Organization of selective attention during preparation for the recognition of global and local characteristics of a visual stimulus in children with different levels of maturity of the regulatory brain systems

Event-related potentials (ERPs) evoked by key stimuli informing a subject about the forthcoming recognition of the global or local level of a hierarchical test figure were analyzed in 7-year-old children with different levels of maturity of the regulatory brain systems. Differences in both the initial ERP components P1, N1, and P2 (which reflect the analysis of the sensory characteristics and significance of a key stimulus) and the late components N3, Pc, and Nc (which reflect the preparation for the recognition of a subsequent test figure) were found. It was shown that, in children with frontal-thalamic regulatory system immaturity (FTRSI), the amplitude of the ERP component N1 is decreased in the caudal areas. In children with an immature bottom-up activation system, a decrease in the amplitude of initial ERP components in the caudal areas was observed in a broader time interval in components P1, N1, and P2. As compared to the control groups of children, in children with immature frontal-thalamic structures, components N3, Pc, and Nc were different in both the caudal and precentral areas. In children with immature lower brainstem activation structures, the late ERP components were different, predominantly, in the parietal and temporo-parieto-occipital areas. Comparison of ERPs in response to global and local key stimuli in children of the control group demonstrated a clear-cut temporal and topographical organization in the period of preparation for subsequent recognition of a prescribed level of the test stimulus: the earlier preparation stages were associated with component N3 in the parietal and temporo-parieto-occipital areas, whereas later stages were associated with Pc changes in the frontal areas. In children with FTRSI, changes in the late components in the caudal areas were poorly expressed and their topographical organization (characteristic of the control group) was absent; the involvement of the frontal areas in the late stages of the key stimulus analysis was restricted. These findings may give grounds to suggest the significance of the frontal-thalamic system in the organization of the response to an expected stimulus. In children with immature lower brainstem activation structures, the type of the key stimulus was reflected in the late ERP components in a diffuse way.     

Age differences of event-related potentials in the perception of successive and spatial components of auditory information

The perception of spatial and successive contexts of auditory information develops during child ontogeny. We compared event-related potentials (ERPs) recorded in 5- to 6-year-old children (N = 15) and adults (N = 15) in response to a digital series with omitted digits to explore age differences in the perception of successive auditory information. In addition, ERPs in response to the sound of a falling drop presented binaurally were obtained to examine the spatial content of auditory information. The ERPs obtained from the omitted digits significantly differed in the amplitude and latency of the N200 and P300 components between adults and children, which supports the hypothesis that the perception of a successive auditory structure is less automatic in children compared to adults. Although no significant differences were found in adults, the sound of a falling drop presented to the left ears of children elicited ERPs with earlier latencies and higher amplitudes of the P300 and N400 components in the right temporal area. Stimulation of the right ear caused an increasing amplitude of the N100 component in children. Thus, the observed differences in the auditory ERPs of children and adults reflect developmental changes in the perception of spatial and successive auditory information.     

Event-related potentials at different stages of the operation of visual working memory

Trace fixation and comparison with incoming information was studied using event-related potentials (ERPs) recorded from various cortical areas during passive viewing and matching of two consecutive pictures. Visual stimuli differing in the spatial location of elements (4 × 4 square patterns with random positions of 4 black and 12 white squares) and phonological stimuli (differently written letters) were used. Trace fixation was studied by comparing the ERPs generated in response to the first (reference) stimulus in the pair with those generated during passive viewing. Sensory analysis of the reference stimuli was observed in the time interval 128–196 ms. For the patterns presented, it was reflected by an increased amplitude of the N1 component in the caudal areas as compared with passive viewing. The phonological stimuli produced a higher amplitude of a positive wave in the frontotemporal area in the same time interval. Processing of subsequent information to be stored in memory was observed in the interval 232–452 ms. Processing of patterns was reflected by a decreased positivity, most pronounced in the left temporo-parieto-occipital area. Comparison of a trace with incoming information was studied by comparing the ERPs generated in response to the first (reference) and second (test) stimuli. The number of cortical areas involved in the sensory analysis of the test stimuli was larger than the number involved in the analysis of the reference stimuli. Comparison of the new information with the trace was reflected by an increased amplitude of the late positive wave (components P3, Pc, and Pc-Nc) in the frontocentral and caudal cortical areas. The topographic changes in the late positive components depended on the type of stimulus.     

Role of the Frontal Cortical Areas in the Analysis of Visual Stimuli at Conscious and Unconscious Levels

Event-related potentials (ERP) in response to complex target stimuli, which consisted of a central recognizable picture and a lateral masked image (analyzed at the unconscious level) were recorded in adult subjects and seven-year-old children. ERP components N200, N300, and P400/N400 had different topography and were differently pronounced in adults and children. In adult subjects, the N200 component that reflects the processing of a sensory stimulus was recorded in the temporo-parieto-occipital and occipital areas. In children, N200 was recorded in the caudal regions and the frontal areas of the cortex. Analysis of different waveforms obtained by subtraction of the ERP to the central stimulus from the ERP to the complex stimulus showed that unconscious stimulus processing in adult subjects is not reflected in the ERP structure. In children, an unconsciously processed image incorporated into a complex stimulus evokes processing negativity in the occipital and frontal cortical areas. Comparison of ERP in groups of children divided by their reflectivity/impulsivity showed that, predominantly, the left frontal area is involved in image analysis at the unconscious level in reflective children and, predominantly, the right frontal area participates in unconscious image analysis in impulsive children. It is suggested that the perfection of the visual recognition of a target stimulus, which contains additional unconsciously processed information, consists in growth of the involvement of the left-hemispheric mechanisms (with respective growth of significance of the left-hemispheric mechanisms) and in a decrease in the role of the frontal areas in analysis of sensory information.     

Functional Organization of the Brain during the Operation of Working Memory

Event-related potentials (ERPs) recorded from various cortical areas during matching of two consecutive pictures were analyzed. Reflecting the process of trace fixation, the ERP to the reference stimulus was characterized by an increase in components P150 and P300 in the occipital and temporo-parieto-occipital areas and components N300 and N400 in the precentral areas as compared with the ERP elicited by the warning stimulus. The ERP to the test stimulus, which reflected trace retrieval and matching with current information, was characterized by a generalized increase in the late positive complex in the interval 300–600 ms. Similarity and/or dissimilarity of the test and reference stimuli was reflected in the parameters of the ERP to the test stimulus. The results testify to the difference in functional and topographic organization of the brain cortex at the initial and late stages of operation of the working memory.     

Influence of genetic variants modulating dopamine activity on the brain processing of auditory information (the <Emphasis Type="Italic">P</Emphasis>300 paradigm)

We studied the influence of catechol-O-methyl transferase gene (COMT) polymorphism on the parameters of components of auditory evoked potentials (EPs) recorded under the conditions of selective attention in mentally healthy relatives of patients with endogenous psychosis. A smaller N100 latency of the EP in response to an insignificant stimulus, smaller N100 amplitude of the EP in response to a significant stimulus, smaller N200 latency, and larger P300 amplitude were found in subjects with the Met/Met genotype (with a higher dopamine activity), and a larger P200 latency was found in Val/Val genotype carriers. There was no influence of MMN gene polymorphism on the mismatch negativity.     

Development of the brain’s organization of working memory in young schoolchildren

In 7–8 and 9–10-years old children, we studied event-related potentials (ERPs) during paired comparison of non-verbalizable visuospatial stimuli presented at an interval of 1.5–1.8 s. Age-related differences were found in the involvement of various cortical areas in the formation and retention of a short-term memory trace of the reference stimulus and during comparison of the short-term trace with the test stimulus presented. In both age groups, working memory was associated with an elevation of the amplitude of the sensory-specific N1 component in the visual cortical areas. Age-related differences in the processing of sensory-specific characteristics of a stimulus were the greatest in the ERPs to the test stimulus: at the age of 9–10, the N1 component amplitude was significantly increased in all caudal leads and, in the occipital and inferior temporal leads, this component was preceded by P1 component. At this age, we observed the early involvement of the inferior frontal cortex, which was not observed at the age of seven. The increase in positivity over that area was observed in the interval of 100–200 ms. Substantial differences between age groups were found in the late ERP component corresponding to cognitive processes. At the age of 7–8, the presentation of both the reference and test stimuli causes the increase in the amplitude of the slow positive complex (SPC) in the caudal liads with the maximum enhancement found in the interval of 300–800 ms in the parietal leads. At the age of 9–10, the SPC increase, much like in adults, was observed in ERP to the test stimulus only. At this age, adult-like specific changes in the late phases of ERPs were observed in the fronto-central regions at the different stages of working memory. They are the increases in the negative N400 wave in the ERP to the reference stimulus and the SPC to the test stimulus. These data show that, at the age of 9–10, the functional organization of working memory of the adult type is formed; however, the extent to which the frontal cortex, and its dorsal regions in particular, is involved into working memory processes does not meet yet a definitive level.     

Functional brain organization of global and local visual perception: Analysis of event-related potentials

Event-related potentials (ERP) of the brain and psychometric indices (reaction time and percentage of correct responses) were studied in adult subjects during recognizing hierarchical visual stimuli (letters), while the subject’s attention was drawn to either the global or the local level of the stimulus. The psychophysical indices demonstrated the global precedence effect, i.e., an increased recognition time of a small letter, which was a part of an incongruent stimulus. The ERP component analysis demonstrated that differences in the regulatory mechanisms of attention and timing and topography of brain organization during processing of visual information depended on the level of recognizing the hierarchical stimulus (global vs. local). Visual recognition at the local level was accompanied by a stronger activation of visual associative areas (P _z and T ₆) at the stage of sensory feature analysis (P1 ERP component), as well as by the predominant involvement of the temporal inferior cortex of the right hemisphere (T ₆) at the stage of sensory categorization (the P2 ERP component) and of the frontal cortex of the right hemisphere at the stage of selection for the relevant target features (the N2 ERP component). Visual recognition at the global level was accompanied by significant involvement of the early sensory selection (the N1 ERP component) and predominant activation of the parietal cortex of the right hemisphere (P ₄) at the stage of sensory categorization (the P2 ERP component), as well as at the stage of identification of the target stimulus (the P3 ERP component). Perception of a stimulus at the global level is assumed to depend mostly on the analysis of its spatial features in the dorsal visual system, whereas perception at the local level involves analysis of the object-related features in the ventral visual system.     

Characteristics of event-related potentials in response to symbolical and alphabetical stimulation matrices used in a P300-based brain-computer interface

In order to create a P300-based brain-computer interface (BCI) (the so-called Farwell-Donchin paradigm, FD) with a symbol matrix used as a stimulus, we compared characteristics of event-related potentials (ERPs) in response to stimulation by 6 × 6 matrices composed of either pictogram symbols or Cyrillic alphabet characters. Nine healthy adults were examined in 18 experiments, during which 28-channel EEGs were recorded in the course of stimulation with matrices of these two types. The obtained ERP data, i.e., amplitudes and peak latencies of the ERP components N1, P3 (with the P3a and P3b sub-components), and N4 were compared and analyzed for different types of stimulation matrices. In at least seven out of nine subjects, P3a, P3b, and N4 ERP amplitudes were larger in response to the symbol matrix than to the character matrix, while N1 amplitudes were larger for the character matrix. For N1 and P3a, the ERP latencies were shorter for the symbol matrix, while for P3b and N4, they were longer for the character matrix. The topography of differential ERP responses to the two types of stimuli was analyzed using a series of paired t-tests. Differences of ERP component amplitudes were determined individually for each of the 28 channels; next, for each site, absolute t-test values were summed for all nine subjects. For all ERP components studied, the t-test for peak amplitudes in response to target and non-target letters identified two separate areas with distinct lateralization. ERP responses to target and non-target symbols differed most in transversely extended areas. Finally, the yield surface of differential response to target letters and target symbols had a complex topography.     

Short latency vestibular evoked potentials (VsEPs) to linear acceleration impulses in rats

In this study, short latency (t<12.7 ms) vestibular evoked potentials (VsEPs) in response to linear acceleration impulses were recorded in 37 rats. A new technique (based on a solenoid) was used for generating linear force impulses that were delivered to the animal's head. The impulse had a maximal peak acceleration of 12 g. During the impulse, the displacement was 50 μm (at 4 g) and the rise time was 1.0 ms. A stimulation rate of 2/s was usually used. The VsEPs (averaged responses to 128 stimulations, digital filter: 300–1500 Hz) were recorded with electrodes on pinna and vertex, and were composed of 4–6 clear waves with mean amplitudes (for a 4 g stimulus) of 1–5 μV. The VsEPs were resistant to white noise masking, and were significantly suppressed (P<0.05) following bilateral application of a saturated KCl solution to the inner ear, showing that contributions of the auditory and somatosensory systems are negligible. The latency of the response decreased as a power law function of stimulus magnitude, and the amplitude of the first wave increased as a sigmoid function of stimulus magnitude. VsEP responses were still present at the lowest intensities attainable (0.06–0.4 g) and reached saturation at 9 g. The amplitude of the later components was reduced when stimulus rate was elevated to 20/s. These results suggest that VsEPs in response to linear accelerations are similar in their nature to VsEPs in response to angular acceleration impulses that were previously recorded. These VsEPs to linear accelerations are most likely initiated in the otolith organs.     

Event-related potentials associated with a shift in the strategy of visual perception during recognition of a hierarchical stimulus

Recording of event-related potentials (ERPs) was used to study the brain mechanisms of shifting the strategy of recognition of the global and local levels of a hierarchical image by adult subjects. A shift in the strategy of visual recognition results in substantial changes in ERP parameters in the caudal and frontocentral cortical areas. The activation effect of the switchover from one recognition strategy to another is associated with an increase in the amplitude of early ERP components (C1, P100, and N150) of the caudal cortical areas. Changes in the late ERP components associated with processing of significant information features during the shift in the recognition strategy are observed in the frontal areas within the interval 388–579 ms, with the amplitude of components N300 and N400 increasing.     

Functional organization of the brain in the period of preparation for recognizing fragmented images in seven- to eight-year-old children and adults

Functional connectivity between the prefrontal cortex and the temporal and temporo-parieto-occipital cortices in the process of preparing for the recognition of fragmented images were analyzed in adults (n = 26) and seven- to eight-year-old children (n = 20).The evaluations of the imaginary part of the complex-valued coherency for the EEG alpha-rhythm (Jα) were used as an index for the strength of cortico-cortical interactions. The Jα value was analyzed in the following three experimental conditions corresponding to different stages of readiness for visual recognition: (1) nonspecific attention holding in the period preceding a warning stimulus (S1); (2) focused attention in the interval preceding a not-yet-recognized target stimulus (S2) and (3) pretuning preceding a recognized stimulus (S3). Adult subjects tended towards a growing level of functional connectivity in α-rhythm in progressing from attention holding to focused attention preceding the emergence of a target stimulus, but children, on the contrary, demonstrated a decreasing trend. Comparing the Jα values in the subgroups of adults and children who showed the highest recognition scores in the solution of cognitive tasks helped reveal age-specific patterns in the rearrangements of cortico-cortical functional connectivity in α-rhythm in the left and right hemispheres at different stages of readiness for recognizing incomplete images. In adults, the maximal Jα values were found in the left hemisphere in the interval preceding the recognition of a target image. At this stage of pretuning, the Jα values at the leads in the left hemisphere in adults significantly exceeded those in children. The Jα values for the right hemisphere in adults were maximal during focused prestimulus attention when the image was not yet recognized and these values were significantly higher than in children under the same experimental conditions. Children showed maximal Jα values in both hemispheres during nonspecific attention. The specifics of functional connectivity observed between the prefrontal, temporal and temporo-parieto-occipital cortices in seven- to eight-year-old children during functional pretuning to the recognition of fragmented images are considered to reflect the relative immaturity of neurophysiological mechanisms underlying the voluntary attention and working memory in children of this age group.     

Ensemble Empirical Mode Decomposition Analysis of EEG Data Collected during a Contour Integration Task

We discuss a data-driven analysis of EEG data recorded during a combined EEG/fMRI study of visual processing during a contour integration task. The analysis is based on an ensemble empirical mode decomposition (EEMD) and discusses characteristic features of event related modes (ERMs) resulting from the decomposition. We identify clear differences in certain ERMs in response to contour vs noncontour Gabor stimuli mainly for response amplitudes peaking around 100 [ms] (called P100) and 200 [ms] (called N200) after stimulus onset, respectively. We observe early P100 and N200 responses at electrodes located in the occipital area of the brain, while late P100 and N200 responses appear at electrodes located in frontal brain areas. Signals at electrodes in central brain areas show bimodal early/late response signatures in certain ERMs. Head topographies clearly localize statistically significant response differences to both stimulus conditions. Our findings provide an independent proof of recent models which suggest that contour integration depends on distributed network activity within the brain.     

Features of temporal dynamics of oscillatory brain activity during creative problem solving in young and elderly adults

Considering evidence from psychological research, successful aging is accompanied by long-term preservation of creative potential despite slowing of mental processes; however, the neurophysiological mechanisms that ensure the maintenance of those abilities are unclear. In this study, we compared temporal dynamics of changes induced by divergent task electrical activity (event-related spectral perturbations, ERSP) in a wide range of EEG frequencies in the younger (YA, N = 80, 22.6 ± 3 years) and older (OA, N = 80, 63.4 ± 6.7 years) age groups. The groups were sex-matched. EEG was recorded while participants performed the “alternate uses task”. The time ranges 200–400, 400–600 and 600–800 ms after stimulus presentation were analyzed. It was found that task performance was associated with distinct patterns of ERSP changes in the θ and α₃ rhythms in young and elderly subjects. The elderly subjects exhibited smaller θ-desyn-chronization of anterior brain areas at the initial stage of creative thinking as compared to young participants. The gradient of fronto-parietal activation was unchanged during the entire interval of analysis in the elderly subjects, whereas it was observed in young adults in the interval 200–400 ms only. Decrease in desynchronization of the parieto-occipital area in the α₃ rhythm in the interval 600–800 ms in elderly subjects was revealed, and it resulted in disappearance of differences between parietal and fronto-temporal areas, while they were preserved in the young group. Significant correlations between ERSP in the α₃ band and originality, in the β₁ band and solution rate were obtained in old adults exclusively. Identified age-related changes in oscillatory activity may be the basis of different strategies in solving creative task in young and elderly adults.     

Functional organization of working memory in seven- to eight-year-old children

Event-related potentials (ERPs) were analyzed during the operation of working memory (WM) using short-term traces of visuospatial and letter stimuli. A comparison of the two stimuli presented at an interval of about 1500 ms showed differences in the degree and mode of the involvement of the cortical areas during the formation and retention of a short-term memory trace (the first stimulus in the pair) and its comparison with the current information (the second stimulus in the pair). At the stage of trace formation, a significant increase was observed in the amplitudes of the components of the ERPs generated during the analysis and processing of sensory-specific information: visuospatial stimuli caused an increase in the N200 component in the O ₁, O ₂, T ₅, T ₆, P ₃, and P ₄ derivations; and letter stimuli caused an increase in the P200 component in the F ₃, F ₄, F ₇, F ₈, C ₃, C ₄, P ₃, P ₄, T ₃, and T ₄ derivations. The amplitude of the slow positive complex (SPC) significantly increased in the caudal cortical areas, which is not true for adults at this stage of the operation of WM. During a comparison of short-term memory traces with current information, the SPC amplitude significantly increased in the caudal cortical areas in seven- to eight-year-old children; the prefrontal cortex was not involved at this stage of the operation of WM. These findings testify to the insufficient maturity of the central executive of WM at an age of seven to eight years.     

Analysis of Age-Related Dynamics and Gender-Specific Characteristics of Spontaneous Bioelectrical Activity and Components of Auditory Evoked Potentials in Junior School Students Living in the Arctic Region of the Russian Federation

We studied neurophysiological characteristics of the age-related development in junior school students (7–8 and 10–11 years of age) living in the Arctic region of the Russian Federation. The background electroencephalograms (EEGs) were recorded during quiet wakefulness with the eyes closed and open, and event related potentials (ERP) were recorded during the passive perception of sound stimuli within the oddball paradigm in the group of children (33 subjects, 18 boys and 15 girls). A decrease of the latency period and the spatial rearrangement of mismatch negativity with an increase in the amplitude in the centrofrontal cortex have been revealed in the groups of children aged 10–11 years during the perception of a rare stimulus and a decrease of the latency period of the Р300 component in the central and parietal areas associated with the maturation of mechanisms for involuntary auditory attention. Age-specific differences in the components of auditory ERP (N1 and N2) have been shown during passive perception of rare and frequent sounds, which reflect the processes of the morphofunctional maturation of the brain cortex in healthy Arctic school students (an increase of the N1 component amplitude, a decrese of the amplitude and the latency period of the N2 component). The analysis of the background EEG characteristics has shown both the common features, such as a decrease with age of the EEG power in the Δ and θ bands in the eyes-open state, and the different direction and topographic specificities in the age-dependent reorganization of bioelectrical activity in boys and girls in the α₁ and α₂ EEG bands.     

Recognition of fragmented images and mechanisms of memory

Analysis of the topography and parameters of event-related potentials (ERPs) recorded during the presentation of incomplete images with different fragmentation aided in study of the role of different cortical zones and the order of their involvement in the recognition process. The role of the frontal cortical areas at different stages of perception of fragmented images was established. The differences in the ERPs induced by recognized and unrecognized stimuli in the frontal and frontal-temporal derivations in the interval 30–83 ms were associated with the appearance of early positivity in response to recognized images and development of early negativity in response to unrecognized stimuli. The N300 component associated with recognition was stronger in these cortical zones during identification of images. A late positive complex appeared in the frontal areas earlier than in other areas. Involvement of the caudal visual areas in the recognition process was reflected by enhancement of the components P100, P250, and N400. Our results suggest that the frontal areas play the main role in the recognition of fragmented images because they are the structures that organize extraction of traces from long-term modality-specific memory using a system of afferent and efferent links and determine the strategy of information analysis necessary for the solution of a given task.     

Evoked potentials of the cerebral cortex during the comparison of visual stimuli

Visual evoked potentials (EP) were recorded when the test subjects accomplished the tasks of a comparison of a current stimulus with the previous one, the stimuli being presented in a continuous sequence. In the first task, rare repetition of two stimuli (Russian letters) in the continuously changing flow of stimuli was relevant, and the test subject had to press the button when it happened; in the second task, the relevant stimulus was a rare change in the flow of stimuli. The influence of the stimulus repetition/change factor on EP was analyzed. The processes related to the comparison of the current and previous stimuli were most manifest in four time intervals: 120–140, 180–210, 260–280, and 350–370 ms. The occipito-temporal component of EP revealed in the interval of 180–210 ms, which we denoted as the negative component of visual mismatch (NCVM), proved a special component, differing in its functional and temporal characteristics from theN _2b component. WhereasN _2b is modulated by the factor of stimulus probability, the NCVM by that of stimulus repetition/change.     

Temporal and topographic characteristics of evoked potentials in the conflict of two consecutive visual stimuli in a working memory task

Behavioral reactions and brain mechanisms involved in processing two matching or mismatching (conflicting) visual stimuli were studied in healthy subjects (mean age 22.57 ± 0.46 years). Line orientations (vertical, horizontal, or 45°) were used as stimuli and were presented with an interval of 1500–1800 ms. The reaction time was shown to increase in the case of a conflict of two orientations as compared with matching orientations. The reaction time depended on the orientation of the reference stimulus and was minimal when a vertical line was used as a reference. An increase in N2 negativity (time window 200–280 ms) in the frontal and parietal cortical areas was identified as an informative indicator of a conflict between the current orientation and the orientation stored in working memory. The dipole sources of N2 were localized to the prefrontal cortex (middle frontal gyrus, frontal pole, and pars orbitalis). The N2 amplitude was found to depend on the orientation of the first stimulus in a pair, being higher in the case of a 45° orientation. The visual areas were shown to play a role in detecting a conflict of two consecutive signals because the early sensory components increased in amplitude. The results implicate cortical structures, including the sensory-specific visual, parietal, and prefrontal areas, in comparing consecutive visual signals and detecting their conflict.     

NMR spin–echo studies of hydration properties of the molecular chaperone α-crystallin in the bovine lens

The water-binding properties of bovine lens α-crystallin, collagen from calf skin and bovine serum albumin (BSA), were investigated with various techniques. The water absorptive capacity was obtained in high vacuum desorption experiments volumetrically, and also gravimetrically in controlled atmosphere experiments. NMR spin–echo technique was used to study the hydration of protein samples and to determine the spin–spin relaxation times (T₂) from the protons of water, absorbed on the proteins. Isolated bovine lenses were sectioned into 11–12 morphological layers (from anterior cortex through nucleus to posterior cortex). Crystallin profiles were obtained for each lens layer using thin-layer isoelectric focusing in polyacrylamide gel (IEF). The water content in relation to dry weight of proteins was measured in individual morphological lens layers. During the water vapor uptake P/P₀=0.75, α-crystallin did not absorb water, suggesting that hydrophobic regions of the protein are exposed to the aqueous solvent. At P/P₀=1.0, the absorption of water by α-crystallin was 17% with a single component decay character of spin–echo (T₂=3 ms). Addition of water to α-crystallin to about 50% of its w/w in the protein sample showed T₂=8 ms with only one single component decay of the spin–echo signal. The single component decay character of the spin–echo indicates at the tightly bound water by α-crystallin. Under a relative humidity P/P₀=1.0, collagen and BSA absorbed correspondingly 19.3% and 28% of water and showed a two-component decay curve with T₂ of about 5 and 40 ms. The findings demonstrate the presence of two water fractions in collagen and BSA which are separated in space. The IEF data suggest a tight binding of water with α-crystallin with similar distribution patterns in the lens layers. The IEF data demonstrate a possible chaperone-like function for α-crystallin in the nucleus and inner cortex of the lens, but not in the outer cortex. To conclude, it was found that α-crystallin can immobilize and bind water to a greater extent than other proteins such as collagen and BSA. These results shed new light on structural properties of α-crystallin and have important implications for understanding the mechanism of the chaperone-like action of this protein in the lens and non-ocular tissues.