Relative performance of the two hands in simple and choice reaction time tasks

There is evidence that the left hemisphere is more competent for motor control than the right hemisphere. This study investigated whether this hemispheric asymmetry is expressed in the latency/duration of sequential responses performed by the left and/or right hands. Thirty-two right-handed young adults (16 males, 16 females; 18-25 years old) were tested in a simple or choice reaction time task. They responded to a left and/or right visual target by moving their left and/or right middle fingers between two keys on each side of the midline. Right hand reaction time did not differ from left hand reaction time. Submovement times were longer for the right hand than the left hand when the response was bilateral. Pause times were shorter for the right hand than the left hand, both when the responses were unilateral or bilateral. Reaction time results indicate that the putatively more efficient response preparation by the left hemisphere motor mechanisms is not expressed behaviorally. Submovement time and pause time results indicate that the putatively more efficient response execution by the left hemisphere motor mechanisms is expressed behaviorally. In the case of the submovements, the less efficient motor control of the left hand would be compensated by a more intense attention to this hand.

Facilitatory effects of an auditory warning stimulus in a visual location identification task and a visual shape identification task

The occurrence of a weak auditory warning stimulus increases the speed of the response to a subsequent visual target stimulus that must be identified. This facilitatory effect has been attributed to the temporal expectancy automatically induced by the warning stimulus. It has not been determined whether this results from a modulation of the stimulus identification process, the response selection process or both. The present study examined these possibilities. A group of 12 young adults performed a reaction time location identification task and another group of 12 young adults performed a reaction time shape identification task. A visual target stimulus was presented 1850 to 2350 ms plus a fixed interval (50, 100, 200, 400, 800, or 1600 ms, depending on the block) after the appearance of a fixation point, on its left or right side, above or below a virtual horizontal line passing through it. In half of the trials, a weak auditory warning stimulus (S1) appeared 50, 100, 200, 400, 800, or 1600 ms (according to the block) before the target stimulus (S2). Twelve trials were run for each condition. The S1 produced a facilitatory effect for the 200, 400, 800, and 1600 ms stimulus onset asynchronies (SOA) in the case of the side stimulus-response (S-R) corresponding condition, and for the 100 and 400 ms SOA in the case of the side S-R non-corresponding condition. Since these two conditions differ mainly by their response selection requirements, it is reasonable to conclude that automatic temporal expectancy influences the response selection process.

Influence of cueing on the preparation and execution of untrained and trained complex motor responses

This study investigated the influence of cueing on the performance of untrained and trained complex motor responses. Healthy adults responded to a visual target by performing four sequential movements (complex response) or a single movement (simple response) of their middle finger. A visual cue preceded the target by an interval of 300, 1000, or 2000 ms. In Experiment 1, the complex and simple responses were not previously trained. During the testing session, the complex response pattern varied on a trial-by-trial basis following the indication provided by the visual cue. In Experiment 2, the complex response and the simple response were extensively trained beforehand. During the testing session, the trained complex response pattern was performed in all trials. The latency of the untrained and trained complex responses decreased from the short to the medium and long cue-target intervals. The latency of the complex response was longer than that of the simple response, except in the case of the trained responses and the long cue-target interval. These results suggest that the preparation of untrained complex responses cannot be completed in advance, this being possible, however, for trained complex responses when enough time is available. The duration of the 1st submovement, 1st pause and 2nd submovement of the untrained and the trained complex responses increased from the short to the long cue-target interval, suggesting that there is an increase of online programming of the response possibly related to the degree of certainty about the moment of target appearance.

Lateral asymmetry of voluntary attention orienting

We recently demonstrated that automatic attention favors the right side of space and, in the present study, we investigated whether voluntary attention also favors this side. Six reaction time experiments were conducted. In each experiment, 12 new 18-25-year-old male right-handed individuals were tested. In Experiments 1, 2, 3 (a, b) and 4 (a, b), tasks with increasing attentional demands were used. In Experiments 1, 2, 3a, and 4a, attention was oriented to one or both sides by means of a central spatially informative visual cue. A left or right side visual target appeared 100, 300, or 500 ms later. Attentional effects were observed in the four experiments. In Experiments 2, 3a and 4a, these effects were greater when the cue indicated the right side than when it indicated the left side (respectively: 16 ± 10 and 44 ± 6 ms, P = 0.015, for stimulus onset asynchrony of 500 ms in Experiment 2; 38 ± 10 and 70 ± 7 ms, P = 0.011, for Experiment 3a, and 23 ± 11 and 61 ± 10 ms, P = 0.009, for Experiment 4a). In Experiments 3b and 4b, the central cue pointed to both sides and was said to be non-relevant for task performance. In these experiments right and left reaction times did not differ. The most conservative interpretation of the present findings is that voluntary attention orienting favors the right side of space, particularly when a difficult task has to be performed.

Estudo comparativo entre a relação do hemisfério acometido no acidente vascular encefálico e a evolução funcional em indivíduos destros / Comparative study on the relationship between stroke hemisphere and functional evolution in right-handed individuals

OBJETIVO: O hemisfério esquerdo é dominante para o controle motor e o direito para a orientação espacial. Este estudo visou testar as hipóteses de que a lesão à esquerda causa maior prejuízo da movimentação voluntária e a lesão à direita resulta em perda na atenção espacial e no controle postural. Indivíduos com lesão à esquerda foram comparados com indivíduos com lesão à direita, com relação ao comprometimento inicial e recuperação três meses pós-lesão. MATERIAIS E MÉTODOS: Vinte e dois indivíduos destros com lesão isquêmica no território da artéria cerebral média (11 à esquerda e 11 à direita) foram avaliados mensalmente nos três primeiros meses pós-lesão em termos de sensibilidade, tônus, força, postura, marcha, independência funcional e atenção espacial. RESULTADOS: Com relação ao comprometimento inicial, não houve diferença na sensibilidade, tônus, força, postura e atenção dos grupos. O grupo com lesão à esquerda apresentou pior desempenho inicial nos testes de marcha e de independência funcional. Com relação à taxa de recuperação, não houve diferenças na sensibilidade, tônus, força, postura, atenção e independência funcional dos dois grupos. Porém, a taxa de recuperação da marcha do grupo com lesão à esquerda foi inferior à do outro grupo. CONCLUSÕES: Foi confirmada a hipótese de que a lesão à esquerda causa maior comprometimento da movimentação voluntária, representada pela marcha e independência funcional, que a lesão à direita. Não foi obtida, no entanto, evidência de que a lesão à direita compromete de modo mais intenso a atenção espacial e a manutenção da postura que a lesão à esquerda.

OBJECTIVE: The left hemisphere is supposed to be dominant for motor control and the right hemisphere dominant for spatial orientation. This study aimed to test the hypothesis that left-side lesions cause greater impairment of voluntary movement, while right-side lesions cause loss of spatial attention loss and postural control. Individuals with left-side lesions were compared with individuals with right-side lesions, in relation to initial impairment and recovery three months after their stroke. METHODS: Twenty-two right-handed individuals with an ischemic lesion in the area of the middle cerebral artery (11 on the left side and 11 on the right side) were assessed monthly, for the first three months after their stroke, in terms of sensitivity, tonus, posture, gait, functional independence and spatial attention. RESULTS: In relation to the initial impairment, there was no difference in sensitivity, tonus, strength, posture and spatial attention between the groups. The left-side lesion group presented worse initial performance in gait and functional independence tests. In relation to the recovery rate, there were no differences in sensitivity, tonus, strength, posture, spatial attention or functional independence between the two groups. However, the gait recovery rate in the left-side lesion group was slower than in the other group. CONCLUSIONS: The hypothesis that left-side lesions cause greater impairment of voluntary movement (represented by gait and functional independence) than do right-side lesions was supported. However, no evidence that right-side lesions cause greater impairment of spatial attention and posture maintenance than do left-side lesions was found.

Evidence for divided automatic attention

A long-standing debate in the literature is whether attention can form two or more independent spatial foci in addition to the well-known unique spatial focus. There is evidence that voluntary visual attention divides in space. The possibility that this also occurs for automatic visual attention was investigated here. Thirty-six female volunteers were tested. In each trial, a prime stimulus was presented in the left or right visual hemifield. This stimulus was characterized by the blinking of a superior, middle or inferior ring, the blinking of all these rings, or the blinking of the superior and inferior rings. A target stimulus to which the volunteer should respond with the same side hand or a target stimulus to which she should not respond was presented 100 ms later in a primed location, a location between two primed locations or a location in the contralateral hemifield. Reaction time to the positive target stimulus in a primed location was consistently shorter than reaction time in the horizontally corresponding contralateral location. This attentional effect was significantly smaller or absent when the positive target stimulus appeared in the middle location after the double prime stimulus. These results suggest that automatic visual attention can focus on two separate locations simultaneously, to some extent sparing the region in between.

Granuloma gigantocelular central del maxilar inferior: Presentación de un caso pediátrico / Giant cell granuloma of the lower jaw: Description of a pediatric case

El granuloma gigantocelular central (GGCC), es una lesión tumoral o seudotumoral, infrecuente de los huesos de la cabeza y cuello, que afecta más frecuentemente los maxilares. Su etiología y patogenia son poco conocidas, sus características histológicas son benignas y su comportamiento biológico puede ser agresivo localmente. Presentamos el caso de un niño de 6 años con esta afección y realizamos una revisión de la entidad y sus diagnósticos diferenciales con otras lesiones de los maxilares.

Giant Cell Granuloma (GCG) is an uncommon condition affecting the bones of the head and neck. The ethiology and pathophysiology are not completely understood. The histlogic characteristics of GCG are benign, but its biologic behavior could locally aggressive. We describe the case of a 6 year-old boy with GCG and performed a review of the entity ant their differential diagnosis with other lesions of the maxillary bones.

Control of attention by a peripheral visual cue depends on whether the target is difficult to discriminate

The influence of a peripheral cue represented by a gray ring on responsivity to a subsequent target varies. When a vertical line inside a ring was a go target and a white small ring inside a ring was a no-go target, reaction time was shorter at the same location relative to a different location. However, no reaction time difference between the two locations occurred when a white cross inside the ring, instead of the white vertical line inside the ring, was the go target. We investigated whether this last finding was due to a forward masking influence of the cue, a requirement of low attention for the discrimination or a lack of attention mobilization by the cue. In Experiment 1, the intensity of the cue was reduced in an attempt to reduce forward masking. In Experiment 2, the vertical line and the cross were presented in the same block of trials so as to be dealt with a common attentional strategy. In Experiments 3 and 4, the no-go target was a 45° rotated cross inside a ring to increase the difficulty of the discrimination. No evidence was obtained that the cross was forward masked by the cue nor that it demanded less attention to be discriminated from the small ring. There was a facilitation of responsivity by the cue when the small ring was replaced by the rotated cross. The results suggest that when the discrimination to be performed is too easy the cue does not mobilize attention.

Tatuajes y "piercing" / Tattoos and piercing

A pesar de estar en el siglo XXI se ha retomado el lenguaje con códigos de comunicación arcaicos. Los jóvenes forman su identidad mediante la interacción con sus pares y los tatuajes y "piercing" tienen sus propios códigos, que son interpretados por el grupo que los lleva. Actualmente los tatuajes y los "piercing" encuentran su lugar predominante en la población adolescente, donde se han reinstalado por ser "moda" y generalmente se aceptan por estar generalizados. Asimismo los observamos en poblaciones marginales: de drogadictos y carcelarias. Realizarse un tatuaje y/o "piercing" implica ciertos riesgos, entre los que podemos mencionar la transmisión de infecciones que pueden ser localizadas en las zonas del tatuaje y/o "piercing"; y/o generalizadas como las virósicas algunas de las cuales conllevan riesgos de salud como el virus del HIV, de las hepatitis A,B,C. Pueden observarse también reacciones alérgicas, de hipersensibilidad, liquenoides, granulomatosas y varias como cicatrices hipertróficas y queloides; asimismo desencadenar un primer episodio de psoriasis, lupus, etc. Dentro de las recomendaciones para informar a la población deberíamos incluir: que las regiones del cuerpo más riesgosas para la realización de los mismos (que debieran evitarse) son aquellas que asientan en cabeza (incluyendo boca, nariz), cuello y órganos genitales. También es importante tener la vacunación antitetánica actualizada, considerar las condiciones de higiene del local donde se va a asistir y el tipo de material a utilizar, debiendo ser en lo posible material descartable. Los cuidados durante los primeros días post práctica son: mantener la zona limpia y seca, baños cortos, secarse sin frotado y no exponerse al sol por tres o cuatro meses. Asimismo es aconsejable ante cualquier reacción concurrir a la consulta profesional.

In spite of being in the XXI century, several archaic codes of communication language have been restablished. Young people form their identity by peer interaction, and tattoos and piercing have their own codes interpreted by the group by whom are exhibited. Nowadays tattoos and piercing have taken their place among adolescents where they have been reinstalled as "fashion" and widely accepted. Also, there are used in marginal populations such as drug users and prison inmates. Having a tattoo and/or piercing implies certain risks among which we are the transition of infectious diseases that could be localized at the site of the tattoo/piercing, or generalized as viral infections such HIV, and hepatitis A, B, or C. Other possible complications are the appearance of allergic, hypersensitivity, lichenoid, and granulomatous reactions, or the triggering of a first episode of psoriasis, lupus, etc. In the recommendations to inform the population we should include that the body regions more unsafe for these practices are: the head (including mouth and nose), neck, and genitalia. Is also very important to have tetanus vaccines updated, considering the hygiene conditions of the tattoo parlor and the quality of the material that is going to be used which should be disposable if possible. The local care in the first days post-practice are: keeping the region clean and dry, short showers, dry without rubbing, and avoid the sun for three or four months. Also is advisable in the case of any reaction seek for professional advice.

Actualización en el diagnóstico y tratamiento de los hemangiomas / Update on diagnosis and treatment of hemangiomas

Enfatizar en la correcta clasificación es aún una alta prioridad en la literatura ya persiste una gran desinformación al respecto. Nuevos progresos en la ciencia han permitido una mejor comprensión de estas lesiones. El avance en el diagnóstico precoz y la experiencia terapéutica han mejorado nuestra habilidad para tratar lesiones extensas y mejorar la calidad de vida de los pacientes.

Emphasis on correct classification is still a high priority in the literature and yet there remains a great deal of misinformation. Many new developments in the basic science of these lesions are allowing better understanding of why these lesions occur while improving our management in these patients. Advances in early diagnosis and therapeutic experience have improved our ability to treat extensive lesions and also improve patients' quality of life.

Relative contribution of expectancy and immediate arousal to the facilitatory effect of an auditory accessory stimulus

An auditory stimulus speeds up a digital response to a subsequent visual stimulus. This facilitatory effect has been related to the expectancy and the immediate arousal that would be caused by the accessory stimulus. The present study examined the relative contribution of these two influences. In a first and a third experiment a simple reaction time task was used. In a second and fourth experiment a go/no-go reaction time task was used. In each of these experiments, the accessory stimulus preceded the target stimulus by 200 ms for one group of male and female volunteers (G Fix). For another group of similar volunteers (G Var) the accessory stimulus preceded the target stimulus by 200 ms in 25 percent of the trials, by 1000 ms in 25 percent of the trials and was not followed by the target stimulus in 50 percent of the trials (Experiments 1a and 1b) or preceded the target stimulus by 200 ms in 6 percent of the trials and by 1000 ms in 94 percent of the trials (Experiments 2a and 2b). There was a facilitatory effect of the accessory stimulus for G Fix in the four experiments. There was also a facilitatory effect of the accessory stimulus at the 200-ms stimulus onset asynchrony for G Var in Experiments 1a and 1b but not in Experiments 2a and 2b. The facilitatory effects observed were larger in the go/no-go task than in the simple task. Taken together, these results suggest that expectancy is much more important than immediate arousal for the improvement of performance caused by an accessory stimulus.

Experimental context modulates warning signal effects

Previous studies have shown that saccadic eye responses but not manual responses were sensitive to the kind of warning signal used, with visual onsets producing longer saccadic latencies compared to visual offsets. The aim of the present study was to determine the effects of distinct warning signals on manual latencies and to test the premise that the onset interference, in fact, does not occur for manual responses. A second objective was to determine if the magnitude of the warning effects could be modulated by contextual procedures. Three experimental conditions based on the kind of warning signal used (visual onset, visual offset and auditory warning) were run in two different contexts (blocked and non-blocked). Eighteen participants were asked to respond to the imperative stimulus that would occur some milliseconds (0, 250, 500 or 750 ms) after the warning signal. The experiment consisted in three experimental sessions of 240 trials, where all the variables were counterbalanced. The data showed that visual onsets produced longer manual latencies than visual offsets in the non-blocked context (275 vs 261 ms; P < 0.001). This interference was obtained, however, only for short intervals between the warning and the stimulus, and was abolished when the blocked context was used (256 vs 255 ms; P = 0.789). These results are discussed in terms of bottom-up and top-down interactions, mainly those related to the role of attentional processing in canceling out competitive interactions and suppressive influences of a distractor on the relevant stimulus.

Simdrome de Parry-Romberg: a proposito de dos casos / Parry- Romberh syndrome: a propos of two cases

El síndrome de Parry-Romberg o hemiatrofia facial progresiva (HFP) es un cuadro de etiología desconocida que se presenta más frecuentemente en las dos primeras décadas de la vida.Precedida en ocaciones de síntomas neurológicos, se instala una hipo o hiperpigmentación localizada en una hemicara y en el transcurso de meses o años una hemiatrofia facial homolateral que involucra pioerl, celular subcutáneo, músculo y frecuentemente cartílago y hueso subyacentes y que progresa hasta que en un momento dado detiene su evolución dejando grados variables de deformidad facial

Acrodermatitis enteropatica / Acridermatitis enterophatica

La acrodermatitis enteropática es una enfermedad autosómica recesiva debida a una malabsorción de zn. Es de poca frecuencia y sus manifestaciones se observan en general desde los primeros meses de vida a las pocas semanas de suspender la lactancia materna. Presentamos una paciente de sexo femenino de 16 meses dwe edad que comenzó con lesiones eritematoescamosas perioficiales, en dorso de dedos de pies, en talones y hueco poplíteo. En dorso de dedos de manos lesiones redondeadas eritematosas, papulosas y algunas de aspecto ampollar. Hiperqueratosis periungueal tanto en mmanos como pies. Cabello escaso y rojizo. Presentaba deposiciones desligadas. Con sospecha de acrodermatitis enteropática se realizaron estudios de laboratorio y biopsia cutánea que confirmaron el diágnostica. Se comenzó con tyerapia de reemplazo con sulfato de zn con evidente mejoría clínica.

Priming effects of a peripheral visual stimulus in simple and go/no-go tasks

The early facilitatory effect of a peripheral spatially visual prime stimulus described in the literature for simple reaction time tasks has been usually smaller than that described for complex (go/no-go, choice) reaction time tasks. In the present study we investigated the reason for this difference. In a first and a second experiment we tested the participants in both a simple task and a go/no-go task, half of them beginning with one of these tasks and half with the other one. We observed that the prime stimulus had an early effect, inhibitory for the simple task and facilitatory for the go/no-go task, when the task was performed first. No early effect appeared when the task was performed second. In a third and a fourth experiment the participants were, respectively, tested in the simple task and in the go/no-go task for four sessions (the prime stimulus was presented in the second, third and fourth sessions). The early effects of the prime stimulus did not change across the sessions, suggesting that a habituatory process was not the cause for the disappearance of these effects in the first two experiments. Our findings are compatible with the idea that different attentional strategies are adopted in simple and complex reaction time tasks. In the former tasks the gain of automatic attention mechanisms may be adjusted to a low level and in the latter tasks, to a high level. The attentional influence of the prime stimulus may be antagonized by another influence, possibly a masking one

Hemangioma en penachos variedad esclerosante: reporte de un caso y revision de la literatura / Tufted hemangioma sclerosant variety: one case report and literature review

Los hemangiomas son los tumores benignos más frecuentes en la infancia. En nuestro servicio, esta patología es seguida y tratada en el sector " Alteraciones Vasculares". Sobre un total de 87.951 consultas anuales de patología dermatológica general (1995-2000) y sobre 454 pacientes (1995-2000) con alteraciones vasculares en particular, hemos constatado un solo caso de hemangioma en penachos, el cual motivó el presente trabajo. Presentamos un paciente de sexo masculino, de 2 años y medio de edad, que consultó en nuestro servicio en noviembre de 1999 presentando un hemangioma en penachos en miembro inferior.

Behavioral correlates of the activity of serotonergic and non-serotonergic neurons in caudal raphe nuclei

We investigated the behavioral correlates of the activity of serotonergic and non-serotonergic neurons in the nucleus raphe pallidus (NRP) and nucleus raphe obscurus (NRO) of unanesthetized and unrestrained cats. The animals were implanted with electrodes for recording single unit activity, parietal oscillographic activity, and splenius, digastric and masseter electromyographic activities. They were tested along the waking-sleep cycle, during sensory stimulation and during drinking behavior. The discharge of the serotonergic neurons decreased progressively from quiet waking to slow wave sleep and to fast wave sleep. Ten different patterns of relative discharge across the three states were observed for the non-serotonergic neurons. Several non-serotonergic neurons showed cyclic discharge fluctuations related to respiration during one, two or all three states. While serotonergic neurons were usually unresponsive to the sensory stimuli used, many non-serotonergic neurons responded to these stimuli. Several non-serotonergic neurons showed a phasic relationship with splenius muscle activity during auditory stimulation. One serotonergic neuron showed a tonic relationship with digastric muscle activity during drinking behavior. A few non-serotonergic neurons exhibited a tonic relationship with digastric and/or masseter muscle activity during this behavior. Many non-serotonergic neurons exhibited a phasic relationship with these muscle activities, also during this behavior. These results suggest that the serotonergic neurons in the NRP and NRO constitute a relatively homogeneous population from a functional point of view, while the non-serotonergic neurons form groups with considerable functional specificity. The data support the idea that the NRP and NRO are implicated in the control of somatic motor output

The early facilitatory effect of a peripheral spatially noninformative prime stimulus depends on target stimulus features

We investigated the dependency of the early facilitatory effect of a prime stimulus (S1) on the physical characteristics of the target stimulus (S2). A go-no go reaction time paradigm was used. The S1 was a gray ring and the S2s were a white vertical line, a white horizontal line, a white cross and a white small ring, all inside a white ring with the same dimensions as the S1. S1 onset-S2 onset asynchrony was 100 ms. The stimuli appeared randomly in any one of the quadrants of a monitor screen. The S2 could occur at the same position as the S1 or at a different one. We observed a strong facilitatory effect when the vertical line or the horizontal line was the go stimulus and no effect when the cross was the go stimulus. These results show that the features of the target stimulus can be decisive for the appearance of the facilitatory effect of a peripheral spatially noninformative prime stimulus.