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Biomedical subjects

G Nyman

Publications and source records attributed to G Nyman.

70 records · Page 4Linked to original sources
PubMed1987

Infant temperament, childhood accidents, and hospitalization.

The role of infant temperament in predicting the incidence of hospitalization and accidents of children under the age of 5 was studied in a prospective follow-up study. Temperament type and profile was originally measured for 1,855 infants (6 to 8 months of age). We obtained data for 270 who had later been hospitalized because of accidents or illnesses. Of these, the temperament of 35 who had suffered a contusion, poisoning, burns, or other accidents were more closely analyzed. The results show that a disproportionate number of all hospitalized children had earlier been characterized as "difficult" in their temperament. This was typical, however, for both the accident group and other hospitalized children. The hospitalized children had a significantly more negative mood and higher intensity of responses to normal everyday life situations. The accident group differed from other hospitalized children in being mainly more persistent but also showed a tendency to higher activity level and negative reactions to new situations. The results do not support a straightforward hypothesis of an early accident prone temperament but point out the significance of temperament in the processes of hospitalization and accidents.

Accidents↗
PubMed1985

Visual illusion mimicking dyslexia. A case history.

A 14-year-old girl with reading difficulties was found to have an unusual illusory movement of objects in the central visual field. The movement could be blocked by using a 26 mm Visolette magnifier with an arrow pasted on its lower surface to function as a reference point. After having read with help of this arrangement for 19 months the girl suddenly could see normally and has now been able to read without difficulties for over 3 years. We report the first documented case of visual illusion as the cause of reading difficulty which disappeared at the age of 15 years, thus years after the maturation of visual functions is thought to be completed. Although visual illusion like the one presented here must be rare, it should be diagnosed, because the treatment is totally different from that of usual dyslexia.

Adolescent↗
PubMed1982

On the continuity, change and clinical value of infant temperament in a prospective epidemiological study.

The temperament of 1855 children born in Helsinki during 1975-76 was recorded at the age of 6-8 months by parental questionnaires. In 1980-81 the continuity of temperamental dimensions was studied in a group of these children by using a temperament questionnaire for 3--7-year-old children. In addition, the clinical usefulness of infant temperament was assessed by analysing the infant temperamental dimensions used was almost negligible, because less than 10% of the total variance of each dimension could be explained by the corresponding dimensions at the infant age. The clinical usefulness of infant temperament questionnaires in prospective epidemiological studies was supported by the observation that children with later paediatric problems (behavioural problems, colic spasms, accidents) had had significantly different temperamental styles at the infant age from those without problems. The results support the importance of negative mood and high intensity of infant's behavioural style as risk factors for later paediatric problems.

Accidents↗
PubMed1982

Topographic instability of spatial vision as a cause of dyslectic disorder: a case study.

A case of severe disorder of spatial perception with concomitant dyslexia is described. The patient, a 15-yr-old girl, has a systematic tendency to misperceive the spatial order of symbols or objects lying on the same horizontal level and within a few degrees of visual angle. The syndrome includes a spatial extinction phenomenon in which an object in her left visual field disturbs the perception of another object in the corresponding symmetry point of her right visual field. The order reversal symptom was abolished if the letters presented for her were shown for less than 15 msec. The disorder is probably due to a pathological interhemispheric interference in the processing of visual topographic information.

Adolescent↗
PubMed1980

Perceived spatial frequency of flickering gratings: a local spatial distortion.

Perceived spatial frequency of a low-frequency grating increases if the grating contrast is temporally modulated at about 4 to 16 Hz. The amount of increase can be up to 50% as estimated by a grating-match technique. It is shown here that the illusion is not a simple spatial-frequency shift phenomenon but also involves local spatial distortions. This was discovered by using the method of distance match, in which the perceived length of a spatial period or its multiples was estimated in a flickering grating. The results indicate that the illusory increase in perceived spatial frequency does not predict the perceived period length of a grating in a simple reciprocal manner. The decrease in the apparent period length is restricted to distances covering only one or two spatial cycles. This points out that care should be taken in interpreting various illusory changes in spatial frequency simply as shifts of frequency. The results are interpreted as demonstrating the operation of a size-analyzing mechanism which has a limited spatial bandwidth and which is sensitive to flicker-induced disturbances.

Humans↗
PubMed1979

Expanding psychiatric service in a hospital emergency room.

Senior medical residents were used to extend psychiatric coverage in a busy hospital emergency room. Their service was supported by the backup consultation of senior psychiatric physicians. The medical residents worked in conjunction with psychiatric residents to provide 24-hour daily emergency psychiatric service to more than 350 patients during a 12-month period. There were no significant differences in the demographic composition of the patient population seen or in the disposition of individual patients made between the medical and psychiatric residents. The hospital was able to expand its psychiatric service in the emergency room without major increases in cost. The medical residents benefited by experiencing a more diversified patient care training program, and they earned a modest supplement to their houser officer salary.

Adult↗
PubMed1979

I. Functional properties of neurons in lateral part of associative area 7 in awake monkeys.

The lateral part of area 7, area 7b, of alert, behaving macaque monkeys was investigated using transdural microelectrode recording technique. Two hundred twenty-eight cells from five hemispheres of four monkeys were isolated and studied. The functional properties of 2% of the cells isolated remained unidentified. Functions of the identified cells were prominently related to the spatial control of arm movements. Of the cells 70% responded to somatosensory (40%) or visual (16%) or both somatosensory and visual (14%) stimulation. The receptive fields of these passively drivable cells were large, covering e.g., the arm or leg or chest or even the skin of the whole body. Most of the visually drivable cells responded to stimuli in both halves of the visual field. Of the cells responding to sensory stimulation 80% were activated by stimuli moving in a certain direction. Of the directionally selective cells 25% received information through more than one sensory channel. The complex stimulus-response relationships of these "convergence" cells revealed the existence of an integrative system which analyzes the direction of a stimulus moving in one sensory system using an other sensory system as a reference. Of all the cells isolated 28% discharged only during active movements of the arms (25%) or eyes (3%). Firing of these neurons was related to contraction of a functionally uniform group of muscles and not individual muscles. Some previous investigations of the parietal association cortex, conducted mainly in area 7a, have shown that most cells were active only when the monkey himself moves his eyes or arms. In our study on area 7b most cells responded to passive stimulation. The discrepancy between the results indicates functional differentiation within area 7.

Animals↗
PubMed1979

II. Functional properties of cells in anterolateral part of area 7 associative face area of awake monkeys.

The most anterior part of area 7 of awake, behaving macaque monkeys was investigated using single cell recording technique. Eighty-five cells from three hemispheres of two monkeys were isolated and studied. These cells showed more complex functional properties than the cells in the primary and secondary cortical fields. Of the cells 61% responded to somatosensory (26%) or visual (2%) or both somatosensory and visual (33%) stimulation; 39% of the cells were active only during the monkey's own movements. Most of the cells studied were active while the monkey was bringing an object to the mouth with its hand, when reaching for an object with lips, or while chewing. The neurons responded selectively to, e.g., palpation of the flexors of the arm, a visual stimulus approaching the face, passive movement of the monkey's hand towards the mouth, or they were active only when the monkey was reaching for an object with its lips or was mouthing it. The cellular activity in the anterolateral part of area 7 was prominently related to the stimulation or motor activity of the face (especially the mouth). In this respect, it differed from the more posterior part of area 7 adjacent to it. The results thus indicate that there is a separate and rather extensive mouth (or face) area in the parietal association cortex of the monkey.

Animals↗
PubMedDate not supplied

Mismatch negativity (MMN) for sequences of auditory and visual stimuli: evidence for a mechanism specific to the auditory modality.

ERPs to sequences of standard and deviant sinusoidal 100 msec tone pips, high-contrast sinusoidal gratings and to their simultaneously presented combinations were recorded. Mismatch negativity (MMN), an ERP component elicited by deviant stimuli, was estimated for the different stimulus sequences in order to find out whether it reflects modality-specific processes or non-specific attentive phenomena. In addition to the auditory modality, we studied whether the mismatch response could be evoked by a deviant visual stimulus in a visual sequence or by a deviant stimulus in either modality. The results show that only auditory stimuli produced the mismatch response, suggesting that MMN is not a manifestation of a general attentional mechanism but is probably specific to the auditory modality.

Acoustic Stimulation↗
PubMedDate not supplied

Frequency change detection in human auditory cortex.

We offer a model of how human cortex detects changes in the auditory environment. Auditory change detection has recently been the object of intense investigation via the mismatch negativity (MMN). MMN is a preattentive response to sudden changes in stimulation, measured noninvasively in the electroencephalogram (EEG) and the magnetoencephalogram (MEG). It is elicited in the oddball paradigm, where infrequent deviant tones intersperse a series of repetitive standard tones. However, little apart from the participation of tonotopically organized auditory cortex is known about the neural mechanisms underlying change detection and the MMN. In the present study, we investigate how poststimulus inhibition might account for MMN and compare the effects of adaptation with those of lateral inhibition in a model describing tonotopically organized cortex. To test the predictions of our model, we performed MEG and EEG measurements on human subjects and used both small- (<1/3 octave) and large- (>5 octaves) frequency differences between the standard and deviant tones. The experimental results bear out the prediction that MMN is due to both adaptation and lateral inhibition. Finally, we suggest that MMN might serve as a probe of what stimulus features are mapped by human auditory cortex.

Adaptation, Physiological↗
PubMedDate not supplied

[The differentiation of color signals by the frog retina].

Multidimensional scaling of principal interstimulus chromatic differences, measured by the value of ERG reaction of the frog retina allowed to construct a model reflecting colour differentiating function of this level. It follows from this model that the frog retina has colour differentiating characteristics answering standard requirements of trichromatic vision. Colour-opponent system of frog is represented by the functions of red-green and blue-yellow opponentness compared with the analogous functions obtained for man.

Animals↗