scholarly journals Associative learning changes cross-modal representations in the gustatory cortex

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Roberto Vincis ◽  
Alfredo Fontanini

A growing body of literature has demonstrated that primary sensory cortices are not exclusively unimodal, but can respond to stimuli of different sensory modalities. However, several questions concerning the neural representation of cross-modal stimuli remain open. Indeed, it is poorly understood if cross-modal stimuli evoke unique or overlapping representations in a primary sensory cortex and whether learning can modulate these representations. Here we recorded single unit responses to auditory, visual, somatosensory, and olfactory stimuli in the gustatory cortex (GC) of alert rats before and after associative learning. We found that, in untrained rats, the majority of GC neurons were modulated by a single modality. Upon learning, both prevalence of cross-modal responsive neurons and their breadth of tuning increased, leading to a greater overlap of representations. Altogether, our results show that the gustatory cortex represents cross-modal stimuli according to their sensory identity, and that learning changes the overlap of cross-modal representations.

2021 ◽  
Author(s):  
Karita E Ojala ◽  
Matthias Staib ◽  
Samuel Gerster ◽  
Christian C Ruff ◽  
Dominik R Bach

Sensory cortices are required for learning to discriminate complex stimuli that predict threat from those that predict safety in rodents. Yet, sensory cortices may not be needed to learn threat associations to simple stimuli. It is unknown whether these findings apply in humans. Here, we investigated the role of primary sensory cortex in discriminative threat conditioning with simple and complex somatosensory conditioned stimuli (CS) in healthy humans. Immediately before conditioning, participants received continuous theta-burst transcranial magnetic stimulation (cTBS) to primary somatosensory cortex either in the CS-contralateral or CS-ipsilateral hemisphere. After overnight consolidation, threat memory was attenuated in the contralateral compared to the ipsilateral group, as indicated by reduced startle eye-blink potentiation. There was no evidence for a difference between simple and complex stimuli, or that CS identification or conditioning was affected, suggesting a stronger effect of cTBS on consolidation than on initial stimulus processing. We propose that non-invasive stimulation of sensory cortex may provide a new avenue for interfering with threat memories in humans.


2019 ◽  
Author(s):  
Ronan Chéreau ◽  
Tanika Bawa ◽  
Leon Fodoulian ◽  
Alan Carleton ◽  
Stéphane Pagès ◽  
...  

ABSTRACTNeurons in primary sensory cortex encode a variety of stimulus features upon perceptual learning. However, it is unclear whether the acquired stimulus selectivity remains stable when the same input is perceived in a different context. Here, we monitored the activity of individual neurons in the mouse primary somatosensory cortex in a reward-based texture discrimination task. We tracked their stimulus selectivity before and after changing reward contingencies, which allowed us to identify various classes of neurons. We found neurons that stably represented a texture or the upcoming behavioral choice, but the majority was dynamic. Among those, a subpopulation of neurons regained selectivity contingent on stimulus-value. These value-sensitive neurons forecasted the onset of learning by displaying a distinct and transient increase in activity, depending on past behavioral experience. Thus, stimulus selectivity of excitatory neurons during perceptual learning is dynamic and largely relies on behavioral contingencies, even in primary sensory cortex.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Laura. R. Koenen ◽  
Robert. J. Pawlik ◽  
Adriane Icenhour ◽  
Liubov Petrakova ◽  
Katarina Forkmann ◽  
...  

2010 ◽  
Vol 104 (2) ◽  
pp. 784-798 ◽  
Author(s):  
Noopur Amin ◽  
Patrick Gill ◽  
Frédéric E. Theunissen

We estimated the spectrotemporal receptive fields of neurons in the songbird auditory thalamus, nucleus ovoidalis, and compared the neural representation of complex sounds in the auditory thalamus to those found in the upstream auditory midbrain nucleus, mesencephalicus lateralis dorsalis (MLd), and the downstream auditory pallial region, field L. Our data refute the idea that the primary sensory thalamus acts as a simple, relay nucleus: we find that the auditory thalamic receptive fields obtained in response to song are more complex than the ones found in the midbrain. Moreover, we find that linear tuning diversity and complexity in ovoidalis (Ov) are closer to those found in field L than in MLd. We also find prevalent tuning to intermediate spectral and temporal modulations, a feature that is unique to Ov. Thus even a feed-forward model of the sensory processing chain, where neural responses in the sensory thalamus reveals intermediate response properties between those in the sensory periphery and those in the primary sensory cortex, is inadequate in describing the tuning found in Ov. Based on these results, we believe that the auditory thalamic circuitry plays an important role in generating novel complex representations for specific features found in natural sounds.


2021 ◽  
Author(s):  
Du Zhang ◽  
Xiaoxiao Wang ◽  
Yanming Wang ◽  
Benedictor Alexander Nguchu ◽  
Zhoufang Jiang ◽  
...  

The topological representation is a fundamental property of human primary sensory cortices. The human gustatory cortex (GC) responds to the five basic tastes: bitter, salty, sweet, umami, and sour. However, the topological representation of the human gustatory cortex remains controversial. Through functional magnetic resonance imaging(fMRI) measurements of human responses to the five basic tastes, the current study aimed to delineate the taste representations within the GC. During the scanning, the volunteers tasted solutions of the five basic tastes, then washed their mouths with the tasteless solution. The solutions were then sucked from the volunteers' mouths, eliminating the action of swallowing. The results showed that the bilateral mid-insula activated most during the taste task, and the active areas were mainly in the precentral and central insular sulcus. However, the regions responding to the five basic tastes are substantially overlapped, and the analysis of contrasts between each taste response and the averaged response to the remaining tastes does not report any significant results. Furthermore, in the gustatory insular cortex, the multivariate pattern analysis (MVPA) was unable to distinguish the activation patterns of the basic tastes, suggesting the possibility of weakly clustered distribution of the taste-preference neural activities in the human insular cortex. In conclusion, the presented results suggest overlapping representations of the basic tastes in the human gustatory insular cortex.


NeuroImage ◽  
2001 ◽  
Vol 13 (6) ◽  
pp. 1226
Author(s):  
Robert Meyer ◽  
Felix Blankenburg ◽  
Jan Ruben ◽  
Jessica Schwiemann ◽  
Sebastian Thees ◽  
...  

2012 ◽  
Vol 108 (5) ◽  
pp. 1278-1287 ◽  
Author(s):  
Rebekah L. Ward ◽  
Luke C. Flores ◽  
John F. Disterhoft

The barrel cortex (BC) is essential for the acquisition of whisker-signaled trace eyeblink conditioning and shows learning-related expansion of the trained barrels after the acquisition of a whisker-signaled task. Most previous research examining the role of the BC in learning has focused on anatomic changes in the layer IV representation of the cortical barrels. We studied single-unit extracellular recordings from individual neurons in layers V and VI of the BC as rabbits acquired the whisker-signaled trace eyeblink conditioning task. Neurons in layers V and VI in both conditioned and pseudoconditioned animals robustly responded to whisker stimulation, but neurons in conditioned animals showed a significant enhancement in responsiveness in concert with learning. Learning-related changes in firing rate occurred as early as the day of learning criterion within the infragranular layers of the primary sensory cortex.


2002 ◽  
Vol 87 (4) ◽  
pp. 2137-2148 ◽  
Author(s):  
Sean M. O'Connor ◽  
Rune W. Berg ◽  
David Kleinfeld

We tested if coherent signaling between the sensory vibrissa areas of cerebellum and neocortex in rats was enhanced as they whisked in air. Whisking was accompanied by 5- to 15-Hz oscillations in the mystatial electromyogram, a measure of vibrissa position, and by 5- to 20-Hz oscillations in the differentially recorded local field potential (∇LFP) within the vibrissa area of cerebellum and within the ∇LFP of primary sensory cortex. We observed that only 10% of the activity in either cerebellum or sensory neocortex was significantly phase-locked to rhythmic motion of the vibrissae; the extent of this modulation is in agreement with the results from previous single-unit measurements in sensory neocortex. In addition, we found that 40% of the activity in the vibrissa areas of cerebellum and neocortex was significantly coherent during periods of whisking. The relatively high level of coherence between these two brain areas, in comparison with their relatively low coherence with whisking per se, implies that the vibrissa areas of cerebellum and neocortex communicate in a manner that is incommensurate with whisking. To the extent that the vibrissa areas of cerebellum and neocortex communicate over the same frequency band as that used by whisking, these areas must multiplex electrical activity that is internal to the brain with activity that is that phase-locked to vibrissa sensory input.


2020 ◽  
Vol 30 (8) ◽  
pp. 4662-4676
Author(s):  
Kevin J Monk ◽  
Simon Allard ◽  
Marshall G Hussain Shuler

Abstract The primary sensory cortex has historically been studied as a low-level feature detector, but has more recently been implicated in many higher-level cognitive functions. For instance, after an animal learns that a light predicts water at a fixed delay, neurons in the primary visual cortex (V1) can produce “reward timing activity” (i.e., spike modulation of various forms that relate the interval between the visual stimulus and expected reward). Local manipulations to V1 implicate it as a site of learning reward timing activity (as opposed to simply reporting timing information from another region via feedback input). However, the manner by which V1 then produces these representations is unknown. Here, we combine behavior, in vivo electrophysiology, and optogenetics to investigate the characteristics of and circuit mechanisms underlying V1 reward timing in the head-fixed mouse. We find that reward timing activity is present in mouse V1, that inhibitory interneurons participate in reward timing, and that these representations are consistent with a theorized network architecture. Together, these results deepen our understanding of V1 reward timing and the manner by which it is produced.


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