Shortening of simple reaction time by peripheral electrical and submotor-threshold magnetic cortical stimulation

Subthreshold transcranial magnetic stimulation (TMS) over the motor cortex can shorten the simple reaction time in contralateral arm muscles if the cortical shock is given at about the same time as the reaction stimulus. The present experiments were designed to investigate whether this phenomenon is due to a specific facilitatory effect on cortical circuitry. The simple visual reaction time was shortened by 20-50 ms when subthreshold TMS was given over the contralateral motor cortex. Reaction time was reduced to the same level whether the magnetic stimulus was given over the bilateral motor cortices or over other points on the scalp (Cz, Pz). Indeed, similar effects could be seen with conventional electrical stimulation over the neck, or even when the coil was discharged (giving a click sound) near the head. We conclude that much of the effect of TMS on simple reaction time is due to intersensory facilitation, although part of it may be ascribed to a specific effect on the excitability of motor cortex.     

Use of mouth pressure twitches induced by cervical magnetic stimulation to assess voluntary activation of the diaphragm

There is a need for a simple method to assess the adequacy of diaphragm activation during voluntary inspiratory efforts in patients with suspected respiratory muscle weakness. We have compared mouth (Pmo,t), oesophageal (Poes,t) and transdiaphragmatic (Pdi,t) twitch pressure elicited by cervical magnetic stimulation (CMS) in five normal men (mean (SD) age 32.2 (1.8) yrs) on two separate study days. Single magnetic stimuli were delivered at functional residual capacity during relaxation and during graded voluntary inspiratory efforts against a closed airway. As voluntary-effort transdiaphragmatic and oesophageal pressure increased, Pdi,t and Poes,t decreased linearly (r range, respectively, 0.82-0.98 and 0.87-0.95). During relaxation, Pmo,t was unreliable due to the poor transmission of intrathoracic pressure, but during inspiratory efforts, the relation between voluntary mouth pressure and Pmo,t was also linear (r range 0.84-0.95). On average, our subjects voluntarily generated 99, 100 and 102% of the maximum transdiaphragmatic, oesophageal and mouth pressures predicted by the respective linear regression equations. Pmo,t was correlated to both Poes,t and Pdi,t during inspiratory efforts, but not during relaxation. These studies confirm that twitch pressures induced by CMS during inspiratory efforts can be assessed at the mouth in normal subjects, providing a simple and non-invasive technique for assessing diaphragm activation during voluntary inspiratory efforts. Potentially, this technique could be made more sensitive and accurate and applied to detect submaximal efforts in patients.     

The influence of load on the lifetime distribution

This paper derives lifetime distributions for components that fail due to overloading. We introduce the notion of energy similarity. This makes it possible to use knowledge about how components behave under different loads in order to establish a probability model. To obtain parametric families, we consider two physically distinct cases: (1) components that function individually and (2) components that function as part of a system. The former leads to univariate and the latter to multivariate models. The results are particularly useful when little or no data is available.     

Telomerase activity is induced in human peripheral B lymphocytes by the stimulation to antigen receptor

To understand the molecular events for the proliferation of B cells, we studied the induction of telomerase activity in vitro after stimulation to B-cell antigen receptor (BCR) on human peripheral B cells. Although unstimulated purified B cells of tonsils and peripheral blood from healthy volunteers do not express detectable telomerase activity, anti-IgM beads induce telomerase activity in these B cells. Soluble anti-IgM antibody (Ab) alone does not induce telomerase activity, but the second signal, given by either one of the cytokines of interleukin-2 (IL-2), IL-4, and IL-13 or by anti-CD40 monoclonal Ab (MoAb), is effective as the costimulation for the induction of the activity. Stimulation with anti-IgM Ab and anti-CD40 MoAb induces telomerase activity in most mature B cells of the tonsils and peripheral blood. The stimuli to both IgM and IgD receptors similarly induce the activity. Induction of telomerase activity is accompanied with the proliferation of B cells, but is not absolutely correlated with the extent of B-cell growth. Phorbol dibutylate (PDB) plus calcium (Ca) ionophore (PDB/Ca), which replace the activation through BCR and the costimulatory molecules, also induce telomerase activity. Moreover, it is suggested that phosphoinositide (PI) 3-kinase plays a role for the induction of telomerase activity in B cells stimulated with anti-IgM Ab and anti-CD40 MoAb. These results suggest that telomerase activity is induced in the B-cell activation of the antigen specific immune response.     

Prepassage questions: The influence of structural importance.

Compared the effects of prepassage questions quizzing information of different structural importance on 104 college students' memory for expository prose passages. In conditions in which information from a high-level passage unit was quizzed by the question, indirect recall (i.e., recall of nonquizzed information) was greater than recall in both low-level and no-question conditions. The low-question condition exceeded the no-question condition only when the analysis was limited to recall of superordinate information from the subtopic cluster containing the quizzed unit. Results indicate that questions that direct Ss' attention to material at the top of the organizational structure facilitate the effective encoding of the central organizational idea within the passage segment. A significant interaction was also found between Ss' Vocabulary Ability and Question Condition. The facilitative effect of high questions declined with increasing vocabulary ability. This interaction is consistent with the view that high- and low-ability people differ in their tendency to use the superordinate organizational structure of the passage and thus in their tendency to benefit from processing aids such as adjunct questions. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cultural influence on the perception of movement: The trapezoidal illusion among Zulus.

In cross-cultural studies it was noted that "the perception of motion as represented in the rotating trapezoidal window is governed, under optimal conditions, by nativistic determinants or by the unconscious utilization of residual (but not immediately relevant) experience, or both… . At the same time, object connotation (meaning) based on closely relevant cultural experience helps to determine the nature of the perceived movement under marginal conditions." 24 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Magnetic stimulation of the brain in generalized epilepsy: reversal of cortical hyperexcitability by anticonvulsants

Observations on experimental models suggest that diffuse cortical hyperexcitability is an important abnormality in the generalized epilepsies. We used the threshold for transcranial magnetic stimulation as an index of motor cortical excitability in 89 neurologically normal control subjects and 56 patients with idiopathic generalized epilepsy (20 untreated and 36 chronically treated with anticonvulsants). Magnetic stimulation was repeated in 10 patients after valproate monotherapy had been commenced and in 23 control subjects. The threshold intensity was significantly lower in the untreated patients (46 +/- 5% [mean +/- 95% confidence interval]) than in the control subjects (56 +/- 2%). Treated patients had significantly higher thresholds (64 +/- 4%) than did untreated patients and control subjects. A significant increase in threshold intensity (8 +/- 2%) occurred in patients retested after starting valproate; there was no significant change in retested control subjects (-1 +/- 2%). Threshold intensity was positively correlated with plasma valproate levels (rs = 0.37). The findings suggest that cortical excitability is increased in idiopathic generalized epilepsy and is reduced following anticonvulsant treatment. Transcranial magnetic stimulation is of use in examining the pathophysiology of generalized epilepsy. Furthermore, changes in threshold intensity in response to anticonvulsant treatment may prove useful in guiding therapy.     

Cardiorespiratory adaptations induced by aerobic training in middle-aged men: the importance of a decrease in sympathetic stimulation for the contribution of dynamic exercise tachycardia

The influence of diuresis and antidiuresis on the expression of heat shock proteins (HSP) 25, 60, 72 and 73 in the renal cortex and outer and inner medulla of Wistar rats was analysed. Medullary osmolality was reduced by long-term diuresis (3% sucrose in the drinking water for 3 weeks) and subsequently enhanced by transition to a concentrating state by giving normal drinking water again in combination with deamino-D-arginine vasopressin (dDAVP) for 5 days. Western blot analyses revealed that neither HSP73 nor HSP60 was influenced by any treatment. The HSP72 level in the medulla was markedly reduced (50%) when osmolality was lowered and increased when tonicity was high. RNAse protection assays showed that the effects on HSP72 are parallelled in general by changes in HSP72 mRNA. While levels of HSP25 were not influenced, isoelectric focusing revealed that the degree of phosphorylation of outer and inner medullary HSP25 increased following both treatments. It thus seems that HSP73 and HSP60 are not directly involved in the long-term adaptation to varying medullary osmolalities. The correlation between changes in osmolality and amounts of the major stress-inducible HSP72 in the medulla implies that medullary hypertonicity is stressful for kidney cells. Furthermore, adaptation to pronounced changes in the osmolality of the environment most likely involves phosphorylation of HSP25.     

The action of tyramine on the hypertensive responses induced by sympathetic stimulation in the pithed rat

This study has evaluated the changes in the characteristics of the H-reflex induced by distention of the urinary bladder in patients with complete lesions of the spinal cord. These findings were compared to induced changes in the systolic blood pressure and some degree of correlation was noted. It is well recognised that distention of the urinary bladder can exert a significant influence on the state of both somatic and autonomic reflex activity in spinal man. Although the mode of action of this stimulus has not been fully delineated, it is of some clinical importance since it may intensify muscular spasticity and autonomic hyperreflexia. This study was undertaken to further explore this relationship utilising the H-wave as a measure of segmental reflex activity. When appropriate, the effect of bladder distention on arterial blood pressure was also measured and an attempt made to correlate these observations with the H-wave findings.     

Effects of voluntary contraction on tibial nerve somatosensory evoked potentials: gating of specific cortical responses

We evaluated vertex-parietal P37, N50, and contralateral N37 somatosensory evoked potentials (SEPs) to posterior tibial nerve stimulation during weak (20 to 30%) and strong (80 to 90%) ipsilateral gastrocnemius-soleus contraction. The results were compared with data obtained during full relaxation. P37 and N50 were attenuated significantly during weak contraction and then abolished during strong contraction, whereas the contralateral N37 was not. The N37 potential spreads over the vertex and over the ipsilateral parietal region during strong contraction. The Cz'-F3 montage was not appropriate for detecting these SEP patterns. These findings suggest that thalamic or cortical gating mechanisms affect specific cortical responses. P37 and N50 could reflect the arrival of the afferent volley into the motor areas from thalamic and cortical (subareas 1 and 2 of S1) projections. N37 could be generated in subarea 3b. Differential analysis of N37 and P37 is required in clinical practice, mainly in those conditions that involve the motor system and in those conditions in which tonic muscular activity is increased.     

Responses of neurons of the first and second somatosensory zones of the cortex to peripheral, thalamic and cortical stimulation

Experiments were performed on cats immobilized with d-tubocurarine or myorelaxin. Neuronal responses were studied in the first somatosensory cortex (SI) to the second somatosensory cortex (SII), ventroposterior nucleus (VP) and contralateral forepaw stimulation. Besides, neuronal responses in SII to SI, VP and contralateral forepaw stimulation were also studied. It was shown that in SII the percentage of neurons excited by afferent volley with two or more synaptic change-overs in the cerebral cortex was larger than in SI. Neurons of SI and SII responded to cortical stimulation ortho- and antidromically, thus confirming the existence of bilateral cortico-cortical connections. Both in SI and SII, PSPs to cortical stimulation were similar in character to PSPs in the same neurons to VP stimulation. In 50.0% of SI neurons and 37.1 of SII neurons the difference in latencies of orthodromic spike potentials to VP and cortical stimulation was less than 1.0 ms. In 19.6% of SI neurons and 41.4% of SII neurons the latency of the response to cortical stimulation was 1.6-4.7 ms shorter than that of the response in the same neuron to VP stimulation. It is supposed that impulses from SI participate significantly in afferent activation of SII neurons.     

The influence of induced abortion on Taiwanese fertility

Data on the outcomes of more than 15,000 pregnancies originating between May 1966 and February 1969 were analyzed. The accuracy of the data was evaluated, rates of induced abortion and stillbirth were reported, and the demographic effect of induced abortion was estimated. The demographic effect was defined as the percentage increase in fertility that would have occurred in the absence of induced abortion, assuming no compensating change in alternative fertility control practices. Our principal findings were as follows: 1. We were unable to determine the completeness with which induced abortion was reported in the Registration Study. During the three years covered by the study, rates of induced abortion increased by 54 percent, reflecting a trend in the incidence or in the reporting of events or in both. We concluded that, in any case, the data for the final year of the study, 1968, were more complete than for the earlier two years. 2. Age-specific rates of induced abortion for 1968 displayed a strong urban-rural gradient, being much higher in the city areas than in the rural areas. Within each urban--rural stratum, the rates increases monotonically with age and reached maximum values in the age group 40 and older (553, 436, and 374 per 1,000 pregnancies for city, urban, and rural areas, respectively). 3. Estimates of the demographic effect indicated that, in the absence of induced abortion, the TFR for all Taiwan would have been 12 percent higher in 1968. Under the same assumption, it was estimated that the TFR would have been higher by 16 percent in city areas, 11 percent in urban areas, and 9 percent in rural areas. This urbanization gradient implies that induced abortion contributed to urban-rural fertility differentials. We estimated that about one-third of those differentials were due to induced abortion. 4. Estimates of the demographic effect were also made after adjusting the rates of induced abortion for an assumed level of underreporting of 50 percent. The adjusted estimate of the demographic effect for all Taiwan in 1968 was 19 percent.     

The influence of a heavy thermal load on REM sleep in the rat

This study was carried out in order to further test the hypothesis that the occurrence of REM sleep in the rat in the form of episodes separated by long intervals (single REM sleep episodes) and by short intervals (sequential REM sleep episodes) is differently influenced by changes in both sleep and ambient related processes. Rats were studied during the exposure to Ta -10 degrees C for 24 or 48 h and during a 12 h recovery period at laboratory Ta (23 degrees C) following either the first or the second 24 h of cold exposure. The exposure to such a low Ta induced an almost complete abolition of REM sleep which was followed, during recovery, by a marked REM sleep rebound. However, in spite of the larger REM sleep deprivation, the REM sleep rebound was weaker following the 48 h-exposure than that following the exposure for 24 h. The increase in the amount of REM sleep during the recovery period was due to an increase in the amount of that occurring in the form of sequential episodes, whilst that in the form of single episodes did not change with respect to control levels. However, the occurrence of REM sleep in the form of sequential episodes was partially impaired during the REM sleep rebound observed in the recovery period following the 48 h-exposure. These results would suggest that the homeostatic regulation of physiological variables may conflict with that of REM sleep occurrence and that the degree of such a contrast is indicated, at low Ta, by the amount of REM sleep in the form of single episodes and, during the following recovery, by the amount of REM sleep in the form of sequential episodes.     

The effects of foveal load and visual context on peripheral letter recognition

Peripheral letter recognition was examined by presenting subjects with a letter triad centered 7.16 degrees to the right of fixation. At the same time, a single letter was presented at the point of fixation that was either the same as one of the letters in the triad or different from any of the triad letters. On other trials, no letter was presented at the point of fixation. Results supported and extended previous foveal load research. The disruptive effect of foveal load does not depend solely on the presence or absence of a foveal stimulus. Recognition of the first letter in non-words was disrupted when a foveal letter was presented that was different from the peripheral letter. Recognition of the middle letter for both words and non-words was disrupted when a foveal letter was presented that was the same as the middle letter. A significant interaction between foveal letter and triad type was also found. No evidence was found to suggest that recognition of a peripheral letter is significantly better when that same letter is also present at the point of fixation.     

The influence of perceptual load on age differences in selective attention

The effect of perceptual load on age differences in visual selective attention was examined in 2 studies. In Experiment 1, younger and older adults made speeded choice responses indicating which of 2 target letters was present in a relevant set of letters in the center of the display while they attempted to ignore an irrelevant distractor in the periphery. The perceptual load of relevant processing was manipulated by varying the central set size. When the relevant set size was small, the adverse effect of an incompatible distractor was much greater for the older participants than for the younger ones. However, with larger relevant set sizes, this was no longer the case, with the distractor effect decreasing for older participants at lower levels of perceptual load than for younger ones. In Experiment 2, older adults were tested with the empty locations in the central set either unmarked (as in Experiment 1) or marked by small circles to form a group of 6 items irrespective of set size; the 2 conditions did not differ markedly, ruling out an explanation based entirely on perceptual grouping.     

The physiological responses induced by superficial acupuncture: a comparative study of acupuncture stimulation during exhalation phase and continuous stimulation

This study investigated the physiological effect of superficial acupuncture stimulation during a patient's exhalation phase in a sitting position (SES). The response to SES was compared to the stimulation applied continuously without considering the respiratory phase (CONT). It evaluated a chronic tension-type headache patient's static electromyographic (EMG) activity, pain response, heart rate, pulse height, and skin conductance level. The results indicated that SES stimulation significantly decreased headache intensity and demonstrated a strong trend towards decreasing static EMG activity compared to CONT stimulation. The study concluded that acupuncture, applied on the same point and at the same depth, produced different physiological effects, depending on whether the stimulation was applied during exhalation only or continuously applied. This suggests that the effect of acupuncture derives not only from point selection matching symptoms, but also from a consideration and utilization of the patient's respiratory phase during stimulation.     

The forgotten variable in conformity research: Impact of task importance on social influence.

Two studies examined how incentives for accuracy (task importance) affected the social influence of inaccurate confederates in a modified Asch situation (S. E. Asch, 1951). Not unexpectedly, when task difficulty was low, incentives for accuracy reduced the social impact of (inaccurate) confederates (Study 1). However, when task difficulty was increased, the reverse was true, with individuals conforming more to an inaccurate confederate norm when incentives for accuracy were high (Studies 1 and 2). The results are discussed in terms of possible mediating mechanisms and also in terms of their historical and pragmatic implications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of electrically induced fatigue on the twitch and tetanus of paralyzed soleus muscle in humans

We analyzed the twitch and summated torque (tetanus) during repetitive activation and recovery of the human soleus muscle in individuals with spinal cord injury. Thirteen individuals with complete paralysis (9 chronic, 4 acute) had the tibial nerve activated every 1,500 ms with a 20-Hz train (7 stimuli) for 300 ms and a single pulse at 1,100 ms. The stimulation protocol lasted 3 min and included 120 twitches and 120 tetani. Minimal changes were found for the acute group. The chronic group showed a significant reduction in the torque and a significant slowing of the contractile speeds of both the twitch and tetanus. The decrease in the peak twitch torque was significantly greater than the decrease in the peak tetanus torque early during the fatigue protocol for the chronic group. The twitch time to peak and half relaxation time were prolonged during fatigue, which was associated with improved fusion of the tetanus torque. At the end of the fatigue protocol, the decrease in the peak twitch torque was not significantly different from the decrease in the peak tetanus torque. After 5 min of rest, the contractile speeds recovered causing the tetanus to become unfused, but the tetanus torque became less depressed than the twitch torque. The differential responses for the twitch and the tetanus suggest an interplay between optimal fusion created from contractile speed slowing and excitation contraction coupling compromise. These issues make the optimal design of functional electrical stimulation systems a formidable task.     

The influence of anterior guidance and condylar guidance on mandibular protrusive movement

We report on a sporadic case of Pfeiffer syndrome in a male newborn with complex craniosynostosis, broad thumbs and great toes and early demise. SSCP and direct sequencing revealed a missense mutation at position 1037 of the exon B (or IIIc) of the FGFR2 gene (codon 342) resulting in a cysteine to serine modification (TGC-TCC). Genotype-phenotype correlations between the FGFRs mutations and the different craniosynostotic syndromes are discussed.     

The importance of visual erotic stimulation in the differential diagnosis of erectile impotence

Associations have been reported between polymorphisms in the gene for alpha 1-antichymotrypsin (ACT) and both Alzheimer's disease (AD) and cerebrovascular disease. An A-to-G substitution at nucleotide position 1,252 of ACT that produces a methionine to valine substitution at codon 389 has been found previously in four of 32 individuals with cerebrovascular disease from a Japanese population. We genotyped 194 individuals [59 controls, 35 with non-AD-type dementia (primarily vascular) and 100 with Alzheimer's-type dementia] for this polymorphism and found none that carry this polymorphism. Therefore, the allelic association of the A1252G mutation of ACT with cerebrovascular disease may be confined to the Japanese population and is not generalizable to other populations.