Functional MRI in cluttering and stuttering

There is now a considerable data base of knowledge on brain functioning in
stuttering (See Guitar, 2006; Ward, 2006 for recent reviews). Recent fMRI
research (Viswanath et al., 2003) showed increased BOLD activity in persons
who stutter during reading in motor centres in the nondominant hemisphere.
These results were confirmed by several other researchers (Fox, 1996; Fox,
2000; Ingham, 2000; Neumann et al., 2003; Preibisch et al, 2003). Viswanath, et
al (2003) also observed reduced activity in the gyrus precentralis (both R and
L) and gyrus post centralis (left hemisphere) in word reading of PWS. Neumann
et al., (2003) and Preibisch et al., (2003) observed overactivation in right
side precentral sensorimotor and frontal regions amongst those who stuttered
during reading amongst 9 right-handed adults who stuttered. While a number of
studies implicate the anomalous cortical processing of motor speech activity,
Ingham et al. (2000) found evidence that motor speech centres are affected even
during imaginary stuttering (Ward, 2006, p.32).
In contrast to this literature, there are only a few imaging studies in which
participants were differentiated as either PWS or PWCS. Significantly, there
have been no published studies on brain functioning during speech tasks which
compare those with pure cluttering, pure stuttering and control speakers. In
order to examine the possibility that cluttering and stuttering are underpinned
by differing neurologic processes, brain scan research which examines only pure
stuttering and pure cluttering is essential.
It is hypothesized that pure cluttering and pure stuttering are two fluency
disorders with different pathogenesis in which cluttering is affected by a
disorder in serial (cascading) speech planning, in which previous planned
syllable strings are interfering with later planned syllables, leading to non
stutter like disfluencies. Alm (2006) refers to this as a disorder of the *stop-
signal* in motor execution, in cluttering. Stuttering can be seen as a disorder
in the *go-signal* of motor execution. In pure stuttering speech planning is
affected by a disorder of starting motor execution of already planned
syllables, leading to stutter like disfluencies.

Aim of the study
The purpose of this study is to study potential differences in brain activity
involved in motor control and coordination (motor cortex, Supplementary Motor
Area, medial cerebellum) as well as language areas (Broca, Wernicke) during the
performance of a range of spoken tasks (increasing in motor complexity) in PWC
compared to PWS in order to discuss neurolinguistic processes that underly
these fluency disorders.

In a observational design we specifically wish to examine whether (1) the
speech planning problems of individuals that clutter are a sign of different
problems in motor execution (2) the problems in speech production of PWC
reflect effects of a decreased attention to motor speech planning? (3) the
activity level of brain areas responsible for language planning are different
in PWC compared to PWS?
Because it has been suggested that both motor and linguistic processes may
underlie cluttering (Ward, 2006) a dynamical paradigm with both motor speech
and language components was selected. To filter the activity of the visual
cortex the speech motor and language paradigm was mirrored by a visual
paradigm. Using a block design, subjects undertake three experiments with
speech tasks or reading strings of signs. fMRI recordings started with
recordings of rest, followed by recordings of experiment (reading signs), rest,
experiment (pronouncing words) and concluded with rest. Within each experiment,
four recordings were made in a shuffled order. All the words and sign strings
were presented in the MRI-scanner using *Presentation* and mirrors on a big
screen. Presentation produced pulses from external devices through the port
device and made start of stimulus sequences on specific pulse/scan possible.
Participants are trained to speak with minimum tongue, jaw and lip
movement and without voicing. Possible artifactual effects because of this are
supposed to be equal for all participants. Subjects are also trained to repeat
the target words they saw on the screen at their fasts rate after the target
was shown till the next target was on the screen. This will be exercised and
trained before the subjects are placed inside the magnet. They are asked to
speak as fast as they could, while still remaining intelligible.
Issues concerning noise, movement, breathing and swallowing were
addressed prior to the scanning procedure. Headphones were worn to protect
against scanner noise, and subjects also wore a plastic stabilizing helmet in
order to minimize artifacts due to head movement.

Participants experience few direct advantage of participation. Knowledge on the
pathogenesis of cluttering and stuttering can result in better designed
treatment protocols based on differential diagnostic criteria. This can be cost
diminishing for speech language therapy to fluency disorders around the world.
Participation in a fMRI study is considered to be without risks for
participants when safety procedures are followed.
Participation takes a time investment of 45 minuten added with travel time.