2.2 To understand how language, memory and emotion are processed in the brain Flashcards
Localization of language
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Brain imaging: show that a large network in the temporal, parietal, and frontal lobes, including both hemispheres, contribute to language.
Anatomical areas associated with language
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PLAATJE
- Figure A: inferior forntal gyrus and the superior temporal gyrus, in which Broca’s area and Werkincke’s area are located. It also includes the ventral parts of the precentral and postcentral gyri, the supramarginal gyrus, the angular gyrus and the medial temporal gyrus.
- Figure C: Heschl’s gyrus (primary auditory cortex) and parts of the superior temporal gyrus referred to as the anterior and posterior superior temporal planes (aSTP and pSTP). Together, Heschl’s gyrus, aSTP, and pSTP constitute the planum temporale
Other regions taking part in language
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- Supplementary motor area: responsible for the rhythmic mouth movements that articulate sounds
- Parts of the thalamus, dorsolateral parts of the caudate nucleus, and the cerebellum
- Visual areas (for reading), sensory pathways, and motor pathways
- Pathways connecting all of these various regions.
Werknicke-Geschwind model
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A model that proposes that comprehension is extracted from sounds in Wernicke’s area and passed over the arcuate fasciculus pathway to Broca’s area to be articulated as speech. Other language functions access this comprehension-speech pathway as well.
Fedorenko and Thompson-Schill model
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The temporal and frontal cortices connected by dorsal and ventral language pathways = extensions of the dorsal and ventral visual streams.
Information form body-sense regions of the parietal cortex also contributes to the dorsal and ventral language pathways and likely contributes to toch language such as Braille.
Fedorenko and Thompson-Schill model
Ventral language pathways:
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Transform sound (phonological) information into meaning (semantic) information, this is more of a top-down process, as it occurs when meaning is given.
Fedorenko and Thompson-Schill Model
Syntax
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Both pathways are involved in syntax (zinsleer), the dorsal pahtway categorises sounds into frequency of association and the ventral pathway extracts meaning from the grammatical organisation of words.
Both pathways are also involved in short- and long-term memory for the phonetic and semantic components of speech and in non-verbal speech.
Damage to the ventral pathways:
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Can cause one to still be able to read, but not be able the understand what it means.
Damage to the dorsal pathway
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Can make one unable to articulate, but can understand words.
Damage to both pathways
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Can make one unable to repeat words or attribute meaning to words.
Speech zones mapped by brain stimulation and surgical lesions: positive effects of cortical stimulation:
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Cortical stimulation produces: either positive effects, eliciting vocalisation that is not speech but rather a sustained or interrupted vowel cry, such as “oh”
Speech Zones Mapped by Brain Stimulation and Surgical Lesions: negative effects of cortical stimulaton
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Or it produces negative effects, inhibiting the ability to vocalise or to use words properly, including a variety of aphasia errors:
- Total speech arrest or an inability to vocalise spontaneousely
- Hestitaion and slurred speech: door: stimulation of the dorsal regions in Broca’s area and the ventral facial regions of premotor and motor cortex.
- Distortion and repitition of words and syllables: these effects primarily result from stimulating Broca’s and Wernicke’s areas and also the face area.
- Number confusion while counting: pat may jump from “6” to “19”, resulting from stimulation of Broca’s or Wernicke’s.
- Inability to name objects despite retained ability to speak: arise from stimulation throughout (anterior)Broca’s and (posterior)Wernicke’s speech zones.
- Misnaming and perseverating: occurs during both Broca’s and Wernicke’s speech zones (anterior and posterior)
Speech zones mapped by TMS
Transcranial magnetic stimulation (TMS)
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With TMS, connections between brain areas and specific brain regions can be mapped. The stimulation does not easily access regions located deep within sulci.
Speech zones mapped by TMS
Anterior regions of Broca’s is implicated in:
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Semantic processing (processing the meaning of words)
Speech zones mapped by TMS
Posterior region of Broca’s area is implicated in:
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Phonological processing (production of words)
Speech zones mapped by brain-imaging
Which widespread brain regions do words activate?
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- Occipital lobe
- Parietal lobe
- Temporal lobe
- Frontal lobe
- Thalamus
- Cerebellum
Speech zones mapped by brain-imaging
Using PET: more specific fucntions for some language areas became clear:
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- No overlap occured in visual and auditory activation during the passive task, implying that processing word forms in the two modalities is completely independent.
- During the speaking tasks, bilateral activation occured in the motor and sensory facial areas and the supplementary speech area as well as activation of the right cerebellum.
- Generating verbs activates the frontal lobe. especially the left inferior region, including Broca’s area.
- The verb-generation task also activated the posterior temporal cortex, anterior cingulate cortex, and cerebellum.
Wernicke’s area
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Mainly for analysing auditory input
Broca’s area
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Displays speech moevemtns and is involved in syntax and memory.
Neural networks for language
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Many models are based on the idea that language is widely distributed in cortical and other brain structures.
There are 2 language-network models that illustrate the distribution in the cortex:
1. Core language network (Fedorenko and Thompson-Schill)
2. Nodes and neural webs for language (Salmelin&Kujala)