN) and on to the primary visual cortex (V1) before arriving at the middle temporal visual area (MT/V5). Alternative subcortical pathways that bypass V1 are thought to convey unconscious visual information. One flows from the retina to the pulvinar (PUL) and on to medial temporal visual area (MT); while the other directly connects the LGN to MT. Evidence for these pathways comes from non-human primates and modest-sized studies in humans with brain lesions. Thus, the aim of the current study was to reconstruct these pathways in a large sample of neurotypical individuals and to determine the degree to which these pathways are myelinated, suggesting information flow is rapid. We used the publicly available 7T (N = 98; 'discovery') and 3T (N = 381; 'validation') diffusion magnetic resonance imaging datasets from the Human Connectome Project to reconstruct the PUL-MT (including all subcompartments of the PUL) and LGN-MT pathways. We found more fibre tracts with greater density in the left hemisphere. Although the left PUL-MT path was denser, the bilateral LGN-MT tracts were more heavily myelinated, suggesting faster signal transduction. We suggest that this apparent discrepancy may be due to 'adaptive myelination' caused by more frequent use of the LGN-MT pathway that leads to greater myelination and faster overall signal transmission.
Topics: Animals; Humans; Adult; Motion Perception; Visual Cortex; Magnetic Resonance Imaging; Vision, Ocular; Visual Perception; Geniculate Bodies; Connectome; Visual Pathways
PubMed: 37608684
DOI: 10.1002/hbm.26467 -
Psychiatry Research Sep 2023Identifying objective biological subtypes that predict long-term functional outcomes is crucial for understanding neurobiological mechanisms and identifying potential...
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.
Topics: Humans; Schizophrenia; Pulvinar; Brain; Cluster Analysis; Cognition
PubMed: 37598626
DOI: 10.1016/j.psychres.2023.115419 -
Journal of Neurosurgery Jan 2024Deep brain stimulation (DBS) is a rapidly growing surgical option for patients with drug-resistant epilepsy who are not candidates for resective/ablative surgery. Recent...
OBJECTIVE
Deep brain stimulation (DBS) is a rapidly growing surgical option for patients with drug-resistant epilepsy who are not candidates for resective/ablative surgery. Recent randomized controlled trials have demonstrated efficacy of DBS of the anterior nucleus of the thalamus (ANT), particularly in frontal or temporal epilepsy, whereas DBS of the centromedian (CM) nucleus appears to be most suitable in well-defined generalized epilepsy syndromes. At the authors' institution, DBS candidates who did not fit the populations represented in these trials were managed with DBS of multiple distinct targets, which included ANT, CM, and less-studied nuclei-i.e., mediodorsal nucleus, pulvinar, and subthalamic nucleus. The goal of this study was to present the authors' experience with these types of cases, and to motivate future investigations that can determine the long-term efficacy of multitarget DBS.
METHODS
This single-center retrospective study of adult patients with drug-resistant epilepsy who underwent multitarget DBS was performed to demonstrate the feasibility and safety of this approach, and to present seizure outcomes. Patients in this cohort had epilepsy with features that were difficult to treat with DBS of the ANT or CM nucleus alone, including multifocal/multilobar, diffuse-onset, and/or posterior-onset seizures; or both generalized and focal seizures.
RESULTS
Eight patients underwent DBS of 2-3 distinct thalamic/subthalamic nuclei. DBS was performed with 2 electrodes in each hemisphere. All leads in each patient were implanted with either frontal or parietal trajectories. There were no surgical complications. Among those with > 6 months of follow-up (n = 5; range 7-21 months), all patients were responders in terms of overall seizure frequency and/or convulsive seizure frequency (i.e., ≥ 50% reduction). Two patients had adverse stimulation effects, which resolved with further programming.
CONCLUSIONS
Multitarget DBS is a procedurally feasible and safe treatment strategy to maximize outcomes in patients with complex epilepsy. The authors highlight their approach to inform future studies that are sufficiently powered to assess its efficacy.
Topics: Adult; Humans; Deep Brain Stimulation; Retrospective Studies; Epilepsy; Drug Resistant Epilepsy; Seizures; Electrodes, Implanted
PubMed: 37486888
DOI: 10.3171/2023.5.JNS23982 -
Frontiers in Computational Neuroscience 2023Convolutional Neural Networks (CNN) are a class of machine learning models predominately used in computer vision tasks and can achieve human-like performance through... (Review)
Review
Convolutional Neural Networks (CNN) are a class of machine learning models predominately used in computer vision tasks and can achieve human-like performance through learning from experience. Their striking similarities to the structural and functional principles of the primate visual system allow for comparisons between these artificial networks and their biological counterparts, enabling exploration of how visual functions and neural representations may emerge in the real brain from a limited set of computational principles. After considering the basic features of CNNs, we discuss the opportunities and challenges of endorsing CNNs as models of the primate visual system. Specifically, we highlight several emerging notions about the anatomical and physiological properties of the visual system that still need to be systematically integrated into current CNN models. These tenets include the implementation of parallel processing pathways from the early stages of retinal input and the reconsideration of several assumptions concerning the serial progression of information flow. We suggest design choices and architectural constraints that could facilitate a closer alignment with biology provide causal evidence of the predictive link between the artificial and biological visual systems. Adopting this principled perspective could potentially lead to new research questions and applications of CNNs beyond modeling object recognition.
PubMed: 37485400
DOI: 10.3389/fncom.2023.1153572