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Previous issue date: 2015-02-13 === Introdu??o: A respira??o abdominal lenta (RAL) estimula o barorreflexo e gera a
arritmia respirat?ria sinusal, causando mudan?a positiva cardiovascular, emocional
e cerebral aguda e cr?nica. Entretanto, embora as pr?ticas meditativas recebam
aten??o crescente nos ?ltimos anos, n?o h? consenso acerca das mudan?as
neurofisiol?gicas subjacentes a elas, principalmente pela falta de informa??o
topogr?fica suficiente. Objetivo: Objetivamos analisar o efeito agudo da RAL
sobre a atividade cerebral, respostas emocionais e cardiovasculares em sujeitos
inexperientes em t?cnicas de medita??o. M?todos: Dezessete homens adultos
saud?veis foram avaliados em duas sess?es diferentes de modo rand?mico e
cruzado. Na condi??o experimental realizaram a RAL em 6 ciclos/minuto e na
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controle mantiveram sua taxa respirat?ria normal, ambas por 20 minutos. Avaliouse
antes e ap?s as respectivas sess?es a atividade cerebral com o
eletroencefalograma (EEG), ansiedade, humor, variabilidade da frequ?ncia
card?aca (VFC) e press?o arterial. O EEG foi analisado pelo sLORETA para
localiza??o das regi?es cerebrais que sofreram mudan?a. Resultados: O
sLORETA evidenciou uma redu??o na banda de frequ?ncia beta no giro frontal
(P<0,01) e c?rtex cingulado anterior (P<0,05) tanto durante quanto e ap?s a RAL
(P<0,05) comparada ao repouso, sem mudan?a na condi??o controle.
Adicionalmente, a ANOVA two-way com medidas repetidas mostrou que n?o
houve efeito na ansiedade (P>0,8) nem no humor (P>0,08). Houve uma melhora
na VFC (P<0,03), aumento do intervalo RR e redu??o da frequ?ncia card?aca ap?s
RAL, assim como aumento no SDNN, RMSSD, pNN50, no componente de baixa
frequ?ncia, raz?o LF/HF e pot?ncia total durante a mesma, sem altera??es na PAS
e PAD. Conclus?o: Conclu?mos que a RAL, mesmo sem altera??es
comportamentais, ? capaz de modificar a atividade cerebral em regi?es
associadas ao processamento emocional. Al?m disso, melhora a VFC sem
modificar a press?o arterial. === Introduction: Slow abdominal breathing (SAB) stimulates baroreflex and
generates respiratory sinus arrhythmia, changing cardiovascular, emotional and
cerebral systems acute and chronically. However, although meditative practices
have been receiving increasingly attention in the last years, there is no
agreement on the neurophysiological changes underlying them, mainly because
of the lack of topographical pieces of information. Purpose: We aimed to
analyze the acute effect of SAB on brain activity, emotional and cardiovascular
responses in untrained subjects in meditative techniques. Methods: Seventeen
healthy adults? men were assessed into two different sessions in a random and
crossed order. Into experimental session, they breathed in 6 cycles/minute and
in control session they kept breathing in normal rate, both for 20 minutes.
xi
Before, during, and after each session we assessed brain activity using
electroencephalography (EEG), anxiety, mood, heart rate variability (HRV) and
blood pressure. The sLORETA software was used to analyze EEG data for
source localization of brain areas in which activity was changed. Results: The
sLORETA showed that beta band frequency was reduced in frontal gyrus
(P<0.01) and anterior cingulate cortex (P<0.05) both during and after SAB
(P<0.05) compared to the moment before it. There was no change in brain
activity in control session. Additionally, a two-way repeated measures ANOVA
showed that there was no effect on anxiety (P>0.8) and mood (P>0.08). There
were improvements in HRV (P<0.03), with increased RR interval and decreased
HR after SAB, as well as increased SDNN, RMSSD, pNN50, low frequency,
LF/HF ratio, and total power during it, with no changes in SBP and DBP.
Conclusions: We conclude that SAB is able to change brain activity in areas
responsible for emotional processing, even without behavioral changes.
Furthermore, SAB improves HRV and does not change blood pressure in
normotensive.
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