Browsing by Author "Hämäläinen, Heikki"
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- Item902 MHz mobile phone does not affect short term memory in humans.(2004-08-09) Haarala, Christian; Ek, Maria; Björnberg, Linda; Laine, Matti; Revonsuo, Antti; Koivisto, Mika; Hämäläinen, HeikkiWe studied the effects of an electromagnetic field EMF as emitted by a 902 MHz mobile phone on human short term memory This study was a replication with methodological improvements to our previous study The improvements included multi centre testing and a double blind design A total of 64 subjects 32 men in two independent laboratories performed a short term memory task n back which poses a varying memory load 0 3 items on the subjects memory They performed the task twice once each under EMF and sham exposure Reaction times RTs and accuracy of the responses were recorded The order of exposure and memory load conditions were counterbalanced across subjects and gender There were no statistically significant differences in performance between the two laboratories We could not replicate our previous results the EMF had no effect on RTs or on the accuracy of the subjects answers The inability to replicate previous findings could have been caused by lack of actual EMF effects or the magnitude of effects being at the sensitivity threshold of the test used
- ItemEffect of a 902 MHz electromagnetic field emitted by mobile phones on human cognitive function: A replication study.(2003-04-15) Haarala, Christian; Björnberg, Linda; Ek, Maria; Laine, Matti; Revonsuo, Antti; Koivisto, Mika; Hämäläinen, HeikkiOur study was a replication and extension with methodological improvements to a previous study on effects of the electromagnetic field EMF emitted by a 902 MHz mobile phone on human cognitive functioning Improvements on the previous study included multicentre testing and a double blind design A total of 64 subjects 32 men and 32 women in two independent laboratories performed a battery of 9 cognitive tasks twice while the EMF was on and while it was off Reaction times RTs and accuracy were recorded The order of exposure and tasks was counterbalanced across subjects and gender There were no statistically significant differences in performance between genders or laboratories Although the RTs and the accuracy of answers were very similar to those of our previous study our previous results were not replicated We concluded that EMF had no effect on RTs or on the accuracy of the subjects answers Further our results indicate that our EMF had no immediate effect on human cognitive functioning or that such effects are so small that they are observed on behavior only occasionally
- ItemEffects of a 902 MHz mobile phone on cerebral blood flow in humans: a PET study.(2003-11-05) Haarala, Christian; Aalto, Sargo; Hautzel, Hubertus; Julkunen, Laura; Rinne, Juha O; Laine, Matti; Krause, Bernd; Hämäläinen, HeikkiFourteen healthy right handed subjects were scanned using PET with a 15O water tracer during exposure to electromagnetic field EMF emitted by a mobile phone and a sham exposure under double blind conditions During scanning the subjects performed a visual working memory task Exposure to an active mobile phone produced a relative decrease in regional cerebral blood flow rCBF bilaterally in the auditory cortex but no rCBF changes were observed in the area of maximum EMF It is possible that these remote findings were caused by the EMF emitted by the active mobile phone A more likely interpretation of the present findings were a result of an auditory signal from the active mobile phone Therefore it is not reasoned to attribute this finding to the EMF emitted by the phone Further study on human rCBF during exposure to EMF of a mobile phone is needed
- ItemEffects of electromagnetic field emitted by cellular phones on the EEG during an auditory memory task: a double blind replication study.(2003-12-29) Krause, Christina M; Haarala, Christian; Sillanmäki, Lauri; Koivisto, Mika; Alanko, Katarina; Revonsuo, Antti; Laine, Matti; Hämäläinen, HeikkiThe effects of electromagnetic fields EMF emitted by cellular phones on the event related desynchronization synchronization ERD ERS of the 4 6 6 8 8 10 and 10 12 Hz electroencephalogram EEG frequency bands were studied in 24 normal subjects performing an auditory memory task This study was a systematic replication of our previous work In the present double blind study all subjects performed the memory task both with and without exposure to a digital 902 MHz field in a counterbalanced order We were not able to replicate the findings from our earlier study All eight of the significant changes in our earlier study were not significant in the present double blind replication Also the effect of EMF on the number of incorrect answers in the memory task was inconsistent We previously reported no significant effect of EMF exposure on the number of incorrect answers in the memory task but a significant increase in errors was observed in the present study We conclude that EMF effects on the EEG and on the performance on memory tasks may be variable and not easily replicable for unknown reasons
- ItemEffects of mobile phone electromagnetic fields: critical evaluation of behavioral and neurophysiological studies.(2011-03-31) Kwon, Myoung Soo; Hämäläinen, HeikkiFor the last two decades a large number of studies have investigated the effects of mobile phone radiation on the human brain and cognition using behavioral or neurophysiological measurements This review evaluated previous findings with respect to study design and data analysis Provocation studies found no evidence of subjective symptoms attributed to mobile phone radiation suggesting psychological reasons for inducing such symptoms in hypersensitive people Behavioral studies previously reported improved cognitive performance under exposure but it was likely to have occurred by chance due to multiple comparisons Recent behavioral studies and replication studies with more conservative statistics found no significant effects compared with original studies Neurophysiological studies found no significant effects on cochlear and brainstem auditory processing but only inconsistent results on spontaneous and evoked brain electrical activity The inconsistent findings suggest possible false positives due to multiple comparisons and thus replication is needed Other approaches such as brain hemodynamic response measurements are promising but the findings are few and not yet conclusive Rigorous study design and data analysis considering multiple comparisons and effect size are required to reduce controversy in this important field of research
- ItemEffects of pulsed and continuous wave 902 MHz mobile phone exposure on brain oscillatory activity during cognitive processing.(2007-04-30) Krause, Christina M; Pesonen, Mirka; Haarala Björnberg, Christian; Hämäläinen, HeikkiThe aim of the current double blind studies was to partially replicate the studies by Krause et al 2000ab 2004 and to further investigate the possible effects of electromagnetic fields EMF emitted by mobile phones MP on the event related desynchronisation synchronisation ERD ERS EEG electroencephalogram responses during cognitive processing Two groups both consisting of 36 male participants were recruited One group performed an auditory memory task and the other performed a visual working memory task in six exposure conditions SHAM no EMF CW continuous wave EMF and PM pulse modulated EMF during both left and right side exposure while the EEG was recorded In line with our previous studies we observed that the exposure to EMF had modest effects on brain oscillatory responses in the alpha frequency range approximately 8 12 Hz and had no effects on the behavioural measures The effects on the EEG were however varying unsystematic and inconsistent with previous reports We conclude that the effects of EMF on brain oscillatory responses may be subtle variable and difficult to replicate for unknown reasons
- ItemElectromagnetic field emitted by 902 MHz mobile phones shows no effects on children's cognitive function.(2005-10-18) Haarala, Christian; Bergman, Monica; Laine, Matti; Revonsuo, Antti; Koivisto, Mika; Hämäläinen, HeikkiThe present study investigated the potential effects of a standard 902 MHz global system for mobile communication GSM mobile phone on 10 14 years old children s cognitive function A total of 32 children 16 boys 16 girls participated with their own and parental consent The subjects were 10 14 years old mean 12 1 years SD 1 1 They performed a battery of cognitive tests twice in a counter balanced order once while exposed to an active mobile phone and once during exposure to an inactive phone The tests were selected from those we used earlier with adults The statistical analyses showed no significant differences between the mobile phone off and on conditions in reaction times and accuracy over all tests or in any single test It was concluded that a standard mobile phone has no effect on children s cognitive function as measured by response speed and accuracy The present results challenge some earlier findings suggesting that the electromagnetic field EMF created by an active mobile phone would facilitate cognitive functioning
- ItemGSM mobile phone radiation suppresses brain glucose metabolism.(2011-12-01) Kwon, Myoung Soo; Vorobyev, Victor; Kännälä, Sami; Laine, Matti; Rinne, Juha O; Toivonen, Tommi; Johansson, Jarkko; Teräs, Mika; Lindholm, Harri; Alanko, Tommi; Hämäläinen, HeikkiWe investigated the effects of mobile phone radiation on cerebral glucose metabolism using high resolution positron emission tomography PET with the 18 F deoxyglucose FDG tracer A long half life 109 minutes of the 18 F isotope allowed a long natural exposure condition outside the PET scanner Thirteen young right handed male subjects were exposed to a pulse modulated 902 4 MHz Global System for Mobile Communications signal for 33 minutes while performing a simple visual vigilance task Temperature was also measured in the head region forehead eyes cheeks ear canals during exposure 18 F deoxyglucose PET images acquired after the exposure showed that relative cerebral metabolic rate of glucose was significantly reduced in the temporoparietal junction and anterior temporal lobe of the right hemisphere ipsilateral to the exposure Temperature rise was also observed on the exposed side of the head but the magnitude was very small The exposure did not affect task performance reaction time error rate Our results show that short term mobile phone exposure can locally suppress brain energy metabolism in humans
- ItemMobile phone affects cerebral blood flow in humans.(2006-06-22) Aalto, Sargo; Haarala, Christian; Brück, Anna; Sipilä, Hannu; Hämäläinen, Heikki; Rinne, Juha OMobile phones create a radio frequency electromagnetic field EMF around them when in use the effects of which on brain physiology in humans are not well known We studied the effects of a commercial mobile phone on regional cerebral blood flow rCBF in healthy humans using positron emission tomography PET imaging Positron emission tomography data was acquired using a double blind counterbalanced study design with 12 male subjects performing a computer controlled verbal working memory task letter 1 back Explorative and objective voxel based statistical analysis revealed that a mobile phone in operation induces a local decrease in rCBF beneath the antenna in the inferior temporal cortex and an increase more distantly in the prefrontal cortex Our results provide the first evidence suggesting that the EMF emitted by a commercial mobile phone affects rCBF in humans These results are consistent with the postulation that EMF induces changes in neuronal activity
- ItemMobile phone effects on children's event-related oscillatory EEG during an auditory memory task.(2006-07-18) Krause, Christina M; Björnberg, Christian Haarala; Pesonen, Mirka; Hulten, Annika; Liesivuori, Tiia; Koivisto, Mika; Revonsuo, Antti; Laine, Matti; Hämäläinen, HeikkiTo assess the effects of electromagnetic fields EMF emitted by mobile phones MP on the 1 20 Hz event related brain oscillatory EEG electroencephalogram responses in children performing an auditory memory task encoding and recognition
- Item[Mobile phones radiate--risk to the health?].(2011-10-14) Jokela, Kari; Auvinen, Anssi; Hämäläinen, HeikkiThe mobile phones radiate electromagnetic energy which is partly absorbed into the tissues in the vicinity of the phone The minor heating in maximum up to 0 3 degrees C may cause some alterations in the expression of genes and proteins similar to physiological response to other stimuli Biophysical studies at the cellular and molecular level have not revealed any well established interaction mechanism through which mobile phone radiation could induce toxic effects below the thermal effect level Research results on various biological effects in vitro and in vivo are continuously published but there is no consistent evidence on well established harmful effects The mobile phone radiation is not carcinogenic for experimental animals or genotoxic for cells According to epidemiological studies and psychophysiological brain function studies the use of mobile phones does not seem to increase the risk of tumors in the head and brain or disturb the function of central nervous system However there is a need for more research on the long term effects of mobile phone radiation particularly on children
- ItemNo effects of mobile phone electromagnetic field on auditory brainstem response.(2009-12-22) Kwon, Myoung-Soo; Jääskeläinen, Satu K; Toivo, Tim; Hämäläinen, HeikkiThe present study investigated the possible effects of the electromagnetic field EMF emitted by an ordinary GSM mobile phone 902 4 MHz pulsed at 217 Hz on brainstem auditory processing Auditory brainstem responses ABR were recorded in 17 healthy young adults without a mobile phone at baseline and then with a mobile phone on the ear under EMF off and EMF on conditions The amplitudes latencies and interwave intervals of the main ABR components waves I III V were compared among the three conditions ABR waveforms showed no significant differences due to exposure suggesting that short term exposure to mobile phone EMF did not affect the transmission of sensory stimuli from the cochlea up to the midbrain along the auditory nerve and brainstem auditory pathways
- ItemNo effects of mobile phone use on cortical auditory change-detection in children: an ERP study.(2010-03-15) Kwon, Myoung Soo; Huotilainen, Minna; Shestakova, Anna; Kujala, Teija; Näätänen, Risto; Hämäläinen, HeikkiWe investigated the effect of mobile phone use on the auditory sensory memory in children Auditory event related potentials ERPs P1 N2 mismatch negativity MMN and P3a were recorded from 17 children aged 11 12 years in the recently developed multi feature paradigm This paradigm allows one to determine the neural change detection profile consisting of several different types of acoustic changes During the recording an ordinary GSM Global System for Mobile Communications mobile phone emitting 902 MHz pulsed at 217 Hz electromagnetic field EMF was placed on the ear over the left or right temporal area SAR 1g 1 14 W kg SAR 10g 0 82 W kg peak value 1 21 W kg The EMF was either on or off in a single blind manner We found that a short exposure two 6 min blocks for each side to mobile phone EMF has no statistically significant effects on the neural change detection profile measured with the MMN Furthermore the multi feature paradigm was shown to be well suited for studies of perception accuracy and sensory memory in children However it should be noted that the present study only had sufficient statistical power to detect a large effect size
- ItemNo effects of short-term GSM mobile phone radiation on cerebral blood flow measured using positron emission tomography.(2012-03-05) Kwon, Myoung Soo; Vorobyev, Victor; Kännälä, Sami; Laine, Matti; Rinne, Juha O; Toivonen, Tommi; Johansson, Jarkko; Teräs, Mika; Joutsa, Juho; Tuominen, Lauri; Lindholm, Harri; Alanko, Tommi; Hämäläinen, HeikkiThe present study investigated the effects of 902 4 MHz global system for mobile communications GSM mobile phone radiation on cerebral blood flow using positron emission tomography PET with the 15 O water tracer Fifteen young healthy right handed male subjects were exposed to phone radiation from three different locations left ear right ear forehead and to sham exposure to test for possible exposure effects on brain regions close to the exposure source Whole brain O H O PET images were acquired 12 times 3 for each condition in a counterbalanced order Subjects were exposed for 5 min in each scan while performing a simple visual vigilance task Temperature was also measured in the head region forehead eyes cheeks ear canals during exposure The exposure induced a slight temperature rise in the ear canals but did not affect brain hemodynamics and task performance The results provided no evidence for acute effects of short term mobile phone radiation on cerebral blood flow
- ItemPerception of the electromagnetic field emitted by a mobile phone.(2008-01-14) Kwon, Myoung Soo; Koivisto, Mika; Laine, Matti; Hämäläinen, HeikkiElectromagnetic sensibility refers to the ability to perceive the electromagnetic field EMF without necessarily developing health symptoms attributed to EMF exposure A large sample of young healthy adults n 84 performed two forced choice tasks on the perception of the GSM mobile phone EMF 902 MHz pulsed at 217 Hz Was the field on and Did the field change 3 conditions x 100 trials for each task n 600 trials in total A monetary prize was announced for good performance correct response rate or 75 n 600 trials The performance was no better than expected by chance and thus none of the participants won the prize Two participants showed extraordinary performance in one of the task conditions Was the field on n 100 trials with correct response rates of 97 P 1 28 x 10 25 and 94 P 9 40 x 10 22 but they failed to replicate the result in the retest of six blocks of the same condition 1 month later Six participants had reported being able to perceive the mobile phone EMF in the preliminary inquiry but they performed no better than the others This study provides empirical evidence against the existence of electromagnetic sensibility to the mobile phone EMF demonstrating the necessity for replication in EMF studies
- ItemPreattentive auditory information processing under exposure to the 902 MHz GSM mobile phone electromagnetic field: a mismatch negativity (MMN) study.(2009-03-02) Kwon, Myoung Soo; Kujala, Teija; Huotilainen, Minna; Shestakova, Anna; Näätänen, Risto; Hämäläinen, HeikkiPrevious studies on the effects of the mobile phone electromagnetic field EMF on various event related potential ERP components have yielded inconsistent and even contradictory results and often failed in replication The mismatch negativity MMN is an auditory ERP component elicited by infrequent deviant stimuli differing in some physical features from the repetitive frequent standard stimuli in a sound sequence The MMN provides a sensitive measure for cortical auditory stimulus feature discrimination regardless of attention and other contaminating factors In this study MMN responses to duration intensity frequency and gap changes were recorded in healthy young adults n 17 using a multifeature paradigm including several types of auditory change in the same stimulus sequence while a GSM mobile phone was placed on either ear with the EMF 902 MHz pulsed at 217 Hz SAR 1g 1 14 W kg SAR 10g 0 82 W kg peak value 1 21 W kg measured with an SAM phantom on or off An MMN was elicited by all deviant types while its amplitude and latency showed no significant differences due to EMF exposure for any deviant types In the present study we found no conclusive evidence that acute exposure to GSM mobile phone EMF affects cortical auditory change detection processing reflected by the MMN
- ItemPulsed and continuous wave mobile phone exposure over left versus right hemisphere: effects on human cognitive function.(2007-04-30) Haarala, Christian; Takio, Fiia; Rintee, Taija; Laine, Matti; Koivisto, Mika; Revonsuo, Antti; Hämäläinen, HeikkiThe possible effects of continuous wave CW and pulse modulated PM electromagnetic field EMF on human cognition was studied in 36 healthy male subjects They performed cognitive tasks while exposed to CW PM and sham EMF The subjects performed the same tasks twice during each session once with left sided and once with right sided exposure The EMF conditions were spread across three testing sessions each session separated by 1 week The exposed hemisphere EMF condition and test order were counterbalanced over all subjects We employed a double blind design both the subject and the experimenter were unaware of the EMF condition The EMF was created with a signal generator connected via amplifier to a dummy phone antenna creating a power output distribution similar to the original commercial mobile phone The EMF had either a continuous power output of 0 25 W CW or pulsed power output with a mean of 0 25 W An additional control group of 16 healthy male volunteers performed the same tasks without any exposure equipment to see if mere presence of the equipment could have affected the subjects performance No effects were found between the different EMF conditions separate hemisphere exposures or between the control and experimental group In conclusion the current results indicate that normal mobile phones have no discernible effect on human cognitive function as measured by behavioral tests