Lecture 14: Language Flashcards

Question

Gunnar Fant (1919-2009)

Answer 1

Pioneer in the development of synthesized speech using formant “How are you?...I love you...” Speech synthesis with just two formant frequencies.

Answer 2

-Car accident in 1999, stroke in brain stem, “locked in” -Can't move any part of his body, except his eyes- Moving eyes is exhausting -Awake and intelligent, can feel -Hadn’t spoken since 1999 – his stroke disconnected “motor plans” formulated in cortex from subcortical motoneurons necessary to produce speech. -Can think of/imagine speech sounds, just can’t produce

Answer 3

-Neurologist who designs electrodes to use as neural implants for brain-machine interface -Implanted an electrode in Ramsey’s brain: left premotor cortex (speech planning area; localized in Erik via fMRI) -Electrode could wirelessly transmit information from surrounding neurons. -Collected extensive neural data, gathered when Kennedy’s team asked Ramsey to imagine speaking specific words. -But they could not decode the data. -In 2006, Kennedy contacted BU researcher Frank guenther

Answer 4

Key idea in model: speech output areas represent intended speech sounds in terms of formant frequencies. Used his computational model to generate design of decoder software that could translate information about neural activity from the electrode in the premotor speech planning area into formant frequencies. Output of decoder drives a speech synthesizer – would this allow Erik Ramsey to learn to control the

Answer 5

After he learned to imitate, Guenther et al. examined whether Erik could alter a synthesized sound (by changing the neural signals that drive the BMI) to a slightly different vowel than what he heard (e.g., hears “UH” as in “hut”, instructed to produce “OO” as in “hoot”). Across 25 sessions with real-time feedback, Erik showed significant improvement: Average hit rate in producing 3 target vowel sounds increased from 45% in first session to 70% in final session, including 89% in final block of final session

Answer 6

Left lateralization of language Language is extremely complex; we don’t know how many psychologically defined functions of language map onto the brain No animal model Early clues from brain damage and disease But they support overly simplified model of language

Answer 7

Silent word generation task: Generate words beginning with the letter presented, and articulate words “silently and entirely” 50 Left-handed subjects 50 Right-handed subjects

Answer 8

-knows object names, some simple semantic knowledge -could read simple sentences -e.g., “The boy that was hit by the girl cried” is too hard

Answer 9

-deficit in language comprehension or production following brain damage or disease problems in spoken/written language -occurs in approximately 40% of stroke

Answer 10

problems in language due to direct disruption of language processing system

Answer 11

problems in language resulting from memory problems

Answer 12

Classical model of language processing (Lichtheim). Damage to the area that stores auditory word images produces Wernicke’s aphasia. Damage to the area that stores motor word images produces Broca’s aphasia. The arrows indicate the direction of information flow.

Answer 13

“Motor image area”= Broca’s area: left inferolateral prefrontal “Auditory image area”= Wernicke’s area: posterior third of left superior temporal gyrus

Answer 14

Broca concluded that speech production brain area is in the left inferior frontal lobe As a result of a lesion in Broca area, there is a breakdown between one's thoughts and one's language abilities. Thus, patients often feel that they know what they wish to say but are unable to produce the words. That is, they are unable to translate their mental images and representations to words

Answer 15

Transient Non- fluent Aphasia Some problems with the classical view of Broca’s aphasia as a non-fluent aphasia produced by damage to the left inferior prefrontal cortex

Answer 16

multiple features of the acoustic signal (varying in temporal duration and psycholinguistic size) contribute to word contribution, not just phonemes

Answer 17

any of the perceptually distinct units of sound in a specified language that distinguish one word from another, for example p, b, d, and t in the English words pad, pat, bad, and bat.

Answer 18

a unit of pronunciation having one vowel sound, with or without surrounding consonants, forming the whole or a part of a word; e.g., there are two syllables in water and three in inferno.

Answer 19

melodic aspects of spoken language (intonation to indicate a question, emotion)

Answer 20

The cohort model is based on the concept that auditory or visual input to the brain stimulates neurons as it enters the brain, rather than at the end of a word. for example: on hearing the sound e, all words beginning with that sound become active (cohort of words) but when more information is revealed the cohort whittles down to fewer words until a point is reached where the evidence is consistent with one word (uniqueness point)

Answer 21

The uniqueness point is that point, measured from the beginnning of the word, at which a word diverges from all other words in the lexicon.

Answer 22

semantic property of a word that relates to the extent to which a word's meaning can evoke sensory images

Answer 23

reflects a negative peak at around 400 ms after the onset of a word the N400 wave is an event-related brain potential (ERP) measured using electroencephalography (EEG). N400 refers to a negativity peaking at about 400 milliseconds after stimulus onset. It has been used to investigate semantic processing, which may be dysfunctional in schizophrenia.

Answer 24

Allan Collins and Ross Quillian developed the network model of semantic memory organization in the late 1960s. This network model indicates that nodes of information (categories) are connected to each other through strong and weak links. Priming allows for our memory to ready associated information for retrieval. con: not all concepts have clear hierarchies

Answer 25

temporal pole

Answer 26

patients with semantic dementia can categorize pictures accurately when exemplars are typical like categorizing a dog as a animal but they struggle with atypical category members like categorizing an ostrich as a bird when asked to select semantic features they choose the typical category answer (they would match green with carrot because more vegetables are green)

Answer 27

Deficits in processing grammatical aspects of language * Can understand sentences with simple grammatical structure “The boy ate the cookie.” * Have trouble understanding sentences with more complex rules (i.e., who hit whom?) “The boy was hit by the girl.” * Broca’s area shows increased activity during processing of grammatically complex sentences à might reflect higher working memory demand halting speech production devoid of function words like of, at, the, and

Answer 28

temporal pole

Answer 29

middle portion of inferior temporal gyri

Answer 30

posterior portions of inferior temporal gyrus

Answer 31

Warrington & Shallice (1984): Differences in processing of sensory-perceptual information (most relevant for distinguishing among living things) vs. functional information (most relevant for distinguishing nonliving things, e.g., manmade objects such as tools). Problems: Patients with selective deficits for living things don’t have more difficulty answering sensory vs. functional questions about animals or objects. Some patients who have difficulties with sensory properties don’t show expected category-specific impairments

Answer 32

categorical organization of semantic knowledge, and indicates that anterior temporal lobe is associated with impairments in naming living things, more posterior regions with impairments in naming manmade objects

Answer 33

We are slower to identify words with a larger auditory neighborhood (i.e., more words that differ on only a single phoneme) * Auditory neighborhood: The number of similar sounding words (i.e., differ from target by a single phoneme; late/rate/hate) * Phoneme: Smallest unit of sound that makes a difference in meaning (e.g., L and R <- late vs. rate)

Answer 34

semantic priming If subjects have to make a decision about a list of words, they are faster at making a decision about a word if the previously presented word is semantically related (e.g., “car” primes “truck”, but not “cloud”)

Answer 35

Our knowledge of words is organized into a semantic network, where words that are more closely related are represented more closely together in this network * Evidence from studies of semantic priming

Answer 36

Semantic networks are categorically organized * Words can be categorized by certain semantic properties (e.g., living, non-living) * Can brain damage destroy a particular category of words within the mental lexicon? * Evidence from category-specific word deficits

Answer 37

Warrington (1970): Studied patients who had category-specific deficits for conceptual/semantic knowledge about certain categories of words: * These patients were fine at pointing to/naming pictures of living things * BUT, they had great difficulty in pointing to/naming non-living, man-made objects like tools * Other patients showed the opposite pattern (double dissociation)

Answer 38

Visual agnosia: Cannot recognize the object they are presented with, but can tell you other conceptual/semantic knowledge about the object (e.g., can’t recognize a picture of a telephone, but can tell you that it rings and you use it to call people) * Category-specific deficit: Can tell you that 2 objects are the same (i.e., can match 2 pictures of telephones), but don’t have access to what that object is for (not a problem of object recognition– deficit is in conceptual knowledge)

Answer 39

* Damasio et al., 1996: Locations of brain lesions are correlated with selective deficits in naming people (mostly anterior temporal lobe), animals, or tools (mostly posterior temporal lobe) à anterior to posterior gradient for living to non-living things Similar pattern in PET study of healthy subjects: Naming people activated mostly temporal pole (anterior portion of temporal lobe), naming animals activated middle portion of inferior temporal gyri, and naming tools activated mostly posterior portions of the inferior temporal gyrus

Answer 40

Sensory and perceptual information is most relevant for distinguishing between living things ...deficits arise from damage to more anterior temporal regions (closer to IT cortex, important for object perception) Functional information is most relevant for distinguishing between nonliving things, such as tools à deficits arise from damage to more posterior temporal-parietal regions (important for sensorimotor functions) * Problems with the sensory-functional explanation: * Patients with selective deficits for living things don’t have more difficulty answering sensory vs. functional questions about animals or objects * Some patients who have difficulties with sensory properties don’t have the expected category-specific impairments * Compromise: Organization of information within semantic memory network is a distributed network of specialized clusters

Answer 41

Functional information is most relevant for distinguishing between nonliving things, such as tools à deficits arise from damage to more posterior temporal-parietal regions (important for sensorimotor functions)

Answer 42

Phillip Kennedy & Frank Guenther: We can use the concept of formant frequencies to create synthetic speech in a locked-in patient (Eric Ramsey) * Can think of/imagine speech sounds, but cannot produce them Implant electrodes in left premotor cortex (speech planning area) and measure activity when asked to imagine speaking words * But… had trouble decoding data from neurons * Key idea: Speech output areas represent intended speech sounds in terms of formant frequencies * Build a decoder that translates neural activity from premotor neurons into formant frequencies, and output can drive a speech synthesizer Eric Ramsey could imitate and alter synthesized sound based on formants– and showed significant improvement with practice!

Answer 43

There is an auditory area that stores information about word sounds that you hear (Wernicke’s area) * There is a speech programming (motor) area that involves the motor component of word output, necessary for speaking (Broca’s area) These 2 areas are connected by a fiber tract: the arcuate fasciculus (AF) Take away point: The association of Broca’s area solely with motor output of speech in Lichtheim’s classical model is too simplistic

Answer 44

* Dronkers et al. (1996): Imaging study showed that out of 22 patients with damage to Broca’s area, only 10 had Broca’s aphasia à damage to other white matter and subcortical structures is also important Broca’s aphasia not only involves problems in speech production, it can also involve comprehension problems

Answer 45

Speech comprehension brain area in superior temporal gyrus (junction between parietal and temporal lobes) * Wernicke thought this area is involved in auditory storage of words

Answer 46

* Problems in word comprehension and producing meaningful sentences (i.e., can’t choose the right words, can’t monitor verbal output) * Fluent speech, but nonsensical sounds or sentences (“word salad”)

Answer 47

There is not a perfect association between Wernicke’s aphasia and damage to Wernicke’s area (out of 70 patients with aphasia, 7 had brain damage outside Wernicke’s area) * Suggests there has to be damage to the surrounding posterior temporal lobe regions, or damage to white matter paths that connect this area to other parts of the brain Wernicke’s aphasia not only involves problems in speech comprehension, it can also involve speech production problems * Some patients can produce made-up words and have naming problems Although Lichtheim’s classical model says that Wernicke’s aphasia reflects loss of linguistic knowledge, which impairs comprehension, there has been evidence against the classical view * Wernicke’s aphasics show intact semantic priming on a lexical decision task (i.e., is this a word or non-word?) despite problems with explicitly comprehending the semantic relationship between words * Example: “doctor” primes “nurse” even though patients fail to comprehend relationship between the two when explicit judgment is required Possible explanation: Perhaps Wernicke’s aphasia involves a problem with processes that normally provide access to linguistic information for use in real time * Evidence favors the idea that patients can’t integrate words into the context of a sentence quickly enough to allow normal comprehension

Answer 48

evidence rejects the simplistic distinction that Broca’s area = output and Wernicke’s area = comprehension * To some degree, both areas are involved in both output and comprehension We can think of these areas a 2 nodes in a larger left hemisphere language processing network that is critical for both comprehension and production * Damage to the entire network produces global aphasia (problems with both comprehension and production)

Answer 49

fMRI study of 3 groups while processing sentences in either written English or ASL 1. Normally hearing, monolingual native English speakers who didn’t know ASL 2. Congenitally deaf individuals whose native language was ASL and learned English late and imperfectly 3. Normally hearing “native signers” who were born to deaf parents and learned both ASL and English as their native language What would activity in Broca’s and Wernicke’s areas look like for these 3 groups when reading English sentences and viewing ASL sentences? When reading English sentences, Broca’s and Wernicke’s areas were active for the hearing group and to some extent native signers, but not for congenitally deaf * When viewing ASL sentences, Broca’s and Wernicke’s areas were active for deaf and native signers, but not for hearing subjects these areas might serve a more general linguistic function (hard-wired for language)