scholarly journals Corticothalamic Projections Gate Alpha Rhythms in the Pulvinar

2021 ◽  
Author(s):  
Nelson Cortes ◽  
Reza Abbas Farishta ◽  
Hugo Ladret ◽  
Christian Casanova
Keyword(s):  
Cortical Area ◽  
Hierarchical Level ◽  
Oscillatory Activity ◽  
Excitatory Postsynaptic Potential ◽  
Area 17 ◽  
Cortical Areas ◽  
Area 21A ◽  
Spiking Activity

AbstractTwo types of corticothalamic (CT) terminals reach the pulvinar nucleus of the thalamus, and their distribution varies according to the hierarchical level of the cortical area they originate from. While type 2 terminals are more abundant at lower hierarchical levels, terminals from higher cortical areas mostly exhibit type 1 axons. Such terminals also evoke different excitatory postsynaptic potential dynamic profiles, presenting facilitation for type 1 and depression for type 2. As the pulvinar is involved in the oscillatory regulation between intercortical areas, fundamental questions about the role of these different terminal types in the neuronal communication throughout the cortical hierarchy are yielded. Our theoretical results support that the co-action of the two types of terminals produces different oscillatory rhythms in pulvinar neurons. More precisely, terminal types 1 and 2 produce alpha-band oscillations at a specific range of connectivity weights. Such oscillatory activity is generated by an unstable transition of the balanced state network’s properties that it is found between the quiescent state and the stable asynchronous spike response state. While CT projections from areas 17 and 21a are arranged in the model as the empirical proportion of terminals types 1 and 2, the actions of these two cortical connections are antagonistic. As area 17 generates low-band oscillatory activity, cortical area 21a shifts pulvinar responses to stable asynchronous spiking activity and vice-versa when area 17 produces an asynchronous state. To further investigate such oscillatory effects through corticothalamo-cortical projections, the transthalamic pathway, we created a cortical feedforward network of two cortical areas, 17 and 21a, with CT connections to a pulvinar-like network. With this model, the transthalamic pathway propagates alpha waves from the pulvinar to area 21a. This oscillatory transfer ceases when reciprocal connections from area 21a reach the pulvinar, closing the cortico-thalamic loop. Taken together, results of our model suggest that the pulvnar shows a bi-stable spiking activity, oscillatory or regular asynchronous spiking, whose responses are gated by the different activation of cortico-pulvinar projections from lower to higher-order areas such as areas 17 and 21a.

scholarly journals Corticothalamic Projections Gate Alpha Rhythms in the Pulvinar

2021 ◽  
Vol 15 ◽  
Author(s):  
Nelson Cortes ◽  
Reza Abbas Farishta ◽  
Hugo J. Ladret ◽  
Christian Casanova
Keyword(s):  
Cortical Area ◽  
Hierarchical Level ◽  
Oscillatory Activity ◽  
Excitatory Postsynaptic Potential ◽  
Area 17 ◽  
Cortical Areas ◽  
Area 21A ◽  
Spiking Activity

Two types of corticothalamic (CT) terminals reach the pulvinar nucleus of the thalamus, and their distribution varies according to the hierarchical level of the cortical area they originate from. While type 2 terminals are more abundant at lower hierarchical levels, terminals from higher cortical areas mostly exhibit type 1 axons. Such terminals also evoke different excitatory postsynaptic potential dynamic profiles, presenting facilitation for type 1 and depression for type 2. As the pulvinar is involved in the oscillatory regulation between intercortical areas, fundamental questions about the role of these different terminal types in the neuronal communication throughout the cortical hierarchy are yielded. Our theoretical results support that the co-action of the two types of terminals produces different oscillatory rhythms in pulvinar neurons. More precisely, terminal types 1 and 2 produce alpha-band oscillations at a specific range of connectivity weights. Such oscillatory activity is generated by an unstable transition of the balanced state network’s properties that it is found between the quiescent state and the stable asynchronous spike response state. While CT projections from areas 17 and 21a are arranged in the model as the empirical proportion of terminal types 1 and 2, the actions of these two cortical connections are antagonistic. As area 17 generates low-band oscillatory activity, cortical area 21a shifts pulvinar responses to stable asynchronous spiking activity and vice versa when area 17 produces an asynchronous state. To further investigate such oscillatory effects through corticothalamo-cortical projections, the transthalamic pathway, we created a cortical feedforward network of two cortical areas, 17 and 21a, with CT connections to a pulvinar-like network with two cortico-recipient compartments. With this model, the transthalamic pathway propagates alpha waves from the pulvinar to area 21a. This oscillatory transfer ceases when reciprocal connections from area 21a reach the pulvinar, closing the CT loop. Taken together, results of our model suggest that the pulvinar shows a bi-stable spiking activity, oscillatory or regular asynchronous spiking, whose responses are gated by the different activation of cortico-pulvinar projections from lower to higher-order areas such as areas 17 and 21a.

Neurotrophic and behavioral effects of occipital cortex transplants in newborn rats

1989 ◽  
Vol 2 (2) ◽  
pp. 189-198 ◽  
Keyword(s):  
Visual Cortex ◽  
Visual Discrimination ◽  
Cortical Area ◽  
Occipital Cortex ◽  
Behavioral Effects ◽  
Cortical Lesion ◽  
Area 17 ◽  
Newborn Rats ◽  
Opposite Hemisphere ◽  
Cortical Areas

AbstractCell suspensions of embryonic occipital cortex were transplanted into newborn rats with large unilateral visual cortex lesions. When the animals were adults, they were tested on a difficult visual discrimination, and subsequently their brains were analyzed for possible neurotrophic effects of the transplants on nonvisual cortical areas which normally form connections with the occipital cortex. Behaviorally, animals with lesions and transplants learn to discriminate between columns and rows of squares at a rate which is identical to normal rats while animals with lesions and no transplants are impaired. Volume and cell-density measures show that the transplants also rescue neurons in cortical area 8 that would normally degenerate following the cortical lesion. No such neurotrophic effect of the transplants is found in cortical area 24 or area 17 contralateral to the lesion. In rats with lesions and no transplants, there is a significant correlation between the amount of area 8 remaining after the lesion and trials to criterion on the columns-rows discrimination, a relationship that does not exist in transplant animals because of their normal learning curve and the consistent sparing of area 8. Injections of HRP into the visual cortex contralateral to the lesion result in variable numbers of labeled cells within the transplant. However, there is no consistent relationship between the number of transplant cells which project to the opposite hemisphere and learning of the discrimination. It is suggested that the learning deficit following the lesion is largely attentional and that the sparing of cortical area 8 (which in rats may include the analog of the frontal eye fields present in the primate cortex) contributes to the sparing of function.

scholarly journals Pairwise correlations of spiking activity changes along the ventral visual cortical pathway of macaque monkeys

2017 ◽  
Author(s):  
Hiroshi Tamura
Keyword(s):  
Cortical Area ◽  
Single Neuron ◽  
Neural Circuitry ◽  
Macaque Monkeys ◽  
Cortical Areas ◽  
Related Information ◽  
Neuron Populations ◽  
Visual Cortical ◽  
Signal Correlation ◽  
Spiking Activity

AbstractSpiking activity often correlates across neurons in the cerebral cortex. Precise spike-timing correlation at millisecond scale reflects underlying neural circuitries. Correlations of stimulus evoked spiking activities affects the distributions of spike counts in a multi-neuron space and reflects stimulus encoding ability of neuron populations. The present study compared the degree of spiking-activity correlation among three areas of the macaque visual system to determine whether neural circuitry and the way to encode stimulus-related information by neuron populations are unique to each area. Spiking activity of multiple single neurons was recorded in macaque primary visual cortex (V1), visual association cortex (V4), and inferior temporal cortex (IT). Cross-correlation of spike trains revealed that single-neuron pairs in IT exhibited the highest incidence of precisely correlated firing, whereas V1 pairs showed the lowest incidence. Although noise correlation, which quantifies similarity in trial-to-trial response fluctuations, differed among cortical areas, signal correlation, which quantifies similarity in stimulus preferences, did not. The degree of temporally precise correlation was positively related to the signal-correlation strength in all three cortical areas and the relation of IT pairs was stronger than that of V1 pairs. Temporally precise correlations between single-neuron and population-level activity also differed among cortical areas and V1 neurons exhibited the lowest incidence of correlated firing with population activities. The differences in spiking-activity correlations among visual cortical areas suggest that each cortical area has unique neuronal circuitry for representing information, and which performs unique neuronal computations.Significance StatementAlthough hierarchical information processing plays a crucial role in the brain and in artificial neural networks, whether hierarchically connected brain areas share neural circuitry and information representation remains unclear. Here, we examined spiking activity across the ventral visual system in macaque monkeys and found that cortical areas differed in how correlated their spiking activity was, suggesting that neural circuitry and the way to encode stimulus-related information by neuron populations are unique to each cortical area.

Visuomotor properties of corticotectal cells in area 17 and posteromedial lateral suprasylvian (PMLS) cortex of the cat

2001 ◽  
Vol 18 (1) ◽  
pp. 77-91 ◽  
Author(s):  
THEODORE G. WEYAND ◽  
ADELE C. GAFKA
Keyword(s):  
Eye Movements ◽  
Oculomotor System ◽  
Oscillatory Activity ◽  
Visual Response ◽  
Area 17 ◽  
Stimulus Motion ◽  
Velocity Amplitude ◽  
Cortical Areas ◽  
Saccade Velocity ◽  
Visual Cortical

We studied the visuomotor activity of corticotectal (CT) cells in two visual cortical areas [area 17 and the posteromedial lateral suprasylvian cortex (PMLS)] of the cat. The cats were trained in simple oculomotor tasks, and head position was fixed. Most CT cells in both cortical areas gave a vigorous discharge to a small stimulus used to control gaze when it fell within the retinotopically defined visual field. However, the vigor of the visual response did not predict latency to initiate a saccade, saccade velocity, amplitude, or even if a saccade would be made, minimizing any potential role these cells might have in premotor or attentional processes. Most CT cells in both areas were selective for direction of stimulus motion, and cells in PMLS showed a direction preference favoring motion away from points of central gaze. CT cells did not discharge with eye movements in the dark. During eye movements in the light, many CT cells in area 17 increased their activity. In contrast, cells in PMLS, including CT cells, were generally unresponsive during saccades. Paradoxically, cells in PMLS responded vigorously to stimuli moving at saccadic velocities, indicating that the oculomotor system suppresses visual activity elicited by moving the retina across an illuminated scene. Nearly all CT cells showed oscillatory activity in the frequency range of 20–90 Hz, especially in response to visual stimuli. However, this activity was capricious; strong oscillations in one trial could disappear in the next despite identical stimulus conditions. Although the CT cells in both of these regions share many characteristics, the direction anisotropy and the suppression of activity during eye movements which characterize the neurons in PMLS suggests that these two areas have different roles in facilitating perceptual/motor processes at the level of the superior colliculus.

scholarly journals Hierarchical Organization of Corticothalamic Projections to the Pulvinar

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Reza Abbas Farishta ◽  
Denis Boire ◽  
Christian Casanova
Keyword(s):  
Higher Order ◽  
Hierarchical Organization ◽  
Hierarchical Level ◽  
Thalamic Nuclei ◽  
Cortical Areas ◽  
Visual Areas ◽  
Cortical Hierarchy ◽  
Area 21A ◽  
Extrastriate Areas ◽  
Corticothalamic Projections

Abstract Signals from lower cortical visual areas travel to higher-order areas for further processing through cortico-cortical projections, organized in a hierarchical manner. These signals can also be transferred between cortical areas via alternative cortical transthalamic routes involving higher-order thalamic nuclei like the pulvinar. It is unknown whether the organization of transthalamic pathways may reflect the cortical hierarchy. Two axon terminal types have been identified in corticothalamic (CT) pathways: the types I (modulators) and II (drivers) characterized by thin axons with small terminals and by thick axons and large terminals, respectively. In cats, projections from V1 to the pulvinar complex comprise mainly type II terminals, whereas those from extrastriate areas include a combination of both terminals suggesting that the nature of CT terminals varies with the hierarchical order of visual areas. To test this hypothesis, distribution of CT terminals from area 21a was charted and compared with 3 other visual areas located at different hierarchical levels. Results demonstrate that the proportion of modulatory CT inputs increases along the hierarchical level of cortical areas. This organization of transthalamic pathways reflecting cortical hierarchy provides new and fundamental insights for the establishment of more accurate models of cortical signal processing along transthalamic cortical pathways.

scholarly journals Pulvinar Modulates Synchrony across Visual Cortical Areas

Vision ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 22
Author(s):  
Nelson Cortes ◽  
Bruno O. F. de Souza ◽  
Christian Casanova
Keyword(s):  
Visual Cortex ◽  
Granger Causality ◽  
Gamma Oscillations ◽  
Oscillatory Activity ◽  
Area 17 ◽  
Feedback Processing ◽  
Area 21A ◽  
Layer I ◽  
Oscillatory Coupling ◽  
Visual Cortical

The cortical visual hierarchy communicates in different oscillatory ranges. While gamma waves influence the feedforward processing, alpha oscillations travel in the feedback direction. Little is known how this oscillatory cortical communication depends on an alternative route that involves the pulvinar nucleus of the thalamus. We investigated whether the oscillatory coupling between the primary visual cortex (area 17) and area 21a depends on the transthalamic pathway involving the pulvinar in cats. To that end, visual evoked responses were recorded in areas 17 and 21a before, during and after inactivation of the pulvinar. Local field potentials were analyzed with Wavelet and Granger causality tools to determine the oscillatory coupling between layers. The results indicate that cortical oscillatory activity was enhanced during pulvinar inactivation, in particular for area 21a. In area 17, alpha band responses were represented in layers II/III. In area 21a, gamma oscillations, except for layer I, were significantly increased, especially in layer IV. Granger causality showed that the pulvinar modulated the oscillatory information between areas 17 and 21a in gamma and alpha bands for the feedforward and feedback processing, respectively. Together, these findings indicate that the pulvinar is involved in the mechanisms underlying oscillatory communication along the visual cortex.

scholarly journals Mechanisms of Synchrony in Heterogeneous Inhibitory Interneuronal Networks for Type 1 versus Type 2 Excitability

2019 ◽  
Author(s):  
Ruben A. Tikidji-Hamburyan ◽  
Carmen C. Canavier
Keyword(s):  
Cutoff Frequency ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Attention And Memory ◽  
Complete Suppression ◽  
Exact Nature ◽  
Shunting Inhibition ◽  
Fast Spiking

AbstractPV+ fast spiking basket interneurons are often implicated in gamma rhythms. Here we focus on mechanisms present in purely inhibitory networks. Neurons with type 1 excitability can fire arbitrarily slowly, whereas those with type 2 excitability cannot fire below a minimum frequency. We systematically examine how excitability type affects synchronization of individual spikes to a population rhythm in the presence of heterogeneity and noise, using model neurons of each type with matched F/I curve, input resistance, time constant and action potential shape. Population synchrony in noisy heterogeneous networks is maintained because neurons either fire within a tight time window or skip that cycle. Type 2 neurons with hyperpolarizing inhibition skip cycles due to their intrinsic dynamics; we show here the cycle skipping mechanism for type 1 neurons or type 2 neurons with shunting inhibition is synaptic and not intrinsic. Type 2 neurons are more resistant than type 1 to partial and complete suppression in networks with hyperpolarizing inhibition that exhibit network gamma. Moreover, type 2 neurons are recruited more rapidly and more completely into theta-nested gamma. In contrast, type 1 networks perform better with shunting inhibition on both counts, because the nonlinear dynamics in that case favor suppression of type 2 compared to type 1 neurons. Conductances that control excitability type may provide a therapeutic target to improve spatial and working memory and other tasks that rely on gamma synchrony or phase amplitude coupling.Author SummaryThe collective, synchronized activity of neurons produces brain rhythms. These rhythms are thought to subserve cognitive functions such as attention and memory encoding and retrieval. Faster rhythms are nested in slower rhythms as a putative way of chunking information. A subset of neurons called fast spiking basket cells tend to inhibit other neurons from firing. These neurons play an important role in oscillations, and in the coupling of faster oscillations to slower ones. In some brain regions these neurons can fire arbitrarily slowly (type 1 dynamics) whereas in others they cannot fire below a minimum cutoff frequency (type 2 dynamics). Mathematically, these distinct origins of rhythmic firing are signatures of very different dynamics. Here, we show that these distinct excitability types affect the ability of networks of these neurons to synchronize their fast oscillatory activity, as well as the ability of slower oscillations to modulate these fast oscillations. The exact nature of the inhibitory coupling, which may vary between brain regions, determines which type synchronizes better and is modulated better.

Type 2 Diabetes Overtakes Type 1 in Hispanic Girls

2008 ◽  
Vol 38 (15) ◽  
pp. 18
Author(s):  
SHERRY BOSCHERT
Keyword(s):  
Type 2 Diabetes
Sign in / Sign up

Export Citation Format

Share Document