Verbal implicit sequence learning in persons who stutter and persons with Parkinson's disease

Area of Science:

• Neuroscience
• Cognitive Psychology
• Speech and Language Pathology

Background:

• Implicit learning systems are crucial for skill acquisition.
• Parkinson's disease (PD) and stuttering (PWS) are neurological conditions that may affect cognitive functions.
• The cortico-striato-thalamo-cortical loop is implicated in motor control and learning.

Purpose of the Study:

• To investigate the integrity of implicit learning in individuals with Parkinson's disease (PPD) and persons who stutter (PWS).
• To compare implicit learning abilities between PPD, PWS, and healthy controls.
• To explore potential links between stuttering and the functional integrity of the cortico-striato-thalamo-cortical loop.

Main Methods:

• A verbal serial reaction time task was administered to 14 PPD, 14 PWS, and 14 control participants over 120 minutes.
• Participants named syllables in response to visual stimuli, unaware of an underlying repeating sequence.
• Reaction times and accuracy were measured to assess implicit and explicit learning.

Main Results:

• Both PWS and PPD groups exhibited slower reaction times in early learning trials compared to controls, indicating learning delays.
• Persons with Parkinson's disease (PPD) showed reduced accuracy in general learning compared to controls.
• All groups displayed similar, limited explicit knowledge of the sequence.
• Both PWS and PPD groups demonstrated significantly impaired implicit sequence learning relative to controls.

Conclusions:

• Implicit learning systems appear compromised in both persons who stutter (PWS) and persons with Parkinson's disease (PPD).
• Stuttering may be associated with compromised functional integrity of the cortico-striato-thalamo-cortical loop.
• These findings highlight potential shared neural underpinnings affecting motor and learning processes in PWS and PPD.