W18- Brain stimulation & SP

What is the central question of Lecture 2?

To what extent does the motor system contribute to speech perception?

What is the Motor Theory of Speech Perception (MTSP)?

The idea that speech is perceived through articulatory gestures rather than acoustic signals.

Who proposed the Motor Theory of Speech Perception?

Liberman (1967).

Why was MTSP proposed?

To explain how listeners understand highly variable speech signals.

What is coarticulation?

Overlap between speech sounds during production.

What criticism challenges a strong version of MTSP?

People with motor cortex damage often retain speech comprehension.

What does this criticism suggest?

Motor cortex cannot be the sole basis of speech perception.

What is the modern view of motor involvement in speech perception?

Motor cortex contributes but is not solely responsible for speech perception.

What is a virtual lesion?

Temporary disruption of a brain region using rTMS.

Why are virtual lesions useful?

They provide causal evidence about brain function.

What was the aim of Meister et al. (2007)?

To investigate whether premotor cortex contributes to speech perception.

Which brain regions were stimulated in Meister et al. (2007)?

Left STG and ventral premotor cortex.

What speech task was used in Meister et al. (2007)?

Phoneme discrimination in noise (Pa, Ta, Ka).

What happened after premotor cortex stimulation in Meister et al. (2007)?

Speech perception was impaired.

What happened after STG stimulation in Meister et al. (2007)?

Tone perception was impaired.

What does Meister et al. (2007) suggest?

Premotor cortex contributes causally to speech perception.

What is a limitation of Meister et al. (2007)?

Small sample size and artificial laboratory task.

What did Andoh & Paus (2011) combine?

TMS and fMRI.

What was the aim of Andoh & Paus (2011)?

To examine effects of disrupting Wernicke's area on speech processing.

What behavioural result was found by Andoh & Paus (2011)?

Accuracy unchanged but reaction times decreased after left stimulation.

What neural effect was observed in Andoh & Paus (2011)?

Increased activation in the contralateral hemisphere.

What is interhemispheric compensation?

Recruitment of the opposite hemisphere following disruption of a brain region.

What does interhemispheric compensation demonstrate?

Adaptive plasticity in speech networks.

What is a Motor Evoked Potential (MEP)?

Muscle activity recorded following TMS stimulation of motor cortex.

What does a larger MEP indicate?

Greater motor cortex excitability.

Why are MEPs useful in speech research?

They reveal motor system involvement during speech perception.

What did Watkins et al. (2003) find?

Hearing and seeing speech increased motor excitability.

What does Watkins et al. (2003) suggest?

Speech perception activates speech-production systems.

What did Fadiga et al. (2002) investigate?

Whether listening to speech activates articulator-specific motor regions.

What was the key finding of Fadiga et al. (2002)?

Tongue-related sounds activated tongue motor representations.

Why is Fadiga et al. (2002) important?

It demonstrates articulator-specific motor activation.

What was the aim of Nuttall et al. (2016)?

To determine whether speech distortion alters motor cortex involvement.

What speech conditions were compared in Nuttall et al. (2016)?

Clear speech and distorted speech.

What control site was used in Nuttall et al. (2016)?

Hand motor cortex.

What happened to hand MEPs in Nuttall et al. (2016)?

No significant effects.

What happened to lip MEPs in Nuttall et al. (2016)?

They increased during speech perception, particularly distorted speech.

How did speech identification relate to lip MEPs?

Greater MEPs were associated with better speech identification.

What does Nuttall et al. (2016) suggest about motor cortex?

It becomes more involved when speech is difficult to understand.

What is ECoG?

Electrocorticography, recording directly from the cortical surface.

What advantage does ECoG have over EEG?

Higher spatial and temporal resolution.

What did ECoG stimulation studies reveal about speech repetition?

It depends on a distributed network of temporal, frontal and motor regions.

Which region was associated with repetition errors during ECoG stimulation?

Posterior and middle superior temporal gyrus.

Which region was associated with motor speech errors during ECoG stimulation?

Precentral gyrus.

What is the strongest conclusion from Lecture 2?

Motor cortex contributes to speech perception, particularly under challenging listening conditions, but speech perception relies on distributed auditory-motor networks.