Introduction to Neurolinguistics, LSA2017 1

Introduction to "Introduction to Neurolinguistics"Jonathan R. Brennan

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Andics et al. 2016 Science 3

"Dogs understand human words and intonation"

— AAAS, August 30, 2016

Andics et al. 2016 Science 4

Andics et al. 2016 Science 5

How do we link brain signals with the cognition behind language to learn...

» What brain systems support language?

» How do they operate?

» How can brain signals enrich our understanding of language?

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What you will know at the end of this course

» Methods used to probe language-using brains

» Geography of language-related brain regions, how they are connected, and how activation (and information?) passes from one region to the next

» Some ideas of how neural circuits process linguistic information

» Many many questions

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What you will do for me

» Attend class and talk

» Read and post to the discussion board

» Out-of-class quizzes

link to syllabus 8

What I will do for you

Try to systematically think with you about:

» Methods

» Neural systems for linking sounds with words

» ...words with concepts

» ...and sentences & sentence meanings

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Agenda

1. Challenges for linking brain language !

2. Clues towards how to move forward

3. Historical context

4. A quick tour of the brain's geography

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bottom-up recognizer

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top-down recognizer

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The connection between linguistic knowledge and measurable brain states is indirect.

We can specify linking hypotheses that indicate how linguistic properties (syntactic structures, phonological features etc.) might bear on brain states.

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The mental states prompted by linguistic input conform to ( ) properties of the grammar... in some way or another.

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"a reasonable model of language use will incorporate, as a basic component, the generative grammar that expresses the speaker-hearer's knowledge of the language"— Chomsky 1965 p. 9

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"Finding algorithms by which Chomsky’s theory may be implemented is a completely different endeavor from formulating the theory itself. In our terms, it is a study at a different level, and both tasks have to be done."— Marr 1982 p. 28

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What do you know when you know a language?

How do you use that knowledge to speak and understand?

What neural circuitry carries out those algorithms?

Compuatational description

Algorithmic description

Implementational description

Linguistics (ish) Psycholinguistics (ish)

Neurolinguistic (ish)

Marr 1982 21

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Peña & DeBello, 2011, ILAR 23

Peña & DeBello, 2011, ILAR 24

Peña & DeBello, 2011, ILAR 25

Agenda

1. Challenges for linking brain language

2. Clues towards how to move forward

3. Historical context !

4. A quick tour of the brain's geography

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» 1861, Paris

» Pierre Paul Broca visits stroke patient only articulates one syllable: Tan

» Normal comprehension, reasoning, problem solving

» Dies two weeks later. Autopsy reveals Local damage to the frontal regions of the left hemisphere

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Aphasia: Language impairement caused by brain damage

Broca's Aphasia (non-fluent):

» Slow, laborious, non-fluent speech

» Short utterances

» Speech understanding (relatively) intact

» Complex grammar comprehension impaired

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Following Broca's work from Vienna, Karl Wernicke begins a survey through Europe in the 1880s.

Documents language deficits due to brain damage. Replicates Broca's findings and identifies new syndromes.

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Wernicke's Aphasia (fluent):

» Fluent, well articulated speech (normal intonation &c.)

» Words are disordered, inappropriate

» Impaired comprehension and reading.

» Stroke damage to posterior left hemisphere

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Wernicke's model for speech comprehension and production

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> 100 years of language in the brain

left-to-right: Wernicke 1881; Geshwind 1970; Friederici 2012 38

Summary so far

» Need linking hypotheses between linguistic computations and brain stuff

» >100 years correlating language deficits with brain lesions has given a surprisingly stable outline of language-related brain regions

» What are the linking hypotheses? Early work uses fundamental divide between comprehension and production. Things will change when we consider linguistic divisions like phonology, morphology, syntax &c.

» Next time: Some obvious and not-so-obvious challenges with this method, and other tools in the toolbox.

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Agenda

1. Challenges for linking brain language

2. Clues towards how to move forward

3. Historical context

4. A quick tour of the brain's geography !

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Navigating the brain

» Basic organizing terminology

» Peripheral, central, cortical

» White vs. grey

» Lobes, sulci and gyri

» Cortical layers and brodmann's areas

» The neuron

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Insula

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Individual variability in the Pars opercularis of the left inferior frontal gyrus

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Neurons

» ~100 billion CNS Neurons with 100 trillion synapses

» Outgoing signals via electoral action potentials transmitted along Axon

» Incoming single received across the synapse by dendrites

» Maturation changes connectivity pattern between neurons

» 1 to 1/1000 sec rate neuronal firing rate

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Cytoarchitectonics: The arrangement of nerve cells in the cerebral cortex

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Brodmann’s Areas: Division of the cerebral cortex into 52 regions based on cytoarchitectonic characteristics

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Brain geography take-aways

» We'll mostly focus on the cortex of the brain: Two hemispheres with four lobes, some structures "hidden" underneath outer sheet. Be able to name these.

» Cell bodies (grey matter) connecting to each other (white matter); complex folding into sulci (valleys) and gyri (peaks)

» Be able to locate anatomical regions with names like Left posterior superior temporal gyrus

» Know the basic parts of the neuron and the difference between cytoarchitectonics and anatomical landmarks

See more in Kemmerer's textbook chapter! 56

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