VSS 2012 Poster now online at F1000.com

A pdf of Jack's poster for VSS2012, Perceptual learning of bimanual coordinated rhythmic movements: Information matters more than movements, is now online at the open access repository F1000.com. Thanks to VSS for sponsoring this conference archive!

Society for Rehabilitation Research 2012

This month I presented a 'work in progress' poster at the SRR conference which was being held at the Leeds Met Rose Bowl conference centre. The experience was a great first 'conference' experience and a lot of interesting people were met. My poster was received with a lot of positive feedback from people in many different areas.

There were many interesting talks for delegates to attend including a discussion on translating academic rehabilitation research into clinical practice. All in all a very good day with a very good free lunch.

University of Leeds International PhD Scholarships

If you are a non-UK student interested in doing a PhD in perception and action, please feel free to contact me. The deadline is 4 July 2012.

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The University has launched a new scholarship for international PhD students. The scholarship will provide full international fees and a maintenance grant of £10,000 pa for three years. There will be up to 9 awards across the university and the deadline for applicants is 4 July 2012. Applicants must normally hold a First Degree at undergraduate level equivalent to at least a UK First Class Honours degree[1] and should be considered to be amongst the ‘best of the best’ (eg successful applicants are likely to be in the top 5% of their MSc/MA and BSc/BA cohorts and already in receipt of prizes and published papers at national or international level).  Applicants should either have graduated with the appropriate First Degree or be in their final year of study.

Applicants who have previously applied for a FIRS scholarship for Session 2012/13 (including those on the reserve list) are eligible to apply for LIRS in Session 2012/13 (provided they meet all other eligibility criteria).

• Applicants MUST first submit a research degree study application form and be in receipt of a University BANNER ID Number to be eligible for a Leeds International Research Scholarship.  Applications without a valid University ID Number will be rejected.  To apply for a place on a research degree programme, please visit: http://www.leeds.ac.uk/students/apply_research.htm
• These awards are only available to applicants who would be liable to pay academic fees at the full international fee rate;
• Applicants must normally hold a First Degree at undergraduate level equivalent to at least a UK First Class Honours degree  and should be considered to be amongst the ‘best of the best’ (eg successful applicants are likely to be in the top 5% of their MSc/MA and BSc/BA cohorts and already in receipt of prizes and published papers at national or international level).  Applicants should either have graduated with the appropriate First Degree or be in their final year of study; 
• Applicants whose first language is not English must have already met the University’s English Language requirements  by 4 July 2012 or be a current undergraduate student in their final year or a current postgraduate student at a University in an English speaking country.  Some Schools require a standard of English higher than the University minimum;
• Applicants must be commencing PhD research study at the University of Leeds for the first time in Session 2012/13;
• These awards are not open to individuals who have already been awarded a Doctoral degree or equivalent qualification;
• Applicants who have previously applied for a Fully-Funded International Research Scholarship (FIRS) for Session 2012/13 (including those currently on the reserve list) are eligible to apply for LIRS in Session 2012/13 (provided they meet all other eligibility criteria).
• LIRS scholarships should not normally be held concurrently with other Scholarships, although it may sometimes be possible for a LIRS award holder to hold another scholarship paying maintenance of no more than £3,590 a year in value.   Successful LIRS award holders may, if they are able to obtain additional funding, hold a bursary which pays travel/accommodation costs etc for UK/overseas fieldwork visits and attendance at conferences.

Application Process:

Application forms, regulations and guidance notes for completion of applications are available from the web address: http://www.leeds.ac.uk/rsa/postgraduate_scholarships/LIRS-AppForm12. Application forms are also available by email request (pg_scholarships@leeds.ac.uk).

Completed application forms should be returned to the Postgraduate Scholarships Office or by email to pg_scholarships@leeds.ac.uk by 4 July 2012 (midnight UK time).

Postgraduate Scholarships Office
Marjorie & Arnold Ziff Building
University of Leeds
Leeds LS2 9JT, UK
Tel: +44 113 3434007
Email: pg_scholarships@leeds.ac.uk
http://scholarships.leeds.ac.uk

VNS, Acetylcholine and Cortical Plasticity

Acetylcholine (ACh) is a neurotransmitter which was first identified by Henry Hallet Dale in 1914 who observed its interaction with heart tissue. This observation was confirmed by Otto Loewi who decided to call it 'Vagusstoff'. Why was it called this? Because it was found to be released by the vagus nerve.

They both won the 1936 nobel prize in Physiology/Medicine. Why is this important? Recently the vagus nerve has become the focus of a lot of neuroscience attention due to the effect of vagus nerve stimulation. Engineer et al (2011) and Engineer et al (2012) both demonstrated how vagus nerve stimulation can be used to condition the brain and by matching stimulation with stimuli, could effectively treat tinnitus. The research showed a remapping effect of auditory neurons. This was tested only in a mouse model but the results were so promising that a project replicating this is currently being recruited for, except to study this effect in humans.

Porter (2011) has demonstrated how matching vagus nerve stimulation with simple motor tasks allows for a remapping of the motor cortices of the mouse brain. The mechanism of action behind vagus nerve stimulation seems to be unknown.

Stimulation of the vagus nerve may release ACh into the cortex, as observed by Otto Loewi, which somehow causes a cortical plastic effect. Again though, we are faced with the question of How?

Well, ACh has long been linked to synaptic plasticity and acts either by:

Directly enhancing currents through NMDA receptors which have been associated with synaptic plasticity with specifics to memory and learning.

or

Indirectly suppressing adaptation; Neural adaptation, also known as 'up regulation' and 'down regulation' is the process whereby neurons stop firing as a result of constant stimulation allowing regulation to occur.

Along with these observed effects, ACh has been noted to effect heart rate which is something also noted in patients receiving vagus nerve stimulation.

It would definitely seem that rather looking at VNS and cortical plasticity...it's time to look at VNS, causing changes in ACh activity causing plasticity.

Guidance Hypothesis

There has been a lot of research looking at the effect that extrinsic feedback and excessive extrinsic feedback has on learning. Salmoni et al (1984) suggested the guidance hypothesis. This hypothesis suggests that even though recurrent feedback provided during practice is beneficial to the learner in order to choose the correct responses, it blocks the processing of other sources of important information that are essential in order to obtain an internal depiction of the movement task that is capable of generating the movement when the feedback is stopped. Faded schedule feedback was a type of feedback tested to see if this would reduce participant dependency on extrinsic feedback. Winstein et al (1990) performed a study which contained two groups. One group received extrinsic feedback for every trial, while the other group used a faded feedback schedule and had a reduced frequency of feedback (50% of the trials). The results showed that the faded feedback group were able to sustain performance during practice at the same level as the group who had feedback on every trial. However when no feedback tests were administered on both groups after 5 minutes and 24 hours, the faded feedback group performed significantly better. By using the faded feedback schedule, participants were able to reduce their dependency on the feedback which enhanced their capability to create the necessary movement pattern when the feedback was taken away. Other researchers have also performed experiments which have shown the beneficial effects that faded feedback can have (e.g. Lee et al 1990, Weeks et al 1993).

The guidance hypothesis therefore suggests that the faded feedback schedule should cause the participant to process other sources of intrinsic information that assists the progression of an internal depiction which is capable of supporting performance when feedback is taken away. If this hypothesis is true, participants should be able to decrease the time that is needed to develop an internal depiction of the task, from days to just minutes. This suggests a faster way of learning.

Kovacs, A. J., Buchanan, J. J., & Shea, C. H. (2009a). Bimanual 1:1 with 90° continuous phase

Kovac et al (2009a) performed a study looking at the effects of Lissajous feedback. 20 participants were asked to perform a 1:1 bimanual coordination task with a 90° relative phase. While doing this the participants received constant Lissajous feedback. This feedback was in the custom of a cursor signifying the joint position of the two limbs put over on a Lissajous template portraying the necessary phase relation between the limbs. When the left limb moved it moved the cursor vertically and when the right limb moved it moved the cursor horizontally. The results showed that the participants were reasonably effective in executing the coordination pattern that was required (variability and relative phase errors low), after only having 5 minutes of practice. When compared with results from participants who had many days of practice, the level of relative phase errors and variability was in fact lower. In this experiment an auditory metronome was not included and vision of the limbs was not allowed. When a metronome was introduced performance decreased as variability and relative phase errors increased considerably.

Other work by Kovac in 2009 (Kovac et al 2009b) showed that when participants are provided again with constant Lissajous feedback, they can successfully perform relative phases between 30° and 150° using only four minutes of practice at both separate relative phases. This and the study previously discussed, seems to suggest that Lissajous feedback inhibits a faster way of learning.

However a problem with the Kovac studies is that it was proved that participants became too heavily dependent on the Lissajous feedback. When the Lissajous feedback was removed performance decreased as there was higher relative phase error and variability. This outcome proposes that the Lissajous plot with cursor and template provided participants a platform by which they were able to notice their coordination mistakes and perform the required adjustments. This decrease in performance when the Lissajous feedback had been removed suggested that participants had not actually learnt the relative phase but instead had learned to use the constant information provided to perform the necessary coordination patterns. Participants had not developed an internal depiction of the task and therefore were reliant on the constant feedback and when that was removed they struggled with the task. This therefore suggests that constant feedback could indeed hinder learning.

tVNS, Caffeine & Motor Learning - Pilot Results

Vagus nerve stimulation has been shown to increase global neural plasticity in the cortex (Engineer et al, 2011). This type of neural plasticity can be used to facilitate changes in the cortex to treat neurological and psychological disorders (Sclaepfer et al, 2007; George et al, 2008; Uthman et al, 2004 & Bodenlos et al, 2007), and has also been shown to increase consolidation effects when used in learning tasks. These experiments used VNS over a period of weeks and months.

These studies all used iVNS which is a form of VNS which relies upon an implanted electrode. Kraus et al (2004) has showed successfully that tVNS, a method of VNS which utilises nerve fibre connections in the auricular canal and is a reliable method of stimulating the vagus nerve.

Caffeine is a heavily used stimulant which acts on the central nervous system by blocking adenosine receptors. This kind of stimulation has been investigated for the possibility of it having beneficial cognitive effects, specifically on memory and learning. The current research landscape of caffeine and it's effect on cognition is quite noisy. Angelucci et al (1999) has shown that caffeine differentially affects the different stages of memory processing and that its effect depends on the particularities of the task itself. Mednick et al (2008) has shown that motor skill learning is significantly decremented by the use of caffeine compared to a control group, however showed that perceptual learning was significantly increased compared to a control group. Tieges et al (2006) has shown that anticipatory processes are benefited by a caffeine supplement, which aids task switching.

In amongst all of this research lies the question still, can caffeine aid learning when it comes to a task that relies on perception and action. More specifically, the task of producing a 90 degree movement.

Participants were recruited through the use of recruitment posters. 2 male participants were recruited to the tVNS group and female 1 participant was recruited to the caffeine group. Control data was acquired from a previous study with the same design.

Participants took part in an experiment which assessed baseline ability at creating a 90 degree movement on day 1, training with either the stimulation or supplement took place on day 2, a post training assessment took place on day 3 and a retention assessment took place on day 10.

Initial results (see figure above) show that control data outperforms both the vagus nerve stimulation and caffeine group. The control group ability on creating a 90 degree movement increased by 0.32 between baseline and post training whilst the caffeine group increased by only 0.12 and the tVNS group increased by only 0.06. The results of this study show that a short training session on one day may not be enough to create a global plastic effect needed to facilitate learning and may actually inhibit learning to an extent.

After a discussion with both Andrew Wilson and Jim Deuchars on the experiment design and pilot data a decision has been made to move forward with a longer training schedule expanded over various days. Retention will also be assessed 7 days after post training assessment and again 14 days after post training assessment to investigate the consolidating effects of tVNS.

Learning a coordinated rhythmic movement with task-appropriate coordination feedback

Augmented feedback is crucial for learning in coordination tasks. This is because the inherent feedback is not often perceptually accessible if the rhythm is not 0° or 180° and must be learnt. It could be argued that some methods of augmented feedback used in learning 90° transform the task from a coordination one and so any data collected may not actually measure the learning of coordination. Therefore this paper looks at using a neutral colour cue as an augmented feedback technique so this does not occur. A green colour indicates to the participant that they are achieving the correct rhythm. This method has been developed because:
1. The relative motions involved are entirely independent of colour
2. Colour has no effect on movement stability in a coordinated rhythmic movement task
Therefore this method of feedback can drive learning without altering the informational content of the task - and it is more likely performance that the study is supposed to be measuring is actually being measured.

There were two groups:
1: 5 participants receiving the colour cue feedback
2: 5 participants receiving no feedback

The groups were balanced down to participants' baseline performance at 90°.

The neutral colour cue was successful when used as the augmented feedback system. Improvement only occured in the group that received the feedback - these participants significantly improved their ability to maintain a 90° rhythm. This did not generalise to 0° or 180° which are stable rhythms and so should not require feedback to achieve, further supporting the use of the neutral colour cue.

This study makes the point that the perception task should be the critically important component in learning the 90° rhythm. The colour cue feedback mechanism was developed in order to make this the case. Using this method, the information processed by the participant is not altered from being visual. This means that the results are more likely to be measuring learning coordination through visual perception rather than transforming the information available for learning to take place.

References  

WILSON, A. D., SNAPP-CHILDS, W., COATS, R. & BINGHAM, G. P. 2010. Learning a coordinated rhythmic movement with task-appropriate coordination feedback. Exp Brain Res, 205, 513-20.

Life in the Lab, 16th Feb 2012

Lots going on in the lab just now, and most of it seemed to cross my desk today.

Masters
1. Jack's having a lot of success recruiting older adults for his learning study. This was always going to be the tricky bit of his Master's and his recruitment plan is really paying off.

2. Dan's pilot data for the VNS study is rolling in; not sure what, if anything is going on yet but it's nice to see the numbers to start figuring it out!

Third year research project groups
3. Met with the throwing group to finally start organising data collection; we move the target into the gym tomorrow and do pilot data collection and testing on Monday.

4. The group looking at the timed up-and-go task in older adults are all ready to roll; I will have some analysed data for them tomorrow from the piloting and we're just waiting to hear back about participant recruitment.

5. The coordination group are collecting data on the unimanual learning study and the whacky perturbation study which just might be working.

I have a paper coming my way for final comments with some great older adult learning data, plus a transfer of learning data set from IU which will make a great complement to Jack's first study. I have one super secret plan ticking along nicely, and another one in the works; plus I'm this close to having time to write up the throwing data from last year.Our second lab meeting tomorrow, Laura from Sarah's lab will present some of her work with spinal cord patients.

In other project news, young Elliott is working on his prehension and is starting to get the hang of it!

Cortical excitability increases over time awake

Today I read an interesting article which will shed doubt on all of science. I read today that the cortex generally becomes more aroused as time awake increases. So, the longer you go without sleep the more excitable your brain is, especially the frontal cortex.

What does this mean for science? Well science is the collection of knowledge acquired in various ways, a lot of which comes from experiments involving human subjects. I would almost be willing to bet that 99% of experiments using human participants have worked around the participants schedule and recruited them whenever. So for example, participant A in group A was tested at 7am (awake for 2/3 hours maybe?) and participant B in group B was tested at 4pm (awake for 8/9 hours maybe?).

Why does cortical excitability cause problems? Well, the longer you stay awake the more likely you are to have hallucinations and staying awake for a long time also reduces depressive symptoms. These signs show that the brain undergoes changes the longer you are awake. So the brain of participant A and participant B are naturally different due to different levels of being awake.

Should sleep wake cycle become a demographic question used when recruiting? Probably yes - Will it? Probably not. Why not? well if we researchers worked around our own schedule we would never have volunteers. The best we can do is try to balance groups in the same way we would balance baseline ability. Try.

But yes, this does make me wonder about science as a whole - how many imaging studies have taken data from a large sample without considering this new and scary fact? (maybe in the same way they didn’t look at caffeine baseline? - that’s a whole other kettle though).

Source: http://cercor.oxfordjournals.org/content/early/2012/02/07/cercor.bhs014

Determining Centre of Mass

As part of the 'timed up and go' test participants will have a marker attached to their centre of mass in order to collect data on factors such as jerk and postural sway. The centre of mass is described as a balance point of an object (Gambino et al, 2006). However before we can do this we need to determine where abouts on the body the centre of mass will be. According to Gambino et al (2006) a person's centre of mass is just below the belly button, which is nearly the geometric centre of a person. In a trial run of our experiment we were placing the marker slightly above the participant's belly button so it is possible that the data we collected maybe be inaccurate as this could have been the wrong positioning for their centre of mass.

Gambino et al (2006) concluded that a female's centre of mass is slightly lower than a males centre of mass. Unfortunately we would not be able to perform the test they did to collect these results as we are working with the frail elderly. The test they completed involved lying on beams in order to record the weight and height of each participant. There is the possibility of an injury and this involves the use of a large amount of equipment.

According to McGinnis (2005) a person's centre of mass is estimated at between 55 and 57% of their height in the anatomical position. Similarly, McGinnis (2005) identifies that a females centre of mass will be slightly lower than a males centre of mass as a result of larger pelvic girdles and narrower shoulders. This way of calculating the centre of mass would be easier to carry out as it requires little of the participants and only a small amount of equipment. If the measurements are not carried out then at least we now have a better understanding of where the centre of mass is on the human body.

References

Gambino,S, Mirochnik, M and Schechter S. (2006) The Physics Factbook.
McGinnis, P.M. (2005) Biomechanics of sport and exercise. Human Kinetics. pp 133.

The influence of augmented feedback and prior learning on the acquisition of a new bimanual coordination pattern

This paper focuses on the affects of two variables when learning a new bimanual coordination pattern; previous experiences and augmented feedback techniques. The main aim of this study is to acquire the new coordination pattern 135˚ relative phase.

Two different types of augmented feedback were compared, visual pursuit tracking and terminal feedback. Terminal augmented feedback consists of a static target lissajous figure combined with actual movement after each trial. Pursuit tracking consists of a static trace of the target lissajous, a dynamic trace of the learner’s movement during the trials and a target moving around the lissajous figure in time with the auditory metronome of 1Hz.


Participants practiced either 90˚ or 135˚ relative phase in two learning sessions and were randomly assigned to a group:

Sessions one and two:
Group 1 – practiced 90˚ relative phase with pursuit tracking
Group 2 – practiced 135˚ relative phase with pursuit tracking
Group 3 – practiced 90˚ relative phase with terminal feedback
Group 4 – practiced 135˚ relative phase with terminal feedback

In session three all four groups performed 30 trials of 135˚ lasting 20 seconds using the same feedback as in previous sessions.

Participants grasped two linear sliding devices parallel to the table and displacements were calculated. Two monitors were used to display the feedback depending on which group you were in.


Generally speaking when trying to perform a novel task most people are biased towards anti phase 180˚. In this case the groups that practiced the 90˚ pattern performed the transfer 135˚ pattern more poorly and were strongly biased towards the newly learned 90˚ pattern. During transfer the pursuit tracking groups performed with a higher mean relative phase (129.6) than the terminal feedback groups (114.9). Following two sessions of practice 90˚ pattern, performance of the transfer pattern was facilitated by pursuit tracking to a much greater extent than terminal feedback. It was suggested that pursuit tracking feedback encouraged the learner to focus on matching the lissajous figures rather than their moving limbs. This supports Wulf and Prinz (2001) who stated that performance and learning benefits if the learner focuses on the environmental effects rather than the movement itself.


WULF, G., & W. PRINZ. 2001. Directing attention to movement effects enhances learning: A review. Psychonomic bulletin & review. 8, pp. 648-660.

HURLEY, S.R., & T.D. LEE. 2006. The influence of augmented feedback and prior learning on the acquisition of a new bimanual coordination pattern. Human movement science. 25, pp.339-348.

Pilot data collection, TUG

For the "up and go" research into older adults, this week some preliminary data was colleceted on a group of 6 university students aged between 20-21. The pilot data was run to check that the set up of the experiment were suitable for the results to be obtained, to see any potential problems that could arise during the actual data collection, and to gather any feedback from the participants. The test was set up as it will be on the day; a line with a lentgh of 3 metres was set out, with a marker as an indicator of where to walk to at one end, and a chair at the other. The markers that collect the data were also set up appropriately, at 50cm from the ctart of the course, and 50cm from the end of the course, to detect what was happening in each segment of the walk. The participants also have a marker attatched to the using a velcro belt, which is place in the approxiate area of their centre of mass. The data was recorded using a programme specifically designed for this experiment, and the data collected was sent straight to a loptop where results can be formatted and analysed.
The participants were all walked through the test, and then given a chance for a practice run. Each participant did 3 runs of 4 different tests. The first was to get up from a sitting position, walk to the marker, turn, walk back to the chair and sit - they then had to repeat this for the second test, but had to do so whilst holding a glass of water. The third condition was to get up from the chair, walk to the marker, which was now covered by an obstacle, walk around that, walk back to the chair and sit back down. The fourth coniditon was the same yet holding a glass of water.
Some of the issues that became apparant during the test were:

1) people adopted different positions when sitting in the chair prior to starting the test, e.g. crossing their legs leaving only one foot on the ground.

2) People talking throughout the test lead them to turn to the person they were having a conversation with, which could effect the way the data is read from the marker.

3) At times, the marker became loose, and detatched from the belt.

4) They completed 12 different trials per person, and whilst it was no problem for them, for
a frail, elderly adult, this could be exhausting.

5) In the feedback, one participant felt the test was 'degrading' due to being attatched to a wire.

All of these issues need to be resolved to the best they can be, without affecting the results of the data collection or inhibiting the findings of the research.

VSS abstract accepted

Congratulations to Jack for getting his poster accepted at this year's Annual Meeting of the Vision Sciences Society in Naples, FL, May 11-16.

Abstract

Perceptual learning of bimanual coordinated rhythmic movements: Information matters more than movements

Jack Leech & Andrew D. Wilson

Prior to training, only two coordinated rhythmic movements are stable: 0° and 180°. Other coordinations (e.g. 90°) must be learned. This pattern emerges from a task dynamic in which relative phase is perceived as the relative direction of motion, modified by the relative speed (Bingham, 2004). People can learn how to move at 90° but this entails learning to use a different information variable (relative position; Wilson & Bingham, 2008). Learning a novel coordination requires feedback; typically this feedback is presented in the form of a transformed display such as a Lissajous plot. This display removes relative direction as a source of information about relative phase, and as a result allows people to move at any required coordination with a minimum of practice – all coordinations become equally easy.  Wilson et al (2010) developed a second form of feedback, coordination feedback, which also drives learning but without altering the information available for relative phase. This study directly compared the two feedback methods. 12 subjects (aged 18-27, M=21) learned to move bimanually at 90° using either Lissajous (N=6) or coordination (N=6) feedback. We tested coordination stability with both displays in baseline, post training and retention sessions, with baseline and post training separated by 5 training sessions. Results indicated that both feedback methods are valid methods that facilitate learning. However there was no transfer of this learning between the feedback methods, confirming that the feedback methods provide different perceptual information and that perceptual learning underpins the improvements in movement stability. The two feedback methods create fundamentally different task dynamics that are informationally distinct from one another, and must be treated as such.

Newton International Fellowships

If you are looking for a post-doc opportunity in the UK, and are trained in perception, action or embodied cognition type research, then this is an excellent funding stream and I would be very interested in hearing from you to come and work in my lab. Please feel free to contact me if interested, and spread the word to other interested parties!

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A new round of Newton International Fellowships - an initiative to fund research collaborations and improve links between UK and overseas researchers - has now opened.

The Newton International Fellowships are funded by the British Academy and the Royal Society and aim to attract the most promising early-career post-doctoral researchers from overseas in the fields of the humanities, the natural, physical and social sciences. The Fellowships enable researchers to work for two years at a UK research institution with the aim of fostering long-term international collaborations.

Newton Fellows will receive an allowance of £24,000 to cover subsistence and up to £8,000 to cover research expenses in each year of the Fellowship. A one-off relocation allowance of up to £2,000 is also available.

In addition, Newton Fellows may be eligible for follow-up funding of up to £6,000 per annum for up to 10 years following completion of the Fellowship to support activities which will help build long term links with the UK.

The scheme is open to post-doctoral (and equivalent) early-career researchers working outside the UK who do not hold UK citizenship.

Applications are to be made via the Royal Society’s online application system which is available at https://e-gap.royalsociety.org/ The closing date for applications is Monday 16 April 2012.

Further details are available from the Newton International Fellowships website: www.newtonfellowships.org

Caffeine as an fMRI booster

fMRI relies on oxygenated changes in the blood which are a result of blood flow and/or blood volume in the body and brain. Caffeine apparently acts as a cerebral vasoconstrictor and has positive effects on the quality of data gained from fMRI studies. This is accomplished by decreasing the baseline BOLD signal (blood oxygen level dependent) which then creates a greater percent change when a task is completed.

This plus side of this interesting find is that it will increase the detection of activation in the brain whilst investigating models or paradigms.

The figure above shows fMRI data from a participant who performed a task before having caffeine exposure and then again after. The top row of data is prior and the bottom is post. As you can see, due to the lower baseline, there was a greater percent change in the participant post caffeine which shows us greater activation.It is important to note here that the same statistical model and analysis was used for both.

This method is great but probably only if it is done along side non-caffeinated imaging studies. This would be because doing it on it's own runs the risk of showing us activated areas which are irrelevant.

However it does have the possibility to increase the sensitivity of our imaging studies without the need for expensive machinery or complex statistical models.

This then poses a more interesting question of; Are any fMRI studies investigating caffeine accurate?

If caffeine lowers the baseline BOLD signal and thus increases the percent change of blood flow when neural activation is observed - are any results accurate?

I suppose this poses a rather phenomenological question of what is really being observed - since the signal change is the natural effect caffeine has on the human brain then you could argue that yes it is. On the other hand you could see that the results of any caffeine fMRI study to be "extreme" as a result of the signal change and should be analysed with care. The obvious way around this is to give participants caffeine supplements after testing the baseline after all, the baseline should be as neutral as possible.

But then again, have you ever tried to have a drink whilst laying down in an fMRI machine? I would imagine it's rather difficult.

Full Text : http://www.radiology.northwestern.edu/research/brain/neuroimaging/using-caffeine-as-a-contrast-booster-in-fmri

This then lead me to think about the effects of caffeine on other forms of imaging tools - with a focus on EEG. Since EEG relies on the neural activation of observed regions of the outer cortex it could also be affected by caffeine.