Basal ganglia contribution to rule expectancy and temporal predictability in speech

Area of Science:

• Neuroscience
• Psycholinguistics
• Speech Processing

Background:

• Basal ganglia (BG) damage is linked to syntactic deficits in speech.
• These deficits may stem from syntax-specific computation or generalized timing impairments.
• Beat perception deficits in music are known in BG patients.

Purpose of the Study:

• Investigate if BG patients' syntactic deficits are due to timing or syntax-specific issues.
• Determine if BG patients have a beat perception deficit in speech.
• Test if regular speech meter can ameliorate syntactic information processing in BG patients.

Main Methods:

• Continuous EEG recordings were used.
• Nineteen BG patients and matched controls listened to sentences with varied metrical and syntactic structures.
• Event-related brain potentials (ERPs), specifically the P600 response, were analyzed.

Main Results:

• Healthy controls showed P600 responses to all expectancy violations.
• BG patients exhibited P600 responses to syntactic and combined violations, but not metrical violations.
• This indicates BG patients have a beat perception deficit in speech.

Conclusions:

• Basal ganglia patients exhibit a beat perception deficit in speech.
• Regular speech meter facilitates the computation of syntactically marked information.
• A sensorimotor system may remediate timing deficits impacting linguistic processing in BG patients.