week 9 - language organisation in the brain Flashcards
language is not unitary, outline what is included in receptive and productive language
receptive -> listening, reading
productive -> speaking, writing
outline what the antaomo-clinical method is
- studies patients with acquired language impairment from brain injury or stroke
- found that depending on where the damage is and lesion size, that different patterns of language deficit can occur.
what are the limitations with the anatomo-clinical method?
- it is impossible to observe relationships between skills and tasks and brain areas in real time
- deficits change over time, usually decrease
what are aphasias
- language disorders due to damage in the language areas of the brain
- causes of these are CVA, strokes, head injury, brain tumours, infections and dementia.
where do aphasias occur
aphasia can be general or affect an isolated aspect of language.
this depends on where the damage is
what are the difficulties found in aphasias
- langauge production - fluency, naming, agrammatism
- repetition
- auditory comprehension
in some aphasias naming is an issue, outline the problems that can occur with this
- word avoidance
- circumlocations
- paraphasia (incorrect word substitute)
outline the 3 types of paraphasias
neologistic -> invention of new words
semantic -> substitution with related word meaning
phonemic -> substitution or rearrangment of sounds
outline agrammatism
- difficulty in producing syntactically well-formed sentences
- tend not to use function words, there is great difficulty in using passive voice
Outline auditory comprehension
- the ability to understand spoken language
- complex process that involves, segmenting sounds into phonemes, combing those to make words.
what are 4 main types of aphasias
brocas -> non-fluent aphasia
wernicke’s -> fluent aphasia
conduction -> difficulty repeating words and sentences
global aphasia -> difficulties in both speaking and comprehending due to extensive brain damage
discuss Broca’s aphasia
- post mortem done of 2 patients, showed damage to the posterior part of the left inferior frontal gyrus (brocas area)
- this area is fundamental for language expression
- they found speech production difficulties such as non-fluent speech
- naming and word-finding difficulties
discuss wernicke’s aphasia
- studied deficits in 2 patients with severe auditory comprehension difficulties - fluent meaningless speech
- damage was seen in the left superior temporal gyrus region known as wernicke’s area.
discuss conduction aphasia
- repetition is a major deficit
- originally associated with damage to fibres in the arcuate fasciculus , more recently areas surrounding the sylvian fissure.
- speech is fluent in production, naming is impacted by paraphasic errors.
what are the levels of language processing
- semantics
- syntax
- lexical access
- phonology
discuss event-related potentials
- electrical potentials recorded from the start of a stimulus
- waveforms are distinguished based on their position, onset of peak, scalp distribution
what is mismatch negativity
- a standard sound and an oddball are presented
- negativity 100-200ms after presentation of the oddball, with a frontal scalp distribution
- it is elicited with any sounds
what are the advantages of event-related potentials
- usually can match the fast rate of language comprehension
- high temporal resolution
- components are multidimensional, so allow for qualitative inferences about underlying nature
discuss the disadvantages of event-related potentials
- many trials are necessary for appropriate averaging
- some trials are lost due to artefacts such as blinking and eye movement
- poor spatial resolution
discuss fMRI’s
- in fMRI stimuli are presented during the scan, to see the inner functions
- images reflect changes in oxygenated blood levels
- high spatial resolution, poor temporal resolution
- intensively used in reading research
outline lexical access in reading and damage to the area
- an area in the posterior of the left inferior temporal gyrus is proposed to be the area of orthographic representations or lexicon
- known as visual word form area (VWFA)
- injury or damage to this area is called pure alexia (inability to read, but functions such as spelling and writing are intact)
