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Times are Changing for Modeling Language and Speech Brain imaging Analysis of sounds Spectral and temporal analysis Phonemes Morphemes Syllables Phrases New approaches in modeling
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The Neurology of Speech and Language: Avians to Humans
David B. Rosenfield, M.D.Director, Speech/Language CenterDirector, EMG/Motor Control Lab.
Professor of NeurologyWeill Cornell Medical College
Times are Changing for Modeling Language and Speech
•Brain imaging•Analysis of sounds
•Spectral and temporal analysis•Phonemes•Morphemes•Syllables•Phrases
• New approaches in modeling
Language
• Representational System
• Generativity
• Drives the motor system
Speech Motor Control System
• Respiratory
• Articulatory
• Phonatory (e.g., laryngeal)
Mammalian Vocalization Involves Coordination of:
• Respiration - anterior horn cells (cerrvical, thoracic, upper lumbar)
• Laryngeal activity - neurons controlling glottic closure (n. ambiguous)
• Articulatory mechanism (supralaryngeal)– V Motor n.– VII n.– Rostal n. ambiguous– XI n.– Upper cervical anterior horn cells
Neuroanatomy of Language• Two principal regions for language
– Sup. temporal areas adjacent to auditory cortex– Inferior frontal cortex adjacent to articulatory
motor cortex• These two regions connected by several
white matter tracts• Extreme capsule• Uncinate fasciculus• Arcuate fasciculus (well developed in humans)
Areas of Language Function• Pars Triangularis (PTR, #45)
– Heteromodal cortex– Located within inferior frontal gyrus
• Pars Opercularis (POP, #44)• Motor Association Cortex
• Planum Temporale (PT, #22)– Auditory Association Cortex
Broca’s and Wernicke’s Area• No cytoarchitectonic signature• Cannot identify by looking under a microscope• Broca’s Area
– Portions of #44 and of #45• Wernicke’s Area
– Portion of #22
Broca’s and Wernicke’s Area• External brain stimulations:
– While talking > cease talking– While not talking > grunt from Broca’s, nothing from
Wernicke’s• Anatomy BA and WA
• Connections are polysnaptic• Connections are bi-directional• No direct connections to n. ambiguous• None below periaqueductal gray
Non-human Primates v. Humans•Language v. Communication Systems•We learn tens of thousands of words/symbols; NHP <40 signs•Humans learn syntax, gen. grammar•Anatomic differences:
•Association cortex•More fronto-temporal connections
Song Learning in Zebra Finches
Sensory learning
Sensorymotor
60-65dCritical period closes
90dCrystallization
25-40dSinging begins
J. neurosci, February 1, 1997 17(3):1147-1167
HVC
RA
LMAN
Area X
DLM
RA
LMAN
DLM
Parasagittal Section of Male Zebra Finch Brain
NIF
FIELD LLMAN
X
HVC
RA
DM
DLMN XII ts
Ts nerve totrachea and syrinx
Learning songMaintaining song
Comparison between ZF Birdsong and Human Speech
Birdsong Human SpeechOccurs early in life ++++ ++++Dependent on auditory
feedback ++++ ++++Dependent on specialized
brain areas ++++ ++++Spectrally complex ++++ ++++Temporally complex ++++ ++++Hierarchically controlled ++++ ++++Modular* ++++ ++++* (E.g., notes, syllables, phrases, phonemes, words, sentences, paragraphs)
“Domestic”
Normal Song 1
Normal Song 2
Repeater Song 1
Repeater Song 2
Rauschecker and Scott, Nature Neuroscience, 2009
Improved Understanding of Our Knowledge of Language and Speech
•Anatomy•Imaging•Physiology•Greater attention in new clinical domains•stuttering•dysphonia•aphasia•rehabilitation