scholarly journals Decoding stimulus features in primate somatosensory cortex during perceptual categorization

2015 ◽  
Vol 112 (15) ◽  
pp. 4773-4778 ◽  
Author(s):  
Manuel Alvarez ◽  
Antonio Zainos ◽  
Ranulfo Romo
Keyword(s):  
Somatosensory Cortex ◽  
Stimulus Frequency ◽  
Downstream Processing ◽  
Vibrotactile Stimulus ◽  
Perceptual Categorization ◽  
Dynamic Representation ◽  
Sensory Feature ◽  
Sensory Features ◽  
Stimulus Features ◽  
Hierarchical Encoding

Neurons of the primary somatosensory cortex (S1) respond as functions of frequency or amplitude of a vibrotactile stimulus. However, whether S1 neurons encode both frequency and amplitude of the vibrotactile stimulus or whether each sensory feature is encoded by separate populations of S1 neurons is not known, To further address these questions, we recorded S1 neurons while trained monkeys categorized only one sensory feature of the vibrotactile stimulus: frequency, amplitude, or duration. The results suggest a hierarchical encoding scheme in S1: from neurons that encode all sensory features of the vibrotactile stimulus to neurons that encode only one sensory feature. We hypothesize that the dynamic representation of each sensory feature in S1 might serve for further downstream processing that leads to the monkey’s psychophysical behavior observed in these tasks.

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.

scholarly journals Sensory computations in the cuneate nucleus of macaques

2021 ◽  
Author(s):  
Aneesha K Suresh ◽  
Charles M. Greenspon ◽  
Qinpu He ◽  
Joshua M Rosenow ◽  
Lee E Miller ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Receptive Fields ◽  
Nerve Fibers ◽  
Geometric Features ◽  
Cuneate Nucleus ◽  
Relevant Stimulus ◽  
Tactile Information ◽  
Conventional View ◽  
Random Dot Patterns ◽  
Stimulus Features

In primates, the responses of individual neurons in primary somatosensory cortex (S1) reflect convergent input from multiple classes of nerve fibers and are selective for behaviorally relevant stimulus features. The conventional view is that these response properties reflect computations that are effected in cortex, implying that sensory signals are not meaningfully processed in the two intervening structures - the Cuneate Nucleus (CN) and the thalamus. To test this hypothesis, we recorded the responses evoked in CN to a battery of stimuli that have been extensively used to characterize tactile coding, including skin indentations, vibrations, random dot patterns, and scanned edges. We found that CN responses are more similar to their S1 counterparts than they are to their inputs: CN neurons receive input from multiple sub-modalities, have spatially complex receptive fields, and exhibit selectivity for geometric features. Thus, CN plays a key role in the processing of tactile information.

Magnitude Estimation and Magnitude Production: Stimulus Frequency Effects on Magnitudes of Lingual Vibrotactile Sensation

1987 ◽  
Vol 64 (2) ◽  
pp. 663-670 ◽  
Author(s):  
Linda Petrosino ◽  
Donald Fucci ◽  
Daniel Harris
Keyword(s):  
Magnitude Estimation ◽  
Stimulus Frequency ◽  
Vibrotactile Stimulus ◽  
Psychophysical Method ◽  
Magnitude Production ◽  
Sensation Level ◽  
Estimation Task ◽  
Growth Functions ◽  
Sensation Magnitude ◽  
Production Values

The methods of magnitude estimation and magnitude production were employed to investigate the effects of stimulus frequency on suprathreshold lingual-vibrotactile sensation-magnitude functions. The method of magnitude estimation was used to obtain numerical judgments of sensation magnitudes for nine stimulus intensities presented to the anterior dorsum of the tongue. The vibrotactile stimulus frequencies employed for 10 subjects ( M age = 21.1 yr.) were 100, 250, and 400 Hz. The numerical responses obtained during the magnitude-estimation task were in turn used as stimuli to obtain magnitude-production values for the same three vibrotactile stimulus frequencies. The results appeared to present two suggestions. First, the effects of stimulus frequency on lingual vibrotactile-sensation magnitudes may be dependent on the psychophysical method used in any particular experiment. Second, lingual-vibrotactile magnitude-estimation scales may demonstrate asymptotic growth functions above about 25 dB sensation level. The limitation in the growth of sensation magnitude occurred for all three vibrotactile stimulus frequencies employed.

scholarly journals BOLD Adaptation in Vibrotactile Stimulation: Neuronal Networks Involved in Frequency Discrimination

2007 ◽  
Vol 97 (1) ◽  
pp. 264-271 ◽  
Author(s):  
Yiwen Li Hegner ◽  
Ralf Saur ◽  
Ralf Veit ◽  
Raymond Butts ◽  
Susanne Leiberg ◽  
...  
Keyword(s):  
Somatosensory Cortex ◽  
Stimulus Frequency ◽  
Superior Temporal Gyrus ◽  
Frequency Discrimination ◽  
Brain Regions ◽  
Adaptation Effect ◽  
Frequency Difference ◽  
Precentral Gyrus ◽  
Vibrotactile Stimulation ◽  
Cortical Areas

The present functional magnetic resonance imaging (fMRI) study investigated human brain regions subserving the discrimination of vibrotactile frequency. An event-related adaptation paradigm was used in which blood-oxygen-level-dependent (BOLD) responses are lower to same compared with different pairs of stimuli (BOLD adaptation). This adaptation effect serves as an indicator for feature-specific responding of neuronal subpopulations. Subjects had to discriminate two vibrotactile stimuli sequentially applied with a delay of 600 ms to their left middle fingertip. The stimulus frequency was in the flutter range of 18–26 Hz. In half of the trials, the two stimuli possessed identical frequency (same), whereas in the other half, a frequency difference of ±2 Hz was used (diff). As a result, BOLD adaptation was observed in the contralateral primary somatosensory cortex (S1), precentral gyrus, superior temporal gyrus (STG); ipsilateral insula as well as bilateral secondary somatosensory cortex and supplementary motor area. When statistically comparing the BOLD time courses between same and diff trials in these cortical areas, it was found that the vibrotactile BOLD adaptation is initiated in the contralateral S1 and STG simultaneously. These findings suggest that the cortical areas responsive to the frequency difference between two serially presented stimuli sequentially process the frequency of a vibrotactile stimulus and constitute a putative neuronal network underlying human vibrotactile frequency discrimination.

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