The Neurology of Speech and Language: Avians to Humans David B. Rosenfield, M.D. Director, Speech/Language Center Director, EMG/Motor Control Lab. Professor of Neurology Weill 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 60-65d Critical period closes 90d Crystallization 25-40d Singing begins J. neurosci, February 1, (3):

HVC RA LMAN Area X DLM RA LMAN DLM Parasagittal Section of Male Zebra Finch Brain

NIFNIF FIELD L LMAN X HVC RA DM DLM N XII ts Ts nerve to trachea and syrinx Learning song Maintaining song

Comparison between ZF Birdsong and Human Speech BirdsongHuman Speech Occurs 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