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The Journal of Comparative Neurology Jan 2021The extrageniculate visual pathway, which carries visual information from the retina through the superficial layers of the superior colliculus and the pulvinar, is...
The extrageniculate visual pathway, which carries visual information from the retina through the superficial layers of the superior colliculus and the pulvinar, is poorly understood. The pulvinar is thought to modulate information flow between cortical areas, and has been implicated in cognitive tasks like directing visually guided actions. In order to better understand the underlying circuitry, we performed retrograde injections of modified rabies virus in the visual cortex and pulvinar of the Long-Evans rat. We found a relatively small population of cells projecting to primary visual cortex (V1), compared to a much larger population projecting to higher visual cortex. Reciprocal corticothalamic projections showed a similar result, implying that pulvinar does not play as big a role in directly modulating rodent V1 activity as previously thought.
Topics: Animals; Female; Primary Visual Cortex; Pulvinar; Rats; Rats, Long-Evans; Visual Cortex; Visual Pathways
PubMed: 32361987
DOI: 10.1002/cne.24937 -
Cognitive, Affective & Behavioral... Jun 2018In the past decade, more and more research has been investigating oculomotor behavior in relation to attentional selection of emotional stimuli. Whereas previous... (Review)
Review
In the past decade, more and more research has been investigating oculomotor behavior in relation to attentional selection of emotional stimuli. Whereas previous research on covert emotional attention demonstrates contradictory results, research on overt attention clearly shows the influence of emotional stimuli on attentional selection. The current review highlights studies that have used eye-movement behavior as the primary outcome measure in healthy populations and focusses on the evidence that emotional stimuli-in particular, threatening stimuli-affect temporal and spatial dynamics of oculomotor programming. The most prominent results from these studies indicate that attentional selection of threatening stimuli is under bottom-up control. Moreover, threatening stimuli seem to have the greatest impact on oculomotor behavior through biased processing via the magnocellular pathway. This is consistent with an evolutionary account of threat processing, which claims a pivotal role for a subcortical network including pulvinar, superior colliculus, and amygdala. Additionally, I suggest a neurobiological model that considers possible mechanisms by which emotional stimuli could affect oculomotor behavior. The present review confirms the relevance of eye-movement measurements in relation to researching emotion in order to elucidate processes involved in emotional modulation of visual and attentional selection.
Topics: Amygdala; Attention; Emotions; Eye Movement Measurements; Eye Movements; Humans; Reaction Time
PubMed: 29633198
DOI: 10.3758/s13415-018-0590-8 -
ELife Apr 2022While there is evidence that the visual cortex retains a potential for plasticity in adulthood, less is known about the subcortical stages of visual processing. Here, we...
While there is evidence that the visual cortex retains a potential for plasticity in adulthood, less is known about the subcortical stages of visual processing. Here, we asked whether short-term ocular dominance plasticity affects the human visual thalamus. We addressed this question in normally sighted adult humans, using ultra-high field (7T) magnetic resonance imaging combined with the paradigm of short-term monocular deprivation. With this approach, we previously demonstrated transient shifts of perceptual eye dominance and ocular dominance in visual cortex (Binda et al., 2018). Here, we report evidence for short-term plasticity in the ventral division of the pulvinar (vPulv), where the deprived eye representation was enhanced over the nondeprived eye. This vPulv plasticity was similar as previously seen in visual cortex and it was correlated with the ocular dominance shift measured behaviorally. In contrast, there was no effect of monocular deprivation in two adjacent thalamic regions: dorsal pulvinar and Lateral Geniculate Nucleus. We conclude that the visual thalamus retains potential for short-term plasticity in adulthood; the plasticity effect differs across thalamic subregions, possibly reflecting differences in their corticofugal connectivity.
Topics: Adult; Dominance, Ocular; Geniculate Bodies; Humans; Neuronal Plasticity; Sensory Deprivation; Thalamus; Vision, Monocular; Visual Cortex
PubMed: 35384840
DOI: 10.7554/eLife.74565 -
Neuroscience and Biobehavioral Reviews Apr 2020Selective attention is a fundamental cognitive function that guides behavior by selecting and prioritizing salient or relevant sensory information of our environment.... (Review)
Review
Selective attention is a fundamental cognitive function that guides behavior by selecting and prioritizing salient or relevant sensory information of our environment. Despite early evidence and theoretical proposal pointing to an implication of thalamic control in attention, most studies in the past two decades focused on cortical substrates, largely ignoring the contribution of subcortical regions as well as cortico-subcortical interactions. Here, we suggest a key role of the pulvinar in the selection of salient and relevant information via its involvement in priority maps. Prioritization may be achieved through a pulvinar-mediated generation of alpha oscillations, which may then modulate neuronal gain in thalamo-cortical circuits. Such mechanism might orchestrate the synchrony of cortico-cortical interaction, by rendering neural communication more effective, precise and selective. We propose that this theoretical framework will support a timely shift from the prevailing cortico-centric view of cognition to a more integrative perspective of thalamic contributions to attention and executive control processes.
Topics: Alpha Rhythm; Attention; Cerebral Cortex; Executive Function; Humans; Nerve Net; Pulvinar
PubMed: 31972202
DOI: 10.1016/j.neubiorev.2020.01.005 -
Japanese Journal of Radiology Apr 2016Various metals are essential nutrients in humans, and metal shortages lead to a variety of deficiency diseases. Metal concentration abnormalities may cause metal... (Review)
Review
Various metals are essential nutrients in humans, and metal shortages lead to a variety of deficiency diseases. Metal concentration abnormalities may cause metal deposition in the brain, and magnetic resonance imaging (MRI) is the most potent and sensitive technique now available for detecting metal deposition given the difficulties associated with performing brain tissue biopsy. However, the brain contains many kinds of metals that affect the signal intensity of MRI, which has led to numerous misunderstandings in the history of metal analysis. We reviewed the history of brain metal analysis with histologic findings. Typically, manganese overload causes high signal intensity on T1-weighted images (T1WI) in the globus pallidus, iron overload causes low signal intensity in the globus pallidus on T2-weighted images, and gadolinium deposition causes high signal intensity in the dentate nucleus, globus pallidus, and pulvinar of thalamus on T1WI. However, because nonparamagnetic materials and other coexisting metals also affect the signal intensity of brain MRI, the quantitative analysis of metal concentrations is difficult. Thus, when analyzing metal deposition using MRI, caution should be exercised when interpreting the validity and reliability of the obtained data.
Topics: Brain; Brain Mapping; Contrast Media; Gadolinium; Humans; Image Enhancement; Magnetic Resonance Imaging; Metals; Reproducibility of Results
PubMed: 26932404
DOI: 10.1007/s11604-016-0532-8 -
Neuron Jan 2016The ventro-lateral pulvinar is reciprocally connected with the visual areas of the ventral stream that are important for object recognition. To understand the mechanisms...
The ventro-lateral pulvinar is reciprocally connected with the visual areas of the ventral stream that are important for object recognition. To understand the mechanisms of attentive stimulus processing in this pulvinar-cortex loop, we investigated the interactions between the pulvinar, area V4, and IT cortex in a spatial-attention task. Sensory processing and the influence of attention in the pulvinar appeared to reflect its cortical inputs. However, pulvinar deactivation led to a reduction of attentional effects on firing rates and gamma synchrony in V4, a reduction of sensory-evoked responses and overall gamma coherence within V4, and severe behavioral deficits in the affected portion of the visual field. Conversely, pulvinar deactivation caused an increase in low-frequency cortical oscillations, often associated with inattention or sleep. Thus, cortical interactions with the ventro-lateral pulvinar are necessary for normal attention and sensory processing and for maintaining the cortex in an active state.
Topics: Animals; Attention; Macaca mulatta; Male; Photic Stimulation; Pulvinar; Thalamus; Vision, Ocular; Visual Cortex; Visual Fields; Visual Pathways
PubMed: 26748092
DOI: 10.1016/j.neuron.2015.11.034 -
Visual Neuroscience Jan 2017Comparative studies have greatly contributed to our understanding of the organization and function of visual pathways of the brain, including that of humans. This... (Review)
Review
Comparative studies have greatly contributed to our understanding of the organization and function of visual pathways of the brain, including that of humans. This comparative approach is a particularly useful tactic for studying the pulvinar nucleus, an enigmatic structure which comprises the largest territory of the human thalamus. This review focuses on the regions of the mouse pulvinar that receive input from the superior colliculus, and highlights similarities of the tectorecipient pulvinar identified across species. Open questions are discussed, as well as the potential contributions of the mouse model for endeavors to elucidate the function of the pulvinar nucleus.
Topics: Animals; Lateral Thalamic Nuclei; Mice; Pulvinar; Superior Colliculi; Visual Pathways
PubMed: 28965504
DOI: 10.1017/S0952523817000050 -
Epilepsy & Behavior : E&B Feb 2021While temporal lobe epilepsy (TLE) is a focal epilepsy, previous work demonstrates that TLE causes widespread brain-network disruptions. Impaired visuospatial attention...
While temporal lobe epilepsy (TLE) is a focal epilepsy, previous work demonstrates that TLE causes widespread brain-network disruptions. Impaired visuospatial attention and learning in TLE may be related to thalamic arousal nuclei connectivity. Our prior preliminary work in a smaller patient cohort suggests that patients with TLE demonstrate abnormal functional connectivity between central lateral (CL) thalamic nucleus and medial occipital lobe. Others have shown pulvinar connectivity disturbances in TLE, but it is incompletely understood how TLE affects pulvinar subnuclei. Also, the effects of epilepsy surgery on thalamic functional connectivity remains poorly understood. In this study, we examine the effects of TLE on functional connectivity of two key thalamic arousal-nuclei: lateral pulvinar (PuL) and CL. We evaluate resting-state functional connectivity of the PuL and CL in 40 patients with TLE and 40 controls using fMRI. In 25 patients, postoperative images (>1 year) were also compared with preoperative images. Compared to controls, patients with TLE exhibit loss of normal positive connectivity between PuL and lateral occipital lobe (p < 0.05), and a loss of normal negative connectivity between CL and medial occipital lobe (p < 0.01, paired t-tests). FMRI amplitude of low-frequency fluctuation (ALFF) in TLE trended higher in ipsilateral PuL (p = 0.06), but was lower in the lateral occipital (p < 0.01) and medial occipital lobe in patients versus controls (p < 0.05, paired t-tests). More abnormal ALFF in the ipsilateral lateral occipital lobe is associated with worse preoperative performance on Rey Complex Figure Test Immediate (p < 0.05, r = 0.381) and Delayed scores (p < 0.05, r = 0.413, Pearson's Correlations). After surgery, connectivity between PuL and lateral occipital lobe remains abnormal in patients (p < 0.01), but connectivity between CL and medial occipital lobe improves and is no longer different from control values (p > 0.05, ANOVA, post hoc Fischer's LSD). In conclusion, thalamic arousal nuclei exhibit abnormal connectivity with occipital lobe in TLE, and some connections may improve after surgery. Studying thalamic arousal centers may help explain distal network disturbances in TLE.
Topics: Arousal; Brain; Epilepsy, Temporal Lobe; Humans; Magnetic Resonance Imaging; Thalamus
PubMed: 33334720
DOI: 10.1016/j.yebeh.2020.107645 -
NeuroImage Oct 2021The thalamic pulvinar and the lateral intraparietal area (LIP) share reciprocal anatomical connections and are part of an extensive cortical and subcortical network...
The thalamic pulvinar and the lateral intraparietal area (LIP) share reciprocal anatomical connections and are part of an extensive cortical and subcortical network involved in spatial attention and oculomotor processing. The goal of this study was to compare the effective connectivity of dorsal pulvinar (dPul) and LIP and to probe the dependency of microstimulation effects on task demands and spatial tuning properties of a given brain region. To this end, we applied unilateral electrical microstimulation in the dPul (mainly medial pulvinar) and LIP in combination with event-related BOLD fMRI in monkeys performing fixation and memory-guided saccade tasks. Microstimulation in both dPul and LIP enhanced task-related activity in monosynaptically-connected fronto-parietal cortex and along the superior temporal sulcus (STS) including putative face patch locations, as well as in extrastriate cortex. LIP microstimulation elicited strong activity in the opposite homotopic LIP while no homotopic activation was found with dPul stimulation. Both dPul and LIP stimulation also elicited activity in several heterotopic cortical areas in the opposite hemisphere, implying polysynaptic propagation of excitation. Despite extensive activation along the intraparietal sulcus evoked by LIP stimulation, there was a difference in frontal and occipital connectivity elicited by posterior and anterior LIP stimulation sites. Comparison of dPul stimulation with the adjacent but functionally dissimilar ventral pulvinar also showed distinct connectivity. On the level of single trial timecourses within each region of interest (ROI), most ROIs did not show task-dependence of stimulation-elicited response modulation. Across ROIs, however, there was an interaction between task and stimulation, and task-specific correlations between the initial spatial selectivity and the magnitude of stimulation effect were observed. Consequently, stimulation-elicited modulation of task-related activity was best fitted by an additive model scaled down by the initial response amplitude. In summary, we identified overlapping and distinct patterns of thalamocortical and corticocortical connectivity of pulvinar and LIP, highlighting the dorsal bank and fundus of STS as a prominent node of shared circuitry. Spatial task-specific and partly polysynaptic modulations of cue and saccade planning delay period activity in both hemispheres exerted by unilateral pulvinar and parietal stimulation provide insight into the distributed interhemispheric processing underlying spatial behavior.
Topics: Animals; Electric Stimulation; Macaca mulatta; Magnetic Resonance Imaging; Male; Microelectrodes; Nerve Net; Parietal Lobe; Pulvinar; Saccades; Spatial Behavior
PubMed: 34147628
DOI: 10.1016/j.neuroimage.2021.118283 -
The Journal of Comparative Neurology Dec 2021The pulvinar is the largest nucleus in the primate thalamus and has topographically organized connections with multiple cortical areas, thereby forming extensive...
The pulvinar is the largest nucleus in the primate thalamus and has topographically organized connections with multiple cortical areas, thereby forming extensive cortico-pulvino-cortical input-output loops. Neurophysiological studies have suggested a role for these transthalamic pathways in regulating information transmission between cortical areas. However, evidence for a causal role of the pulvinar in regulating cortico-cortical interactions is sparse and it is not known whether pulvinar's influences on cortical networks are task-dependent or, alternatively, reflect more basic large-scale network properties that maintain functional connectivity across networks regardless of active task demands. In the current study, under passive viewing conditions, we conducted simultaneous electrophysiological recordings from ventral (area V4) and dorsal (lateral intraparietal area [LIP]) nodes of macaque visual system, while reversibly inactivating the dorsal part of the lateral pulvinar (dPL), which shares common anatomical connectivity with V4 and LIP, to probe a causal role of the pulvinar. Our results show a significant reduction in local field potential phase coherence between LIP and V4 in low frequencies (4-15 Hz) following muscimol injection into dPL. At the local level, no significant changes in firing rates or LFP power were observed in LIP or in V4 following dPL inactivation. Synchronization between pulvinar spikes and cortical LFP phase decreased in low frequencies (4-15 Hz) both in LIP and V4, while the low frequency synchronization between LIP spikes and pulvinar phase increased. These results indicate a causal role for pulvinar in synchronizing neural activity between interconnected cortical nodes of a large-scale network, even in the absence of an active task state.
Topics: Animals; Electrophysiology; Macaca; Muscimol; Pulvinar; Visual Cortex; Visual Pathways
PubMed: 34013540
DOI: 10.1002/cne.25193