Neuron spike activity was recorded in the retrosplenial area of the cortex during execution of acquired cyclic operant food-procuring behavior (COFPB) in adult (8–12 months) and elderly (20–27 months) LongEvans rats. As compared with adult rats, elderly animals showed a signifi cant decrease in the proportion of neurons specialized for COFPB. The normalized discharge frequency of all neurons in elderly animals during execution of basic food-procuring acts was signifi cantly greater than that in adults. Elderly rats showed signifi cantly fewer pairs of acts with signifi cant differences in discharge frequency than adults, indicating that neuron activity on execution of COFPB was more uniform. These data indicate that in old age, learning involves less “extension” of existing experience due to formation of new neuronal specializations than in earlier stages of an individual’s life and that the internal system structure of the newly formed behavior is more “homogeneous.”
Psychological studies have indicated that erotic images are evaluated in the context of positive emotions as the most intense, associated with the greatest degree of emotional arousal, among the whole gamut of pleasant and unpleasant stimuli. It is diffi cult to discriminate the cortical zones directly associated with emotional arousal from the activity of structures responsible for assessing emotional stimuli in the inducement/reward system. The aim of the present work was to identify differences in cerebral activity using functional MRI scans (fMRI) in men during assessment of the intensity of pleasant images, including erotic images, or unpleasant and neutral images. Comparison of tasks involving the assessment of pleasant images of the erotic type with tasks containing neutral or unpleasant stimuli revealed signifi cantly more marked activation in the posterior cingulate cortex, the prefrontal cortex, and the globus pallidus on the right side. Comparison of tasks with pleasant and neural stimuli revealed an increase in the activity of the right anterior central gyrus. Thus, the process of assessment of the intensity of emotional images of erotic type was related to activation of brain areas belonging not only to the neural representation of the emotions, but also to the cognitive system controlling emotional arousal and the motivational domain, which needs to be considered when using erotic images as powerful positive emotional stimuli.
Tonic brain activity has significant influences on the nature of a subject’s responses to target sensory stimuli. We report here studies of the dynamics of the background activity in the gamma-rhythm range of the EEG in rabbits during execution of an “active oddball” paradigm modified for animals – a task widely used for studies of attention. Increased levels of power and coherence in background gamma activity were found to reflect expectation of a target stimulus, correct responses to stimuli being executed at a particular level of background gamma activity which probably corresponds to the optimum level of sustained (tonic) attention. Decreases in the level of gamma activity led to missed responses to the target stimulus, while excess levels lead to erroneous responses to non-target signals (false anxiety). These dynamics of background gamma activity are interpreted as resulting from oscillations in the level of tonic cholinergic activation of right cerebral cortex.
A central pattern generator (CPG) is defined as a set of neurons whose members work together to generate organized motor output activity. A round-table discussion on central pattern generators was held on November 21, 2012 as part of the Fifth All-Russian Conference on Animal Behavior in Moscow. The main topics of discussion were: 1) the mechanisms of the organization and rearrangement of pattern-generating neuron ensembles; 2) the possibility that structures of the central pattern generator type have a role in controlling non-motor brain functions; and 3) the evolutionary and ontogenetic aspects of central pattern generators.
We report here an analysis of specific brain activity measured by fMRI during solution of spatial and verbal tasks in 15 healthy subjects and nine patients with dysarthria or mild sensorimotor aphasia. In healthy subjects, activation of Brodmann area (BA) 19 and Broca’s area was more characteristic of verbal thought, while greater bilateral activation of the temporal-parietal-occipital zone, along with the left insula and visual fields 17 and 18 on the left, was specific for spatial thought. In patients with speech disorders, the distribution of areas specific to one task or another underwent significant changes, with non-activation of areas of brain activation characteristic of healthy subjects. Despite the absence of clinical signs of cognitive impairments, the mean verbal task solution time was significantly longer and the proportion of correct responses was smaller in patients than in healthy subjects.
The ability of the Corvidae to understand the logical structure in string-pulling tasks was studied in a set of experiments with varied position of strings. It was demonstrated that some hooded crows (Corvus cornix L.) and common ravens (Corvus corax L.) successfully completed the tasks where the strings were not intersected but placed so that the bait was positioned opposite the forepart of the empty string. Hooded crows also solved the task where the baits were attached to both strings, but one of the strings was disrupted. The task with two intersected strings where the bait was positioned opposite the forepart of the empty string was not solved by the crows. The results suggest the ability of both examined species to grasp the logical structure of such kind of tasks.
Changes in 272 EEG parameters were studied in 252 women and 97 men during the period of life from age 16 years to age 45 years with a step of one month. Correlation and approximation analysis showed more progressive age-related decreases in the amplitude and power of α, θ, and δ but not β oscillations in women than men, particularly in the right posterior leads. A general ontogenetic tendency to nonlinear decreases in the amplitude and power of EEG rhythms with age was seen in people of both genders. The frequencies of rhythms generally showed compensatory increases during ontogeny. Thus, neurologically healthy men and women showed different means of achieving the same end – adaptive responding of the brain to age-related changes.
Learning to control a “brain–computer interface” (BCI) system was studied using specially developed training. Training included performance of slow cyclic movements with the right and left hands (the durations of each movement corresponded to the durations of the hand motor imagery when working with the BCI), imagining these movements, and also sitting calmly before movements started. Control of the BCI was tested before and after training. The Eysenck personality questionnaire was used to assess the level of emotional stability (neuroticism). Comparison of the accuracy of classifi cation of the state of the brain during motor imagery before and after training showed that the success in learning to control the BCI depended on subjects’ scores on the neuroticism scale. After training, the separability of brain states on motor imagery with the left and right hands increased signifi cantly in users with low, but not in those with high, neuroticism; furthermore, separability of brain states in the latter decreased signifi cantly during right hand motor imagery and at rest. The subjective diffi culty of the imaginary (but not real) movements was greater when scores on the neuroticism scale were higher. These results provide evidence of the need to consider the emotional stability of users when developing methods of training to BCI control.
The parameters of the verbal and sensorimotor responses to the Müller-Lyer and Ponzo illusions were determined in two groups spending five days in support unloading produced by “dry” immersion. Subjects in the “immersion” (IM) group were not exposed to any treatment other than immersion. Subjects of the “immersion + weight loading” (IM + L) group underwent weight loading using a Penguin axial loading costume for 4 h each day. Differences in the verbal and sensorimotor responses were seen in the two groups, along with differences in assessments of the two illusions. Verbal reports indicated that the strength of the Ponzo and Müller-Lyer illusions decreased linearly as the experiment progressed; sensorimotor responses indicated that being in the Penguin suit led to increases in illusion strength; the strength of the Müller-Lyer illusion increased after immersion fi nished. It is suggested that the main factor affecting illusion strength is gravitational unloading, which decreases the level of activation of the left hemisphere, leading to use of a metric representation system mainly associated with activity in the right hemisphere.
The effects of working memory (WM) capacity on mathematical ability are well known. This relationship is seen mainly for the capacity of visuospatial WM, while the capacity of the phonological loop of WM, which is associated with processing sound and speech information, has been suggested to have a minor effect on mathematical ability in adults. Nonetheless, involvement of the language neural networks in mathematical thought remains controversial. We have studied the effects of the capacity of the phonological loop of WM on the rate and correctness of solution of mathematical and verbal tasks in young, healthy, right-handed volunteers who either had higher education or were students at institutions teaching mathematics and humanities. Subjects in the mathematics group (N = 10) solved all tasks with measures of solution correctness (CA) and response time (RT) which were significantly better than values for subjects of the humanities group (N = 10). The capacity of the phonological loop of WM showed no difference between the two groups but had different effects on CA and RT values for tasks in mathematicians and humanities specialists. Spearman correlation analysis for each group separately showed that the capacity of WM had positive effects on CA for all mathematical tasks only in the mathematicians group, where it had no effect on RT, while the reverse tendency was seen in the humanities group. The capacity of WM in the mathematicians group correlated inversely with RT for logical tasks on arithmetic sequences. Our results provide indirect evidence that WM in the verbal domain can influence mathematical ability, especially when tasks require the involvement of logical thought.
Differences in the parameters of memory-guided saccades and saccades to visual stimuli were demonstrated. Increases in the latent periods of memory-guided saccades as compared with saccades to visual stimuli provided evidence of slowing of saccade programming based on the extraction of information from working memory. Differently directed lateral differences were seen in the latent periods and durations of saccades to visual targets and memory-guided saccades, reflecting the leading role of the left hemisphere in the programming of saccades to visual stimuli and the right hemisphere in the programming of memory- guided saccades. Comparison of parameters of the temporospatial dynamics of initiation potentials P-1 and N-1, which develop in the last 100 msec of the latent periods of saccades, suggest that there are different mechanisms for the final step of programming saccades to visual stimuli and memory-guided saccades. Decreases in the latent period of the P-1 and N-1 peak potentials before memory-guided saccades may be evidence showing acceleration of the initiation processes for memory-guided saccades as compared with visually evoked saccades. This provides grounds for suggesting that the slowing of the programming of memory-guided saccades occurs at steps preceding saccade initiation.
This review presents current data on possible mechanisms forming synergies in health, particularly at the cortical level. The mechanisms of formation of pathological synergies, taking account of the anatomical and physiological characteristics of the upper limbs and the hypothesis, that synergistic patterns are transformed in patients with spastic hemiparesis are discussed. Current views of the pathophysiological bases of the formation of pathological synergies based on neuroimaging and neurophysiological study data are presented, along with a method for noninvasive stimulation of the brain. The question of the correction and transformation of pathological synergies in rehabilitation practice is discussed. Particular attention is paid to clinical and instrumented evaluation of synergies and the use of validated clinical scales and instrumented methods such as video movement analysis, electromyography, magnetic and contactless tracking systems, and virtual reality technologies.
A community of hamadryas baboons (Papio hamadryas) consists of a unique organization with four structural levels and marked hierarchical relationships between males and females. This makes it an ideal system for testing the hypothesis that relationship quality influences reconciliation between individuals. Post-conflict reconciliation was studied in hamadryas baboons. The behavior of 436 conflicting pairs was studied. Reconciliation was found to be characteristic of pairs of different composition, including: 1) pairs consisting of a male and a female from his harem; 2) pairs consisting of two females from the same harem; 3) pairs consisting of two related animals; 4) pairs consisting of two males; 5) pairs including a female and a young (almost adult) male. Significant differences in reconciliatory tendencies were seen in different pair categories, along with a high level of selectivity of the interactions between former antagonists, evidencing that the probability of reconciliation between hamadryas baboon individuals depends on the quality of the relationships between them. Keywords: hamadryas baboons, reconciliation, male-female bonds.
Experiments were performed on four European rabbits (Oryctolagus cuniculus). Rabbits underwent implantation of silver-plated electrodes into the bone over the primary visual cortex to record evoked potentials. Evoked potentials to substitution of threshold visual stimuli of intensity 0.28 and 0.31 cd/m2 were initially recorded, after which these stimuli were supplemented by sounds (2000 Hz, 84 dB, 40 msec). Sounds presented alone did not induce responses. Measurement of the amplitude of the N1 wave (85–110 msec) showed that the magnitudes of the response to substitution of sound + light complexes were significantly greater, by a factor of 1.6, than responses to substitution of light stimuli. Paired substitutions of light stimuli of eight intensities over the range 0.28–20.2 cd/m2 were then performed, and factor analysis was used to reconstruct the intensity sensory space. This was compared with a similarly obtained sensory space constructed with light stimuli accompanied by sounds. Analysis of the distances between the ends of the vectors representing the stimuli showed that addition of sounds led to enlargement of the space occupied by low-intensity light (0.28, 1.02, 3.05, and 6.35 cd/m2) by an average factor of 1.4 and ordered the positions of light in the space – strictly from the less to the more intense. At the same time, sounds shrank the space delimited by stimuli of greater intensities (8.48, 13.7, 16.8, 20.2 cd/m2) by a mean factor of 1.33. It is suggested that addition of sounds leads to improvements in the discrimination of lowintensity lights and leads to some degree of restriction to the discrimination of high intensities. The sensory spaces constructed from these substitutions of complex sound + light stimuli, as in the case of light stimuli, were two-dimensional, providing evidence supporting the suggestion that these stimuli are integrated into the single complexes when delivered simultaneously.
In recent years, possible therapeutic effects of transcranial direct current stimulation (tDCS) have been widely investigated in studies dealing with different types of neural pathologies. Initially, tDCS was applied for treatment of patients with motor stroke; later on, it was introduced into studies of patients with Alzheimer’s disease, multiple sclerosis, Parkinson’s disease, schizophrenia, and post-stroke aphasia. Recent reviews of tDCS application in patients with post-stroke aphasia did not provide coherent evidence on the tDCS efficiency. There were no uniform protocols of stimulation used, patients’ selection criteria were highly divergent, and the reports of treatment outcomes varied dramatically. In this review, we will focus on the reported heterogeneity of tDCS effects, trying to disentangle its putative underpinnings rooted in the diversity of lesion types, aphasia severity, and recovery stages. Given the current theoretical models suggesting the qualitatively different patterns of brain activity to accompany post-stroke aphasia recovery, a number of physiological factors should be taken into account to choose optimal tDCS parameters. With this in mind, we assess results of ten studies applying tDCS in post-stroke aphasia treatment, and, based on this analysis, suggest directions for further research in this rapidly developing field.