scholarly journals The state of somatosensory cortex during neuromodulation

2012 ◽  
Vol 108 (4) ◽  
pp. 1010-1024 ◽  
Author(s):  
Morgana Favero ◽  
Gladis Varghese ◽  
Manuel A. Castro-Alamancos
Keyword(s):  
Somatosensory Cortex ◽  
Slow Wave Sleep ◽  
Slow Oscillations ◽  
Synaptic Inputs ◽  
Sensory Inputs ◽  
Activated State ◽  
Cellular Excitability ◽  
Inhibitory Conductance ◽  
State Changes ◽  
Cholinergic Activation

During behavioral quiescence, such as slow-wave sleep and anesthesia, the neocortex is in a deactivated state characterized by the presence of slow oscillations. During arousal, slow oscillations are absent and the neocortex is in an activated state that greatly impacts information processing. Neuromodulators acting in neocortex are believed to mediate these state changes, but the mechanisms are poorly understood. We investigated the actions of noradrenergic and cholinergic activation on slow oscillations, cellular excitability, and synaptic inputs in thalamocortical slices of somatosensory cortex. The results show that neuromodulation abolishes slow oscillations, dampens the excitability of principal cells, and rebalances excitatory and inhibitory synaptic inputs in thalamocortical-recipient layers IV–III. Sensory cortex is much more selective about the inputs that can drive it. The source of neuromodulation is critically important in determining this selectivity. Cholinergic activation suppresses the excitatory and inhibitory conductances driven by thalamocortical and intracortical inputs. Noradrenergic activation suppresses the excitatory conductance driven by intracortical inputs but not by thalamocortical inputs and enhances the inhibitory conductance driven by thalamocortical inputs but not by intracortical inputs. Thus noradrenergic activation emphasizes thalamocortical (sensory) inputs relative to intracortical inputs, while cholinergic activation suppresses both.

scholarly journals Selection of stimulus parameters for enhancing slow wave sleep events with a Neural-field theory thalamocortical computational model

2021 ◽  
Author(s):  
Felipe A. Torres ◽  
Patricio Orio ◽  
María-José Escobar
Keyword(s):  
Computational Model ◽  
Slow Wave ◽  
Memory Consolidation ◽  
Closed Loop ◽  
Slow Wave Sleep ◽  
Brain Activity ◽  
Sensory Stimulation ◽  
Sleep Spindles ◽  
Slow Oscillations ◽  
Closed Loop Stimulation

AbstractSlow-wave sleep cortical brain activity, conformed by slow-oscillations and sleep spindles, plays a key role in memory consolidation. The increase of the power of the slow-wave events, obtained by auditory sensory stimulation, positively correlates to memory consolidation performance. However, little is known about the experimental protocol maximizing this effect, which could be induced by the power of slow-oscillation, the number of sleep spindles, or the timing of both events’ co-occurrence. Using a mean-field model of thalamocortical activity, we studied the effect of several stimulation protocols, varying the pulse shape, duration, amplitude, and frequency, as well as a target-phase using a closed-loop approach. We evaluated the effect of these parameters on slow-oscillations (SO) and sleep-spindles (SP), considering: (i) the power at the frequency bands of interest, (ii) the number of SO and SP, (iii) co-occurrences between SO and SP, and (iv) synchronization of SP with the up-peak of the SO. The first three targets are maximized using a decreasing ramp pulse with a pulse duration of 50 ms. Also, we observed a reduction in the number of SO when increasing the stimulus energy by rising its amplitude. To assess the target-phase parameter, we applied closed-loop stimulation at 0º, 45º, and 90º of the phase of the narrow-band filtered ongoing activity, at 0.85 Hz as central frequency. The 0º stimulation produces better results in the power and number of SO and SP than the rhythmic or aleatory stimulation. On the other hand, stimulating at 45º or 90º change the timing distribution of spindles centers but with fewer co-occurrences than rhythmic and 0º phase. Finally, we propose the application of closed-loop stimulation at the rising zero-cross point using pulses with a decreasing ramp shape and 50 ms of duration for future experimental work.Author summaryDuring the non-REM (NREM) phase of sleep, events that are known as slow oscillations (SO) and spindles (SP) can be detected by EEG. These events have been associated with the consolidation of declarative memories and learning. Thus, there is an ongoing interest in promoting them during sleep by non-invasive manipulations such as sensory stimulation. In this paper, we used a computational model of brain activity that generates SO and SP, to investigate which type of sensory stimulus –shape, amplitude, duration, periodicity– would be optimal for increasing the events’ frequency and their co-occurrence. We found that a decreasing ramp of 50 ms duration is the most effective. The effectiveness increases when the stimulus pulse is delivered in a closed-loop configuration triggering the pulse at a target phase of the ongoing SO activity. A desirable secondary effect is to promote SPs at the rising phase of the SO oscillation.

Intrinsic discharge patterns and somatosensory inputs for neurons in raccoon primary somatosensory cortex

1994 ◽  
Vol 72 (6) ◽  
pp. 2827-2839 ◽  
Author(s):  
P. J. Istvan ◽  
P. Zarzecki
Keyword(s):  
Somatosensory Cortex ◽  
Cortical Neurons ◽  
Primary Somatosensory Cortex ◽  
Membrane Properties ◽  
Postsynaptic Potentials ◽  
Synaptic Inputs ◽  
Ionic Conductances ◽  
Discharge Patterns ◽  
Intrinsic Membrane Properties ◽  
Stimulation Of

1. Discharge patterns of neurons are regulated by synaptic inputs and by intrinsic membrane properties such as their complement of ionic conductances. Discharge patterns evoked by synaptic inputs are often used to identify the source and modality of sensory input. However, the interpretation of these discharge patterns may be complicated if different neurons respond to the same synaptic input with a variety of discharge patterns due to differences in intrinsic membrane properties. The purposes of this study were 1) to investigate intrinsic discharge patterns of neurons in primary somatosensory cortex of raccoon in vivo and 2) to use somatosensory postsynaptic potentials evoked by stimulation of forepaw digits to determine thalamocortical connectivity for the same neurons. 2. Conventional intracellular recordings with sharp electrodes were made from 121 neurons in the cortical representation of glabrous skin of digit four (d4). Intracellular injection of identical current pulses (100-120 ms in duration) elicited various patterns of discharge in different neurons. Neurons were classified on the basis of these intrinsic patterns of discharge, rates of spike adaptation, and characteristics of spike waveforms. Three main groups were identified: regular spiking (RS) neurons, intrinsic bursting (IB) neurons, and fast spiking (FS) neurons. Subclasses were identified for the RS and IB groups. 3. Neurons were tested for somatosensory inputs by stimulating electrically d3, d4, and d5. Excitatory postsynaptic potentials (EPSPs) were elicited in 100% of the neurons by electrical stimulation of d4, the "on-focus" digit. EPSPs were usually followed by inhibitory postsynaptic potentials (IPSPs). Many neurons (41%) responded with EPSP-IPSP sequences after stimulation of d3 or d5, the "off-focus" digits. 4. Latencies of somatosensory EPSPs and IPSPs were used to determine the synaptic order in the cortical circuitry of RS, IB, and FS neurons. EPSPs with monosynaptic thalamocortical latencies were recorded in RS, IB, and FS neurons. 5. We conclude that precise patterns of neural discharge in primary somatosensory cortex cannot be reliable estimates of sensory inputs reaching these neurons because patterns of discharge are so strongly influenced by intrinsic membrane properties. Ionic conductances governing patterns of neuronal discharge seem almost identical in intact cortex of raccoon, rat, and cat, and in slices of rodent cortex, because similar patterns of discharge are found. The consistency of patterns of discharge across species and types of preparation suggests that these intrinsic membrane properties are a general property of cerebral cortical neurons and should be considered when evaluation sensory coding by these neurons.

scholarly journals The non-linear mixed representations in somatosensory cortex support simple and complex tasks

2021 ◽  
Author(s):  
Ramon Nogueira ◽  
Chris C. Rodgers ◽  
Randy M. Bruno ◽  
Stefano Fusi
Keyword(s):  
Somatosensory Cortex ◽  
Neural Activity ◽  
High Speed ◽  
Barrel Cortex ◽  
Broad Class ◽  
High Dimensional ◽  
Complex Tasks ◽  
Sensory Inputs ◽  
Neural Representations ◽  
Non Linear

Adaptive behavior in humans, rodents, and other animals often requires the integration over time of multiple sensory inputs. Here we studied the behavior and the neural activity of mice trained to actively integrate information from different whiskers to report the curvature of an object. The analysis of high speed videos of the whiskers revealed that the task could be solved by integrating linearly the whisker contacts on the object. However, recordings from the mouse barrel cortex revealed that the neural representations are high dimensional as the inputs from multiple whiskers are mixed non-linearly to produce the observed neural activity. The observed representation enables the animal to perform a broad class of significantly more complex tasks, with minimal disruption of the ability to generalize to novel situations in simpler tasks. Simulated recurrent neural networks trained to perform similar tasks reproduced both the behavioral and neuronal experimental observations. Our work suggests that the somatosensory cortex operates in a regime that represents an efficient compromise between generalization, which typically requires pure and linear mixed selectivity representations, and the ability to perform complex discrimination tasks, which is granted by non-linear mixed representations.

Neuropeptide-Mediated Facilitation and Inhibition of Sensory Inputs and Spinal Cord Reflexes in the Lamprey

1999 ◽  
Vol 81 (4) ◽  
pp. 1730-1740 ◽  
Author(s):  
Maria Ullström ◽  
David Parker ◽  
Erik Svensson ◽  
Sten Grillner
Keyword(s):  
Spinal Cord ◽  
Substance P ◽  
Motor Neurons ◽  
Ventral Root ◽  
Sensory Level ◽  
Synaptic Inputs ◽  
Sensory Inputs ◽  
Reflex Responses ◽  
Spinal Cord Reflexes ◽  
Root Responses

Neuropeptide-mediated facilitation and inhibition of sensory inputs and spinal cord reflexes in the lamprey. The effects of neuromodulators present in the dorsal horn [tachykinins, neuropeptide Y (NPY), bombesin, and GABAB agonists] were studied on reflex responses evoked by cutaneous stimulation in the lamprey. Reflex responses were elicited in an isolated spinal cord preparation by electrical stimulation of the attached tail fin. To be able to separate modulator-induced effects at the sensory level from that at the motor or premotor level, the spinal cord was separated into three pools with Vaseline barriers. The caudal pool contained the tail fin. Neuromodulators were added to this pool to modulate sensory inputs evoked by tail fin stimulation. The middle pool contained high divalent cation or low calcium Ringer to block polysynaptic transmission and thus limit the input to the rostral pool to that from ascending axons that project through the middle pool. Ascending inputs and reflex responses were monitored by making intracellular recordings from motor neurons and extracellular recordings from ventral roots in the rostral pool. The tachykinin neuropeptide substance P, which has previously been shown to potentiate sensory input at the cellular and synaptic levels, facilitated tail fin-evoked synaptic inputs to neurons in the rostral pool and concentration dependently facilitated rostral ventral root activity. Substance P also facilitated the modulatory effects of tail fin stimulation on ongoing locomotor activity in the rostral pool. In contrast, NPY and the GABAB receptor agonist baclofen, both of which have presynaptic inhibitory effects on sensory afferents, reduced the strength of ascending inputs and rostral ventral root responses. We also examined the effects of the neuropeptide bombesin, which is present in sensory axons, at the cellular, synaptic, and reflex levels. As with substance P, bombesin increased tail fin stimulation-evoked inputs and ventral root responses in the rostral pool. These effects were associated with the increased excitability of slowly adapting mechanosensory neurons and the potentiation of glutamatergic synaptic inputs to spinobulbar neurons. These results show the possible behavioral relevance of neuropeptide-mediated modulation of sensory inputs at the cellular and synaptic levels. Given that the types and locations of neuropeptides in the dorsal spinal cord of the lamprey show strong homologies to that of higher vertebrates, these results are presumably relevant to other vertebrate systems.

scholarly journals Activity-Dependent Downscaling of Subthreshold Synaptic Inputs during Slow-Wave-Sleep-like Activity In Vivo

Neuron ◽  
2018 ◽  
Vol 97 (6) ◽  
pp. 1244-1252.e5 ◽  
Author(s):  
Ana González-Rueda ◽  
Victor Pedrosa ◽  
Rachael C. Feord ◽  
Claudia Clopath ◽  
Ole Paulsen
Keyword(s):  
Slow Wave ◽  
Slow Wave Sleep ◽  
Synaptic Inputs ◽  
Activity Dependent

scholarly journals Cellular mechanisms for response heterogeneity among L2/3 pyramidal cells in whisker somatosensory cortex

2014 ◽  
Vol 112 (2) ◽  
pp. 233-248 ◽  
Author(s):  
Justin Elstrott ◽  
Kelly B. Clancy ◽  
Haani Jafri ◽  
Igor Akimenko ◽  
Daniel E. Feldman
Keyword(s):  
Somatosensory Cortex ◽  
Pyramidal Cells ◽  
Dendritic Morphology ◽  
Membrane Properties ◽  
Intrinsic Excitability ◽  
High Threshold ◽  
Cellular Mechanisms ◽  
Inhibitory Conductance

Whisker deflection evokes sparse, low-probability spiking among L2/3 pyramidal cells in rodent somatosensory cortex (S1), with spiking distributed nonuniformly between more and less responsive cells. The cellular and local circuit factors that determine whisker responsiveness across neurons are unclear. To identify these factors, we used two-photon calcium imaging and loose-seal recording to identify more and less responsive L2/3 neurons in S1 slices in vitro, during feedforward recruitment of the L2/3 network by L4 stimulation. We observed a broad gradient of spike recruitment thresholds within local L2/3 populations, with low- and high-threshold cells intermixed. This recruitment gradient was significantly correlated across different L4 stimulation sites, and between L4-evoked and whisker-evoked responses in vivo, indicating that a substantial component of responsiveness is independent of tuning to specific feedforward inputs. Low- and high-threshold L2/3 pyramidal cells differed in L4-evoked excitatory synaptic conductance and intrinsic excitability, including spike threshold and the likelihood of doublet spike bursts. A gradient of intrinsic excitability was observed across neurons. Cells that spiked most readily to L4 stimulation received the most synaptic excitation but had the lowest intrinsic excitability. Low- and high-threshold cells did not differ in dendritic morphology, passive membrane properties, or L4-evoked inhibitory conductance. Thus multiple gradients of physiological properties exist across L2/3 pyramidal cells, with excitatory synaptic input strength best predicting overall spiking responsiveness during network recruitment.

scholarly journals Optical study of interactions among propagation waves of neural excitation in the rat somatosensory cortex evoked by forelimb and hindlimb stimuli

2018 ◽  
Vol 119 (5) ◽  
pp. 1934-1946 ◽  
Author(s):  
Noriyuki Hama ◽  
Minako Kawai ◽  
Shin-Ichi Ito ◽  
Akihiko Hirota
Keyword(s):  
Somatosensory Cortex ◽  
Sensory Stimulation ◽  
Optical Recording ◽  
The State ◽  
Sensory Cortex ◽  
Induced Response ◽  
Relative Timing ◽  
Single Wave ◽  
Sensory Inputs ◽  
Neural Excitation

Multisite optical recording has revealed that the neural excitation wave induced by a sensory stimulation begins at a focus and propagates in the cortex. This wave is considered to be important for computation in the sensory cortex, particularly the integration of sensory information; however, the nature of this wave remains largely unknown. In the present study, we examined the interaction between two waves in the rat sensory cortex induced by hindlimb and forelimb stimuli with different interstimulus intervals. We classified the resultant patterns as follows: 1) the collision of two waves, 2) the hindlimb response being evoked while the forelimb-induced wave is passing the hindlimb focus, and 3) the hindlimb response being evoked after the forelimb-induced wave has passed the hindlimb focus. In pattern 1, the two waves fused into a single wave, but the propagation pattern differed from that predicted by the superimposition of two singly induced propagation courses. In pattern 2, the state of the interaction between the two waves varied depending on the phase of optical signals constituting the forelimb-induced wave around the hindlimb focus. Although no hindlimb-induced wave was observed in the rising phase, the propagating velocity of the forelimb-induced wave increased. At the peak, neither the hindlimb-induced response nor a modulatory effect on the forelimb-induced wave was detected. In pattern 3, the hindlimb-induced wave showed a reduced amplitude and spatial extent. These results indicate that the state of the interaction between waves was strongly influenced by the relative timing of sensory inputs. NEW & NOTEWORTHY Sensory stimulation-induced cortical excitation propagates as a wave and spreads over a wide area of the sensory cortex. To elucidate the characteristics of this relatively unknown phenomenon, we examined the interaction between two individually induced waves in the somatosensory cortex. Either the waves collided or the preceding wave affected the emergence of the following one. Our results indicate that the state of the interaction was strongly influenced by the relative timing of sensory inputs.

scholarly journals Hippocampal Sharp Wave-Ripples Linked to Slow Oscillations in Rat Slow-Wave Sleep

2006 ◽  
Vol 96 (1) ◽  
pp. 62-70 ◽  
Author(s):  
Matthias Mölle ◽  
Oxana Yeshenko ◽  
Lisa Marshall ◽  
Susan J. Sara ◽  
Jan Born
Keyword(s):  
Slow Wave ◽  
Slow Wave Sleep ◽  
Temporal Dynamics ◽  
Slow Oscillation ◽  
Network Activity ◽  
Event Correlation ◽  
Slow Oscillations ◽  
Sharp Wave ◽  
Neuronal Network Activity ◽  
Up And Down States

Slow oscillations originating in the prefrontal neocortex during slow-wave sleep (SWS) group neuronal network activity and thereby presumably support the consolidation of memories. Here, we investigated whether the grouping influence of slow oscillations extends to hippocampal sharp wave-ripple (SPW) activity thought to underlie memory replay processes during SWS. The prefrontal surface EEG and multiunit activity (MUA), along with hippocampal local field potentials (LFP) from CA1, were recorded in rats during sleep. Average spindle and ripple activity and event correlation histograms of SPWs were calculated, time-locked to half-waves of slow oscillations. Results confirm decreased prefrontal MUA and spindle activity during EEG slow oscillation negativity and increases in this activity during subsequent positivity. A remarkably close temporal link was revealed between slow oscillations and hippocampal activity, with ripple activity and SPWs being also distinctly decreased during negative half-waves and increased during slow oscillation positivity. Fine-grained analyses of temporal dynamics revealed for the slow oscillation a phase delay of approximately 90 ms with reference to up and down states of prefrontal MUA, and of only approximately 60 ms with reference to changes in SPWs, indicating that up and down states in prefrontal MUA precede corresponding changes in hippocampal SPWs by approximately 30 ms. Results support the notion that the depolarizing surface-positive phase of the slow oscillation and the associated up state of prefrontal excitation promotes hippocampal SPWs via efferent pathways. The preceding disfacilitation of hippocampal events temporally coupled to the negative slow oscillation half-wave appears to serve a synchronizing role in this neocorticohippocampal interplay.

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