Comments on MEG studies of epileptic patients: a nonscientific attack on IJN and scientists of remote (!) countries by crease and purpura.
Explore the source record for details and available documents.
Epilepsy↗
Biomedical subjects
U Tan
Publications and source records attributed to U Tan.
The relationship of latency characteristics of the Hoffmann reflex from the right and left thenar muscles to serum testosterone levels in right-handed male and female subjects.
The latency characteristics of the Hoffmann reflex from the right and left thenar muscles were analyzed in right-handed young men and women relative to serum testosterone levels. There was no correlation between the H-reflex latencies and serum testosterone levels in the female subjects. In the male subjects, the H-reflex latencies from the right and left sides were found to be negatively linearly related to the serum testosterone levels. The right minus left latencies were found to be inversely correlated with serum testosterone levels in women; there was no correlation between these variables in men. It was also established that the right-left differences in the H-reflex latencies were directly related to the degree of the right-hand preference in the female subjects. It was concluded that testosterone may, at least, contribute to the spinal-motor lateralization in women, but not in men. The results were also discussed with regard to the testosterone hypothesis of cerebral lateralization, sex-related differences, hand preference, hand skill, and intelligence.
Adult↗
The inverse relationship between nonverbal intelligence and the latency of the Hoffmann reflex from the right and left thenar muscles in right- and left-handed subjects.
The relationship between nonverbal reasoning ability and the latency of the Hoffmann (H) reflex was studied in right- and left-handed subjects. The nonverbal reasoning ability was assessed by the Cattell's Culture Fair Intelligence test. Hand preference was assessed by the Edinburgh Handedness Inventory. Hoffmann reflex was recorded from thenar muscles of the right and left thumbs. In left-handers (total sample), IQ was found to be significantly and negatively linearly related to the H-reflex latency from the left side. In strong left-handers, there was a significant negative linear relationship between IQ and the H-reflex latency from right and left sides, but with a higher correlation for the left side. In weak left-handers, IQ did not show any significant relation to the H-reflex latencies from the right and left sides. In right-handers (total sample), there was a significant negative linear correlation between IQ and the H-reflex latency from the right side. In right-handed women without familial sinistrality (FS-), IQ was found to be inversely related to the H-reflex latency from the right and left side, but with a higher correlation for the right side. In right-handed women with FS, IQ did not show any significant relation to the H-reflex latency from the right and left sides. In right-handed men with right eye preference and FS-, IQ was found to be negatively linearly related to the H-reflex latency from the right and left sides equally. In right-handed men with right eye FS+, mixed eye FS-, +, mixed eye-right foot (FS-), mixed eye-mixed foot, and left eye preference there was no significant relationship between IQ and the H-reflex latency from the right and left sides. Only in strong left-handers there was a significant, positive linear correlation between IQ and the right minus left (R-L) difference of latencies. The H-reflex latency from the right and left sides was not significantly correlated with the R-L difference of latencies in left-handers. In right-handed women with right eye preference FS-, and in right-handed men with right eye preferences FS-, The H-reflex latency from the right side was found to be positively linearly correlated with the R-L difference of latencies. In right-handed women FS+, and in right-handed men FS+, and mixed or left eye preference, the H-reflex latency from the left side was found to be negatively linearly related to the R-L difference of latencies.(ABSTRACT TRUNCATED AT 400 WORDS)
Female↗
Association of serum testosterone levels with latencies of somatosensory evoked potentials from right and left posterior tibial nerves in right-handed young male and female subjects.
The relationships between serum testosterone levels and somatosensory evoked potential (SEPs) latencies from the right and left posterior tibial nerves (PTNs) were studied in right-handed young men and women. The corrected P1 (P39) and N1 (N49) latencies from the right PTN (left hemisphere) were found to be significantly longer in females than males. The corrected P2 and N2 latencies from both PTNs were longer in females than males. Testosterone was not associated with N1 latencies. In females, there was a negative linear correlation between testosterone and latencies from the right and left PTNs. These relationships were complex in males depending upon foot and eye preferences. The following results were obtained from males: no correlation with P1, N1, and P2, but a direct relation with P2 from left PTN in total sample; in males with right eye and right foot preference, a direct correlation only with P1 from right and left PTNs; in mixed- and left-eyed males, inverse correlations with P1, N1, and P2 latencies especially from right PTN; in right-eyed males, direct correlation with P1, inverse correlation with P2 from left PTN; in right-footed males, direct correlation with P1 and N2 waves from right and left PTNs. The interpeak latencies also showed sex-related differences. The overall results suggested that the left brain would be the main target for testosterone effects in both sexes, which may be beneficial for females but mainly disadvantageous for males.
Adolescent↗
Testosterone and somatosensory evoked potentials from right and left posterior tibial nerves in right-handed young adults.
The relationship between serum testosterone level and somatosensory evoked potentials (SEP) from right and left posterior tibial nerves (PTN) was studied in right-handed young adults. Hand preference was assessed by the Edinburgh Handedness Inventory. The amplitudes of P39 and N49 components of the SEPs from the left and right hemispheres of men and only from the left hemisphere of women were found to be negatively linearly and significantly correlated with serum testosterone. There was no significant correlation between P58 and N76 components and serum testosterone in these subjects. The correlations were found to be more prominent for the left hemisphere than the right hemisphere. The data were also analyzed considering eye and foot preferences. It was concluded that testosterone could be associated with the development of the somatosensory system during adolescence.
Adolescent↗
A close relationship exists between hand skill and the excitability of motor neurons innervating the postural soleus muscle in right-handed male subjects.
The claim that there is no consistent inhibition of the H-reflex from the dominant leg was examined and rejected. Hand preference was assessed by the Edinburgh Inventory, and hand skill by the peg moving task. It was re-established that there is an inverse relationship between hand skill and the excitability of motoneurons innervating the postural soleus muscle in right-handed subjects without familial sinistrality. There was no significant difference between the recovery curves from the right and left sides in subjects with familial sinistrality. There was a positive linear correlation between the asymmetry index for hand skill greater than zero (right-hand dominance) and the asymmetry index for the H-reflex recovery curve greater than zero (left dominance in motoneuronal excitability). It was concluded that there is indeed a spinal motor asymmetry in postural leg muscles related to handedness.
Adult↗
There is an inverse relationship between the reflex size from wrist flexors and paw preference in spinal cats.
The relationship between paw preference and reflex size from wrist flexors was studied in spinal cats. Paw preference was assessed by a food-reaching test. The monsynaptic H reflex and the polysynaptic reflexes were recorded from the median or ulnar nerves following stimulation of the same nerves electrically. The mono- and polysynaptic reflexes were found to be significantly larger on the left side than the right side in right-preferent spinal cats and vice versa in left-preferent spinal cats.
Animals↗
The left brain determines the degree of left-handedness.
The contribution of right- and left-hand skills to left-handedness was studied in 42 left-handed male subjects. Hand preference was assessed by the Edinburgh Handedness Inventory. Hand skill was assessed by a peg-moving task; 10 trials were given to each hand. Peg-moving times decreased linearly with each trial (visuomotor learning). Both hands exhibited equal learning capacities. The learning curves were the same for the left-hands of left-handers with and without familial sinistrality (FS). The right-hand of left-handers with FS was found to be slower than that without FS. The right- and left-hand skills and their learning curves were about the same in left-handers with right-hand writing, exhibiting no difference from the left-hand skill and learning curve of left-handers with left-hand writing. Right-hand skill decreased linearly as left-hand preference increased from -40 to -100; left-hand skill was not related to hand preference. Right-minus left (R-L) time for peg moving increased linearly with hand preference from -40 to -100. R-L time for peg moving linearly decreased as the right-hand skill increased; the left-hand skill was not associated with R-L time for peg moving. It was concluded that the right hand (left brain) determines left-handedness; the neural structures only on the left side exhibit pronounced plastic changes to genetic and environmental influences in left-handers.
Adult↗
Relation of hand skill to spatial reasoning in male and female left-handers with left- and right-hand writing.
The relation of mental ability for spatial reasoning (Cattell's Culture Fair Intelligence Test) to hand skill assessed by peg-moving task was studied in normal left-handers. Nonlinear, quadratic relationships were established between these two parameters exhibiting different characteristics according to sex and writing hand. It was concluded that the contributions of the right and left cerebral hemispheres to the cognitive-motor output of the brain depend on sex and writing hand as well as the degree of left-handedness in left-handers.
Adolescent↗
Relation of spatial reasoning ability to hand performance in male and female left-handers to familial sinistrality and writing hand.
The relation of mental ability for spatial reasoning to hand performance was studied in male and female left-handers considering familial sinistrality and writing hand. Hand performance was assessed by a dot-filling test; hand preference was assessed by the Edinburgh Handedness Inventory (Geschwind scores). Nonverbal intelligence (spatial reasoning) was measured by the Cattell's Culture Fair Intelligence Test. The relationship between IQ and hand performance was found to be more complicated than expected. This was associated with sex, familial sinistrality, and writing hand, which created different patterns in interactions between motor and cognitive systems. It was concluded that the brain benefits from different strategies by using both hemispheres in a competitive and complementary manner where necessary to achieve a high visual-spatial performance depending upon genetic preprograms.
Adult↗
Relation of testosterone and hand preference in right-handed young adults to sex and familial sinistrality.
The relationship between serum testosterone level and the degree of hand preference was studied in right-handed young adults. Hand preference was assessed by the Edinburgh Handedness Inventory. Serum testosterone level was determined using tritium-marked-radioimmunoassay. There was no significant correlation between these variables in males without FS. In males with FS and in females with and without FS, the serum testosterone levels were found to be negatively linearly correlated with the degree of the right-hand preference. Similar results were obtained with respect to foot and eye preferences. It was concluded that not only prenatal testosterone but adult testosterone also may exert a life long influence on cerebral lateralization; this effect seems to be much more pronounced in the female than male brain, which may exert a female-like pattern under genetic control.
Adolescent↗
The relationship between the degree of paw preference and excitability of motor neurons innervating foreleg flexors in right- and left-preferent cats.
The relationship between the degree of paw preference and the degree of excitability of motor neurons innervating the foreleg flexor muscles was studied in unanesthetized spinal cats. The paw preference was assessed by a food-reaching test. The cats were spinalized at the first cervical segment of the spinal cord. It was found that there is an inverse relationship between the degree of H-reflex excitability and the degree of paw preference in right- and left-preferent cats. This main result was discussed with respect to functional implications and evolution of human handedness.
Animals↗
Testosterone and hand skill in right-handed men and women.
The relationship between serum testosterone level and hand skill was studied in right-handed young adults. Hand preferences was assessed by the Edinburgh Handedness Inventory. Hand skill was assessed by the peg moving task. Serum testosterone level was determined using tritium-marked-radioimmunoassay. In the total sample, only the right-hand skill showed a direct correlation and an inverse correlation with serum testosterone for men and women, respectively. In male subjects with right-eye preference, both hand skills exhibited a direct relation to serum testosterone. In the total sample, there was a direct and an inverse relationship between the difference in skill between hands and serum testosterone in men and women, respectively. This was, however, affected by right-eye and right-foot preference. It was concluded that the serum testosterone in young adults is associated with hand skill exhibiting fundamental differences between men and women; the left cerebral hemisphere seems to be the main target of testosterone.
Adolescent↗
Testosterone and hand performance in right-handed young adults.
The relationship between serum testosterone level and hand performance was studied in right-handed young adults without familial sinistrality. Hand performance was measured by a dot-filling task, which was found to be associated with serum testosterone depending upon sex. In women, the right- and left-hand performance was found to be negatively linearly related to testosterone; there was no significant correlation between the right- minus left-hand performance and testosterone. In men, right- and left-hand performance were found to be directly and inversely related to testosterone, respectively. This pattern exhibited some variations depending on eye and foot preferences. The difference in performance between hands was found to be positively linearly related to serum testosterone levels in men.
Adolescent↗
Testosterone and nonverbal intelligence in right-handed men and women.
The relationship between serum testosterone level and nonverbal intelligence was studied in right-handed young adults. Hand preference was assessed by the Edinburgh Handedness Inventory. Serum testosterone level was determined using tritium-marked-radioimmunoassay. Only in men, nonverbal intelligence (Cattell's Culture Fair Intelligence Test) was found to be significantly and directly related to serum testosterone levels. It was concluded that the serum testosterone in young adults is associated with nonverbal intelligence exhibiting fundamental differences between men and women.
Adolescent↗
Relationship of testosterone and nonverbal intelligence to hand preference and hand skill in right-handed young adults.
The relationship between serum testosterone level and nonverbal intelligence was studied in right-handed young adults with regard to handedness. Hand preference was assessed by the Edinburgh Handedness Inventory. Hand skill was measured by a peg moving task. Serum testosterone level was determined using tritium-marked-radioimmunoassay. Visual-spatial performance (nonverbal intelligence) was measured by Cattell's Culture Fair Intelligence Test. In men with consistent right-hand preference (GSs: 80 to 100), IQ was found to be positively linearly related to serum testosterone, which exhibited two regression lines belonging to low and high difference in skill between hands. In females with consistent right-handedness, there was a negative linear correlation between IQ and serum testosterone, which also exhibited two different regression lines according to difference in skill between hands. In males with moderate right-hand preference (GSs 50 to 75), IQ was found to be positively linearly related to serum testosterone, exhibiting two different (same slopes) regression lines according to difference in skill between hands. In females with moderate right-hand preference, IQ first increased and then decreased with serum testosterone, exhibiting a quadratic relationship. These results suggested that serum testosterone in young adults may be associated with visual-spatial performance depending upon sex, hand preference, and hand skill.
Adolescent↗
Paw preference in cats: distribution and sex differences.
Paw preference assessed by a food-reaching test was studied in male and female cats. Of the total sample (N = 66), 34 (51.5%) were right-preferent, 24 (36.4%) left-preferent, and 8 (12.1%) ambilateral. In the total sample, there was evidence for an overall paw preference, general paw preference, right-, and left-paw preference. The distribution of the right- minus left-paw reaches was neither normal, nor U or J shaped. Of the males (N = 24), 10 (41.7%) were right-pawed, 12 (50.5%) left-pawed, and 2 (8.3%) ambilateral. In males, there was evidence for an overall, general, and right-, left-paw preference relative to no preference. The right- minus left-paw reaches fitted to guassian data with two prominent peaks due to the right- and left-preferents. In females (N = 42), 22 (52.4%) were right-preferent, 14 (33.3%) left-preferent, and 6 (14.3%) ambilateral. There was an overall, general, and right-preference but not a left-preference relative to no preference. The distribution of the right- minus left-paw reaches was neither normal nor U or J shaped. The female right-preferents showed a right-bias compared to males. The left-preferent males were more left-preferent than the right-preferent males are right preferent. The mean right- minus left- paw reaches for the female right-preferents were significantly higher than those for the male right-preferents. There was no significant difference between the right- minus left-paw reaches of the male and female left-preferents. The paw preferences exhibited consistency over time; no learning tendencies were established during testing periods for at least 10 days. Considering the mean right-paw reaches for each successive day (N = 10), the mean right-paw uses in the right-preferents was higher in females than males. The mean left-paw uses in left-preferents was about the same for males and females. In males, the mean left-paw uses for the left-pawed males were higher than the right-paw reaches for the male right-preferents. In females, there was no difference between the right paw reaches of the right-preferents and the left-paw reaches of the left-preferents. It was concluded that there is a right-bias in paw preference of cats, which is caused by the female right-preferents under the influence of a biological factor.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
A close relationship between hand skill and the excitability of motor neurons innervating the postural soleus muscle in right-handed female subjects.
The claim that there is not a consistent inhibition of the H-reflex from the dominant leg was examined and rejected. Hand preference was assessed by the Edinburgh Inventory, and hand skill by the peg moving task. All the subjects were right-handed in preference and skill. It was re-established that there is an inverse relationship between hand skill and the excitability of motoneurons innervating the postural soleus muscle in right-handed female subjects without familial sinistrality. There was no significant difference between the recovery curves from the right and left sides in subjects with familial sinistrality. The H reflex from right leg was different between these right-handers. There was a positive linear correlation between the asymmetry index of hand skill greater than zero (right-hand dominance) and the asymmetry index for H-reflex recovery curve greater than zero (left dominance in reflex activity). It was concluded that there is a spinal motor asymmetry in postural leg muscles to handedness.
Adult↗