Functional imaging in neuroenhancement

Increasingly demanding tasks, competition for competence and time pressure have lead to attempts of neuroenhancement (NE) among students and employees. NE is designed to increase cognitive abilities by modulating brain processes through the use of pharmaceutics. Substances such as methylphenidate (i.e. Ritalin®), modafinil (i.e. Vigil®) and caffeine are common candidates for enhancing cognitive abilities such as executive functions, inhibition control and memory (Wood et al., 2014). Until today, there has not been a study investigating memory enhancement in functional magnetic resonance imaging (fMRI). Using fMRI, 48 healthy participants were tested for drug effects in a single-dose, double-blind and randomized study using a declarative memory task. During memory recall, methylphenidate dependent deactivations were found in the fronto-parietal and temporal regions whereas no BOLD alterations were seen during encoding. On the behavioral level, methylphenidate enhanced subject’s judgement confidence and performance during late recall. During encoding, caffeine led to deactivations in the precentral gyrus whereas modafinil did not show any BOLD signal alterations at all. To get an overview over the existing neuroimaging literature, all published studies on the effects of the aforementioned drug agents were reviewed in addition. In line with this study, previous publications emphasized that methylphenidate seems to alter task relevant brain areas. Our main finding of task-related deactivations may point to the reduction of task-functioning distractions. Thereby, we conclude a drug-dependent increase of efficiency in data processing.Zunehmende Arbeitsbelastung, erhöhter Zeitdruck und größere Verantwortung haben dazu geführt, dass für Studenten und Arbeitnehmer das Phänomen Neuroenhancement (NE) eine zunehmende Relevanz erlangt hat. Darunter wird die Steigerung der kognitiven Leistung durch pharmazeutischen Eingriff auf zentralnervöse Prozesse verstanden. Substanzen wie z.B. Methylphenidat (Ritalin®), Modafinil (Vigil®) und Koffein gelten als aussichtsreiche Kandidaten zur Leistungssteigerung, die möglicherweise Einfluss auf kognitive Prozesse, wie z.B. Exekutive Funktionen, Inhibitionskontrolle und Gedächtnis ausüben können (Wood et al., 2014). Keine bisher publizierte Studie hat den Fokus auf neuronale Korrelate der deklarativen Gedächtnissteigerung gelegt. Aus dem Grund sind zusätzlich alle bisher veröffentlichten bildgebenden Studien zu Methylphenidat, Modafinil und Koffein zu einer strukturierten Übersicht zusammengefasst worden. Mittels funktionaler Magnetresonanztomographie (fMRT) wurden 48 gesunde Probanden, doppelt verblindet und randomisiert auf Steigerung der deklarativen Gedächtnisleistung getestet. Obwohl die Wirksamkeit der drei Substanzen ausführlich für klinische Patientenpopulationen untersucht wurde, gibt es kaum Wissen über die möglichen behavioralen und neuronalen Auswirkungen auf gesunde, erwachsene Menschen. Entgegen der Erwartung, dass die getesteten Substanzen klassische Gedächtnis assoziierte Regionen aktivieren, wurden unterschiedliche substanzspezifische Effekte gefunden. Wahrend des Abrufs von Gedächtnisinhalten deaktivierte Methylphenidat fronto-parietale und temporale Regionen. Dagegen führte die Applikation von Koffein zu einer verringerten BOLD Antwort im Gyrus Präcentralis während der Lernphase. Modafinil führte zu keiner Veränderung im Vergleich zu Placebo. Auf Verhaltensebene förderte Methylphenidat den späten Abruf von Gedächtnisinhalten, wohingegen die beiden anderen Substanzen keine Effekte hinsichtlich der Lernleistung vorwiesen. Vor dem Hintergrund bisheriger bildgebender Studien zeigt die vorliegende Arbeit, dass Neuroenhancement neben der Aktivierung leistungsrelevanter Gehirnregionen auch durch Reduzierung von störenden Einwirkungen funktionieren kann und damit womöglich die Effektivität der Informationsverarbeitung erhöht

Neural representations used by brain regions underlying speech production

Thesis (Ph.D.)--Boston UniversitySpeech utterances are phoneme sequences but may not always be represented as such in the brain. For instance, electropalatography evidence indicates that as speaking rate increases, gestures within syllables are manipulated separately but those within consonant clusters act as one motor unit. Moreover, speech error data suggest that a syllable's phonological content is, at some stage, represented separately from its syllabic frame structure. These observations indicate that speech is neurally represented in multiple forms. This dissertation describes three studies exploring representations of speech used in different brain regions to produce speech. The first study investigated the motor units used to learn novel speech sequences. Subjects learned to produce a set of sequences with illegal consonant clusters (e.g. GVAZF) faster and more accurately than a similar novel set. Subjects then produced novel sequences that retained varying phonemic subsequences of previously learned sequences. Novel sequences were performed as quickly and accurately as learned sequences if they contained no novel consonant clusters, regardless of other phonemic content, implicating consonant clusters as important speech motor representations. The second study investigated the neural correlates of speech motor sequence learning. Functional magnetic resonance imaging (fMRI) revealed increased activity during novel sequence productions in brain regions traditionally associated with non-speech motor sequence learning - including the basal ganglia and premotor cortex - as well as regions associated with learning and updating speech motor representations based on sensory input - including the bilateral frontal operculum and left posterior superior temporal sulcus (pSTs). Behavioral learning measures correlated with increased response for novel sequences in the frontal operculum and with white matter integrity under the pSTs, implicating functional and structural connectivity of these regions in learning success

Convergent and divergent fMRI responses in children and adults to increasing language production demands

In adults, patterns of neural activation associated with perhaps the most basic language skill—overt object naming—are extensively modulated by the psycholinguistic and visual complexity of the stimuli. Do children's brains react similarly when confronted with increasing processing demands, or they solve this problem in a different way? Here we scanned 37 children aged 7–13 and 19 young adults who performed a well-normed picture-naming task with 3 levels of difficulty. While neural organization for naming was largely similar in childhood and adulthood, adults had greater activation in all naming conditions over inferior temporal gyri and superior temporal gyri/supramarginal gyri. Manipulating naming complexity affected adults and children quite differently: neural activation, especially over the dorsolateral prefrontal cortex, showed complexity-dependent increases in adults, but complexity-dependent decreases in children. These represent fundamentally different responses to the linguistic and conceptual challenges of a simple naming task that makes no demands on literacy or metalinguistics. We discuss how these neural differences might result from different cognitive strategies used by adults and children during lexical retrieval/production as well as developmental changes in brain structure and functional connectivity

Motor versus body awareness: Voxel-based lesion analysis in anosognosia for hemiplegia and somatoparaphrenia following right hemisphere stroke

This is the accepted manuscript version of the following article: Valentina Moro, Simone Pernigo, Manos Tsakiris, Renato Avesani, Nicola M. J. Edelstyn, Paul M. Jenkinson, and Aikaterini Fotopoulou, ‘Motor versus body awareness: Voxel-based lesion analysis in anosognosia for hemiplegia and somatoparaphrenia following right hemisphere stroke’, Cortex, Vol 83, pp. 62-77, first published online 15 Jul 2016. The version of record is available online at doi: http://dx.doi.org/10.1016/j.cortex.2016.07.001 Published by Elsevier. © Elsevier Ltd. All rights reserved.Anosognosia for hemiplegia (AHP) is informative about the neurocognitive basis of motor awareness. However, it is frequently associated with concomitant symptoms, such as hemispatial neglect and disturbances in the sense of body ownership (DSO). Although double dissociations between these symptoms have been reported, there is ongoing debate about whether they are manifestations of independent abnormalities, or a single neuro- cognitive deficit. We aimed to investigate the specificity of lesions associated with AHP by surpassing four, existing methodological limitations: (a) recruit a relatively large sample of patients (total N 1⁄4 70) in a multi-centre study; (b) identify lesions associated with AHP in grey and white matter using voxel-based methods; (c) take into account the duration of AHP and concomitant neglect symptoms; and (d) compare lesions against a control hemiplegic group, patients suffering from AHP and DSO, and a few, rare patients with selective DSO. Results indicated that acute AHP is associated with a wide network, mainly including: (1) the Rolandic operculum, (2) the insula and (3) the superior temporal gyri. Subcortically, damage mainly involved the basal ganglia and white matter, mostly the superior corona radiate, arcuate fasciculus and the part of the ventral, superior longitu- dinal fasciculus. Persistent symptoms were linked with wider damage involving fronto- temporal cortex and long white matter tracts. A shift in the latero-medial direction (mainly involving the basal ganglia and surrounding white matter) emerged when DSO was taken accounted for. These results suggest that while bodily awareness is processed by areas widely distributed across the brain, intact subcortical structures and white matter tracts may be necessary to support basic feelings of owning and controlling contralateral body parts. An accurate and ‘up-to-date’ awareness of our motor abilities, however, may rely also on intact processing in cortical areas which presumably allow higher-order in- ferences about the current state of the body.Peer reviewedFinal Accepted Versio

Emotional Prosody Processing in the Schizophrenia Spectrum.

THESIS ABSTRACT Emotional prosody processing impairment is proposed to be a main contributing factor for the formation of auditory verbal hallucinations in patients with schizophrenia. In order to evaluate such assumption, five experiments in healthy, highly schizotypal and schizophrenia populations are presented. The first part of the thesis seeks to reveal the neural underpinnings of emotional prosody comprehension (EPC) in a non-clinical population as well as the modulation of prosodic abilities by hallucination traits. By revealing the brain representation of EPC, an overlap at the neural level between EPC and auditory verbal hallucinations (AVH) was strongly suggested. By assessing the influence of hallucinatory traits on EPC abilities, a continuum in the schizophrenia spectrum in which high schizotypal population mirrors the neurocognitive profile of schizophrenia patients was established. Moreover, by studying the relation between AVH and EPC in non-clinical population, potential confounding effects of medication influencing the findings were minimized. The second part of the thesis assessed two EPC related abilities in schizophrenia patients with and without hallucinations. Firstly, voice identity recognition, a skill which relies on the analysis of some of the same acoustical features as EPC, has been evaluated in patients and controls. Finally, the last study presented in the current thesis, assessed the influence that implicit processing of emotional prosody has on selective attention in patients and controls. Both patients studies demonstrate that voice identity recognition deficits as well as abnormal modulation of selective attention by implicit emotion prosody are related to hallucinations exclusively and not to schizophrenia in general. In the final discussion, a model in which EPC deficits are a crucial factor in the formation of AVH is evaluated. Experimental findings presented in the previous chapters strongly suggests that the perception of prosodic features is impaired in patients with AVH, resulting in aberrant perception of irrelevant auditory objects with emotional prosody salience which captures the attention of the hearer and which sources (speaker identity) cannot be recognized. Such impairments may be due to structural and functional abnormalities in a network which comprises the superior temporal gyrus as a central element

Functional imaging studies of visual-auditory integration in man.

This thesis investigates the central nervous system's ability to integrate visual and auditory information from the sensory environment into unified conscious perception. It develops the possibility that the principle of functional specialisation may be applicable in the multisensory domain. The first aim was to establish the neuroanatomical location at which visual and auditory stimuli are integrated in sensory perception. The second was to investigate the neural correlates of visual-auditory synchronicity, which would be expected to play a vital role in establishing which visual and auditory stimuli should be perceptually integrated. Four functional Magnetic Resonance Imaging studies identified brain areas specialised for: the integration of dynamic visual and auditory cues derived from the same everyday environmental events (Experiment 1), discriminating relative synchronicity between dynamic, cyclic, abstract visual and auditory stimuli (Experiment 2 & 3) and the aesthetic evaluation of visually and acoustically perceived art (Experiment 4). Experiment 1 provided evidence to suggest that the posterior temporo-parietal junction may be an important site of crossmodal integration. Experiment 2 revealed for the first time significant activation of the right anterior frontal operculum (aFO) when visual and auditory stimuli cycled asynchronously. Experiment 3 confirmed and developed this observation as the right aFO was activated only during crossmodal (visual-auditory), but not intramodal (visual-visual, auditory-auditory) asynchrony. Experiment 3 also demonstrated activation of the amygdala bilaterally during crossmodal synchrony. Experiment 4 revealed the neural correlates of supramodal, contemplative, aesthetic evaluation within the medial fronto-polar cortex. Activity at this locus varied parametrically according to the degree of subjective aesthetic beauty, for both visual art and musical extracts. The most robust finding of this thesis is that activity in the right aFO increases when concurrently perceived visual and auditory sensory stimuli deviate from crossmodal synchrony, which may veto the crossmodal integration of unrelated stimuli into unified conscious perception

The influence of time and money on product evaluations: A neurophysiological analysis

"Time is money" is how a common saying goes, reflecting a widespread assumption in many people\u27s everyday life. It seems that money and time are very similar concepts which might even be exchangeable all together. However, the neurophysiological processes underlying the activation of time or money are not yet completely understood. In order to understand in how far and in which dimensions the concept of time versus the concept of money effects human behavior we enquired the neural differences of the time versus money effect. This paper broadens the understanding of both concepts and investigates the posited distinct mindsets of time and money using functional magnetic resonance imaging (fMRI) technology. A sample of 44 righthanded adults has been analyzed. Our data supports the idea of the existence of two distinct mindsets for time and money. However, contrasting both conditions in one general linear model only a few significant differences have been found. The insula seems to be a crucial locus for the neural difference of both mindsets. Higher insula activation in the time condition suggests stronger urge for the product primed with time

Electrophysiological and functional magnetic resonance imaging investigations on the influence of spatial and feature-based attention on the flanker effect

Attention represents an almost ubiquitous field in neuroscientific research. It can be manipulated in many ways including direction, intensity or selectivity of attention. An unanswered question remains concerning the possibility to suppress distracting information through top-down attentional control. The present doctoral thesis addresses this topic and furthermore contrasts two main attention types (spatial and feature-based allocation). For this purpose, both anatomical and temporal data were collected and brought together in a common source analysis

Attenuation of Neural Response during Substance-Free Activity and Monetary Reward Processing in Individuals with Opiate Use Disorder and Moderate Depressive Symptoms

Co-occurring opiate use disorder and depressive symptoms is prevalent and especially concerning given its association with more severe substance use characteristics and poorer outcomes compared to opiate use disorder in the absence of depressive symptoms. Theories and findings propose dysfunctional reward processing, namely reduced reward responsivity in populations with individuals with substance use disorder and depression; however, inconsistencies across studies prompt the consideration of alternative conceptualizations of reward dysregulation, such as attenuation of reward responsivity across time. Thus, the current study tested attenuation of neural response in a priori regions-of-interest and task-based functional connectivity between reward-related and prefrontal cortical regions during anticipation and receipt of both substance-free and monetary reward among individuals with opiate use disorder and co-occurring depressive symptoms (OUDD) relative to healthy controls (HC). Sixteen OUDD participants from an inpatient detoxification facility and seventeen HC from the community underwent functional magnetic resonance imaging (fMRI) and completed two reward tasks, the Activity Incentive Delay (AID) and Monetary Incentive Delay (MID) tasks. Results indicate attenuation of activation in the right anterior cingulate cortex (ACC) across both OUDD and HC groups. Group differences in global connectivity and connectivity attenuation between reward-related and prefrontal cortical regions were observed. Specifically, greater attenuation of connectivity between the right ACC and left middle frontal gyrus (MFG) predicted more frequent substance use at a one-month follow-up. Findings support attenuation of connectivity during reward processing as a potential biomarker for opiate use disorder and co-occurring depressive symptoms.Doctor of Philosoph