Atenção consiste em conjunto de processos que leva à seleção ou priorização no processamento de certas categorias de informação, em detrimento de outras, possibilitando um processamento mais eficiente do que seria possível caso o sistema nervoso processasse os estímulos presentes no ambiente simultaneamente. A atenção participa da maioria das funções cognitivas humanas. Depende, portanto, de região cerebral com privilégios anátomo-fisiológicos, como o lobo parietal, cujo padrão de conectividade (áreas unimodais, córtex pré-motor, colículo superior, giro cingulado, giro parahipocampal, insula, córtex orbitofrontal) possibilita a integração sensório-motora e cognitiva necessária à atenção. Desde o início da década de 80 estudos sobre o lobo parietal tem sugerido uma reavaliação de suas funções, modificando a percepção comum de que esteja relacionado exclusivamente a desempenhar funções espaciais, incluindo uma suposta especialização do lobo parietal direito na distribuição da atenção no espaço. No entanto, a base fisiológica para a especialização do lobo parietal na orientação atencional é mal compreendida pelas seguintes razões: 1- lesão unilateral do lobo parietal direito determina deficiência de processamento atencional em relação ao hemiespaço contralateral, e raramente ocorre após lesão do lobo parietal esquerdo; 2- o processamento das informações pelo sistema visual humano varia sensivelmente em relação aos campos visuais, e a metodologia dos testes atencionais tradicionais não considera que o desempenho dos voluntários pode ser limitado pela visibilidade dos estímulos; a localização dos estímulos tem sido avaliada independentemente da disposição dos alvos no campo visual. Nossa proposta é padronizar as condições de estimulação no teste de Posner para orientação da atenção, considerando os limiares específicos de cada voluntário e avaliar as deficiências de orientação da atenção endógena e exógena nos planos horizontal, vertical e diagonal, em pacientes portadores de dano nos lobos parietais direito e esquerdo, secundário a neoplasia, e compará-las entre si e com voluntários saudáveis. Desse modo poderíamos contribuir para o conhecimento sobre as bases neurais da atenção e para o desenvolvimento de estratégias eficazes e individualizadas de reabilitação / Attention consists of processes that lead to selection or prioritization in processing certain categories of information over others, allowing more efficient processing than would be possible if the nervous system had to process the stimuli in the environment simultaneously. Attention integrates most of human cognitive functions. Therefore it depends on specific brain regions with anatomical and physiological privileges, such as the parietal lobe, which pattern of connectivity (unimodal areas, premotor cortex, superior colliculus, cingulate gyrus, parahippocampal gyrus, insula, orbitofrontal cortex) enables sensorimotor and cognitive integration required for attention. Since early of 1980´s the common perception that parietal lobe is related solely to performance of spatial tasks, including a supposed specialization of the right parietal lobe for the distribution of attention in space is changing. The physiological basis for the specialization of the parietal lobe in orienting of attention is poorly understood for the following reasons: 1 - unilateral lesion of the right parietal lobe attentional determines disability in attention processing of information which comes from the contralateral space, and rarely occurs after injury of the left parietal lobe 2 - the processing of information by the human visual system varies considerably in relation to visual fields, and traditional attentional testing methodology does not consider that performance of the volunteers may be limited by the visibility of the stimuli; the location of the stimuli has been evaluated independently on the targets position in the visual field. Our proposal is to standardize the conditions of stimulation in the Posner test for orienting of attention, considering the specific visual thresholds of each subject and evaluate exogenous and endogenous orientation of attention deficiencies in horizontal, vertical and diagonal plans, in patients with damage to the right and left parietal lobes, secondary to brain tumor, and compare them among themselves and with healthy volunteers. Thereby this approach could contribute for the knowledge about the neural bases of attention and therefore help to develop effective strategies for rehabilitation

Investigamos, no Experimento, se o estímulo precedente, que captura a atenção quando existem demarcações, deixa de capturar a atenção na ausência de demarcações por ter seu processamento filtrado precocemente. Além disso, investigamos, nos experimentos 2, 3 e 4, se alterações no fundo da tela, que gerassem maior competição no processamento dos estímulos presentes na cena visual, poderiam levar à captura da atenção, mesmo sem a presença das demarcações classicamente utilizadas. Observamos que quando a intensidade dos estímulos competidores presentes na tela era alta, o estímulo precedente passou a capturar a atenção. Explicamos esse resultado com a hipótese de que as demarcações são importantes por adicionarem ruído ao processamento dos estímulos apresentados, influenciando a representação desses estímulos e, portanto, a possibilidade de um estímulo capturar a atenção. Por fim, no Experimento 5, investigamos se os resultados da tarefa de escolha de local seriam replicados em uma tarefa de discriminação de forma. / In Experiment 1 we investigated if a peripheral stimulus, which is able to capture attention when there are placeholders on the screen, is no longer able to capture attention in the absence of placeholders because is early filtered. In Experimento 2, 3 and 4 we investigated if changes on screen background, which would generate stronger processing competition between stimuli, could lead to attentional capture even in absence of placeholders. Accorging to our results the peripheral stimuli is able to capture attention when competing stimuli of high intensity are presented togueter on screen. Our explanation is that placeholders are important because they add noise to stimuli processing, affecting stimuli representation and, therefore, the probability that a stimulus will capture attention. Lastly, in Experimento 5 we investigated if similar results would be obtained in a form discrimination task.

The role of attention and perceptual resources were studied in a one-back task and a letter-search task, both using the same stimuli. In the letter task, pictures were used as task-irrelevant and distracting emotional stimuli. The emotional processing of the pictures was measured through the Late Positive Potential (LPP), an event-related potential (ERP) recorded with EEG. LPP activity was significantly greater to emotional than neutral stimuli during the one-back task; this shows that emotional stimuli were processed during an easy task (low load). However, LPP activity dropped for all stimuli during the difficult perceptual task (high load). Selective processes of attention are discussed, in relation to Load Theory and the ability to ignore task-irrelevant, but emotionally significant, stimuli.

Our brains handle vast amounts of information incoming through our senses. Continuously exposed to sensory input, the sense of touch, however, may miss tactile stimuli, no matter how much attention we pay to them. In four empirical studies, this thesis tested (1) the feasibility of investigating undetectable stimulation by electrical finger nerve pulses, (2) how its neural correlates dissociate from detectable stimulation and (3) whether and how selective somatosensory attention nevertheless affects the neural representation of undetectable stimuli. The first two studies showed that there is a natural range of electrical stimulation intensities that cannot be detected. A rigorous statistical evaluation with Bayes factor analysis indicated that the evidence of chance performance after undetectable stimulation reliably outweighed evidence of above-chance performance. A subsequent study applying electroencephalography (EEG) revealed qualitative differences between the processing of detectable and undetectable stimulation, which is evident in altered event-related potentials (ERP). Specifically, undetectable stimulation evokes a single component that is not predictive of stimulus detectability but lacks a subsequent component, which correlates with upcoming stimulus detection. The final study showed that attention nevertheless affects neural processing of undetectable stimuli in a top-down manner as it does for detectable stimuli and fosters the view of attention and awareness being two separate and mostly independent mechanisms. The influence of the pre-stimulus oscillatory (~10 Hz) alpha amplitude—a putative marker of attentional deployment—on the ERP depended on the current attentional state and indicates that both processes are interacting but not functionally matching.:1 Touch, Consciousness, And Attention – Theoretical Considerations ........ 1-11 1.1 A Neural Account To (Un-) Consciousness ............................................ 1-12 1.2 Controlling detectability of external stimulation ...................................... 1-14 1.3 Thresholds in the light of signal detection theory ................................... 1-17 1.4 Selective attention in touch .................................................................... 1-19 1.5 Research questions ............................................................................... 1-21 2 Empirical Evidence .................................................................................... 2-25 2.1 General methods .................................................................................... 2-25 2.1.1 Stimulation ........................................................................................... 2-25 2.1.2 Threshold assessment procedure ....................................................... 2-25 2.1.3 Behavioral analysis .............................................................................. 2-26 2.1.4 Electrophysiological measurement ...................................................... 2-28 2.1.5 Analysis of event-related potentials ..................................................... 2-30 2.1.6 Spectral Analysis resolved over time ................................................... 2-30 2.2 Psychophysical assessment of subthreshold stimulation ........................ 2-33 2.2.1 A method for assessing the individual absolute detection threshold (ADTH) ......................................................................................................... 2-33 2.2.2 Validation of absolute detection threshold assessment by signal detection theory measures and Bayesian Null-Hypothesis testing ................ 2-39 2.3 Non-invasive neural markers of unconscious perception ....................... 2-47 2.3.1 Neural Correlates of Undetectable Somatosensory Stimulation in EEG and fMRI ...................................................................................................... 2-47 2.3.2 Prediction of stimulus perception by features of the evoked potential for different stimulation intensities along the psychometric function ................. 2-51 2.4 The role of Rolandic Alpha Activity in Somatosensation and its Relation to Attention ................................................................................................. 2-75 3 General Discussion and Conclusions ...................................................... 3-101 3.1 Summary of empirical results ................................................................ 3-101 3.2 Neural processing of undetectable stimulation ..................................... 3-102 3.3 Attention, awareness and neural oscillatory activity ............................. 3-104 3.4 Limits of the current studies and future perspectives ........................... 3-109 References .................................................................................................... 113 Summary ....................................................................................................... 137 Zusammenfassung ........................................................................................ 143 Curriculum Vitae ............................................................................................ 151 Selbständigkeitserklärung ............................................................................. 155 Nachweis über die Anteile der Co-Autoren .................................................... 157

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that manifests as a developmentally inappropriate pattern of inattention, and hyperactivity or impulsivity. ADHD is a multifactorial disorder with inter alia deficits in selective attention processing. The current diagnosis of ADHD is error-prone as it relies on subjective descriptions and external observations of behavior. Measures that are less reliant on subjective descriptions can enable more accurate and informative diagnoses of ADHD. Wang et al. (2016) have identified two event-related potential (ERP) components, posterior contralateral N2 (N2pc) and distractor positivity (PD) as predictors of ADHD symptom severity in children. N2pc reflects target selection and PD reflects distractor suppression during visual selective attention. The present study aimed to examine how target-evoked N2pc and distractor-evoked PD related to attentional capacity in non-clinical adults. Participants were presented with a visual search paradigm and a self-report scale, the Everyday Life Attention Scale (ELAS). The amplitude of target-evoked N2pc and distractor-evoked PD amplitude was compared to ELAS score in multiple linear regression models. Results displayed that the peak amplitude of target-evoked N2pc was a significant predictor of attentional capacity (as measured with ELAS), while the peak amplitude of distractor-evoked PD was not associated with attentional capacity. Participants with higher attentional capacity (ELAS score) displayed less negative peak amplitudes of target-evoked N2pc. This seems to suggest that target selection, but not distractor suppression in nonclinical adults can predict attentional capacity. However, due to a limited sample size, further research is needed before drawing any major conclusions.

The current study assessed abnormal attention in 71 undergraduate men, approximately half of which displayed elevated psychopathic traits, as they attended to cues on the Police Officer's Dilemma. In the computerized task, participants are instructed to shoot men holding guns and not shoot men holding neutral objects. However, research has shown that irrelevant racial cues in the task can influence participants to shoot unarmed Black men more frequently than unarmed White men; a phenomenon termed shooter bias. Contrary to expectations, individuals with elevated psychopathic traits tended to erroneously shoot unarmed Black men more frequently compared to those with low psychopathy scores. Additional analyses indicated that the interpersonal and lifestyle facets were associated with more interference in determining unarmed Black men as not threatening relative to unarmed White men and the affective domain was associated with faster responses to shooting armed Black men relative to armed White men. Additionally, prejudicial attitudes (i.e., social dominance orientation) moderated the relationship between the affective psychopathic traits and shooting armed Black men by increasing the number of armed Black men identified as threatening relative to armed White targets. These findings are discussed in the context of the relationship between psychopathic traits and prejudicial attitudes and recent refinements to etiological theories of psychopathy.

由於資訊科技的進步，網頁資訊更豐富與複雜，本研究從兩方面，一方面找出複雜的網頁是如何被使用者所認知？另一方面網頁介面設計的好不好？該如何設計才能降低網頁資訊的複雜度使其更易讀的方法。若網站介面設計能搭配使用者的認知，將有助網站設計出能降低複雜度又易讀的網頁，幫助使用者完成任務。因此，研究目的為瀏覽者是如何知覺與認知複雜的網頁？網頁介面的版面配置設計的好不好？研究問題為腦中模版是否影響網頁瀏覽？找出降低資訊複雜度的螢幕設計的原則？ 本研究分別設計四個實驗驗證四個假設，實驗一的目的是驗證使用者腦中模板對資訊選擇有影響。方法是比較實驗未進行前，瀏覽者大腦中所認知的電子商務網頁配置概圖，得到瀏覽者腦中既有的模板是什麼，再進行選擇注意實驗，比較瀏覽者畫出來電子商務網站的回憶圖與未進行實驗前的模板間的一致性。結論為模板與實際組的卡方值均為不顯著，因此，可以得知瀏覽者瀏覽電子商務網站時腦中的模板確實影響網頁選擇注意。 實驗二的目的是驗證使用者因為任務需要不同資訊的選擇策略對造成其網頁的認知不同；方法是實驗中透過使用者進行搜尋的任務中，根據其瀏覽策略將搜尋任務第一頁的瀏覽與最後一頁不同的瀏覽目標，因要達成的選擇策略不同所以其選擇注意不同。結論為第一頁與最後一頁的的瀏覽分析可以得知不同資訊的選擇策略將影響網頁介面的螢幕配置認知。 實驗三的目的螢幕配置會影響選擇注意。方法計算文獻整理的六個指標的理論值之後，實証為讓使用者到四個國家的yahoo網頁進行任務，會因網頁配置不同，影響使用者對四個不同國家的yahoo網頁的認知選擇注意不同。結論為四個國家卡方值為顯著，表示四個國家的介面配置不同確實會影響不同的選擇注意。 實驗四的目的証明網頁設計易讀性理論值與實證的順序是相同的。方法計算文獻整理的六個指標的理論值之後，實証為將四個日韓台美不同的yahoo網頁的配置，兩個為一組，分六組進行實驗，以了解四個國家網頁哪個配置讓瀏覽者較容易閱讀。結論為理論的順序：日(0.099)>美(0.095)>台(0.086)>韓(0.078)；實證的順序：美>日>台>韓；日美優於台韓故順序一致。 根據實驗的結論，我們知道使用者面對複雜的網頁資訊時，會根據腦中的模版來分析與過濾網頁上面的資訊，而且瀏覽者對於資訊的選擇確實會影響網頁螢幕的配置像對空白與色彩..等的差異，並且根據文獻找出的指標確實與實際狀況符合。所以，建議設計師在網頁layout設計，要按照使用者的工作任務經驗，及各工作任務的可能模版特質來設計資訊呈現內容。並根據六個整理出來的指標列為參考的網頁設計元素，將元素差異及元素關係的因素，如資訊在畫面上的位置、形成區塊的空白、框線、對比顏色、文字大小，以及關鍵詞等因素善加運用，按照工作任務性質，做適當安排。將有效降低使用者認知複雜度達成任務。 / Due to the fast growth of information technology, website information has become richer and more complex, and this piece of research will target on two main related areas. One is to find out how those complicated webpage were cognized by their users? The other is to discuss whether if the existing webpage interface design is good or not, and how webpage information should be designed in order to reduce its complicity and make it easier to read. If the webpage interface is able to collocate with users’ cognition, it will help websites to create webpage with low complicity and ease of read, and thereby assisting users to complete their missions. Therefore, the research aim would be to understand how browsers sense and perceive webpage and its complicity. Is the interface and layout design suitable for such webpage? In addition, the key question is to ask if internet browsing would be affected by our brain templates, and to further find out the principles for low information complicity screen design. The research body consists of four experiments which are set to prove 4 hypotheses. First experiment is to prove that users’ brain templates have effects on the choices of information. The main method is to obtain the e-commerce webpage layout from browsers’ brain before carrying out any further tasks, and see what the initial templates look like. And then by taking the selective attention tests, to compare the similarity between the memorial mappings of the e-commerce website with the initial template. The result has shown that the chi-square values between template and real group are both not significant, therefore, it is predicted that when users are browsing e-commerce websites, the brain templates do have effects on webpage selective attention. Experiment two aims to examine if differences in webpage cognition occur as users could have various choices of information due to different needs. When users browse the internet, because of the targets change, the strategies used in first page and last page also differs, and so does the selective attention. To conclude, from the first and last pages browsing analysis we can know that different information choice strategies will have impacts on the webpage interface layout. Third experiment focuses on the display layout which affects selective attentions. By calculating six theoretical values from indicators in literature reviews, and in order to prove the theory users are asked to carry out missions on Yahoo! websites in four countries, and because the webpage layouts are different, the users’ selective attentions also varies in these four countries. The chi-square values of the four countries are significant, which means different webpage layout will alter selective attentions. The last one proves that the theoretical values of legibility in webpage design are proportional to the case studies. In order to understand which Yahoo! website is the easiest to read out of these four countries, they were divided into groups of two and carried out six sets of experiments. Theoretical result shows that Japan (0.099)>US (0.095)>Taiwan (0.086)>Korea (0.078), where practical result shows US>Japan>Taiwan>Korea, and therefore both proved that US and Japan are better than Taiwan and Korea. According to the results of experiments, we can know that when users face complex web information, they tend to use the templates created in their brain to analyze and filter those information, and the choices of information that browsers made do affect webpage and screen layout, such as different spacing and coloring; which just corresponds with our literature indications. Hence, when designing webpage layout, designers are recommended to demonstrate the content by following users’ actual experiences, plus some possible behaviors under different work and mission conditions. In addition, the six indicators should also be used as design references, and key factors such as the positioning of information, spacing, bordering, contrast, font sizes and keywords should also be taken into consideration in order to make appropriate arrangement to suit different work properties, which will lower the cognition complicity for users effectively, and thereby fulfill its tasks.

Zahlreiche Untersuchungen belegen, dass räumlich selektive Aufmerksamkeit visuelle und auditive Reizverarbeitung beeinflusst. Bestehende Modellvorstellungen sind, aufgrund der geringen Kenntnisse vergleichbarer somatosensorischer Effekte, schwer zu einem allgemeinen Mechanismus generalisieren. Mittels zeitlich-räumlich hoch aufgelöster Messmethoden wurde in dieser Dissertation Effekte räumlich selektiver Aufmerksamkeit auf die bewusste Wahr-nehmung und kortikale Verarbeitung somatosensorischer Reize untersucht. Im Einzelnen wurde gezeigt, dass die räumlich selektive Aufmerksamkeit die Maskierung eines überschwelli-gen Reizes an einer Hand durch einen starken Reiz an der anderen Hand moduliert. Mittels Elektroenzephalografie (EEG) wurde nachgewiesen, dass nach der Stimulation die Verarbei-tung in einem fronto-parietalen Netzwerk den Zugang ins Bewusstsein signalisiert. Der Be-fund einer der bewussten Wahrnehmung zeitlich vorausgehenden neuronalen Desynchronisa-tion im frontalen Kortex und in S1 erlaubt eine Erweiterung bestehender Modellvorstellun-gen. In einer simultanen EEG-funktionelle Magnetresonanztomografie (fMRT) -Studie wurde gezeigt, dass räumlich selektive Aufmerksamkeit die Signalverarbeitung während einer frühen sensorischen Phase der Reizverarbeitung beeinflusst (50 ms). Dieser Effekt korrelierte mit den Blutflußveränderungen in S1. Zusammenfassend zeigen die Studien, dass räumlich selektive Aufmerksamkeit zwar frühe somatosensorische Aktivität in S1 sowie die Wahrnehmung so-matosensorischer Reize moduliert, dies jedoch keine hinreichende Bedingung für die bewusste Wahrnehmung ist. Hingegen ist die attentional kontrollierte Desynchronisation somatosenso-rischer Rhythmen vor der Stimulation, die eine verstärkte fronto-parietale Reizverarbeitung nach sich zieht, hierfür entscheidend. / Numerous studies have shown that selective orientation of attention to a stimulus location modulates visual and auditory stimulus processing. Due to the relatively little knowledge about comparable effects of attention in the somatosensory system, existing models can barely be assigned to general cortical mechanisms. The studies conducted in this dissertation should therefore contribute to this knowledge. Effects of spatial selective attention on conscious per-ception and cortical processing of somatosensory stimuli have been investigated by applying recording methods with high temporal and spatial resolutions. Specifically, it was shown that spatial selective attention modulates masking of supra-threshold stimulus on one hand by a strong stimulus applied to the other hand. Using electroencephalography (EEG), it was dem-onstrated that processing in a fronto-parietal network but not early S1-activation signals the entry into conscious perception. The finding of neuronal desynchronisation in the frontal cor-tex and S1 preceding conscious stimulus perception permits the extension of the existing models. With the aim of localizing the temporal effects of spatial selective attention, a simul-taneous EEG-functional magnetic resonance imaging (fMRI)-study was conducted. In con-trast to findings of visual attention, it was shown that orientation of attention enhances soma-tosensory processing at an early stage of stimulus processing (50 ms). This effect correlated with the changes of cortical blood flow in S1. Together, these studies show that spatial-selective attention modulates early activity in S1 as well as conscious perception of somatosen-sory stimuli. Nevertheless, this is not sufficient for an entrance into conscious perception. Instead, attentionally controlled pre-stimulus desynchronisation of somatosensory rhythmic activity, followed by an increased fronto-parietal stimulus processing are necessary prerequi-sites for conscious perception.

Syftet med föreliggande studie var att undersöka effekten av en dos mindfulness session på 45 minuter och dess relation till: (1) Upprätthållandet av uppmärksamhetsförmågan, (2) exekutiv uppmärksamhetsförmåga samt (3) perceptuell förmåga. En experimentell studie genomfördes på idrottare (n=48) som uppfyllde särskilda krav för att få ingå i studien. Resultatet visade inga signifikanta skillnader gällande samtliga tre variabler mellan experimentgrupp och kontrollgrupp. Avslutningsvis diskuteras studiens resultat och implikationer i förhållande till tidigare forskning, med stöd av teoretiska referensramar. / The purpose of this study was to examine the effect of one 45 minute mindfulness session on: (1) Sustained attention abilities, (2) executive attention abilities, and (3) perceptual abilities. An experimental study was carried out on athletes (n = 48) who all met the specific requirements for being able to participate in this study. The results showed no significant difference in all three variables between the experiment group and the control group. In conclusion, the results and implications are discussed in relation to previous research, supported by theoretical frames of references.

Le but de cette étude était d'évaluer le rôle des boucles des ganglions de la base et des voies dopaminergiques sur les mécanismes « bottom-up » et « « top-down » du contrôle de l'attention visuelle (AV). Nous avons comparé les performances sur 3 tâches informatisés, appropriées à l'étude de la capture attentionnelle (CA), des mécanismes de sélection de la réponse motrice et d'initiation du mouvement, de deux groupes de patients avec maladie de Parkinson (MP) - un groupe étant évalué dans trois différentes conditions de stimulation électrique (sans stimulation, ou stimulation sélective de la partie sensorimotrice, SM, ou de la partie associative, AS, du noyau subthalamique, NST), l'autre groupe étant évalué dans deux différentes conditions de traitement médical (avec ou sans levodopa) - avec celles d'un groupe des sujets contrôles. Nos résultats suggèrent dans la MP un affaiblissement des mécanismes « top-down » de contrôle de l'AV, ce qui pourrait aussi expliquer indirectement l'augmentation de la CA. Le traitement dopaminergique est efficace dans le rétablissement des mécanismes « top-down » de l'AV, suggérant une implication des voies dopaminergiques dans ce domaine cognitif. Ces voies semblent aussi jouer un rôle dans les mécanismes « bottom-up » de l'attention, comme l'a suggéré le renforcement de la CA sous traitement dopaminergique. La stimulation du NST a montré un effet similaire à celui obtenu par un traitement dopaminergique, en favour d'une implication directe des boucles des ganglions de la base dans le contrôle de l'AV. Nos résultats ont mis en évidence une spécialisation fonctionnelle de différents sous-territoires du NST en ce qui concerne les mécanismes de « top-down ». La stimulation SM produit des effets marqués sur les processus d'initiation de mouvement et des effets positifs sur les mécanismes endogènes de l'AV, alors que la stimulation de la partie AS semble être plus particulièrement efficace dans l'amélioration des mécanismes de sélection de cible. / We aimed to investigate the possible role of cortico-basal ganglia loops and dopaminergic pathways in the mechanisms of top-down and bottom-up control of visual attention (VA). We compared the performances on 3 computerized tasks, respectively suitable to study attentional capture (AC), motor response selection and movement initiation, of two groups of patients with Parkinson's disease (PD), one evaluated in different sets of electrical stimulation (without stimulation, or selective stimulation of the sensorimotor, SM, or associative, AS, parts of the subthalamic nucleus, STN), the other in different conditions of medication (with or without levodopa), with those of a group of controls. Our results showed that in PD there is a weakening of the mechanisms underlying the top-down control of VA, which also would account indirectly account for the enhancement of AC. Dopaminergic treatment proved to be effective in restoring the top-down mechanisms of VA, suggesting an involvement of dopaminergic pathways in this cognitive domain. These pathways seem to play a role also in the bottom-up mechanisms of attention, as suggested by the enhancement of AC under dopaminergic treatment. The STN-stimulation showed a similar effect to that obtained by dopaminergic treatment, establishing a direct involvement of the basal ganglia loops in VA control. Our results highlighted a functional specialization of different sub-territories of the STN in relation to the top-down mechanisms. SM stimulation produced marked effects on the movement initiation processes and appreciable positive effects on endogenous VA mechanisms, while AS stimulation seems to be especially effective in improving the mechanisms of target selection.