scholarly journals Sequence learning attenuates cortical responses in both frontal and perceptual cortices in early infancy

2021 ◽  
Author(s):  
Sagi Jaffe-Dax ◽  
Anna Herbolzheimer ◽  
Vikranth Rao Bejjanki ◽  
Lauren L Emberson

Prior work using a variety of imaging modalities has found that the frontal lobe is involved in higher-order sequential and statistical learning in young infants. Separate lines of work have found evidence of modulation of posterior sensory cortices during and after learning tasks. How do these processes relate together? Here, we build from a well-regarded EEG task that found evidence that the frontal lobe of young infants tracked higher-order sequential information (Basirat et al., 2014) and ask whether posterior perceptual cortices respond differentially to predictable vs. unpredictable sequences as well. First, replicating and extending past work, we found evidence of frontal lobe involvement in this task. Second, consistent with our hypotheses, we found that there is a corresponding attenuation of neural responses in the posterior perceptual cortices (temporal and occipital) to predictable compared to unpredictable audiovisual sequences. This study provides convergent evidence that the frontal lobe is crucial for higher-level learning in young infants but that it likely works as part of a large, distributed network of regions to modulate infant neural responses as a result of learning. Overall, this work challenges the view that the infant brain is not dynamic and disconnected, lacking in long-range neural connections. Instead, this paper reveals patterns of a highly dynamic and interconnected infant brain that change rapidly as a result of new, learnable experiences.

2019 ◽  
Author(s):  
Hsiang-Yun Sherry Chien ◽  
Christopher J. Honey

SummaryHow does information from seconds earlier affect neocortical responses to new input? Here, we used empirical measurements and computational modeling to study the integration and forgetting of prior information. We found that when two groups of participants heard the same sentence in a narrative, preceded by different contexts, the neural responses of each group were initially different, but gradually fell into alignment. We observed a hierarchical gradient: sensory cortices aligned most quickly, followed by mid-level regions, while higher-order cortical regions aligned last. In some higher order regions, responses to the same sentence took more than 10 seconds to align. What kinds of computations can explain this hierarchical organization of contextual alignment? Passive linear integration models predict that regions which are slower to integrate new information should also be slower to forget old information. However, we found that higher order regions could rapidly forget prior context. The data were better captured by a model composed of hierarchical autoencoders in time (HAT). In HAT, cortical regions maintain a temporal context representation which is actively integrated with input at each moment, and this integration is gated by prediction error. These data and models suggest that sequences of information are combined throughout the cortical hierarchy using an active and gated integration process.


2020 ◽  
Author(s):  
Moritz Köster ◽  
Miriam Langeloh ◽  
Christine Michel ◽  
Stefanie Hoehl

AbstractExamining how young infants respond to unexpected events is key to our understanding of their emerging concepts about the world around them. From a predictive processing perspective, it is intriguing to investigate how the infant brain responds to unexpected events (i.e., prediction errors), because they require infants to refine their predictive models about the environment. Here, to better understand prediction error processes in the infant brain, we presented 9-month-olds (N = 36) a variety of physical and social events with unexpected versus expected outcomes, while recording their electroencephalogram. We found a pronounced response in the ongoing 4 – 5 Hz theta rhythm for the processing of unexpected (in contrast to expected) events, for a prolonged time window (2 s) and across all scalp-recorded electrodes. The condition difference in the theta rhythm was not related to the condition difference in infants’ event-related activity on the negative central (Nc) component (.4 – .6 s), which has been described in former studies. These findings constitute critical evidence that the theta rhythm is involved in the processing of prediction errors from very early in human brain development, which may support infants’ refinement of basic concepts about the physical and social environment.


2020 ◽  
Vol 32 (7) ◽  
pp. 1369-1380 ◽  
Author(s):  
Nicola Binetti ◽  
Alessandro Tomassini ◽  
Karl Friston ◽  
Sven Bestmann

Timing emerges from a hierarchy of computations ranging from early encoding of physical duration (time sensation) to abstract time representations (time perception) suitable for storage and decisional processes. However, the neural basis of the perceptual experience of time remains elusive. To address this, we dissociate brain activity uniquely related to lower-level sensory and higher-order perceptual timing operations, using event-related fMRI. Participants compared subsecond (500 msec) sinusoidal gratings drifting with constant velocity (standard) against two probe stimuli: (1) control gratings drifting at constant velocity or (2) accelerating gratings, which induced illusory shortening of time. We tested two probe intervals: a 500-msec duration (Short) and a longer duration required for an accelerating probe to be perceived as long as the standard (Long—individually determined). On each trial, participants classified the probe as shorter or longer than the standard. This allowed for comparison of trials with an “Objective” (physical) or “Subjective” (perceived) difference in duration, based on participant classifications. Objective duration revealed responses in bilateral early extrastriate areas, extending to higher visual areas in the fusiform gyrus (at more lenient thresholds). By contrast, Subjective duration was reflected by distributed responses in a cortical/subcortical areas. This comprised the left superior frontal gyrus and the left cerebellum, and a wider set of common timing areas including the BG, parietal cortex, and posterior cingulate cortex. These results suggest two functionally independent timing stages: early extraction of duration information in sensory cortices and Subjective experience of duration in a higher-order cortical–subcortical timing areas.


2020 ◽  
Vol 117 (45) ◽  
pp. 28442-28451
Author(s):  
Monzilur Rahman ◽  
Ben D. B. Willmore ◽  
Andrew J. King ◽  
Nicol S. Harper

Sounds are processed by the ear and central auditory pathway. These processing steps are biologically complex, and many aspects of the transformation from sound waveforms to cortical response remain unclear. To understand this transformation, we combined models of the auditory periphery with various encoding models to predict auditory cortical responses to natural sounds. The cochlear models ranged from detailed biophysical simulations of the cochlea and auditory nerve to simple spectrogram-like approximations of the information processing in these structures. For three different stimulus sets, we tested the capacity of these models to predict the time course of single-unit neural responses recorded in ferret primary auditory cortex. We found that simple models based on a log-spaced spectrogram with approximately logarithmic compression perform similarly to the best-performing biophysically detailed models of the auditory periphery, and more consistently well over diverse natural and synthetic sounds. Furthermore, we demonstrated that including approximations of the three categories of auditory nerve fiber in these simple models can substantially improve prediction, particularly when combined with a network encoding model. Our findings imply that the properties of the auditory periphery and central pathway may together result in a simpler than expected functional transformation from ear to cortex. Thus, much of the detailed biological complexity seen in the auditory periphery does not appear to be important for understanding the cortical representation of sound.


2021 ◽  
Author(s):  
Joseph T Francis ◽  
Anna Rozenboym ◽  
Lee von Kraus ◽  
Shaohua Xu ◽  
Pratik Chhatbar ◽  
...  

Lost sensations, such as touch, could be restored by microstimulation (MiSt) along the sensory neural substrate. Such neuroprosthetic sensory information can be used as feedback from an invasive brain-machine interface (BMI) to control a robotic arm/hand, such that tactile and proprioceptive feedback from the sensorized robotic arm/hand is directly given to the BMI user. Microstimulation in the human somatosensory thalamus (Vc) has been shown to produce somatosensory perceptions. However, until recently, systematic methods for using thalamic stimulation to evoke naturalistic touch perceptions were lacking. We have recently presented rigorous methods for determining a mapping between ventral posterior lateral thalamus (VPL) MiSt, and neural responses in the somatosensory cortex (S1), in a rodent model (Choi et al., 2016; Choi and Francis, 2018). Our technique minimizes the difference between S1 neural responses induced by natural sensory stimuli and those generated via VPL MiSt. Our goal is to develop systems that know what MiSt will produce a given neural response and possibly a more natural "sensation." To date, our optimization has been conducted in the rodent model and simulations. Here we present data from simple non-optimized thalamic MiSt during peri-operative experiments, where we MiSt in the VPL of macaques with a somatosensory system more like humans. We implanted arrays of microelectrodes across the hand area of the macaque S1 cortex as well as in the VPL thalamus. Multi and single-unit recordings were used to compare cortical responses to natural touch and thalamic MiSt in the anesthetized state. Post stimulus time histograms were highly correlated between the VPL MiSt and natural touch modalities, adding support to the use of VPL MiSt towards producing a somatosensory neuroprosthesis in humans.


2019 ◽  
Author(s):  
Kelly K Chong ◽  
Alex G Dunlap ◽  
Dorottya B Kacsoh ◽  
Robert C Liu

SUMMARYFrequency modulations are an inherent feature of many behaviorally relevant sounds, including vocalizations and music. Changing trajectories in a sound’s frequency often conveys meaningful information, which can be used to differentiate sound categories, as in the case of intonations in tonal languages. However, it is not clear what features of the neural responses in what parts of the auditory cortical pathway might be more important for conveying information about behaviorally relevant frequency modulations, and how these responses change with experience. Here we uncover tuning to subtle variations in frequency trajectories in mouse auditory cortex. Surprisingly, we found that auditory cortical responses could be modulated by variations in a pure tone trajectory as small as 1/24th of an octave. Offset spiking accounted for a significant portion of tuned responses to subtle frequency modulation. Offset responses that were present in the adult A2, but not those in Core auditory cortex, were plastic in a way that enhanced the representation of an acquired behaviorally relevant sound category, which we illustrate with the maternal mouse paradigm for natural communication sound learning. By using this ethologically inspired sound-feature tuning paradigm to drive auditory responses in higher-order neurons, our results demonstrate that auditory cortex can track much finer frequency modulations than previously appreciated, which allows A2 offset responses in particular to attune to the pitch trajectories that distinguish behaviorally relevant, natural sound categories.


2021 ◽  
Vol 05 (03) ◽  
pp. 1-1
Author(s):  
Nasim Foroughi ◽  
◽  
Brooke Donnelly ◽  
Mark Williams ◽  
Sloane Madden ◽  
...  

To compare neural responses to high and low-energy food images in patients with Anorexia Nervosa (AN) and an age-matched Healthy Control (HC) group. 25 adolescents with AN and 21 HCs completed a diagnostic interview, self-report questionnaires and fMRI, during which they viewed food images evoking responses of disgust, happiness, or fear. Following whole brain analyses, neural responses in six regions of interest were examined in a series of between-group contrasts, across the three emotive categories. Compared to the HCs, people in the AN group showed increased responsivity to high-energy (1) disgust images in temporal lobe, frontal lobe, insula, and cerebellum anterior lobe; (2) fear images in occipital lobe, temporal, and frontal lobes and (3) happy images in frontal lobe, cerebellum anterior lobe, sub-lobar, and cuneus. More activity was observed in response to low-energy (1) disgust food images in the temporal lobe, frontal lobe, insula, cerebellum anterior and posterior lobes, parietal lobe, occipital lobe, and limbic lobe; (2) and happy food images in frontal lobes. Few correlations were found with levels of eating disorder symptoms. The findings highlight the emotional impact of diverse high and low-energy foods for people with AN. People without AN may have a better capacity to filter salient from non-salient information relating to the current task when viewing high energy foods. In summary, for those with AN, it would seem their ability to efficiently ‘sort-out’ information (especially information pertaining to disorder-relevant stimuli such as food images) to complete the task at hand, may be diminished.


2021 ◽  
pp. 1-16
Author(s):  
Heejung Jung ◽  
Tor D. Wager ◽  
R. McKell Carter

Abstract Functions in higher-order brain regions are the source of extensive debate. Although past trends have been to describe the brain—especially posterior cortical areas—in terms of a set of functional modules, a new emerging paradigm focuses on the integration of proximal functions. In this review, we synthesize emerging evidence that a variety of novel functions in the higher-order brain regions are due to convergence: convergence of macroscale gradients brings feature-rich representations into close proximity, presenting an opportunity for novel functions to arise. Using the TPJ as an example, we demonstrate that convergence is enabled via three properties of the brain: (1) hierarchical organization, (2) abstraction, and (3) equidistance. As gradients travel from primary sensory cortices to higher-order brain regions, information becomes abstracted and hierarchical, and eventually, gradients meet at a point maximally and equally distant from their sensory origins. This convergence, which produces multifaceted combinations, such as mentalizing another person's thought or projecting into a future space, parallels evolutionary and developmental characteristics in such regions, resulting in new cognitive and affective faculties.


Neuroforum ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Patrick O. Kanold

Abstract The cerebral cortex is essential for our sensory experiences and conscious thought. Its neural connections, in particular sensory areas of the cerebral cortex, are shaped and sculpted by our early sensory experiences. Onset of these first sensory experiences of the world mark an important developmental event, enabling our worldy interactions to shape the makeup of our cerebral cortex. These long-lasting effects of early sensory experience are particularly striking in human communication, since early exposure to the mother’s language is required to detect all nuances in the underlying sounds. Early interactions with the world are mediated by a key set of neurons, subplate neurons, which remain part of the developing cerebral cortex until most of them disappear at later stages of development. They play a crucial role in the developing mammalian brain. Here I review the circuitry and functional roles of cortical subplate neurons, focusing on their purpose in the development of primary sensory cortices.


Cephalalgia ◽  
2010 ◽  
Vol 30 (8) ◽  
pp. 910-918 ◽  
Author(s):  
Rina Lev ◽  
Yelena Granovsky ◽  
David Yarnitsky

This study aimed to identify the cortical mechanisms underlying the processes of interictal dishabituation to experimental pain in subjects suffering from migraine with aura (MWA). In 21 subjects with MWA and 22 healthy controls, cortical responses to two successive trials of noxious contact-heat stimuli were analyzed using EEG-tomography software. When compared with controls, MWA patients showed significantly increased pain-evoked potential amplitudes accompanied by reduced activity in the orbitofrontal cortex (OFC) and increased activity in the pain matrix regions, including the primary somatosensory cortex (SI) ( p < .05). Similarly to controls, MWA subjects displayed an inverse correlation between the OFC and SI activities, and positive interrelations between other pain-specific regions. The activity changes in the OFC negatively correlated with lifetime headache duration and longevity ( p < .05). Reduced inhibitory functioning of the prefrontal cortex is a possible cause for disinhibition of the pain-related sensory cortices in migraine. The finding of OFC hypofunction over the disease course is in keeping with current concepts of migraine as a progressive brain disorder.


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