Monetary rewards modulate inhibitory control

The ability to override a dominant response, often referred to as behavioral inhibition, is considered a key element of executive cognition. Poor behavioral inhibition is a defining characteristic of several neurological and psychiatric populations. Recently, there has been increasing interest in the motivational dimension of behavioral inhibition, with some experiments incorporating emotional contingencies in classical inhibitory paradigms such as the Go/NoGo and Stop Signal Tasks (SSTs). Several studies have reported a positive modulatory effect of reward on performance in pathological conditions such as substance abuse, pathological gambling, and Attention Deficit Hyperactive Disorder (ADHD). However, experiments that directly investigate the modulatory effects of reward magnitudes on the performance of inhibitory tasks are scarce and little is known about the finer grained relationship between motivation and inhibitory control. Here we probed the effect of reward magnitude and context on behavioral inhibition with three modified versions of the widely used SST. The pilot study compared inhibition performance during six blocks alternating neutral feedback, low, medium, and high monetary rewards. Study One compared increasing vs. decreasing rewards, with low, high rewards, and neutral feedback; whilst Study Two compared low and high reward magnitudes alone also in an increasing and decreasing reward design. The reward magnitude effect was not demonstrated in the pilot study, probably due to a learning effect induced by practice in this lengthy task. The reward effect per se was weak but the context (order of reward) was clearly suggested in Study One, and was particularly strongly confirmed in study two. In addition, these findings revealed a 'kick start effect' over global performance measures. Specifically, there was a long lasting improvement in performance throughout the task when participants received the highest reward magnitudes at the beginning of the protocol. These results demonstrate a dynamical behavioral inhibition capacity in humans, as illustrated by the reward magnitude modulation and initial reward history effects. © 2014 Herrera, Speranza, Hampshire and Bekinschtein

Decision-making in frontotemporal dementia: Clinical, theoretical and legal implications

Background: The behavioral variant of frontotemporal dementia (bvFTD) is characterized by progressive changes in personality and social interaction, loss of empathy, disinhibition and impulsivity, most of which generally precede the onset of cognitive deficits. In this study, we investigated decision-making cognition in a group of patients with an early bvFTD diagnosis whose standard neuropsychological performance was within normal range for all variables. Methods: The Iowa Gambling Task was administered to this group of early bvFTD patients, to a group of early bvFTD patients who had shown impaired performance on the classical neuropsychological battery and to healthy controls. Results: Decision-making was impaired in both bvFTD patient groups, whether they had shown impaired or normal performance in the classical neuropsychological evaluation. Conclusions: Patients with early bvFTD may perform normally on standard cognitive tests, and yet develop severe deficits in judgment and decision-making. In many current legal systems, early bvFTD patients showing preserved cognitive functioning who commit unlawful acts run the risk of not being able to plead insane or not guilty on the grounds of diminished responsibility beyond reasonable doubt. This represents a unique legal and ethical dilemma. Our findings have important implications for medicolegal decisions relating to capacity and culpability, and regarding the philosophical concept of 'free will'.Fil: Manes, Facundo Francisco. Instituto de Neurología Cognitiva; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Favaloro; ArgentinaFil: Torralva, Teresa. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro; ArgentinaFil: Ibañez, Agustin Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Diego Portales; Chile. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro; ArgentinaFil: Roca, María. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro; ArgentinaFil: Bekinschtein, Tristán Andrés. Instituto de Neurología Cognitiva; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gleichgerrcht, Ezequiel. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro; Argentin

Intracranial high-γ connectivity distinguishes wakefulness from sleep.

Neural synchrony in the γ-band is considered a fundamental process in cortical computation and communication and it has also been proposed as a crucial correlate of consciousness. However, the latter claim remains inconclusive, mainly due to methodological limitations, such as the spectral constraints of scalp-level electroencephalographic recordings or volume-conduction confounds. Here, we circumvented these caveats by comparing γ-band connectivity between two global states of consciousness via intracranial electroencephalography (iEEG), which provides the most reliable measurements of high-frequency activity in the human brain. Non-REM Sleep recordings were compared to passive-wakefulness recordings of the same duration in three subjects with surgically implanted electrodes. Signals were analyzed through the weighted Phase Lag Index connectivity measure and relevant graph theory metrics. We found that connectivity in the high-γ range (90-120 Hz), as well as relevant graph theory properties, were higher during wakefulness than during sleep and discriminated between conditions better than any other canonical frequency band. Our results constitute the first report of iEEG differences between wakefulness and sleep in the high-γ range at both local and distant sites, highlighting the utility of this technique in the search for the neural correlates of global states of consciousness

Direct brain recordings reveal continuous encoding of structure in random stimuli

The brain excels at processing sensory input, even in rich or chaotic environments. Mounting evidence attributes this to the creation of sophisticated internal models of the environment that draw on statistical structures in the unfolding sensory input. Understanding how and where this modeling takes place is a core question in statistical learning and predictive processing. In this context, we address the role of transitional probabilities as an implicit structure supporting the encoding of a random auditory stream. Leveraging information-theoretical principles and the high spatiotemporal resolution of intracranial electroencephalography, we analyzed the trial-by-trial high-frequency activity representation of transitional probabilities. This unique approach enabled us to demonstrate how the brain continuously encodes structure in random stimuli and revealed the involvement of a network outside of the auditory system, including hippocampal, frontal, and temporal regions. Linking the frame-works of statistical learning and predictive processing, our work illuminates an implicit process that can be crucial for the swift detection of patterns and unexpected events in the environment.Fil: Fuhrer, Julian. University of Oslo; NoruegaFil: Kyrre, Glette. University of Oslo; NoruegaFil: Ivanovic, Jugoslav. University of Oslo; NoruegaFil: Gunnar Larsson, Pål. University of Oslo; NoruegaFil: Bekinschtein, Tristán Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Cambridge; Reino UnidoFil: Kochen, Sara Silvia. Universidad Nacional Arturo Jauretche. Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos. Provincia de Buenos Aires. Ministerio de Salud. Hospital Alta Complejidad en Red El Cruce Dr. Néstor Carlos Kirchner Samic. Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos; ArgentinaFil: Knight, Robert T.. University of California at Berkeley; Estados UnidosFil: Tørresen, Jim. University of Oslo; NoruegaFil: Solbakk, Anne Kristin. University of Oslo; Noruega. Helgeland Hospital; NoruegaFil: Endestad, Tor. University of Oslo; Noruega. Helgeland Hospital; NoruegaFil: Blenkmann, Alejandro Omar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Oslo; Norueg

The man who feels two hearts: the different pathways of interoception

Recent advances in neuroscience have provided new insights into the understanding of heart–brain interaction and communication. Cardiac information to the brain relies on two pathways, terminating in the insular cortex (IC) and anterior cingulate cortex (ACC), along with the somatosensory cortex (S1-S2). Interoception relying on these neuroanatomical pathways has been shown to modulate social cognition. We report the case study of C.S., a patient with an external heart (an extracorporeal left-univentricular cardiac assist device, LVAD). The patient was assessed with neural/behavioral measures of cardiac interoception complemented by neuropsychological and social cognition measures. The patients performance on the interoception task (heartbeat detection) seemed to be guided by signals from the artificial LVAD, which provides a somatosensory beat rather than by his endogenous heart. Cortical activity (HEP, heartbeat-evoked potential) was found decreased in comparison with normal volunteers, particularly during interoceptive states. The patient accurately performed several cognitive tasks, except for interoception-related social cognition domains (empathy, theory of mind and decision making). This evidence suggests an imbalance in the patients cardiac interoceptive pathways that enhances sensation driven by the artificial pump over that from the cardiac vagal-IC/ACC pathway. A patient with two hearts, one endogenous and one artificial, presents a unique opportunity to explore models of interoception and heart–brain interaction.Fil: Couto, Juan Blas Marcos. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro. Facultad de Medicina. Instituto de Neurociencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Salles, Alejo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Neurociencia Integrativa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sedeño, Lucas. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro. Facultad de Medicina. Instituto de Neurociencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Peradejordi Lastras, Margarita Ana. Universidad Favaloro; ArgentinaFil: Barttfeld, Pablo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Neurociencia Integrativa; ArgentinaFil: Canales Johnson, Andres. Universidad Diego Portales; ChileFil: Vidal Dos Santos, Hector Yamil. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Neurociencia Integrativa; ArgentinaFil: Huepe, David. Universidad Diego Portales; ChileFil: Bekinschtein, Tristán Andrés. Instituto de Neurología Cognitiva; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sigman, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física. Laboratorio de Neurociencia Integrativa; Argentina. Universidad Torcuato Di Tella; ArgentinaFil: Favaloro, Roberto. Universidad Favaloro; ArgentinaFil: Manes, Facundo Francisco. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro. Facultad de Medicina. Instituto de Neurociencias; ArgentinaFil: Ibañez, Agustin Mariano. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro. Facultad de Medicina. Instituto de Neurociencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Enhanced working memory binding by direct electrical stimulation of the parietal cortex

Recent works evince the critical role of visual short-term memory (STM) binding deficits as a clinical and preclinical marker of Alzheimer's disease (AD). These studies suggest a potential role of posterior brain regions in both the neurocognitive deficits of Alzheimer's patients and STM binding in general. Thereupon, we surmised that stimulation of the posterior parietal cortex (PPC) might be a successful approach to tackle working memory deficits in this condition, especially at early stages. To date, no causal evidence exists of the role of the parietal cortex in STM binding. A unique approach to assess this issue is afforded by single-subject direct intracranial electrical stimulation of specific brain regions during a relevant cognitive task. Electrical stimulation has been used both for clinical purposes and to causally probe brain mechanisms. Previous evidence of electrical currents spreading through white matter along well defined functional circuits indicates that visual working memory mechanisms are subserved by a specific widely distributed network. Here, we stimulated the parietal cortex of a subject with intracranial electrodes as he performed the visual STM task. We compared the ensuing results to those from a non-stimulated condition and to the performance of a matched control group. In brief, direct stimulation of the parietal cortex induced a selective improvement in STM. These results, together with previous studies, provide very preliminary but promising ground to examine behavioral changes upon parietal stimulation in AD. We discuss our results regarding: (a) the usefulness of the task to target prodromal stages of AD; (b) the role of a posterior network in STM binding and in AD; and (c) the potential opportunity to improve STM binding through brain stimulation.Fil: Birba, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Hesse Rizzi, Eugenia Fátima. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Sedeño, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Mikulan, Ezequiel Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: García, María del Carmen. Hospital Italiano; ArgentinaFil: Avalos, Juan Carlos. Hospital Italiano; ArgentinaFil: Gonzalez Adolfi, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Legaz, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Bekinschtein, Tristán Andrés. University of Cambridge; Reino UnidoFil: Zimerman, Máximo. Instituto de Neurología Cognitiva; Argentina. Universidad Favaloro; ArgentinaFil: Parra, Mario. Heriot-Watt University; Reino Unido. University of Edinburgh; Reino Unido. NHS Research Scotland; Reino Unido. Universidad Autónoma del Caribe; ColombiaFil: García, Adolfo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Ibáñez Barassi, Agustín Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Universidad Autónoma del Caribe; Colombia. Universidad Adolfo Ibañez; Chile. Australian Research Council ; Australi

Early detection of intentional harm in the human amygdala

A decisive element of moral cognition is the detection of harm and its assessment as intentional or unintentional. Moral cognition engages brain networks supporting mentalizing, intentionality, empathic concern and evaluation. These networks rely on the amygdala as a critical hub, likely through frontotemporal connections indexing stimulus salience. We assessed inferences about perceived harm using a paradigm validated through functional magnetic resonance imaging, eye-tracking and electroencephalogram recordings. During the task, we measured local field potentials in three patients with depth electrodes (n = 115) placed in the amygdala and in several frontal, temporal, and parietal locations. Direct electrophysiological recordings demonstrate that intentional harm induces early activity in the amygdala (5 200 ms), which-in turn-predicts intention attribution. The amygdala was the only site that systematically discriminated between critical conditions and predicted their classification of events as intentional. Moreover, connectivity analysis showed that intentional harm induced stronger frontotemporal information sharing at early stages. Results support the 'many roads' view of the amygdala and highlight its role in the rapid encoding of intention and salience-critical components of mentalizing and moral evaluation.Fil: Hesse Rizzi, Eugenia Fátima. Universidad de Buenos Aires; Argentina. Universidad Diego Portales; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Mikulan, Ezequiel Pablo. Universidad Diego Portales; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Decety, Jean. University of Chicago; Estados UnidosFil: Sigman, Mariano. Universidad de Buenos Aires; Argentina. Universidad Torcuato Di Tella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Del Carmen Garcia, María. Hospital Italiano. Instituto Universitario - Escuela de Medicina; ArgentinaFil: Silva, Walter. Hospital Italiano. Instituto Universitario - Escuela de Medicina; ArgentinaFil: Ciraolo, Carlos. Hospital Italiano. Instituto Universitario - Escuela de Medicina; ArgentinaFil: Vaucheret, Esteban. Hospital Italiano. Instituto Universitario - Escuela de Medicina; ArgentinaFil: Baglivo, Fabricio. Universidad Favaloro; Argentina. Universidad de Buenos Aires; Argentina. Universidad Diego Portales; Chile. Instituto de Neurología Cognitiva; ArgentinaFil: Huepe, David. Universidad Diego Portales; ChileFil: Lopez, Vladimir. Pontificia Universidad Católica de Chile; ChileFil: Manes, Facundo Francisco. Universidad Diego Portales; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; ArgentinaFil: Bekinschtein, Tristán Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Cambridge; Reino UnidoFil: Ibañez, Agustin Mariano. Universidad Diego Portales; Chile. Universidad Autonoma del Caribe; Colombia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentin

From neural signatures of emotional modulation to social cognition: Individual differences in healthy volunteers and psychiatric participants

It is commonly assumed that early emotional signals provide relevant information for social cognition tasks. The goal of this study was to test the association between (a) cortical markers of face emotional processing and (b) social-cognitive measures, and also to build a model which can predict this association (a and b) in healthy volunteers as well as in different groups of psychiatric patients. Thus, we investigated the early cortical processing of emotional stimuli (N170, using a face and word valence task) and their relationship with the social-cognitive profiles (SCPs, indexed by measures of theory of mind, fluid intelligence, speed processing and executive functions). Group comparisons and individual differences were assessed among schizophrenia (SCZ) patients and their relatives, individuals with attention deficit hyperactivity disorder (ADHD), individuals with euthymic bipolar disorder (BD) and healthy participants (educational level, handedness, age and gender matched). Our results provide evidence of emotional N170 impairments in the affected groups (SCZ and relatives, ADHD and BD) as well as subtle group differences. Importantly, cortical processing of emotional stimuli predicted the SCP, as evidenced by a structural equation model analysis. This is the first study to report an association model of brain markers of emotional processing and SCP.Fil: Ibañez, Agustin Mariano. Instituto de Neurologia Cognitiva. Laboratorio de Psicologia Experimental y Neurociencia; Argentina. Universidad Diego Portales; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aguado, Jaume. Universidad de Barcelona; EspañaFil: Báez Buitrago, Sandra Jimena. Instituto de Neurologia Cognitiva. Laboratorio de Psicologia Experimental y Neurociencia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Huepe, David. Universidad Diego Portales; ChileFil: Lopez, Vladimir. Pontificia Universidad Católica de Chile; ChileFil: Ortega, Rodrigo. Universidad de Chile; Chile. Pontificia Universidad Católica de Chile; ChileFil: Sigman, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires; Argentina. Universidad Torcuato Di Tella; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Mikulan, Ezequiel Pablo. Instituto de Neurologia Cognitiva. Laboratorio de Psicologia Experimental y Neurociencia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lischinsky, Alicia Graciela. Instituto de Neurologia Cognitiva. Laboratorio de Psicologia Experimental y Neurociencia; ArgentinaFil: Torrente, Fernando. Instituto de Neurologia Cognitiva. Laboratorio de Psicologia Experimental y Neurociencia; ArgentinaFil: Cetkovich Bakmas, Marcelo Gustavo. Instituto de Neurologia Cognitiva. Laboratorio de Psicologia Experimental y Neurociencia; ArgentinaFil: Torralva, Teresa. Instituto de Neurologia Cognitiva. Laboratorio de Psicologia Experimental y Neurociencia; ArgentinaFil: Bekinschtein, Tristán Andrés. Instituto de Neurología Cognitiva; Argentina. Medical Research Council. Cognition and Brain Sciences Unit; Reino UnidoFil: Manes, Facundo Francisco. Instituto de Neurologia Cognitiva. Laboratorio de Psicologia Experimental y Neurociencia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Enhanced Working Memory Binding by Direct Electrical Stimulation of the Parietal Cortex

Recent works evince the critical role of visual short-term memory (STM) binding deficits as a clinical and preclinical marker of Alzheimer’s disease (AD). These studies suggest a potential role of posterior brain regions in both the neurocognitive deficits of Alzheimer’s patients and STM binding in general. Thereupon, we surmised that stimulation of the posterior parietal cortex (PPC) might be a successful approach to tackle working memory deficits in this condition, especially at early stages. To date, no causal evidence exists of the role of the parietal cortex in STM binding. A unique approach to assess this issue is afforded by single-subject direct intracranial electrical stimulation of specific brain regions during a relevant cognitive task. Electrical stimulation has been used both for clinical purposes and to causally probe brain mechanisms. Previous evidence of electrical currents spreading through white matter along well defined functional circuits indicates that visual working memory mechanisms are subserved by a specific widely distributed network. Here, we stimulated the parietal cortex of a subject with intracranial electrodes as he performed the visual STM task. We compared the ensuing results to those from a non-stimulated condition and to the performance of a matched control group. In brief, direct stimulation of the parietal cortex induced a selective improvement in STM. These results, together with previous studies, provide very preliminary but promising ground to examine behavioral changes upon parietal stimulation in AD. We discuss our results regarding: (a) the usefulness of the task to target prodromal stages of AD; (b) the role of a posterior network in STM binding and in AD; and (c) the potential opportunity to improve STM binding through brain stimulation

Monetary rewards modulate inhibitory control

The ability to override a dominant response, often referred to as behavioral inhibition, is considered a key element of executive cognition. Poor behavioral inhibition is a defining characteristic of several neurological and psychiatric populations. Recently, there has been increasing interest in the motivational dimension of behavioral inhibition, with some experiments incorporating emotional contingencies in classical inhibitory paradigms such as the Go/NoGo and Stop Signal Tasks (SSTs). Several studies have reported a positive modulatory effect of reward on performance in pathological conditions such as substance abuse, pathological gambling, and Attention Deficit Hyperactive Disorder (ADHD). However, experiments that directly investigate the modulatory effects of reward magnitudes on the performance of inhibitory tasks are scarce and little is known about the finer grained relationship between motivation and inhibitory control. Here we probed the effect of reward magnitude and context on behavioral inhibition with three modified versions of the widely used SST. The pilot study compared inhibition performance during six blocks alternating neutral feedback, low, medium, and high monetary rewards. Study One compared increasing vs. decreasing rewards, with low, high rewards, and neutral feedback; whilst Study Two compared low and high reward magnitudes alone also in an increasing and decreasing reward design. The reward magnitude effect was not demonstrated in the pilot study, probably due to a learning effect induced by practice in this lengthy task. The reward effect per se was weak but the context (order of reward) was clearly suggested in Study One, and was particularly strongly confirmed in study two. In addition, these findings revealed a 'kick start effect' over global performance measures. Specifically, there was a long lasting improvement in performance throughout the task when participants received the highest reward magnitudes at the beginning of the protocol. These results demonstrate a dynamical behavioral inhibition capacity in humans, as illustrated by the reward magnitude modulation and initial reward history effects. © 2014 Herrera, Speranza, Hampshire and Bekinschtein