Response Preparation Deficits in Parkinsons Disease

1
Response Preparation Deficits in Parkinsons
Disease Kristie A. Spencer Emily
Blond University of Washington
Speech Reaction Time
Manual Reaction Time (Cognitive Task)
EVIDENCE OF SPEECH PROGRAMMING DEFICITS? Key to
tables below
There is growing support for a disruption of
response preparation in people with Parkinsons
disease (PD) that is distinct from a disruption
of response execution (Hocherman et al., 2004,
Low et al., 2002). Two themes have emerged
regarding the nature of the response preparation
difficulty (1) disrupted maintenance of a
response prior to execution, and (2) abnormal
switching from a prepared response to a different
response. Both deficit types are reported
during limb (e.g., Romero et al., 2003) and
cognitive (Mollion et al., 2003) tasks. Many
questions remain unanswered regarding the
presence and nature of these deficits during
speech preparation, the relationship preparatory
deficits may have to the dysarthria of PD, and
the role of dopaminergic medications in the
manifestation of these deficits.
Off Medications
On Medications
Off Medications
On Medications
Switch
Switch
Same
Switch
Same
Switch
Same
Same
Individual mean RT - Individual baseline RT
Difference Score
Individual mean RT - Individual baseline RT
Difference Score
Individual mean RT - Individual baseline RT
Difference Score
Individual mean RT - Individual baseline RT
Difference Score

• S abnormal RT patterns unique to
  speech task
• S presence of dysarthria or hypophonia

Determination of aberrant RT performance
Difference Score of participant with PD was gt
1.5 SDs of the average difference score of the
controls
REACTION TIME TASKS
MANUAL (Greater cognitive demand)

• STIMULI
• 1-2 syllable low frequency words
• Primes matched targets on 75 of trials
• Word onsets changed for incongruent targets
• Example shopper-shopper maintain
• shopper-chopper switch

Task As quickly as possible, press the same
button if the word on the red screen and green
screen match, and the different button if the
word on the red screen and green screen do not
match.

• PROTOCOL
• Both tasks required 128 trials (2 sets of 64)
• Maintenance assessed via prime-target match
  (delay condition in particular)
• Switching assessed via prime-target mismatch
  (no-delay condition in particular)
• Following the screenings and a
  speech/cognitive- linguistic test battery,
  participants returned for a 2nd and 3rd session
  to complete the Manual and Speech RT tasks both
  ON and OFF (minimum 15 hrs) PD medication. Order
  of withdrawal was counterbalanced.

SPEECH (Greater programming demand)
Task Prepare to say the word on the red screen
say the word on the green screen as fast as
possible.
DISCUSSION POINTS
Six participants with PD (S6, S15, S16, S19, S20,
S22) had speech maintenance or speech shifting
difficulties that could NOT be attributed to
cognitive set maintenance, cognitive set
switching, or motor execution factors. Five of
these six participants had dysarthria or
hypophonia. Impaired switching of speech
responses only occurred when participants were
off of medications PD medication may
facilitate switching of speech motor programs.
Trouble with maintenance of speech motor program
was more common, but less influenced by
medication state. Maintenance and switching of
cognitive sets may be disrupted by intake of PD
medications. This finding is particularly true
for the no delay RT condition, which requires
rapid decision making. This RT protocol appears
sensitive to possible speech and cognitive
processing issues in a relatively mild sample of
individuals with PD. Additional testing, with
efforts to recruit persons of increased severity,
is underway.
PARTICIPANTS
CONTROLS
PD

• 27 adults (11 male)
• Age M 59.4 yrs, SD 10.1 (range 42-80)
• Education M 17.6 yrs, SD 3.3 (range 12-25)

• 25 adults (15 male)
• Age M 65.2 yrs, SD 8.3 (range 41-79)
• Education M 17.2 yrs, SD 2.8 (range 12-23)
• Years since dx M 6.8 (range 6 mo 22 yrs)
• Modified Hoehn Yahr M 1.7 (range I III)
• 2 with dysarthria 12 with hypophonia only

This work was partially supported by Grant
RO3-DC007066 from NIH (National Institute on
Deafness and Other Communication Disorders),
Grant P30 DC004661 (Human Subjects Recruitment
Core), the American Speech-Language-Hearing
Foundation, and the American Speech-Language-Heari
ng Associations Advancing Academic-Research
Careers Award.