scholarly journals From an invariant sensory code to a perceptual categorical code in secondary somatosensory cortex

2020 ◽  
Author(s):  
Román Rossi Pool ◽  
Antonio Zainos ◽  
Manuel Alvarez ◽  
Gabriel Diaz-de Leon ◽  
Ranulfo Romo
Keyword(s):  
Somatosensory Cortex ◽  
Frontal Lobe ◽  
Sensory Information ◽  
Control Task ◽  
Hierarchical Processing ◽  
Secondary Somatosensory Cortex ◽  
Categorical Information ◽  
Intrinsic Fluctuations ◽  
Sensory Responses ◽  
Sensory Code

Abstract A crucial role of cortical networks is the conversion of sensory inputs into perception. In the cortical somatosensory network, neurons of the primary somatosensory cortex (S1) show invariant sensory responses, while frontal lobe neuronal activity correlates with the animal’s perceptual behavior. Here, we report that in the secondary somatosensory cortex (S2), neurons with invariant sensory responses coexist with neurons whose responses correlate with perceptual behavior. Importantly, the vast majority of the neurons fall along a continuum of combined sensory and categorical dynamics. These distinct neural responses exhibit analogous timescales of intrinsic fluctuations, suggesting that they belong to the same hierarchical processing stage. Furthermore, during a non-demanding control task, the sensory responses remained unaltered while perceptual responses vanished. Sensory information increased and categorical information diminished during this control task, suggesting that processing depended on the task context. Conclusively, S2 neurons exhibit intriguing dynamics that are intermediate between S1 and frontal lobe.

scholarly journals From an invariant sensory code to a perceptual categorical code in second somatosensory cortex

2020 ◽  
Author(s):  
Román Rossi-Pool ◽  
Antonio Zainos ◽  
Manuel Alvarez ◽  
Ranulfo Romo
Keyword(s):  
Somatosensory Cortex ◽  
Frontal Lobe ◽  
Neural Responses ◽  
Hierarchical Processing ◽  
Sensory Inputs ◽  
Secondary Somatosensory Cortex ◽  
Intrinsic Fluctuations ◽  
Sensory Responses ◽  
Sensory Code

A crucial role of cortical networks is the conversion of sensory inputs into perception. In the cortical somatosensory network, neurons of the primary somatosensory cortex (S1) show invariant sensory responses, while frontal lobe neuron responses correlate with the animal’s perceptual behavior. But, where in the cortical somatosensory network are the sensory inputs transformed into perceptual behavior? Here, we report that in the secondary somatosensory cortex (S2), neurons with invariant sensory responses coexist with neurons whose responses correlate with the animal’s perceptual behavior. These distinct neural responses exhibit analogous timescales of intrinsic fluctuations, suggesting that they belong to the same hierarchical processing stage. Furthermore, during a non-demanding control task, the sensory responses remained unaltered while perceptual responses vanished. Conclusively, the S2 population responses exhibit intermediate dynamics between S1 and frontal lobe neurons. These results suggest that the conversion of touch into perception crucially depends on S2.

scholarly journals A continuum of invariant sensory and behavioral-context perceptual coding in secondary somatosensory cortex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Román Rossi-Pool ◽  
Antonio Zainos ◽  
Manuel Alvarez ◽  
Gabriel Diaz-deLeon ◽  
Ranulfo Romo
Keyword(s):  
Somatosensory Cortex ◽  
Frontal Lobe ◽  
Sensory Information ◽  
Behavioral Context ◽  
Secondary Somatosensory Cortex ◽  
Relevant Evidence ◽  
Categorical Information ◽  
Sensory Responses ◽  
Processing Mechanism

AbstractA crucial role of cortical networks is the conversion of sensory inputs into perception. In the cortical somatosensory network, neurons of the primary somatosensory cortex (S1) show invariant sensory responses, while frontal lobe neuronal activity correlates with the animal’s perceptual behavior. Here, we report that in the secondary somatosensory cortex (S2), neurons with invariant sensory responses coexist with neurons whose responses correlate with perceptual behavior. Importantly, the vast majority of the neurons fall along a continuum of combined sensory and categorical dynamics. Furthermore, during a non-demanding control task, the sensory responses remain unaltered while the sensory information exhibits an increase. However, perceptual responses and the associated categorical information decrease, implicating a task context-dependent processing mechanism. Conclusively, S2 neurons exhibit intriguing dynamics that are intermediate between those of S1 and frontal lobe. Our results contribute relevant evidence about the role that S2 plays in the conversion of touch into perception.

Time-Dependent, Layer-Specific Modulation of Sensory Responses Mediated by Neocortical Layer 1

2006 ◽  
Vol 96 (6) ◽  
pp. 3170-3182 ◽  
Author(s):  
Dan Shlosberg ◽  
Yael Amitai ◽  
Rony Azouz
Keyword(s):  
Somatosensory Cortex ◽  
Cortical Neurons ◽  
Sensory Information ◽  
Time Dependent ◽  
Inhibitory Influence ◽  
Sensory Responses ◽  
Specific Regulation ◽  
Sensory Evoked

An essential component of feedback and top-down information in the cortical column arrives at layer 1 (L1) where it contacts distal dendrites of pyramidal neurons. Although much is known about the anatomical organization of L1 fibers, their contribution to sensory information processing remains to be determined. We assessed the physiological significance of L1 inputs by performing extracellular recordings in vivo from neurons in the primary somatosensory cortex of rodents. We found that blocking activity in L1 increases whisker-evoked response magnitude and variance, suggesting that L1 exerts an inhibitory influence on whisker responses. However, when pairing L1 stimulation with whisker deflection, the interval between the stimuli determined the outcome of the interaction, with facilitation of sensory responses dominating the short intervals (≤10 ms) and suppression prevailing at longer intervals (>10 ms). These temporal interactions resulted in a time-dependent regulation of direction tuning of cortical neurons. The synaptic mechanisms underlying L1 inputs’ influences were examined using whole cell recordings in vitro while pairing L1 and white-matter stimulations. We found time-dependent, layer-specific differences in synaptic summation of the two inputs, with supralinearity at shorter intervals and sublinearity at longer intervals that resulted mainly from shunting inhibition. Taken together, our results demonstrate that L1 inputs impose a time- and layer-specific regulation on sensory-evoked responses. This in turn may lead to a dynamic transmission of sensory information in the somatosensory cortex.

scholarly journals Learning a tactile sequence induces selectivity to action decisions and outcomes in the mouse somatosensory cortex

2020 ◽  
Author(s):  
Michael R. Bale ◽  
Malamati Bitzidou ◽  
Elena Giusto ◽  
Paul Kinghorn ◽  
Miguel Maravall
Keyword(s):  
Somatosensory Cortex ◽  
Barrel Cortex ◽  
Temporal Integration ◽  
Target Sequence ◽  
Two Photon ◽  
Secondary Somatosensory Cortex ◽  
Sequence Recognition ◽  
Sensory Features ◽  
Sensory Responses ◽  
Stimulus Features

AbstractSequential temporal ordering and patterning are key features of natural signals used by the brain to decode stimuli and perceive them as sensory objects. To explore how cortical neuronal activity underpins sequence recognition, we developed a task in which mice distinguished between tactile ‘words’ constructed from distinct vibrations delivered to the whiskers, assembled in different orders. Animals licked to report the presence of the target sequence. Mice could respond to the earliest possible cues allowing discrimination, effectively solving the task as a ‘detection of change’ problem, but enhanced their performance when deliberating for longer. Optogenetic inactivation showed that both primary somatosensory ‘barrel’ cortex (S1bf) and secondary somatosensory cortex were necessary for sequence recognition. Two-photon imaging of calcium activity in S1bf layer 2/3 revealed that, in well-trained animals, neurons had heterogeneous selectivity to multiple task variables including not just sensory input but also the animal’s action decision and the trial outcome (presence or absence of a predicted reward). A large proportion of neurons were activated preceding goal-directed licking, thus reflecting the animal’s learnt response to the target sequence rather than the sequence itself; these neurons were found in S1bf as soon as mice learned to associate the rewarded sequence with licking. In contrast, learning evoked smaller changes in sensory responses: neurons responding to stimulus features were already found in naïve mice, and training did not generate neurons with enhanced temporal integration or categorical responses. Therefore, in S1bf sequence learning results in neurons whose activity reflects the learnt association between the target sequence and licking, rather than a refined representation of sensory features.

Inter- and intra-hemispheric spatiotemporal organization of spontaneous electrocortical oscillations

1996 ◽  
Vol 76 (1) ◽  
pp. 423-437 ◽  
Author(s):  
K. D. MacDonald ◽  
B. Brett ◽  
D. S. Barth
Keyword(s):  
Time Series ◽  
Somatosensory Cortex ◽  
Phase Locking ◽  
Sensory Information ◽  
Gamma Oscillations ◽  
Sensory Cortex ◽  
Electrode Arrays ◽  
Sharp Wave ◽  
Lower Amplitude ◽  
The Right

1. Two 64-channel epipial electrode arrays were positioned on homologous locations of the right and left hemisphere, covering most of primary and secondary auditory and somatosensory cortex in eight lightly anesthetized rats. Array placement was verified with the use of cytochrome oxidase histochemistry. 2. Middle-latency auditory and somatosensory evoked potentials (MAEPs and MSEPs, respectively) and spontaneous oscillations in the frequency range of 20-40 Hz (gamma oscillations) were recorded and found to be spatially constrained to regions of granular cortex, suggesting that both phenomena are closely associated with sensory information processing. 3. The MAEP and MSEP consisted of an initial biphasic sharp wave in primary auditory and somatosensory cortex, respectively, and a similar biphasic sharp wave occurred approximately 4-8 ms later in secondary sensory cortex of the given modality. Averaged gamma oscillations also revealed asynchronous activation of sensory cortex, but with a shorter 2-ms delay between oscillations in primary and secondary regions. Although the long latency shift of the MAEP and MSEP may be due in part to asynchronous activation of parallel thalamocortical projections to primary and secondary sensory cortex, the much shorter shift of gamma oscillations in a given modality is consistent with intracortical coupling of these regions. 4. Gamma oscillations occurred independently in auditory and somatosensory cortex within a given hemisphere. Furthermore, time series averaging revealed that there was no phase-locking of oscillations between the sensory modalities. 5. Gamma oscillations were loosely coupled between hemispheres; oscillations occurring in auditory or somatosensory cortex of one hemisphere were often associated with lower-amplitude oscillations in homologous contralateral sensory cortex. Yet, the fact that time series averaging revealed no interhemispheric phase-locking suggests that the corpus callosum may not coordinate the bilateral gamma oscillations, and that a thalamic modulatory influence may be involved.

scholarly journals A supragranular nexus for the effects of neocortical beta events on human tactile perception

2019 ◽  
Author(s):  
Robert G. Law ◽  
Sarah Pugliese ◽  
Hyeyoung Shin ◽  
Danielle Sliva ◽  
Shane Lee ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Spectral Power ◽  
Sensory Information ◽  
Sensory Perception ◽  
Higher Order ◽  
Beta Band ◽  
Top Down ◽  
Sensory Suppression ◽  
Neuronal Mechanisms ◽  
Event Rates

AbstractTransient neocortical events with high spectral power in the 15–29Hz beta band are among the most reliable predictors of sensory perception: High prestimulus beta event rates in primary somatosensory lead to sensory suppression, most effective at 100–300ms prestimulus latency. However, the synaptic and neuronal mechanisms inducing beta’s perceptual effects have not been completely localized. We combined human MEG with neural modeling designed to account for these macroscale signals to interpret the cellular and circuit mechanisms that underlie the influence of beta on tactile detection. Extending prior studies, we modeled the hypothesis that higher-order thalamic bursts, sufficient for beta event generation in cortex, recruit supragranular GABAB inhibition acting on a 300ms time scale to suppress sensory information. Consistency between model and MEG data supported this hypothesis and led to a further prediction, validated in our data, that stimuli are perceived when beta events occur simultaneously with tactile stimulation. The post-event suppressive mechanism explains an array of studies that associate beta with decreased processing, while the during-event mechanism may demand a reinterpretation of the role of beta events in the context of coincident timing.Significance statementSomatosensory beta events – transient 15-29Hz oscillations in electromagnetic recordings – are thought to be generated when “top-down” bursts of spikes presumably originating in higher-order thalamus arrive in upper layers of somatosensory cortex. Physiological evidence had shown that the immediate action of these top-down projections should be excitatory; however, after a beta event, sensory perception is noticeably inhibited for approximately 300ms. The source of this post-event sensory suppression, in particular, had been unresolved. Using a detailed computational model of somatosensory cortex, we find evidence for the hypothesis that these bursts couple indirectly to GABAB inhibition in upper layers of cortex, and that beta events first briefly disinhibit sensory relay before a longer period of inhibition.

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