Ushakov, V.L.

Background. Ideas about relationships between “I”, egocentric spatial orientation and the sense of bodily “Self ” date back to work by classics of philosophy and psychology. Cognitive neuroscience has provided knowledge about brain areas involved in self-ref­erential processing, such as the rostral prefrontal, temporal and parietal cortices, often active as part of the default mode network (DMN).

Objective and Method. Little is known about the contribution of inferior parietal areas to self-referential processing. Therefore, we collected observations of everyday be­havior, social communication and problem solving in patients with brain lesions local­ized either in the left inferior parietal cortex (LIPC group, n = 45) or the right inferior parietal cortex (RIPC group, n = 58).

Results. A key characteristic of the LIPC group was an overestimation of task com­plexity. This led to a prolonged phase of redundant and disruptive contemplations pre­ceding task solution. In the RIPC group, we observed disorders in reflective control and voluntary regulation of behavior. Abilities for experiencing emotions, understanding mental states, and social communication were to a great extent lost. Results are inter­preted within a multilevel framework of cognitive-affective organization (velichkovsky, 2002). In particular, we highlight the role of right-hemisphere mechanisms in self-refer­ential cognition, emotional and corporeal awareness. This is consistent with recent data on a profound asymmetry in connectivity of left and right hippocampi within the DMN (Ushakov et al., 2016)

Conclusion. It seems that the center of egocentric spatial representation plays a spe­cial role in accessing self-related data. Normally, the right hippocampus provides a holis­tic representation of surrounding and, thus, an easy-to-find gateway into much of what we used to call “subjective experience”. This heuristics becomes misleading in the case of right-sided brain lesions.

We investigated whole-brain functional magnetic resonance imaging (fMRI) activation in a group of 21 healthy adult subjects during perception, imagination and remembering of two dynamic visual scenarios. Activation of the posterior parts of the cortex prevailed when watching videos. The cognitive tasks of imagination and remembering were accompanied by a predominant activity in the anterior parts of the cortex. An independent component analysis identified seven large-scale cortical networks with relatively invariant spatial distributions across all experimental conditions. The time course of their activation over experimental sessions was task-dependent. These detected networks can be interpreted as a recombination of resting state networks. Both central and peripheral networks were identified within the primary visual cortex. The central network around the caudal pole of BA17 and centers of other visual areas was activated only by direct visual stimulation, while the peripheral network responded to the presentation of visual information as well as to the cognitive tasks of imagination and remembering. The latter result explains the particular susceptibility of peripheral and twilight vision to cognitive top-down influences that often result in false-alarm detections.

Background. Concepts of movement and action are not completely synonymous, but what distinguishes one from the other? Movement may be defined as stimulus- driven motor acts, while action implies realization of a specific motor goal, essential for cognitively driven behavior. Although recent clinical and neuroimaging studies have revealed some areas of the brain that mediate cognitive aspects of human motor behavior, the identification of the basic neural circuit underlying the interaction between cognitive and motor functions remains a challenge for neurophysiology and psychology.

Objective. In the current study, we used functional magnetic resonance imaging (fMRI) to investigate elementary cognitive aspects of human motor behavior.

Design. Twenty healthy right-handed volunteers were asked to perform stimulus-driven and goal-directed movements by clenching the right hand into a fist (7 times). The cognitive component lay in anticipation of simple stimuli signals. In order to disentangle the purely motor component of stimulus-driven movements, we used the event-related (ER) paradigm. FMRI was performed on a 3 Tesla Siemens Magnetom Verio MR-scanner with 32-channel head coil.

Results. We have shown differences in the localization of brain activity depending on the involvement of cognitive functions. These differences testify to the role of the cerebellum and the right hemisphere in motor cognition. In particular, our results suggest that right associative cortical areas, together with the right posterolateral cerebellum (Crus I and lobule VI) and basal ganglia, de ne cognitive control of motor activity, promoting a shift from a stimulus-driven to a goal-directed mode.

Conclusion. These results, along with recent data from research on cerebro-cerebellar circuitry, redefine the scope of tasks for exploring the contribution of the cerebellum to diverse aspects of human motor behavior and cognition.