M. V. Kireev

An ER-fMRI study of Russian inflectional morphology

The generation of regular and irregular past tense verbs has long been a testing ground for different models of inflection in the mental lexicon. Behavioral studies examined a variety of languages, but neuroimaging studies rely almost exclusively on English and German data. In our fMRI experiment, participants inflected Russian verbs and nouns of different types and corresponding nonce stimuli. Irregular real and nonce verbs activated inferior frontal and inferior parietal regions more than regular verbs did, while no areas were more activated in the opposite comparison. We explain this activation pattern by increasing processing load: a parametric contrast revealed that these regions are also more activated for nonce stimuli compared to real stimuli. A very similar pattern is found for nouns. Unlike most previously obtained results, our findings are more readily compatible with the single-system approach to inflection, which does not postulate a categorical difference between regular and irregular forms.

Cerebral mechanisms of error detection during deceptive responses in the normal state and under the influence of alcohol

Event-related potentials (ERPs) were studied during deceptive and truthful responses of subjects that were in the normal state or under the influence of alcohol. The psychological task was designed in such a way that the subjects themselves decided whether or not they would tell a lie. Thirteen healthy volunteers participated in the study. An actual deceptive answer was characterized by a higher amplitude of the frontocentral ERP N190 component compared to the ERP accompanying a truthful answer. Alcohol consumption inverted the ratio between the amplitudes of this component in the cases of deceptive and truthful answers (with a higher amplitude in the latter case). The obtained result suggests that a deceptive action activates the so-called cerebral error detector. Under the influence of alcohol, the cerebral error detection system functioned abnormally, so that a deceptive action was not perceived as erroneous. This disturbance of automatic control may account for the lower amplitude of the late positive component of ERPs, which, in our opinion, reflects the process of making a decision on a deceptive response. This may explain why, e.g., alcohol consumption by a driver is hazardous: the activity is mainly controlled by conscious processes (the probability of making “the only right decision” in a critical situation is decreased, reactions become slow, etc.). Thus, the experimental model where the subject consumes a small amount of alcohol may be used for studying the altered functional mode of the cerebral error detector. Such studies seem promising in terms of searching for and developing methods for noninvasive modification of the error detector activity that could be used, e.g., in treatment for obsessions.

Stages of the cerebral mechanisms of deceptive responses

Cerebral mechanisms of perceiving and telling lies were studied by recording event-related potentials (ERPs) both after an actual deceptive response and during the time interval when the subject decided to tell a lie. Ten healthy volunteers participated in the study. The test consisted of their playing a game against a computer. The subjects could choose between deceptive and truthful answers so as to win the game. The subjects gave a deceptive answer intentionally, the structure of the test ensuring equal numbers of deceptive and truthful answers. The relaxation times in the cases of truthful and deceptive answers did not differ significantly from each other. The comparison of ERPs accompanying deceptive and truthful answers showed the existence of a negativity with a latent period of 90 ms in the regions of the right frontal, central, and right parietal derivations. This negativity indicated that the brain reacted to a deceptive answer even if this a priori “erroneous” act ensured reaching the goal and, in this sense, was subjectively relevant. In terms of the cerebral error detector mechanism, this phenomenon may be regarded as a special case of a general response of the brain to giving an incorrect (deceptive) answer, rather than a response to a lie per se. The interval of time when, presumably, the decision on a deceptive answer was being made was found to contain the late positive component P540, which is most likely to be involved in the preparation of the deceptive answer and the intention to tell a lie.

Changes in functional connectivity within the fronto-temporal brain network induced by regular and irregular Russian verb production

Functional connectivity between brain areas involved in the processing of complex language forms remains largely unexplored. Contributing to the debate about neural mechanisms underlying regular and irregular inflectional morphology processing in the mental lexicon, we conducted an fMRI experiment in which participants generated forms from different types of Russian verbs and nouns as well as from nonce stimuli. The data were subjected to a whole brain voxel-wise analysis of context dependent changes in functional connectivity [the so-called psychophysiological interaction (PPI) analysis]. Unlike previously reported subtractive results that reveal functional segregation between brain areas, PPI provides complementary information showing how these areas are functionally integrated in a particular task. To date, PPI evidence on inflectional morphology has been scarce and only available for inflectionally impoverished English verbs in a same-different judgment task. Using PPI here in conjunction with a production task in an inflectionally rich language, we found that functional connectivity between the left inferior frontal gyrus (LIFG) and bilateral superior temporal gyri (STG) was significantly greater for regular real verbs than for irregular ones. Furthermore, we observed a significant positive covariance between the number of mistakes in irregular real verb trials and the increase in functional connectivity between the LIFG and the right anterior cingulate cortex in these trails, as compared to regular ones. Our results therefore allow for dissociation between regularity and processing difficulty effects. These results, on the one hand, shed new light on the functional interplay within the LIFG-bilateral STG language-related network and, on the other hand, call for partial reconsideration of some of the previous findings while stressing the role of functional temporo-frontal connectivity in complex morphological processes.

Functional magnetic resonance study of deliberate deception

The goal of the study was analysis of the cerebral mechanisms of deliberate deception. The eventrelated functional magnetic resonance (ER fMRI) imaging technique was used to assess the changes in the functional brain activity by means of recording the blood oxygen level-dependent (BOLD) signal. Twelve right-handed healthy volunteers aged 19–44 years participated in the study. The BOLD images were obtained during three experimental trials: deliberate deception, manipulative honest and control truthful trials (catch trials). The deliberate deception and manipulative honest actions were characterized by a BOLD signal increase in the anterior cingulate (Brodmann’s area (BA) 32), frontal (BAs 9/10, 6), and parietal (BA 40) cortices as compared with a truthful response. Comparison of the ER fMRI data with the results of earlier studies where event-related potentials (ERPs) were recorded under similar conditions indicates the involvement of the brain mechanism of error detection in deliberate deception.

Deceptive but Not Honest Manipulative Actions Are Associated with Increased Interaction between Middle and Inferior Frontal gyri

The prefrontal cortex is believed to be responsible for execution of deceptive behavior and its involvement is associated with greater cognitive efforts. It is also generally assumed that deception is associated with the inhibition of default honest actions. However, the precise neurophysiological mechanisms underlying this process remain largely unknown. The present study was aimed to use functional magnetic resonance imaging to reveal the underlying functional integration within the prefrontal cortex during the task which requires that subjects to deliberately mislead an opponent through the sequential execution of deceptive and honest claims. To address this issue, we performed psychophysiological interaction (PPI) analysis, which allows for statistical assessment of changes in functional relationships between active brain areas in changing psychological contexts. As a result the whole brain PPI-analysis established that both manipulative honest and deceptive claiming were associated with an increase in connectivity between the left middle frontal gyrus and right temporo-parietal junction (rTPJ). Taking into account the role played by rTPJ in processes associated with the theory of mind the revealed data can reflect possible influence of socio-cognitive context on the process of selecting manipulative claiming regardless their honest or deceptive nature. Direct comparison between deceptive and honest claims revealed pattern enhancement of coupling between the left middle frontal gyrus and the left inferior frontal gyrus. This finding provided evidence that the execution of deception relies to a greater extent on higher-order hierarchically-organized brain mechanisms of executive control required to select between two competing deceptive or honest task sets.

Functional Interactions between the Caudate Nuclei and Inferior Frontal Gyrus Providing Deliberate Deception

The goal of the present study was to investigate functional interactions between brain structures during deliberate deception. On the basis of the results obtained and literature data, the following hypothesis has been formulated: the functional interaction between the brain areas responsible for executive control of the behavior localized in the prefrontal cortex (inferior frontal gyrus) and elements of the error detection system of the brain underlie deliberate deception. This hypothesis has been tested using psychophysiological interaction (PPI) analysis, which has revealed that deceptive actions (in comparison to truthful ones) are related to an increased functional connectivity between the left caudate nucleus and left inferior frontal gyrus. The experimental data support our hypothesis that the interaction of the brain systems responsible for executive control and error detection underpins the brain maintenance of execution of deceptive actions.

Contemporary Methods for Functional Tomographic Neuroimaging in Studies of Brain Functions in Health and Pathology

Contemporary functional tomographic neuroimaging methods (fMRI and PET) have for many years been applied actively not only in basic studies of brain functions, but also in clinical practice. This article considers the main characteristics of the signals recorded and the principles of constructing images, as well as the requirements for obtaining adequate results. The advantages and fundamental limitations of contemporary tomographic methods of studying brain functions are discussed. The need to use complex approaches consisting of combined studies in investigating the brain is demonstrated, and methods for studying the functional integration of the brain are proposed.

Factor Structure of Regional Cerebral Blood Flow and Glucose Metabolism Rate as a Tool to Study the Default Mode of the Brain

The functional connectivity of anatomical and functional brain structures in the state of operational rest was assessed on the basis of positron emission tomography (PET) data to study the so-called default mode of the brain, i.e., the brain’s spontaneous activity at rest.It is concluded that the possibility of identifying neuroanatomical systems of the default mode (default mode network) in routine clinical PET studies of the cerebral blood flow and glucose metabolism is important for studying the functional organization of the brain in the normal state and its rearrangements in pathologies.

Organization of the Brain Systems of Aim-Directed Behavior: New Data

Currently, the dominating approach to studying functional brain organization is based on the so-called activation studies, in the frameworks of which the functional specializations of different brain structures in the context of studied nature of activity are specified according to their energy states. The concept of organization of brain systems is formed largely thanks to such activation research. However, our studies devoted to the analysis of functional relations between different nodes of the brain systems show that they are much more complicated than they are presented in the activation studies. The structure of brain systems is not limited to those elements that are involved in its work by changing their local neuronal activity. This fact dramatically changes our views on how the brain systems are organized.