ABSTRACT
INTRODUCTION: Health professionals are asked to promote health, especially organ transplantation; however, they do not always have specific training. OBJECTIVE: To analyze information about donation and organ transplantation among Spanish medical students. METHOD: The population under study is medical students in Spanish universities using the database of the International Donor Collaborative Project, stratified by geographic area and academic year (n = 9275). The instrument used is the attitude questionnaire for organ donation for "PCID-DTO-Ríos" transplantation, validated with an explained variance of 63.203% and α = 0.834. The Student t test was applied together with the χ2 test, complemented by an analysis of the remainders, and Fisher's exact test was applied. RESULTS: Of the students, 74% indicate that they have received information from university professors about organ transplant. Concerning specific issues with the donation, it is notable that only 66.7% (n = 6190) know and accept the concept of brain death as the death of a person. However, only 22% consider themselves as having good information, and 35.3% indicate that their information is scarce or void. Students indicate having received information about transplant from other extra-university sources, such as television and Internet (80.9%), books and magazines (73.2%), and the press (66.9%). From the information obtained in the sociofamilial field, 60.7% have obtained information from the family and 58.1% from friends. Of this information, 9% has been negative from friends, 7.5% from family, 6% from the Internet and television, and 4% from university professors. CONCLUSION: Spanish medical students believe they have little information about organ transplantation and have received negative information.
Subject(s)
Health Knowledge, Attitudes, Practice , Organ Transplantation/education , Students, Medical , Tissue and Organ Procurement , Adult , Faculty , Female , Humans , Male , Spain , Surveys and QuestionnairesABSTRACT
INTRODUCTION: Awareness of organ donation among Spanish doctors and medical students is very positive. However, the emerging group of professionals of non-Spanish nationality studying in Spain has not been analyzed. OBJECTIVE: To analyze the differences in the attitudes toward the different types of donation among medical students, according to their nationality. METHODS: The population under study is medical students in Spanish universities using the database of the International Collaborative Donor Project, stratified by geographic area and academic year. Groups under study include students of non-Spanish nationality as group 1 (n = 1570) and students of Spanish nationality as Group 2 (n = 7705). Instruments are validated questionnaires of attitude toward donation "PCID-DTO-Ríos," "PCID-DVR-Ríos," "PCID-DVH-Ríos," and "PCID-XenoTx-Ríos." RESULTS: The attitude toward the donation of own organs after death is similar in both groups (P = .703). Non-Spaniards are 79.2% in favor compared to 79.6% of Spaniards. Living kidney donation, both unrelated (33.3% vs 29.3% in favor; P = .001) and related (91.2% vs 89, 6% in favor; P = .047), is more favorable among non-Spanish students. There are no differences regarding non-related living liver donation (29.7% vs 29.3% in favor; P = .063), but there are differences in the results for related living liver donation (94.1% vs 88%; P < .001). The attitude toward xenotransplantation of organs is similar (80.8% vs 80.8%; P = .999). CONCLUSIONS: Awareness of the donation of organs among Spanish medical students is similar to non-Spanish students studying in Spain, except the attitude toward living donation.
Subject(s)
Emigrants and Immigrants , Health Knowledge, Attitudes, Practice/ethnology , Students, Medical , Tissue and Organ Procurement , Adult , Ethnicity , Female , Humans , Living Donors , Male , Organ Transplantation , Spain , Surveys and QuestionnairesABSTRACT
INTRODUCTION: Despite sensitization of medical students toward the donation of organs, a non-negligible percentage of students are not in favor of donation. OBJECTIVE: To analyze the reasons of Spanish medical students who do not have a favorable attitude toward the donation of their own organs after death. METHOD: The population under study is medical students in Spanish universities, using the database of the International Donor Collaborative Project, stratified by geographic area and academic year. The questionnaire completion was anonymous and self-administered. The study group is medical students with an unfavorable attitude toward organ donation. The assessment instrument used is a validated questionnaire of attitude toward the donation of organs for transplant, "PCID-DTO-Ríos." The reasons against the donation are valued in the questionnaire through a question. RESULTS: Of the participants included in the PCID, students who are not in favor of organ donation were selected (n = 1899). Of them, 8.1% (n = 154) are against and 91.1% (n = 1745) are doubtful. The main reasons indicated are the fear of apparent death in 11.4% of respondents, fear of possible mutilation after donation in 11.1%, and religious reasons in 2.6%. Of those, 6.9% indicate other reasons but do not clearly specify the reasons, using words such as "fear" (2.5%) or "doubts about the process" (4.1%); 66.2% (n = 1257) indicated an "assertive refusal" ("I don't want to express my reasons"). CONCLUSION: Twenty percent of Spanish medical students are not in favor of donating their organs and are not in favor of showing their reasons.
Subject(s)
Health Knowledge, Attitudes, Practice , Organ Transplantation , Students, Medical , Tissue and Organ Procurement , Adult , Female , Humans , Male , Spain , Surveys and Questionnaires , Universities , Young AdultABSTRACT
INTRODUCTION: Religious factors have conditioned the attitude toward organ donation and transplantation (ODT) since the beginning of transplantation, despite the fact that most religions are in favor of transplantation. OBJECTIVE: To assess the impact of religious beliefs of medical students on their attitude toward ODT. METHOD: Population under study: Medical students in Spanish universities. STUDY SAMPLE: Stratified by geographical area and academic course. Assessment instrument: Attitude ODT questionnaire PCID-DTO-Ríos, anonymous and self-administered. RESULTS: Of all students, 42% (n = 3907) declare themselves atheists or agnostics. The remaining 58% (n = 5368) declare themselves to be religious, the majority being Catholic (55%, n = 5102). Of the rest, 0.2% are Muslims (n = 8), 0.1% Protestants (n = 1), and the remaining 2.7% (n = 257) indicate other religious doctrines but do not want to specify it. Regarding their attitude toward ODT, those who consider themselves atheists or agnostics have a more favorable attitude than those who consider themselves religious (84% versus 76%; P < .001). Among those who follow some kind of religion, Catholics are more in favor of ODT than non-Catholics (77% vs 64%, P < .001). Note that among the religious, only 57% (n = 3050) know which religion is in favor of transplantation, while 22% (n = 1,152) consider that it has not been pronounced on the matter, 13% (n = 723) think the religion is against donation, and the remaining 8% (n = 443) do not know. CONCLUSION: The religion professed by medical students conditions their attitude toward donation, with the atheists and agnostics being more in favor of donation.
Subject(s)
Health Knowledge, Attitudes, Practice , Religion , Students, Medical/psychology , Tissue and Organ Procurement , Adult , Female , Humans , Male , Spain , Surveys and QuestionnairesABSTRACT
The involvement of health professionals from their training period is important for the promotion of living liver donation. There are data that indicate that the awareness of living donation is lower in areas with high rates of deceased donation. OBJECTIVE: To analyze the attitude toward living liver donation among Spanish medical students, according to donation rates of their regions. METHOD: Population under study: Medical students in Spanish universities. Database of the Collaborative International Donor Project, stratified by geographic area and academic course. The completion was anonymous and self-administered. Groups under study: group 1 (n = 1136): students in universities of regions with >50 donors per million population (pmp); group 2 (n = 2018): students in region universities with <40 donors pmp. Assessment instrument: the attitude questionnaire for living liver donation Proyecto Colaborativo Internacional Donante sobre Donación de Vivo Hepático-Ríos (PCID-DVH Ríos). RESULTS: The attitude toward related liver donation is more favorable among the students of regions with <40 donors pmp than among those of >50 donors pmp. Thus, in group 1, a total of 88% (n = 1002) of students are in favor compared with 91% (n = 1831) of group 2 (P=.02). The psychosocial profile of each study group about their attitude toward living related liver donation is analyzed. There is a similar profile between the 2 groups, although there are differences in some variables such as age, a belief that one might need a transplant, family discussion about donation and transplantation, discussion with friends about donation and transplantation, and knowing about a donor. CONCLUSIONS: The awareness of living related donation among Spanish medical students is greater among the regions with lower organ donation rates.
Subject(s)
Health Knowledge, Attitudes, Practice , Liver Transplantation/psychology , Living Donors , Social Behavior , Students, Medical/psychology , Adult , Awareness , Female , Humans , Living Donors/supply & distribution , Male , Middle Aged , Surveys and Questionnaires , Tissue and Organ ProcurementABSTRACT
The awareness of organ donation among health professionals is important at the time of transplant promotion. In this sense, the training and awareness of the professionals in training is fundamental. OBJECTIVE: To analyze the differences in the attitude toward organ donation and the factors that condition it among medical students of regions with donation rates >50 donors per million population (pmp) with respect to those with rates <40 donor pmp. METHOD: Population under study: medical students in Spanish universities. Database of the Collaborative International Donor Project, stratified by geographic area and academic course. The completion was anonymous and self-administered. Groups under study: Group 1 (n = 1136): students in universities of regions with >50 donors pmp. Group 2 (n = 2018): university students in regions with <40 donors pmp. Assessment instrument: attitude questionnaire for organ donation for transplant PCID-DTO-Ríos. RESULTS: The attitude toward organ donation for transplantation is similar among students from the autonomous communities with >50 donors pmp and with <40 donors pmp. In group 1, 79% (n = 897) of students are in favor compared with 81% (n = 1625) of group 2 (P=.29). The psychosocial profile toward donation is similar in both groups relating to the following variables (P < .05): sex, having discussed transplantation with family and as a couple, considering the possibility of needing a transplant, involvement in prosocial activities, attitude toward the manipulation of corpses, knowledge of the brain death concept, and religion. CONCLUSIONS: The awareness of organ donation in Spanish medical students is quite homogeneous and is not related to the local donation rates of each region.
Subject(s)
Health Knowledge, Attitudes, Practice , Social Behavior , Students, Medical/psychology , Tissue and Organ Procurement , Adult , Awareness , Female , Humans , Male , Organ Transplantation/psychology , Surveys and QuestionnairesABSTRACT
INTRODUCTION: Medical students represent a new generation of medical thought, and if they have a favourable attitude towards organ donation this will greatly encourage its promotion. OBJECTIVE: To analyse the attitude of medical students in Spanish universities towards the donation of their own organs and to determine the factors affecting this attitude. MATERIAL AND METHODS: Type of study: A sociological, interdisciplinary, multicentre, and observational study in Spain. STUDY POPULATION: Students studying a degree in medicine enrolled in Spain (n = 34,000). SAMPLE SIZE: A sample of 9598 students (confidence of 99% and precision of ±1%), stratified by geographical area and academic year. Instrument of measurement: A validated questionnaire of attitude towards organ donation and transplantation (PCID-DTO RIOS) was self-administered and completed anonymously. RESULTS: The questionnaire completion rate was 95.7% (n = 9.275). 80% were in favour of donation, 2% against and 18% were undecided. The following main variables were related to a favourable attitude: being of the female sex (Odds Ratio = 1.739); being in the sixth year of the degree (OR = 2.506); knowing a donor (OR = 1.346); having spoken about the subject with one's family (OR = 2.132) and friends (OR = 1.333); having a family circle that is in favour, more specifically, having a father (OR = 1.841), mother (OR = 2.538) or partner in favour (OR = 2.192); being a blood donor (OR = 2.824); acceptance of the mutilation of the body if it were necessary (OR = 2.958); and being an atheist or an agnostic (OR = 1.766). CONCLUSIONS: Spanish medical students generally have a favourable attitude towards organ donation, although 20% are not in favour.
Subject(s)
Health Knowledge, Attitudes, Practice , Students, Medical/psychology , Tissue and Organ Procurement/statistics & numerical data , Adult , Female , Humans , Male , Spain , Surveys and Questionnaires , Tissue Donors/supply & distributionABSTRACT
OBJECTIVE: To analyze the level of understanding of the brain death concept among medical students in universities in Spain. METHODS: This cross-sectional sociological, interdisciplinary, and multicenter study was performed on 9598 medical students in Spain. The sample was stratified by geographical area and academic year. A previously validated self-reported measure of brain death knowledge (questionnaire Proyecto Colaborativo Internacional Donante sobre la Donación y Transplante de Organos) was completed anonymously by students. RESULTS: Respondents completed 9275 surveys for a completion rate of 95.7%. Of those, 67% (n = 6190) of the respondents understood the brain death concept. Of the rest, 28% (n = 2652) did not know what it meant, and the remaining 5% (n = 433) believed that it did not mean that the patient was dead. The variables related to a correct understanding of the concept were: (1) being older ( P < .001), (2) studying at a public university ( P < .001), (3) year of medical school ( P < .001), (4) studying at one of the universities in the south of Spain ( P = .003), (5) having discussed donation and transplantation with the family ( P < .001), (6) having spoken to friends about the matter ( P < .001), (7) a partner's favorable attitude toward donation and transplantation ( P < .001), and (8) religious beliefs ( P < .001). CONCLUSIONS: Sixty-seven percent of medical students know the concept of brain death, and knowledge improved as they advanced in their degree.
Subject(s)
Brain Death/classification , Health Knowledge, Attitudes, Practice , Students, Medical/psychology , Adult , Cross-Sectional Studies , Female , Humans , Male , Spain , Surveys and Questionnaires , Young AdultABSTRACT
An oil-based formulation of the EG95 vaccine to protect grazing animals against infection with Echinococcus granulosus was formulated in Argentina. The efficacy of the vaccine was monitored by serology in sheep and llama (Lama glama) and was compared to the serology in sheep previously published using a QuilA-adjuvanted vaccine. Long-term efficacy was also tested in sheep by challenging with E. granulosus eggs of the G1 strain 4 years after the beginning of the trial. The serological results for both sheep and llama were similar to those described previously, except that there was a more rapid response after the first vaccination. A third vaccination given after 1 year resulted in a transient boost in serology that lasted for about 12 months, which was similar to results previously described. Sheep challenged after 4 years with three vaccinations presented 84·2% reduction of live cysts counts compared with control group, and after a fourth vaccination prior to challenge, this reduction was 94·7%. The oil-based vaccine appeared to be bio-equivalent to the QuilA vaccine.
Subject(s)
Antibodies, Protozoan/blood , Antigens, Helminth/immunology , Camelids, New World/immunology , Echinococcosis/veterinary , Echinococcus granulosus/immunology , Helminth Proteins/immunology , Sheep Diseases/prevention & control , Sheep/immunology , Vaccination/veterinary , Adjuvants, Immunologic , Animals , Argentina , Echinococcosis/immunology , Echinococcosis/parasitology , Immunization, Secondary , Quillaja Saponins/immunology , Sheep Diseases/immunology , Sheep Diseases/parasitology , Vaccines/immunologyABSTRACT
INTRODUCTION: The attitude of medical students towards living kidney donation (LKD) is of great interest given that they will become promoters of this technique in the near future. OBJECTIVE: To analyse the attitude of Spanish medical students towards related and unrelated LKD and to determine the factors affecting this attitude. MATERIALS AND METHODS: Type of study: A sociological, interdisciplinary, multicentre, and observational study. STUDY POPULATION: Medical students enrolled in Spain (n = 34.000). SAMPLE SIZE: A sample of 9598 students (99 % confidence and precision of ±1 %), stratified by geographical area and academic year. Measurement instrument: A validated questionnaire (PCID-DVR RIOS) was administered and completed anonymously. RESULTS: There was a completion rate of 95.7 % (n = 9275); 93 % (n = 8630) were in favour of related LKD, and 30 % (n = 2784) were in favour of unrelated LKD. The following factors were associated with this attitude: (1) age (p = 0.008); (2) sex (p < 0.001); (3) year of university degree (p < 0.001); (4) a belief that a transplant might be necessary in the future (p < 0.001); (5) attitude towards deceased organ donation (p < 0.001); (6) a willingness to accept a kidney from a living donor (p < 0.001); (7) attitude towards living liver donation (p < 0.001); (8) a partner's attitude towards donation (p < 0.001); (9) having spoken about the subject with one's family (p < 0.001), or friends (p < 0.001); (10) pro-social behaviour (p < 0.001); (11) the respondent's religious attitude (p < 0.001); and (12) fear of possible mutilation of the body after donation (p < 0.001). CONCLUSIONS: The attitude of medical students towards LKD is very favourable when it is the related kind of donation, and it is associated with factors of general knowledge about organ donation and transplantation and social interaction and religion.
Subject(s)
Attitude of Health Personnel , Kidney Transplantation , Living Donors/psychology , Nephrectomy , Students, Medical/psychology , Surveys and Questionnaires , Tissue and Organ Procurement , Female , Humans , Male , Spain , Young AdultABSTRACT
INTRODUCTION: Brain death is generally accepted as a concept to indicate death. It was introduced about 40 years ago, and it was considered the ideal situation for donation of organs. METHODS: During this time, however, there have been problems in the understanding of this concept both in the medical profession and in the general population. University students from medical and non-medical schools were tested for their understanding of this concept. RESULTS: Our results show that less than one third of the non-medical students identified brain death as death. The data from the medical students changed as they progressed through their studies, but only 2/3 of the graduating medical class believed that brain death is death. CONCLUSION: Similar results have been seen in other universities around the world, and a renewed effort on the re-education of the concept of brain death may be worthwhile. Although we cannot extrapolate these results to the general population, the confusion is probably similar; hence an effort should be made to solve this problem.
Subject(s)
Brain Death , Terminology as Topic , Education, Medical , Education, Nursing , Health Knowledge, Attitudes, Practice , Humans , Schools, Medical , Students , Students, MedicalABSTRACT
OBJECTIVE: The observation of a voluntary movement executed by another person is associated with an alpha and beta EEG desynchronization over the motor cortex, thought to reflect activity from the human "mirror neuron" system. The aim of our work was to study the changes in local field potentials (LFP) recorded from the subthalamic nucleus (STN) and their relationship with cortical activity, during movement observation. METHODS: Bilateral EEG and STN LFP recordings were acquired in 18 patients with Parkinson's disease, through surgically implanted electrodes for deep brain stimulation. Oscillatory changes during movement execution and movement observation were compared with two different control conditions (simple stimulus and rotating stimulus observation), in "off" and "on" motor states. Time-frequency transforms and event-related coherence were used for the analysis. RESULTS: Movement observation was accompanied by bilateral beta reduction in subthalamic power and cortico-STN coherence, which was smaller than the decrease observed during movement execution, but significant when compared with the two control conditions. CONCLUSIONS: Movement observation is accompanied by changes in the beta oscillatory activity of the STN, similar to those observed in the EEG. SIGNIFICANCE: These changes suggest that the basal ganglia might be engaged by the activity of the human mirror system.
Subject(s)
Basal Ganglia/physiology , Imitative Behavior/physiology , Motor Cortex/physiology , Movement/physiology , Parkinson Disease/physiopathology , Subthalamic Nucleus/physiology , Action Potentials/physiology , Adult , Aged , Beta Rhythm , Biological Clocks/physiology , Deep Brain Stimulation , Electroencephalography , Electrophysiology , Evoked Potentials, Motor/physiology , Female , Humans , Male , Middle Aged , Neural Pathways/physiology , Neurons/physiology , Psychomotor Performance/physiologyABSTRACT
BACKGROUND: Cognitive functions are supported by brain networks and they are highly dependent on the integrity of long white matter tracts that mediate the information flow between such distant cortical areas. Brain damage in multiple sclerosis (MS) may produce cognitive impairment by preferentially damaging these tracts, thereby impairing brain synchrony. Auditory amplitude modulation following responses (AMFR), are oscillatory steady-state responses to rhythmic auditory stimuli that indirectly measure brain synchrony. OBJECTIVE: To study the effect of MS lesions in brain synchrony and its relationship with cognitive function. METHODS: We assessed the correlation between cognitive performance, as assessed with the brief repeatable battery-neuropsychology (BRB-N), and the AMFR in a group of 27 MS patients and 22 healthy controls. RESULTS: The maximal AMFR frequency - but not the amplitude - in the 30-60 Hz range was lower in patients with cognitive impairment than in patients with no cognitive impairment or the healthy controls (39.79 Hz, 43.85 Hz, and 43.84 Hz, respectively, P < 0.05). Indeed, the frequency of the AMFR was negatively correlated with the scores obtained in verbal memory, attention, and executive function. The multiple regression analysis indicates that the AMFR was the best predictor of the BRB-N scores after controlling for potential confounding factors such as age, education, disability, and years of disease evolution. CONCLUSIONS: These results suggest that the loss of synchronization in different central nervous system (CNS) pathways caused by demyelinating lesions might involve both the slowing of brain oscillatory activity and less efficient cognitive processing.
Subject(s)
Cognition Disorders/physiopathology , Electroencephalography , Evoked Potentials, Auditory , Multiple Sclerosis, Chronic Progressive/physiopathology , Multiple Sclerosis, Relapsing-Remitting/physiopathology , Adult , Cognition Disorders/diagnosis , Disability Evaluation , Female , Humans , Male , Memory , Middle Aged , Multiple Sclerosis, Chronic Progressive/diagnosis , Multiple Sclerosis, Relapsing-Remitting/diagnosis , Neuropsychological TestsABSTRACT
The terms "oscillations" or "oscillatory activity" are frequently used not only to define the rhythmic fluctuations of the postsynaptic potentials of a neuronal group (local field potentials) or a cortical region (EEG, MEG), but also to indicate the rhythmic discharge pattern of action potentials from a neuron or a small group of neurons. Oscillatory activity makes possible the synchronization of different neuronal groups from nearby or distant cortical regions that participate in the same motor, sensory or cognitive task. The presence of oscillatory activity is usually associated to the existence of synchronization, but both phenomena are not necessarily always equivalent. Abnormalities of oscillatory activities or synchronization within or between different brain structures have been described in several neurological and psychiatric diseases; these abnormalities might play a relevant pathophysiological role in Parkinson's disease (and other movement disorders), schizophrenia or epilepsy. This review discusses all these aspects, with emphasis on their potential role both as a basic mechanism in brain function and as a pathophysiological substrate for some of the symptoms and signs observed in several diseases.
Subject(s)
Brain/physiopathology , Epilepsy/physiopathology , Parkinson Disease/physiopathology , Schizophrenia/physiopathology , Action Potentials , Brain/physiology , Epilepsy/therapy , Humans , Nerve Net , Parkinson Disease/therapy , Schizophrenia/therapyABSTRACT
The video-EEG is a common diagnostic tool nowadays. The technical achievements of the last decade have brought a simplification of the equipment required to obtain good quality recordings, with little more than a computer and a video camera being necessary. However, the medical and technical staff must be well trained to execute and interpret the study. It is very useful in the diagnosis of paroxysmal events, for the classification and characterization of epileptic seizures and to quantify epileptiform discharges. Due to the importance of a correct diagnosis to avoid mistreating many neurological patients, this tool should be accessible to clinicians. In spite of the advances of recent years, 20-30% of patients diagnosed with epilepsy are not really epileptic, a fact that it is excessive and unacceptable.
Subject(s)
Electroencephalography/methods , Video Recording , Electroencephalography/instrumentation , Epilepsy/diagnosis , HumansABSTRACT
The polysomnography is a standardized diagnostic tool in neurology. It is used to study sleep structure and can diagnose many sleep disorders. Since this test is not always adequately available as it is a complex test that requires a qualified team and staff, its most necessary and urgent indications should be stressed in order to thus avoid the waiting lists. In this paper we review the primary indications of the nocturnal sleep studies in the different groups of neurological disorders. We review the bibliography, selecting the papers that help to specify when the polysomnographic study would be indicated and those situations in which it may be indispensable or urgent.
Subject(s)
Nervous System Diseases/diagnosis , Polysomnography , Cerebrovascular Disorders/diagnosis , Cerebrovascular Disorders/physiopathology , Dementia/diagnosis , Dementia/physiopathology , Demyelinating Diseases/diagnosis , Demyelinating Diseases/physiopathology , Epilepsy/diagnosis , Epilepsy/physiopathology , Headache/diagnosis , Headache/physiopathology , Humans , Mental Disorders/diagnosis , Mental Disorders/physiopathology , Movement Disorders/diagnosis , Movement Disorders/physiopathology , Nervous System Diseases/physiopathology , Neuromuscular Diseases/diagnosis , Neuromuscular Diseases/physiopathologyABSTRACT
Steady-state potentials are oscillatory responses generated by rhythmic stimulation of a sensory pathway. The frequency of the response, which follows the frequency of stimulation and potentially indicates the preferential working frequency of the auditory neural network, is maximal at a stimulus rate of 40 Hz for auditory stimuli in humans, but may be different in other species. Our aim was to explore the responses to different frequencies in the rat. The stimulus was a tone modulated in amplitude by a sinusoid with linearly-increasing frequency from 1 to 250 Hz ("chirp"). Time-frequency transforms were used for response analysis in 12 animals, awake and under ketamine/xylazine anesthesia. We studied whether the responses were due to increases in amplitude or to phase-locking phenomena, using single-sweep time-frequency transforms and inter-trial phase analysis. A progressive decrease in the amplitude of the response was observed from the maximal values (around 15 Hz) up to the limit of the test (250 Hz). The high-frequency component was mainly due to phase-locking phenomena with a smaller amplitude contribution. Under anesthesia, the amplitude and phase-locking of lower frequencies (under 100 Hz) decreased, while the phase-locking over 200 Hz increased. In conclusion, amplitude-modulation following responses differ between humans and rats in response range and frequency of maximal amplitude. Anesthesia with ketamine/xylazine modifies differentially the amplitude and the phase-locking of the responses. These findings should be taken into account when assessing the changes in cortical oscillatory activity related to different drugs, in healthy rodents and in animal models of neurodegenerative diseases.
Subject(s)
Anesthesia , Cerebral Cortex/physiology , Evoked Potentials, Auditory/physiology , Pitch Discrimination/physiology , Wakefulness/physiology , Acoustic Stimulation/methods , Animals , Brain Mapping , Dose-Response Relationship, Radiation , Electroencephalography , Fourier Analysis , Male , Rats , Rats, WistarABSTRACT
OBJECTIVE: Stimulus-induced movements are accompanied by a definite pattern of oscillatory changes, that include a frontal 15 Hz synchronization, a central peri-movement desynchronization, and a contralateral beta rebound after the movement. Our aim was to study the oscillatory changes related to the forced termination of a single complex motor program (signature) and compare them with those observed after the normal termination of the movement. METHODS: Fifty-eight reference-free EEG channels were analyzed in 10 healthy subjects. A 2000 Hz tone (S1, go signal) indicated the subject to begin to write his/her complete signature. A second 2000 Hz tone 0.8 s afterwards (50% probability: S2, stop signal) indicated the subject to stop immediately. Movement-related energy changes were evaluated by means of time-frequency (Gabor) transforms. RESULTS: A frontal 15 Hz synchronization was observed after S1, but not after S2. The amplitude of the post-movement beta increase was significantly lower when the movement was abnormally terminated (p=0.005), while the peri-movement decrease was similar. CONCLUSIONS: The forced termination of a motor program reduces significantly the amplitude of the post-movement beta increment, conserving its temporal pattern. Also, the presence of the 15 Hz frontal synchronization only after S1, together with the results of previous studies, suggests that the frontal mechanisms involved in go/no go and stop signals are very different. SIGNIFICANCE: Our results indicate that the beta rebound is an active process, independent of the peri-movement beta decrease, which is influenced by how the movement is terminated.
Subject(s)
Biological Clocks/physiology , Choice Behavior/physiology , Frontal Lobe/physiology , Movement/physiology , Acoustic Stimulation/methods , Adult , Analysis of Variance , Brain Mapping , Electroencephalography , Electromyography/methods , Female , Fourier Analysis , Humans , Male , Psychomotor Performance/physiology , Reaction TimeSubject(s)
Insomnia, Fatal Familial/physiopathology , Polysomnography , Video Recording , Circadian Rhythm/genetics , Codon/genetics , Fatal Outcome , Humans , Insomnia, Fatal Familial/genetics , Male , Memory Disorders/etiology , Middle Aged , Mutation, Missense/genetics , Neuropsychological Tests , Personality Disorders/etiology , Point Mutation/genetics , Prion Proteins , Prions/genetics , Terminology as TopicABSTRACT
The origin of agriculture was a signal development in human affairs and as such has occupied the attention of scholars from the natural and social sciences for well over a century. Historical studies of climate and vegetation are closely associated with crop plant evolution because they can reveal the ecological contexts of plant domestication together with the antiquity and effects of agricultural practices on the environment. In this article, we present paleoecological evidence from three lakes and a swamp located in the Central Balsas watershed of tropical southwestern Mexico that date from 14,000 B.P. to the modern era. [Dates expressed in B.P. years are radiocarbon ages. Calibrated (calendar) ages, expressed as cal B.P., are provided for dates in the text.] Previous molecular studies suggest that maize (Zea mays L.) and other important crops such as squashes (Cucurbita spp.) were domesticated in the region. Our combined pollen, phytolith, charcoal, and sedimentary studies indicate that during the late glacial period (14,000-10,000 B.P.), lake beds were dry, the climate was cooler and drier, and open vegetational communities were more widespread than after the Pleistocene ended. Zea was a continuous part of the vegetation since at least the terminal Pleistocene. During the Holocene, lakes became important foci of human activity, and cultural interference with a species-diverse tropical forest is indicated. Maize and squash were grown at lake edges starting between 10,000 and 5,000 B.P., most likely sometime during the first half of that period. Significant episodes of climatic drying evidenced between 1,800 B.P. and 900 B.P. appear to be coeval with those documented in the Classic Maya region and elsewhere, showing widespread instability in the late Holocene climate.