9-9 Brain Rythyms

neuroimaging

what techniques are used to map language? (fMRI, EEG, MEG, etc)

segmentation, decoding

two operations that must be executed to add the white spaces to speech

neural oscillations

what helps segment the incoming speech for comprehension?

neural oscillations

ongoing, rhythmic fluctuations in the excitability of neural populations (clusters of neurons firing action potentials together at rhythmic rate on and off repeatedly)

-they reflect shifting excitability of neural populations between depolarized and hyperpolarized states

-often measured with electrophysiological methods (EEG/MEG)

cortical tracking

the ability for neural oscillations to track spoken language

phase lock

what do cortical oscillations to do the overall loudness and speech rate of continuous speech?

phase locking

rhythm and timing of brain waves synchronize with the timing of incoming speech (loudness doens’t change)

-brain’s oscillation consistently lines up with peaks in syllable rhythym

quasi rhythmic

what rythym does speech have? (loose, approximate rhythym)

-contains recurring patterns of stressed syllables, pauses, pitch changes, and phrase boundaries

-Timing varies based on word length, emphasis, emotion, and speaking rate

-stressed words not necessairly seperated by equal amounts of time

efficiently

some phases of oscillatory activity where activity is closer to threshold than others, meaning the information are processed more ________

consistent phase

what do oscillations with a random phase before speech take on after onset of sensory input? (reset by external stimulus)

oscillatory frequency bands

groups of frequency bands that play a role in encoding acoustic and linguistic information that occur at timescales equivalent to the frequency of the oscillations

neural oscillations

what segments incoming spoken language into discrete units for analysis?

delta, theta, alpha, beta, gamma

most common rhythms

-slower bands process info that unfolds across longer periods

-faster bands are more engaged for rapidly unfolding info

delta

oscillations at 0.5-4Hz (lowest/slowest)

delta

which oscillation is associated with encoding words, building syntactic structures, processing prosodic cues liek emotion pitch, and assists with speech comprehension

delta

which oscillation is approximate rate of words and phrases

theta

oscillations at 4-8 Hz

theta

which oscillation is similar rate as syllable production?

theta

which oscillation is implicated in syllabic processing and associated with speech clarity?

alpha

oscillation at 8-12 Hz

alpha

which oscillation assists with filtering irrelevant information?

beta

oscillation at 12-25 Hz

beta

oscillation associated with auditory motor coupling

gamma

oscillations at 30-50Hz

gamma

oscillation with approximate rate of phonemic detail

gamma

which oscillation encodes rapid fluctuations in auditory signal?

gamma

which oscillation is bottom up afferent?

(lower level processing of acoustic and phonetic structures in speech)

delta, theta

which oscillations are top down efferent?

(synthesis of higher auditory and linguistic objects and modulates gamma activity)

theta gamma coupling

theta oscillations track the syllabic structure of speech which provides a temporal frame to group phonetic features encoded by gamma oscillations

cortical tracking

what is a promising tool for assessing speech and language processing in different populations that is inexpensive and is a temporally precise measure of rhythmic encoding

increased cortical tracking of speech

occurs when the brain works overtime to compensate for degraded signals or processing difficulties, as seen in non-responsive patients with severe brain injuries, adults with hearing loss expending extra effort in the delta-theta range, and individuals with primary progressive aphasia using heightened theta tracking to make sense of speech.

no, Higher cortical tracking often just means the brain is struggling and overworking to hear, which is why older adults with stronger tracking actually perform worse when understanding speech in a noisy room

does magnitude of cortical tracking matter?