***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Abstract . The aim of this study was to investigate the effects of  inner and heard speech  on cerebral hemodynamics and oxygenation in the anterior prefrontal cortex ( PFC ) using functional near-infrared spectroscopy and to test whether potential effects were caused by alterations in the arterial carbon dioxide pressure ( PaCO2 ) . Twenty-nine healthy adult volunteers performed  six different tasks of inner and heard speech  according to a r and omized crossover design . During the tasks , we generally found a decrease in PaCO2 ( only for inner speech ) , tissue oxygen saturation ( StO2 ) , oxyhemoglobin ( [ O2Hb ] ) , total hemoglobin ( [ tHb ] ) concentration and an increase in deoxyhemoglobin concentration ( [ HHb ] ) . Furthermore , we found significant relations between changes in [ O2Hb ] , [ HHb ] , [ tHb ] , or StO2 and the participants ’ age , the baseline PETCO2 , or certain speech tasks . We conclude that changes in breathing during the tasks led to lower PaCO2 ( hypocapnia ) for inner speech . During heard speech , no significant changes in PaCO2 occurred , but the decreases in StO2 , [ O2Hb ] , and [ tHb ] suggest that changes in PaCO2 were also involved here . Different verse types ( hexameter and alliteration ) led to different changes in [ tHb ] , implying different brain activations . In conclusion , StO2 , [ O2Hb ] , [ HHb ] , and [ tHb ] are affected by interplay of both PaCO2 reactivity and functional brain activity Different types of exercise training have the potential to induce structural and functional brain plasticity in the elderly . Thereby , functional brain adaptations were observed during cognitive tasks in functional magnetic resonance imaging studies that correlated with improved cognitive performance . This study aim ed to investigate if exercise training induces functional brain plasticity during challenging treadmill walking and elicits associated changes in cognitive executive functions . Forty-two elderly participants were recruited and r and omly assigned to either interactive cognitive-motor video game dancing ( DANCE ) or balance and stretching training ( BALANCE ) . The 8-week intervention included three sessions of 30 min per week and was completed by 33 participants ( mean age 74.9 ± 6.9 years ) . Prefrontal cortex ( PFC ) activity during preferred and fast walking speed on a treadmill was assessed applying functional near infrared spectroscopy pre- and post-intervention . Additionally , executive functions comprising shifting , inhibition , and working memory were assessed . The results showed that both interventions significantly reduced left and right hemispheric PFC oxygenation during the acceleration of walking ( p < 0.05 or trend , r = 0.25–0.36 ) , while DANCE showed a larger reduction at the end of the 30-s walking task compared to BALANCE in the left PFC [ F(1 , 31 ) = 3.54 , p = 0.035 , r = 0.32 ] . These exercise training induced modulations in PFC oxygenation correlated with improved executive functions ( p < 0.05 or trend , r = 0.31–0.50 ) . The observed reductions in PFC activity may release cognitive re sources to focus attention on other processes while walking , which could be relevant to improve mobility and falls prevention in the elderly . This study provides a deeper underst and ing of the associations  between exercise training , brain function during walking , and cognition in older adults Recently , real time imaging of the cortical control of gait became possible with functional near-infrared spectroscopy ( fNIRS ) . So far , little is known about the activations of various cortical areas in more complex forms of gait , such as precision stepping . From previous work on animals and humans one would expect precision stepping to elicit extra activity in the sensorimotor cortices ( S1/M1 ) , supplementary motor area ( SMA ) , as well as in prefrontal cortices ( PFC ) . In the current study , hemodynamic changes in the PFC , SMA , M1 , and S1 were measured with fNIRS . In contrast to previous fNIRS gait studies , the technique was optimized by the use of reference channels ( to correct for superficial hemodynamic interference ) . Eleven subjects r and omly performed ten trials of treadmill walking at 3 km/h ( normal walking )  and ten trials of 3 km/h treadmill walking on predefined spots for the left and right foot presented on the treadmill ( precision stepping ) . The walking trials of approximately 35 seconds were alternated with rest periods of 25 - 35 seconds consisting of quiet st and ing . The PFC revealed profound activation just prior to the onset of both walking tasks . There was also extra activation of the PFC during the first half of the task period for precision stepping . The SMA showed mainly increased activation prior to the start of both tasks . In contrast , the sensorimotor cortex did not show a change in activation during either task as compared to a condition of st and ing . The SMA , M1 , and S1 revealed no significant differences between normal walking and precision stepping . It was concluded that fNIRS is suited to record the planning and initiation of gait . The lack of M1/S1 activation during gait suggests that even in the current precision stepping task the control of ongoing gait depended mostly on subcortical automatisms , while motor cortex contributions did not differ between st and ing and walking The effect of motor activity on the left fronto- central region of the human brain was analyzed spatially and temporally by using noninvasive near-infrared light ( NIR ) topography . The changes in oxygenation states caused by motor activity were measured using intensity-modulated NIR spectroscopy at ten measurement positions on the head surface . The subject r and omly performed unilateral finger opposition for 30 s as motor stimulation . When the subject performed contralateral ( right ) finger movement , significant increases in both oxygenated hemoglobin ( oxy-Hb ) and total hemoglobin ( total-Hb ) and decreases in deoxygenated hemoglobin ( deoxy-Hb ) were observed in a particular area . By mapping the static topograms of the changes of each Hb and comparing them with an anatomical image of MRI , it was found that the particular area was located on the motor cortex along the central sulcus . By mapping the dynamic topograms of the changes of total-Hb , which reflect the cerebral blood volume , and analyzing the spatiotemporal hemodynamic changes associated with the brain activity , it was found that the regional change in cerebral blood volume in the primary motor area overlaps the global change around the motor cortex . These results demonstrate that NIR topography can be used to effectively observe the human brain activity Objectives . Neurobiologically , panic disorder ( PD ) is supposed to be characterised by cerebral hypofrontality . Via functional near-infrared spectroscopy ( fNIRS ) , we investigated whether prefrontal hypoactivity during cognitive tasks in PD- patients compared to healthy controls ( HC ) could be replicated . As intermittent theta burst stimulation ( iTBS ) modulates cortical activity , we furthermore investigated its ability to normalise prefrontal activation . Methods . Forty-four PD- patients , r and omised to sham or verum group , received 15 iTBS-sessions above the left dorsolateral prefrontal cortex ( DLPFC ) in addition to psychoeducation . Before first and after last iTBS-treatment , cortical activity during a  verbal fluency task  was assessed via fNIRS and compared to the results of 23 HC . Results . At baseline , PD- patients showed hypofrontality including the DLPFC , which differed significantly from activation patterns of HC . However , verum iTBS did not augment prefrontal fNIRS activation . Solely after sham iTBS , a significant increase of measured fNIRS activation in the left inferior frontal gyrus ( IFG ) during the phonological task was found . Conclusion . Our results support findings that PD is characterised by prefrontal hypoactivation during cognitive performance . However , verum iTBS as an “ add-on ” to psychoeducation did not augment prefrontal activity . Instead we only found increased fNIRS activation in the left IFG after sham iTBS application . Possible reasons including task-related psychophysiological arousal are discussed The hemodynamic response measured by Near Infrared Spectroscopy ( NIRS ) is temporally delayed from the onset of the underlying neural activity . As a consequence , NIRS based brain-computer-interfaces ( BCIs ) and neurofeedback learning systems , may have a latency of several seconds in responding to a change in participants ' behavioral or mental states , severely limiting the practical use of such systems . To explore the possibility of reducing this delay , we used a multivariate pattern classification technique ( linear support vector machine , SVM ) to decode the true behavioral state from the measured neural signal and systematic ally evaluated the performance of different feature spaces ( signal history , history gradient , oxygenated or deoxygenated hemoglobin signal and spatial pattern ) . We found that the latency to decode a change in behavioral state can be reduced by 50 % ( from 4.8 s to 2.4 s ) , which will enhance the feasibility of NIRS for real-time applications Near-infrared spectroscopy ( NIRS ) has been used to noninvasively monitor adult human brain function in a wide variety of tasks . While rough spatial correspondences with maps generated from functional magnetic resonance imaging ( fMRI ) have been found in such experiments , the amplitude correspondences between the two recording modalities have not been fully characterized . To do so , we simultaneously acquired NIRS and blood-oxygenation level-dependent ( BOLD ) fMRI data and compared Delta(1/BOLD ) ( approximately R(2 ) ( * ) ) to changes in oxyhemoglobin , deoxyhemoglobin , and total hemoglobin concentrations derived from the NIRS data from subjects performing a simple motor task . We expected the correlation with deoxyhemoglobin to be strongest , due to the causal relation between changes in deoxyhemoglobin concentrations and BOLD signal . Instead we found highly variable correlations , suggesting the need to account for individual subject differences in our NIRS calculations . We argue that the variability result ed from systematic errors associated with each of the signals , including : ( 1 ) partial volume errors due to focal concentration changes , ( 2 ) wavelength dependence of this partial volume effect , ( 3 ) tissue model errors , and ( 4 ) possible spatial incongruence between oxy- and deoxyhemoglobin concentration changes . After such effects were accounted for , strong correlations were found between fMRI changes and all optical measures , with oxyhemoglobin providing the strongest correlation . Importantly , this finding held even when including scalp , skull , and inactive brain tissue in the average BOLD signal . This may reflect , at least in part , the superior contrast-to-noise ratio for oxyhemoglobin relative to deoxyhemoglobin ( from optical measurements ) , rather than physiology related to BOLD signal interpretation Objective : To determine whether brain activity over the prefrontal cortex measured in real time during walking predicts falls in high-functioning older adults . Method : We examined166 older persons ( mean age 75 years , 51 % women ) enrolled in a prospect i ve aging study . High-functioning status defined as the absence of dementia or disability with normal gait diagnosed by study clinicians . The magnitude of task-related changes in oxygenated hemoglobin levels over the prefrontal cortex was measured with functional near-infrared spectroscopy during motor ( walking at normal pace ) and cognitive ( reciting alternate letters of the alphabet ) single tasks and a dual-task condition ( walking while reciting alternate letters of the alphabet ) . Incident falls were prospect ively assessed over a 50-month study period . Results : Over a mean follow-up of 33.9 ± 11.9 months , 116 falls occurred . Higher levels of prefrontal cortical activation during the dual-task walking condition predicted falls ( hazard ratio adjusted for age , sex , education , medical illnesses and general mental status 1.32 , 95 % confidence interval 1.03–1.70 ) . Neither behavioral outcomes ( velocity or letter rate ) on the dual task  nor brain activation patterns on the single tasks ( normal walk or talk alone ) predicted falls in this high-functioning sample . The results remained robust after accounting for multiple confounders and for cognitive status , slow gait , previous falls , and frailty . Conclusions : Prefrontal brain activity levels while performing a cognitively dem and ing walking condition predicted falls in high-functioning seniors . These findings implicate neurobiological processes early in the pathogenesis of falls BACKGROUND  Falls  are common and associated with reduced independence and mortality in Parkinson 's disease . Previous research has been conducted on falls-prevalent or advanced disease cohorts . OBJECTIVE This study identifies risk factors for first fall for 36 months in a newly diagnosed , falls-naïve cohort . METHODS A total of 121 consecutive Parkinson 's disease patients were recruited .  Falls data  were collected prospect ively during 36 months from diagnosis via monthly falls diaries and telephone follow-up  for 117 participants . Assessment comprised a comprehensive battery of clinical , gait , and cognitive measures . Significant predictors were identified from decision-tree analysis and survival analysis with time to first fall during 36 months as the dependent variable . FINDINGS At baseline , 26 ( 22 % ) participants reported retrospective falls . At 36 months , the remaining cohort ( n = 91 ) comprised 47 fallers ( 52 % ) and 30 ( 33 % ) nonfallers and 14 ( 15 % ) participants with incomplete diaries . Fallers presented with a significantly higher disease severity , poorer ability to st and on one leg , slower gait speed , increased stance time variability , and higher swing time asymmetry . Median time to first fall was 847 days . Gait speed , stance time , and Hoehn & Yahr III stage emerged as significant predictors of first fall , hazard ratio 3.44 ( 95 % confidence interval [ CI ] 1.58 
    Output:
    
Differences in fNIRS signals between studies were found in rest vs. walking , speed of walking , usual vs. complex walking and easy vs. difficult tasks .
In conclusion , there are considerable technical and method ological challenges in conducting fNIRS studies during walking which can introduce inconsistencies in study findings .