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Cognitive Neuroscience (Fach) / language (Lektion)

Cognitive Neuroscience

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  • Decomposing the speech signal - The listener has to encode a continously varying waveform into discrete sound patterns. - Basic Soundpatterns of a language: Phonemes
  • Phonemes - bundle of features (e.g. place and manner of articulation) - smalltest structure units that distinguish meaning (e.g. run - rum) - cognitive abstractions or categories
  • Phonological categories - Phonological category membership is an all-or-nothing property: All members are equal - Phonological categories are the basis of storage (Abspeicherung) of lexical forms - Phonological categories participate in a wide variety of combinatorial computations
  • Neural bases of Categorial Perception Phillips et al., 2000: Manipulation of voice onset time = The timing between plosive ( Konsonanten, bei deren Artikulation der Atemluftstrom vollkommen blockiert wird) releases and the onset of vocalfold vibration, e.g. pa = long VOT; ba = short VOT Die Aussage der Studie check ich nicht ganz, es geht um die akustische und die phonologische Repräsentation und das Oddball Paradigma...  
  • Categorical perception - Seems to be innate: Newborns already display categorical perception for phonemes (Eimas, 1971) - In the first year of life the sensitivity for phoneme categories that are not relevant in their mother tongue declines gradually (for a review see Kuhl, 2004)
  • Multiple Timescales of Speech Segmental information (e.g. speech sound) ~ 20-40 ms timescale Suprasegmental information (e.g. syllables) ~ 150-300 ms timescale
  • Classical language areas in the left hemisphere Carl Wernicke reported 1874 a series of patients who were able to produce speech but not understand it. These patients exhibited lesions in the superior convolution of the temporal lobe. Broca aphasia: Impairments in speech output
  • Multi-time resolution model (von...?) Hickok and Poeppel, 2007; Poeppel et al., 2008: left: processing on the 20-40 ms timescale (segments) right: processing on the 150-300 ms timescale (suprasegmental)
  • Multi-time resolution model; Human Brain Imaging (von...?) Boemio et al., 2005:                 short timescales                                              long timescales
  • Multi-time resolution model; Human Brain Imaging II (von...?) Boemio et al., 2005: The evidence for a rigthward asymmetry of slow integration is growing and the evidence for a leftward asymmetry of rapid integration is unsettled. Minimally, both hemispheres are equipped to deal with subtle ('feinen') temporal variation Superior temporal sulcus (STS) activation for long timescales in the right hemisphere.
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  • Multi-time resolution model; EEG (von...?) Abrahms et al., 2008: Right hemisphere follows speech envelope more accurately than left hemisphere. The young boy left home. black: Speech envelope red: Right Hemisphere EEG blue: Left Hemisphere EEG
  • Speech-comprehension: Dual-stream model of speech perception and language (von...?)   (Hickok & Poeppel, 2007) green: Encoding the speech signal orange: Categorization Dorsal-left-lateralised: Maps acoustic signal to frontal lobe articulatory networks. Ventral-bilateral: Processes speech signal for comprehension.
  • Phonological networks in the brain (von...?) Okada & Hickok, 2006: Lexical phonological networks in the superior temporal sulcus (STS). Activation of the STS presumbly reflects the partial activation of larger neural networks when high density words (those with many similar sounding neighbours) compared to low density words (those with few similar sounding neighbours) are processed (coloured blobs).
  • Activation of stored words First: Cohort activation Evidence from Priming (Zwitserlood, 1989): Faster reaction times to semantically associated words. Evidence from Eye Movements (Allopena et al., 1998) Evidence from Hand Movements (Spivey et al., 2005)
  • Mapping sound to meaning: Ventral Path Dual-stream model of speech perception and language (Hickok&Poeppel, 2007): Combinatorial network: Syntactic and compositional semantic operations Lexical interface: Mapping between phonological representations in the STS and the widley distributed semantic representations
  • Koordination beider Hände/ Finger Bei niedrigen Frequenzen kann man beide Zeigefinger anti-phasisch bewegen. Bei hohen Frequenzen geht dies nicht mehr. ---> Evidenz für zeitliche Kopplung "Koordinative Strukturen"

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