Effect of Rotating Auditory Scene on Postural Control in Normal Subjects, Patients With Bilateral Vestibulopathy, Unilateral, or Bilateral Cochlear Implants

Objective: The aim of this study was to investigate the impact of a rotating sound stimulation on the postural performances in normal subjects, patients with bilateral vestibulopathy (BVP), unilateral (UCI), and bilateral (BCI) cochlear implantees.Materials and Methods: Sixty-nine adults were included (32 women and 37 men) in a multicenter prospective study. The group included 37 healthy subjects, 10 BVP, 15 UCI, and 7 BCI patients. The average of age was 47 ± 2.0 (range: 23–82). In addition to a complete audiovestibular work up, a dynamic posturography (Multitest Framiral, Grasse) was conducted in silence and with a rotating cocktail party sound delivered by headphone. The center of pressure excursion surface (COPS), sensory preferences, as well as fractal, diffusion, and wavelet analysis of stabilometry were collected.Results: The rotating sound seemed to influenced balance in all subgroups except in controls. COPS increased with sound in the BVP and BCI groups in closed eyes and sway-referenced condition indicating a destabilizing effect while it decreased in UCI in the same condition suggesting stabilization (p < 0.05, linear mixed model corrected for age, n = 69). BVP had higher proprioceptive preferences, BCI had higher vestibular and visual preferences, and UCI had only higher vestibular preferences than controls. Sensory preferences were not altered by rotating sound.Conclusions: The rotating sound destabilized BVP and BCI patients with binaural hearing while it stabilized UCI patients with monaural hearing and no sound rotation effect. This difference suggests that binaural auditory cues are exploited in BCI patients for their balance

Funzioni di alto livello nella corteccia somatosensoriale secondaria (SII)

Le proprietà della corteccia somato-sensoriale secondaria (SII) sono state largamente discusse in molteplici studi sia nella scimmia, sia nell’uomo, suggerendo che quest’area assolva funzioni di alto livello nel processamento dello stimolo tattile, quali, ad esempio, l’apprendimento o la memoria. Recentemente, alcuni studi su scimmia hanno evidenziato che, oltre agli stimoli somato-sensoriali, SII risponde anche alla stimolazione dello spazio peri-personale, all’esecuzione di azioni, alla vista di oggetti in movimento ed all’osservazione di azioni, candidando SII ad essere un’area complessa, non limitata a sole funzioni somato-sensoriali. Partendo dallo studio delle risposte di SII agli stimoli tattili, lo scopo di questa tesi è di investigare la risposta di quest’area a stimoli complessi, con particolare attenzione a task di integrazione visuo-tattile e all’osservazione di azioni nell’uomo. Con queste finalità, gli esperimenti presentati sono stati condotti mediante elettroencefalografia stereotassica (stereo-EEG) su pazienti epilettici farmaco-resistenti, impiantati come parte della loro valutazione pre-chirurgica. In una prima fase, sono stati studiati la distribuzione spaziale ed il profilo temporale delle risposte intra-corticali alla stimolazione del nervo mediano controlaterale ed ipsilaterale. I risultati ottenuti indicano che mentre la corteccia somato-sensoriale primaria (SI), il giro precentrale ed il solco intra-parietale rispondono solo alla stimolazione controlaterale, la corteccia somato-sensoriale secondaria e l’insula posteriore sono attivate bilateralmente. Inoltre, queste ultime sono caratterizzate da una risposta tonica e duratura nel tempo. Questa potrebbe rappresentare un meccanismo di ritenzione temporale dell’informazione tattile ed essere l’espressione di funzioni di alto livello quali appunto la memoria e l’apprendimento degli stimoli. Nella seconda sezione della tesi, per testare il possibile coinvolgimento dell’opercolo parietale nell’integrazione visuo-tattile, la stimolazione del nervo mediano controlaterale è stata somministrata congiuntamente ad una stimolazione visiva (i.e. flash). I risultati ottenuti evidenziano un aumento in ampiezza della componente tonica, se comparato alla sola stimolazione tattile, localizzato nell’insula posteriore e nelle porzioni più rostrali dell’opercolo parietale mentre SII mostra un comportamento del tutto inalterato. Tuttavia, tenendo in considerazione che studi su primati non umani riportano risposte visiva in SII a stimoli biologici, sono necessarie ulteriori indagini per comprendere quale tipologia di stimolazione determina l’attivazione di quest’area. Infine, la terza parte della tesi mostra le risposte intra-corticali di SI e SII ad un task motorio che include compiti di afferramento e manipolazione di oggetti, e all’osservazione delle stesse azioni eseguite da un altro individuo. I risultati evidenziano un’attivazione bilaterale di SII, sia durante l’esecuzione sia durante l’osservazione di azioni, con un profilo temporale sincrono. Al contrario SI è attiva solo durante l’esecuzione: l’input a SI durante l’osservazione non ha dunque una natura somato-sensoriale ma piuttosto deve essere sostenuto da un circuito visuo-motorio capace di operare in maniera simultanea. In conclusione, questa tesi dimostra il ruolo cruciale di SII non solo nel processamento degli stimoli tattili ma anche nell’integrazione di stimoli visuo-motori.The somatosensory properties of the second somatosensory cortex (SII) have been largely described by many studies in both monkeys and humans, suggesting for this area a high-order role in tactile stimulation processing with functions including tactile learning and memory. More interestingly, recent studies on monkeys showed that beyond somatosensory stimuli, SII responds to a wider number of stimuli including peripersonal space stimulation, active movements, observation of objects displacement and action observation. Taking into account these results, SII is a candidate to be more than just a somatosensory area. Starting from its somatosensory properties, this thesis aims to disentangle the role of SII in more complex tasks with particular attention to visuo-tactile integration and action observation in humans. To this purpose, the experiments presented in this thesis are carried with stereotactic electroencephalography (stereo-EEG) on drug-resistant epileptic patients to take advantage of its high temporal and spatial resolution. Firstly, I investigated the spatial distribution and the temporal profile of the intracortical responses to both contralateral and ipsilateral median nerve stimulation. Results indicated that while the primary somatosensory area, precentral gyrus and intra-parietal sulcus respond only to the contralateral stimulation, the secondary somatosensory cortex and posterior insula are activated bilaterally. Furthermore, these regions exhibit a tonic long-lasting temporal profile, which might represent a mechanism of temporal retention of the tactile information, and thus be the signature of high-level somatosensory functions such as tactile memory and awareness. In a second stage of the thesis, to test the possible involvement of parietal operculum in visuo-tactile integration, we administered to patients contralateral median nerve stimulation jointly with visual stimulation (i.e. flash) to about 100 drug-resistant epileptic patients. Results underline an enhancement of the tonic components relative to tactile stimulation only, limited to posterior insula and to the rostral areas of parietal operculum, with SII maintaining an unaltered behavior. Considering previous findings in non-human primates, which reported visual responses in SII in response to biological stimuli, further researches are needed to understand which threshold in the stimulus might determine the eventual activation of this area. With this aim, the third part of this thesis presents the intracortical responses of both SI and SII to a motor task requiring reaching, grasping and manipulation, as well as to the observation of the same actions performed by another individual. The results obtained highlighted that SII activates bilaterally, both during the execution and the observation of actions, with a synchronous temporal profile. Conversely, SI activates only during the execution, leading to the conclusion that the input to SII during the observation condition has not a somatosensory nature, but rather that it is sustained by visuo-motor circuits operating simultaneously. Taking together all the evidence, this thesis demonstrates the pivotal role of SII not only in somatosensory functions, as largely reported in literature, but also in the integration of visuo-motor stimuli

The Organization of the Primate Insular Cortex

Long perceived as a primitive and poorly differentiated brain structure, the primate insular cortex recently emerged as a highly evolved, organized and richly connected cortical hub interfacing bodily states with sensorimotor, environmental, and limbic activities. This insular interface likely substantiates emotional embodiment and has the potential to have a key role in the interoceptive shaping of cognitive processes, including perceptual awareness. In this review, we present a novel working model of the insular cortex, based on an accumulation of neuroanatomical and functional evidence obtained essentially in the macaque monkey. This model proposes that interoceptive afferents that represent the ongoing physiological status of all the organs of the body are first being received in the granular dorsal fundus of the insula or “primary interoceptive cortex,” then processed through a series of dysgranular poly-modal “insular stripes,” and finally integrated in anterior agranular areas that serve as an additional sensory platform for visceral functions and as an output stage for efferent autonomic regulation. One of the agranular areas hosts the specialized von Economo and Fork neurons, which could provide a decisive evolutionary advantage for the role of the anterior insula in the autonomic and emotional binding inherent to subjective awareness

다중손가락 과제 수행 시 인간의 감각 및 인지 처리 과정의 정량화

학위논문 (박사) -- 서울대학교 대학원 : 사범대학 체육교육과, 2021. 2. 박재범.The continuously varied states of human body and surrounding environment require instantaneous motor adaptations and the understanding of motor goal to achieve desired actions. These sensory and cognitive processes have been investigated as elements in motor control during last five decades. Specially, the task dependency on sensory and cognitive processes suggest the effects of movement properties in terms of environment situation and motor goal. However, these effects were mostly empirically summarized with the measurements of either neural activity or simple motor accomplishment unilaterally. The current thesis addresses the quantification of sensory and cognitive processes based on simultaneous measurements of brain activity and synergic motor performance during multi-digit actions with different movement properties. Multi-digit action as a representation of synergic movements has developed into a widespread agency to quantify the efficacy of motor control, as the reason applied in this thesis. In this thesis, multi-digit rotation and pressing tasks were performed with different movement directions, frequencies, feedback modalities, or task complexities. (Chapter 3) The changes of movement direction induced a decrease in motor synergy but regardless of which direction. (Chapter 4 and 5) Increased frequency of rhythmic movement reduced synergic motor performance associate with decreased sensory process and less efficient cognitive process. (Chapter 6) More comprehensive feedback modality improved synergic performance with increased sensory process. (Chapter 7) Increased movement complexity had a consistent but stronger effect as increased frequency on synergic performance and efficiency of cognitive process. These observations suggest that several movement properties affect the contributions of sensory and cognitive processes to motor control which can be quantified through either neural activity or synergic motor performance. Accordingly, those movement properties may be applied in the rehabilitation of motor dysfunction by developing new training programs or assistant devices. Additionally, it may be possible to develop a simplified while efficient method to estimate the contribution of sensory or cognitive process to motor control.시시각각으로 변화하는 신체 상태와 주변 환경의 상호작용 속에서 알맞은 움직임을 수행하기 위해서는 그에 따른 즉각적인 운동 적응(motor adaptation) 과정와 과제 목표에 대한 이해가 필요하다. 이를 위해 인간의 감각 및 인지 처리과정은 운동 제어 분야의 중요한 요소로 여겨졌다. 선행연구에 따르면, 운동 과제에 따라 변화하는 감각 및 인지 처리과정은 주변 환경과 과제의 목표에 따라 움직임의 특성에 영향을 미친다고 보고되어왔다. 그러나 이러한 영향은 대부분 단순한 운동과제 수행 결과 또는 측정된 신경 활동에 의해 경험적으로 요약된 결과에 국한되어 있다. 따라서 본 논문은 다양한 움직임 특성을 가진 다중 손가락 과제 수행 시, 뇌 활동 (Brain activity)과 더불어 손가락들 간의 협응적인 움직임의 수행 결과를 동시 측정하여 과제의 특성에 따른 감각 및 인지 처리과정의 변화를 분석했다. 다중 손가락 과제는 운동 제어의 성능 효율성을 정량화하기 위해 사용되는 대표적인 과제다. 본 논문에서는 다양한 조건의 움직임 방향, 움직임의 주기빈도, 감각 피드백 양식 또는 과제 난이도에 따른 다중 손가락 회전 동작 및 힘 생성 과제를 사용했다. 연구 결과로는, (문단 3) 움직임 방향이 변화하기 전에 변화할 방향에 상관없이 협응적인 움직임이 악화되었다. (문단 4와 5) 움직임의 주기빈도가 증가할수록 협응적인 움직임이 악화됐으며, 이와 관련된 감각 및 인지 처리과정의 효율성도 감소되었다. (문단 6) 단일 감각 피드백 제공조건에 비해 종합적인 감각 피드백은 증가된 감각 처리과정과 함께 협응적인 움직임을 향상시켰다. (문단 7) 과제의 난이도가 증가할수록 협응적인 움직임과 인지 처리과정의 효율성은 감소되었으며, 움직임의 주기빈도 조건에 비해 과제의 난이도에 따라 협응적인 움직임과 인지 처리과정에 미치는 영향은 상대적으로 더 크게 나타났다. 이러한 결과는 움직임 특성에 따른 뇌 활동과 협응적인 과제 수해 결과를 통해 운동 제어 과정에서 감각 및 인지 처리과정의 기여정도를 정량화할 수 있다는 점을 시사한다. 따라서 움직임 특성에 따른 감각 및 인지 처리 과정의 기여정도의 변화는 운동 기능 장애를 가진 사람들의 새로운 재활 훈련 프로그램 및 움직임 보조 장치를 개발하기 위한 실험적인 근거로 적용될 수 있다. 또한 감각 또는 인지 과정이 운동 제어에 미치는 영향을 추정하기 위한 효율적인 방법을 개발하는데 도움이 될 것이다.Chapter 1. Introduction 1 1.1 Problem statement 1 1.2 Study objective 2 1.3 Organization of dissertation 3 Chapter 2. Background 6 2.1 Motor system 6 2.1.1 Ascending pathway 6 2.1.2 Descending pathway 8 2.1.3 Brain networks 9 2.2 Motor synergy 11 2.2.1 Synergy in performance 12 2.2.2 Synergy in muscles 13 2.2.3 Synergy in neurons 14 2.3 Motor control 15 2.1.1 Sensory process 16 2.1.2 Cognitive process 19 Chapter 3. Effect of movement direction: Multi-Finger Interaction and Synergies in Finger Flexion and Extension Force Production 23 3.1 Abstract 23 3.2 Introduction 24 3.3 Method 28 3.4 Results 35 3.4.1 Maximal voluntary contraction (MVC) force and finger independency 36 3.4.2 Timing indices 37 3.4.3 Multi-finger synergy indices in mode space 39 3.4.4 Multi-finger synergy indices in force space 43 3.5 Discussion 44 3.5.1 Finger independency during finger flexion and extension 44 3.5.2 Multi-finger synergies in force and mode spaces 46 3.5.3 Anticipatory synergy adjustment 48 Chapter 4. Effect of Frequency: Brain Oxygenation Magnitude and Mechanical Outcomes during Multi-Digit Rhythmic Rotation Task 51 4.1 Abstract 51 4.2 Introduction 51 4.3 Methods 55 4.4 Results 61 4.4.1 PET imaging 61 4.4.2 Finger forces 62 4.4.3 UCM analysis 64 4.4.4 Correlation between neural activation and mechanics 65 4.5 Discussion 66 4.5.1 Regions involved in feedback 67 4.5.2 Regions involved in feedforward 69 4.5.3 Corporation of feedforward and feedback 71 4.6 Conclusions 72 Chapter 5. Effect of frequency: Prefrontal Cortex Oxygenation during Multi-Digit Rhythmic Pressing Actions using fNIRS 74 5.1 Abstract 74 5.2 Introduction 74 5.3 Method 77 5.4 Results 84 5.4.1 Performance 84 5.4.2 Multi-digit coordination indices 84 5.4.3 Functional connectivity (FC) 87 5.5 Discussion 88 5.6 Conclusion 91 Chapter 6. Effect of Sensory Modality: Multi-Sensory Integration during Multi-Digit Rotation Task with Different Frequency 92 6.1 Abstract 92 6.2 Introduction 92 6.3 Method 94 6.4 Results 100 6.4.1 Performance 100 6.4.2 Multi-digit coordination indices 101 6.5 Discussion 101 6.6 Conclusion 103 Chapter 7. Effect of Task Complexity: Prefrontal Cortex Oxygenation during Multi-Digit Pressing Actions with Different Frequency Components 104 7.1 Abstract 104 7.2 Introduction 104 7.3 Method 106 7.4 Results 112 7.4.1 Performance 112 7.4.2 Multi-finger coordination indices 113 7.4.3 Functional connectivity (FC) 114 7.5 Discussion 115 7.5.1 Relation between Frequency and task complexity 115 7.5.2 Cognitive process in motor control 116 7.5.3 Relation between motor coordination and cognitive process 118 7.6 Conclusion 119 Chapter 8. Conclusions and Future Work 120 8.1 Summary of conclusions 120 8.2 Future work 121 Bibliography 122 Abstract in Korean 160Docto

“Functional MRI Study of Human Gustatory Cortex: Technological Advancements and Applications to Basic and Clinical Neurosciences”

2017 - 2018The purpose of brain plasticity is generating adaptive behaviours while predicting, interpreting, and responding to more and more complex tasks. Some of the most riveting questions in neuroscience revolve around the relationship between neural circuit structure, neural dynamics, and complex behaviour. The capability to understand the mechanisms that govern the brain under certain conditions is extremely helpful to predict human behaviour and to find possible brain alterations caused by or determining specific pathologies. … [edited by Author]XVII n.s. (XXXI ciclo

Neuroanatomical Correlates of Bifactor Model of Internalizing Psychopathology Across The Lifespan

High rates of comorbidity between internalizing disorders and heterogeneity in the behavioral manifestations of a single disorder have made it challenging to identify biological signatures of specific mental illnesses. This may in part be due to the case-control frameworks which dominate psychopathology research, frameworks which draw stark distinctions between patients and healthy individuals despite evidence that such distinctions may not reflect the distribution of behavior across the population. To address these issues, there has been a recent emphasis on employing dimensional models of psychopathology which characterize psychopathology as arising through the interaction of behaviors that are continuously distributed throughout the general population. In the current dissertation project, we first propose a novel six-factor dimensional model of internalizing psychopathology and demonstrate that dimensions in this model show preferential associations with specific internalizing disorders. We then employ gray matter morphometry analyses to identify the degree to which individual differences in internalizing dimensions are associated with structural properties of gray matter across the brain. Finally, we evaluate which dimensions are driven by genes or the environment, as well as the degree to which relationships between these dimensions and gray matter structure result from overlapping genetic or environmental influences. Our findings suggest 1) previous dimensional models of internalizing psychopathology may be improved by including cognitive dimensions of behavior, including rumination and repetitive negative thought, 2) the brain regions associated with internalizing dimensions are more distributed than the regions identified in case-control studies while also changing with age and differing by sex, and 3) behaviors that are common across internalizing disorders are largely genetic in nature, whereas behaviors that are specific to anxiety may be influenced by shared environmental factors.</p