scholarly journals The ex-illiterate brain: The critical period, cognitive reserve and HAROLD model

2009 ◽  
Vol 3 (3) ◽  
pp. 222-227 ◽  
Author(s):  
Maria Vania Silva Nunes ◽  
Alexandre Castro-Caldas ◽  
Dolores Del Rio ◽  
Fernado Maestú ◽  
Tomás Ortiz

Abstract The lifelong acquisition of cognitive skills shapes the biology of the brain. However, there are critical periods for the best use of the brain to process the acquired information. Objectives: To discuss the critical period of cognitive acquisition, the concept of cognitive reserve and the HAROLD (Hemispheric Asymmetry Reduction in Older adults) model. Methods: Seven women who learned how to read and to write after the age of 50 (ex-illiterates) and five women with 10 years of regular schooling (controls) were submitted to a language recognition test while brain activity was being recorded using magnetoencephalography. Spoken words were delivered binaurally via two plastic tubs terminating in ear inserts, and recordings were made with a whole head magnetometer consisting of 148 magnetometer coils. Results: Both groups performed similarly on the task of identifying target words. Analysis of the number of sources of activity in the left and right hemispheres revealed significant differences between the two groups, showing that ex-illiterate subjects exhibited less brain functional asymmetry during the language task. Conclusions: These results should be interpreted with caution because the groups were small. However, these findings reinforce the concept that poorly educated subjects tend to use the brain for information processing in a different way to subjects with a high educational level or who were schooled at the regular time. Finally, the recruiting of both hemispheres to tackle the language recognition test occurred to a greater degree in the ex-illiterate group where this can be interpreted as a sign of difficulty performing the task.

2008 ◽  
Vol 31 (4) ◽  
pp. 398-399
Author(s):  
James E. Swain ◽  
John D. Swain

AbstractIf connectionist computational models explain the acquisition of complex cognitive skills, errors in such models would also help explain unusual brain activity such as in creativity – as well as in mental illness, including childhood onset problems with social behaviors in autism, the inability to maintain focus in attention deficit and hyperactivity disorder (ADHD), and the lack of motivation of depression disorders.


2021 ◽  
Vol 33 (S1) ◽  
pp. 90-91
Author(s):  
Alena Sidenkova

IntroductionThe aging processes are accelerating in all regions of the world. The involvement of older people in production and social processes determines the need to maintain a high level of social and psychological adaptation, despite the progressive pathology of the brain caused by its aging. This increases the relevance of research related to the study of biological reserves of the brain and psychological and social mechanisms of human adaptation in late adulthood. The risk of developing cognitive disorders is not fatal. According to some observations, even in the hippocampal type of UKR, despite the content of amyloid in the brain, the functional and social activity of the elderly remains high. Prospective studies show that people with high cognitive reserve have a lower risk of developing dementia. Cognitive reserve is the brain’s resistance to damage. Cognitive reserve is the ability of the brain to cope with the consequences of damage caused by external influences, brain stroke, chronic brain ischemia, neurodegenerative diseases, and age-related changes. Cognitive reserve is the brain’s ability to functionally compensate for and minimize clinical manifestations of cognitive impairment. The mechanisms of cognitive reserve in normal and Alzheimer’s disease are different. In healthy older adults, a higher cognitive reserve correlates with larger brain sizes and effective strategies for performing cognitive tasks. In the early stages of Alzheimer’s disease and Alzheimer’s disease, the size of the brain decreases. But high brain activity helps preserve cognitive resources. Excessive brain activity in dementia is a compensatory mechanism. This is confirmed by the results of functional magnetic resonance imaging of the brain. Of course, the degree of brain atrophy is a predisposing factor for dementia, but it is not a mandatory factor for cognitive decline. So, the symptoms of dementia do not appear until you have crossed the critical border of damage to the brain substance. Progressive brain atrophy underlies the clinical manifestations of dementia in neurodegenerative diseases, but the correlation between the degree of brain damage and cognitive impairment is not linear.Research materials and methodsAn observational 10-year longitudinal study was conducted. In 2006, moderate cognitive impairment was found in 66 patients. The group of patients included 49 women and 49 men. Their average age in 2006 was 59.3±5.2 years. In 2006, the severity of cognitive decline was 26.2±1.9 points on the MMSE scale. This corresponds to indicators of moderate cognitive impairment. Research methods: clinical and psychopathological, psychometric, statistical. Questionnaire “Loss and acquisition of personal resources” (N. Vodopyanova, M. Stein), MMSE scale.Research resultIn 2006, amyloid was detected in the spinal fluid of all patients selected for the study group. If a patient developed dementia, they were given specific therapy. The dynamics of cognitive functions in patients was different. Mild dementia was formed in 53% of patients. Moderate dementia was formed in 10.6% of patients. Moderate cognitive impairment (pre-dementia) persisted in 36.4% of patients. Hereditary burden of dementia in patients with moderate dementia was detected 2 times more often. Back in 2006, we identified the leading sensory systems of patients. The master sensor system determines the modality of the main information flow. This is the most important part of the information that a person interacts with. This is the basis of interaction with reality. This is the basis of cognitive functions. Correlations of age-specific lesions of the corresponding sensory systems with the severity of cognitive decline were found in patients with the corresponding sensory modality (Spearman’s Correlation Coefficient-r, p<0.05): presbyacoussis – auditory r=0.667, presbyopia-visual r=0.705. The influence of psychosocial factors on the condition of patients was studied. In dementia, significant history of psychotrauma was found in 35.7%. Moderate stress was detected in the group of patients with moderate cognitive impairment in 33.3%. Moderate stress was detected in the group of patients with dementia in 83.3%. Stress of loss of life meaning was detected more often in patients with dementia 76.7%. It is important not only what stresses a person endures, but how they can cope with them. Dementia patients were statistically more likely to have unproductive coping strategies that did not help them cope adequately with stress.ConclusionsThe concept of cognitive reserve suggests possible causes of heterogeneity in the dynamics of cognitive decline in the initial stages of atrophic-degenerative brain diseases: biological causes and psychosocial causes. The concept of cognitive reserve helps to study and develop individual programs for the prevention of severe cognitive disorders.


2011 ◽  
Vol 2011 ◽  
pp. 1-17 ◽  
Author(s):  
Jocelyn J. LeBlanc ◽  
Michela Fagiolini

Cortical circuits in the brain are refined by experience during critical periods early in postnatal life. Critical periods are regulated by the balance of excitatory and inhibitory (E/I) neurotransmission in the brain during development. There is now increasing evidence of E/I imbalance in autism, a complex genetic neurodevelopmental disorder diagnosed by abnormal socialization, impaired communication, and repetitive behaviors or restricted interests. The underlying cause is still largely unknown and there is no fully effective treatment or cure. We propose that alteration of the expression and/or timing of critical period circuit refinement in primary sensory brain areas may significantly contribute to autistic phenotypes, including cognitive and behavioral impairments. Dissection of the cellular and molecular mechanisms governing well-established critical periods represents a powerful tool to identify new potential therapeutic targets to restore normal plasticity and function in affected neuronal circuits.


Author(s):  
Zoe Drayson ◽  
Andy Clark

Many models of cognitive ability and disability rely on the idea of cognition as abstract reasoning processes implemented in the brain. Research in cognitive science, however, emphasizes the way that our cognitive skills are embodied in our more basic capacities for sensing and moving, and the way that tools in the external environment can extend the cognitive abilities of our brains. It is important to address the implications of research in embodied cognition and extended cognition for how we think about cognitive impairment and rehabilitation, how cognitive reserve mitigates neural impairment, and the distinction between medical and social models of disability.


2021 ◽  
Vol 288 (1958) ◽  
pp. 20211025
Author(s):  
Margaret T. T. Wong-Riley

The landmark studies of Wiesel and Hubel in the 1960's initiated a surge of investigations into the critical period of visual cortical development, when abnormal visual experience can alter cortical structures and functions. Most studies focused on the visual cortex, with relatively little attention to subcortical structures. The goal of the present review is to elucidate neurochemical and synaptic mechanisms common to the critical periods of the visual cortex and the brain stem respiratory system in the normal rat. In both regions, the critical period is a time of (i) heightened inhibition; (ii) reduced expression of brain-derived neurotrophic factor (BDNF); and (iii) synaptic imbalance , with heightened inhibition and suppressed excitation. The last two mechanisms are contrary to the conventional premise. Synaptic imbalance renders developing neurons more vulnerable to external stressors. However, the critical period is necessary to enable each system to strengthen its circuitry, adapt to its environment, and transition from immaturity to maturity, when a state of relative synaptic balance is attained. Failure to achieve such a balance leads to neurological disorders.


Endocrinology ◽  
2011 ◽  
Vol 152 (6) ◽  
pp. 2409-2415 ◽  
Author(s):  
Charles E. Roselli ◽  
Charles T. Estill ◽  
Henry L. Stadelman ◽  
Mary Meaker ◽  
Fred Stormshak

Sheep exposed to testosterone during a critical period from gestational day (GD) 30 to GD 90 develop masculine genitals and an enlarged male-typical ovine sexually dimorphic nucleus of the preoptic area (oSDN). The present study tested the hypothesis that separate critical periods exist for masculinization of these two anatomical end points. Pregnant ewes were treated with testosterone propionate (TP) either from GD 30 to GD 60 (early TP) or GD 60 to GD 90 (late TP). Control (C) pregnant ewes were treated with corn oil. Fetuses were delivered at GD 135 and the volume of the oSDN was measured. Early TP females possessed a penis and a scrotum devoid of testes, whereas late TP and C females had normal female genitals. Neither period of TP exposure grossly affected the genitals of male fetuses. Despite masculinized genitals, the mean volume of the oSDN in early TP females (0.32 ± 0.06 mm3) was not different from C females (0.24 ± 0.02 mm3) but was significantly enlarged in late TP females (0.49 ± 0.04 mm3; P &lt; 0.05 vs. C) when the genitals appeared normal. In contrast, the volume of the oSDN in late TP males (0.51 ± 0.02 mm3) was not different from C males (0.51 ± 0.04 mm3) but was significantly smaller in the early TP males (0.35 ± 0.04 mm3; P &lt; 0.05 vs. C). These results demonstrate that the prenatal critical period for androgen-dependent differentiation of the oSDN occurs later than, and can be separated temporally from, the period for development of masculine genitals.


2010 ◽  
Vol 24 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Włodzimierz Klonowski ◽  
Pawel Stepien ◽  
Robert Stepien

Over 20 years ago, Watt and Hameroff (1987 ) suggested that consciousness may be described as a manifestation of deterministic chaos in the brain/mind. To analyze EEG-signal complexity, we used Higuchi’s fractal dimension in time domain and symbolic analysis methods. Our results of analysis of EEG-signals under anesthesia, during physiological sleep, and during epileptic seizures lead to a conclusion similar to that of Watt and Hameroff: Brain activity, measured by complexity of the EEG-signal, diminishes (becomes less chaotic) when consciousness is being “switched off”. So, consciousness may be described as a manifestation of deterministic chaos in the brain/mind.


1999 ◽  
Vol 13 (2) ◽  
pp. 117-125 ◽  
Author(s):  
Laurence Casini ◽  
Françoise Macar ◽  
Marie-Hélène Giard

Abstract The experiment reported here was aimed at determining whether the level of brain activity can be related to performance in trained subjects. Two tasks were compared: a temporal and a linguistic task. An array of four letters appeared on a screen. In the temporal task, subjects had to decide whether the letters remained on the screen for a short or a long duration as learned in a practice phase. In the linguistic task, they had to determine whether the four letters could form a word or not (anagram task). These tasks allowed us to compare the level of brain activity obtained in correct and incorrect responses. The current density measures recorded over prefrontal areas showed a relationship between the performance and the level of activity in the temporal task only. The level of activity obtained with correct responses was lower than that obtained with incorrect responses. This suggests that a good temporal performance could be the result of an efficacious, but economic, information-processing mechanism in the brain. In addition, the absence of this relation in the anagram task results in the question of whether this relation is specific to the processing of sensory information only.


Author(s):  
V. A. Maksimenko ◽  
A. A. Harchenko ◽  
A. Lüttjohann

Introduction: Now the great interest in studying the brain activity based on detection of oscillatory patterns on the recorded data of electrical neuronal activity (electroencephalograms) is associated with the possibility of developing brain-computer interfaces. Braincomputer interfaces are based on the real-time detection of characteristic patterns on electroencephalograms and their transformation  into commands for controlling external devices. One of the important areas of the brain-computer interfaces application is the control of the pathological activity of the brain. This is in demand for epilepsy patients, who do not respond to drug treatment.Purpose: A technique for detecting the characteristic patterns of neural activity preceding the occurrence of epileptic seizures.Results:Using multi-channel electroencephalograms, we consider the dynamics of thalamo-cortical brain network, preceded the occurrence of an epileptic seizure. We have developed technique which allows to predict the occurrence of an epileptic seizure. The technique has been implemented in a brain-computer interface, which has been tested in-vivo on the animal model of absence epilepsy.Practical relevance:The results of our study demonstrate the possibility of epileptic seizures prediction based on multichannel electroencephalograms. The obtained results can be used in the development of neurointerfaces for the prediction and prevention of seizures of various types of epilepsy in humans. 


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