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PubMed1972

Brain functions.

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Animals↗
PubMed1998

Crossed aphasia in a dextral: a test of the Alexander-Annett theory of anomalous organization of brain function.

A case of crossed aphasia is presented in a strongly right-handed 77-year-old white female without history of familial sinistrality or prior neurological illness. She developed a right middle cerebral artery infarction documented by CT and accompanied by obvious clinical signs of a conduction aphasia with some resolution but continuing obvious language defect after 9 weeks in rehabilitation. Comprehensive neuropsychological and aphasia testing suggested anomalous lateralization of phonologic-output aspects of language, emotional prosody, motor planning and body schema modules with usual lateralization of lexical-semantic aspects of language and visuo-spatial functions. Experimental validation of the uncrossed lexical-semantic aspects of language using tachistoscope methods found support for the Alexander-Annett theory that different aspects of language can be dissociated in their lateralization. The subject had difficulty identifying a semantic associate of a picture presented to the left visual field (7 errors out of 10) relative to right visual field presentation (2 errors out of 10). Bilateral free naming errors (6 and 5 errors in the left and right visual fields, respectively) occurred consistent with the aphasic presentation, suggesting phonologic-output dysfunction from the right cerebral vascular accident. Implications of the results for aphasia classification are discussed.

Aged↗
PubMed1993

Near infrared spectroscopy (NIRS): a new tool to study hemodynamic changes during activation of brain function in human adults.

In healthy human adults, cerebral concentrations of oxygenated hemoglobin ([HbO2]) and deoxygenated hemoglobin ([HbR]) were assessed during brain activation using near infrared spectroscopy (NIRS). Measurements were made either in the frontal cortex (n = 10) during performance of cognitive tasks or in the occipital cortex (n = 6) during visual stimulation (flash-light exposure, picture observation). The typical findings during brain activation were an increase in [HbO2] and a decrease in [HbR]. We demonstrate that these findings are not due to alterations in skin blood flow. NIRS is a simple bedside technique for the assessment of hemodynamic alterations accompanying brain activation.

Adult↗
PubMed2005

A device for the detection of cognitive brain functions in completely paralyzed or unresponsive patients.

Unresponsive patients with remaining cognitive abilities may be able to communicate with a brain-computer interface (BCI) such as the Thought Translation Device (TTD). Before initiating TTD learning, which may imply considerable effort, it is important to classify the patients' state of awareness and their remaining cognitive abilities. A tool for detection of cognitive activity (DCA) in the completely paralyzed was developed and integrated into the TTD which is a psychophysiological system for direct brain communication. In the present version, DCA entails five event-related brain-potential (ERP) experiments and investigates the capability of a patient to discriminate, e.g., between semantically related and unrelated concepts and categories. ERPs serve as an indicator of the patients' cortical information processing. Data from five severely brain-injured patients in persistent vegetative state diagnosed as unresponsive and five healthy controls are presented to illustrate the methodology. Two patients showing the highest responsiveness were selected for TTD training. The DCA integrated in the TTD allows screening of cognitive abilities and direct brain communication in the patients' home.

Adult↗
PubMed1997

[The role of psychosocial stress in childhood for structural and functional brain development:neurobiological basis of developmental psychopathology].

This review summarizes some important principles of human brain development. Special emphasis is placed on the role of psychosocial stress during childhood on the developing brain. Depending on the degree of cognitive, behavioral and socio-emotional maturation, previous experiences and actual context, psychosocial stressors may be perceived by children as being either controllable (challenge) or uncontrollable (disaster). Controllable stress experiences are associated with a preferential activation of the central and peripheral noradrenergic system, i.e., of a system endowed with the gating of cortical information processing and the facilitation and stabilization of neuronal pathways and synaptic connections involved in behavioral responding. Uncontrollable stress responses are elicited if all previously acquired behavioral or cognitive strategies are inadequate or fail to overcome the stressor. The resulting severe and long-lasting activation of the central stress responsive systems will finally lead to a full activation of the HPA system, accompanied by adrenocortical cortisol release. The major central effect of this response is the destabilization of previously established neuronal circuits and synaptic connections. Thus, severe uncontrollable psychosocial stress may act as an important trigger of and a prerequisite for the reorganization of neuronal connectivity. It may, above a certain threshold, threaten the mental and affective stability, integrity, and the future development of a child. The long-term consequences of psychosocial stress on the structural and functional maturation of the brain are documented by findings from animal research and by results in the field of developmental psychopathology in children. The role of risk and protective factors during different phases of child development is briefly summarized and the need for a biopsychosocial model concerning the relationship between human brain development and behavior is emphasized.

Adaptation, Psychological↗