Chapter 13 Flashcards
left and right hemisphere connect to..
..each hemisphere connects so muscles and skin receptors on their contralateral body side
-exceptions: trunk and facial muscles (controlled by both), taste and smell are uncrossed
lateralization
each hemispheres has a different function
connection of the two hemispheres through …
- the corpus callous ( set of axons)
- anterior commissure and hippocampal commissure
visual connection of hemispheres
- both eyes are connected to both hemispheres
- information from the right visual field falls into the left half of each retina which connects to the left hemisphere - optic chiasm (cross) axons from the left half of the right retina got o the left hemisphere (and vice versa)
split- brain operations
- surgically damage of corpus callosum in severe epilepsy
- either remove the focus point within corpus callosum where seizures begin or cut out the whole corpus callous
consequences of damaged corpus callosum
- split brain people remain fairly normal
- but : struggle on unfamiliar tasks when both hands are needed
- can use both hands independently in ways other people cannot
-> BUT hemispheres still do not act in complete isolation!
=> left hemisphere is responsible for speech production,
whilst both hemispheres can comprehend
- > split brain patients can understand with both hemispheres but only information shown to the left hemisphere can be vocalized!
-as time passes after the surgery, brain learns to use smaller connections between hemispheres to make up for the lost corpus callosum
the interpreter
tendency of the left hemisphere to make up explanations for what the right hemisphere did
comparison left and right hemisphere
- right hemisphere (holistic): better than the left at comprehending spatial relationships
- > focuses more on overall patterns whereas the left focuses on detail
- > right hemisphere sees the ‘bigger picture’, relates what’s been heard to the overall context
- is more responsive to emotional processing -> more fine tuned to gestures, tone of voice, sarcasm, happiness or sadness of others
- left hemisphere (analytical): responsible for processing language
- > but without right hemisphere, left hemispheres understanding would be very literal
plantum temporale (temporal cortex) is larger in 1……..hemisphere from when we are born -> resulting in 2…. handedness
1- left , 2- right
Maturation of the Corpus Callosum
- gradually grows and thickens as some axons are myelinated in childhood/adolescence
- matures through discarding many axons
- > overproduction in early development and two neurons connected each other to corpus callosum. These two neurons need to have corresponding functions
- connections that integrate info from both hemispheres develops between 3-5 years
- > before, some behaviors of children resemble adult split brain behaviors
human language has..
- productivity = ability to improvise new combinations to represent new ideas
- this makes human language distinct
teaching language to chimpanzees
- attempts failed because humans vocalize while breathing out, chimpanzees vocalize whilst breathing in
- when taught to communicate in symbols, it remained unclear whether they understood the meaning
- > their use was short in productivity
- > only used symbols to request and not to describe
- However, they were able to differentiate between who, where, and what questions
teaching language to bonobos
- > Bonobos are similar to humans in many aspects (sex face to face, outside of fertile periods, build bonds, male contributes to childcare)
- > Kanzi could understand, follow instructions, describe, but not produce
- > learned when he was young, learned by observation since his mom was taught
teaching language to non primates (parrot)
- african gray parrot could speak without food rewards
- > has implications for how to teach people who do not learn language well
- our language has evolved from other species
- > we cannot decide whether chimpanzees or parrots have language unless we define it more clearly
possible explanation for development of language in humans
- development of the phonological loop might have facilitated language
- > stronger connections between auditory cortex and pre-frontal cortex => better auditory memory
- language developed out of gestures
- > especially mouth gestures in monkeys
evolutionary theory on language
- humans have evolved bigger brains and language is a by-product of this
- criticism: whales have even bigger brains but no language
- > not everyone with a full sized brain and normal intelligence has normal language ( williams syndrome)
williams syndrome
people can speak normally but have low intelligence
language acquisition device (LAD) ( chomsky)
- language as a built in mechanism
- > kids learn so quickly as if they were biologically prepared
- > FOXP2 gene regulates proteins that promote synapse formation in cerebral cortex
- > this has an effects of jaw- and throat structures related to speaking
Bilingualism/ sensitive periods for language acquisation
- people who learned a second language before 12 have native-like proficiency
- bilinguals from infancy show bilateral activity during speech of both languages
- > people who learn after age 6 show only left hemisphere activation for both languages
- bilinguals have better attention control
- a child who learns no language within the critical period will not become proficient at any language later in life
aphasia
language impairment
- brain damage in general can be a way to study specializations for language by correlating damage brain region to deficits in verbal behavior
Broca’s Aphasia
- Nonfluent Aphasia
- brain damage in left frontal cortex impairs language production
- mostly: broca’s aphasia relate to combined damage to several brain parts, not only broca’s area
- awkward communication forms: speaking, writing, gesturing
- generally omit pronouns, prepositions, conjunctions (closed class words) “apple green” instead of “the apple is green”
- > have actual struggle saying closed class words out loud -> linked to difficulties understanding the meaning, not difficulties in pronunciation
- still residual knowledge of grammar
- > can say when a sentence is grammatically incorrect but not how to improve it
- > infer meaning themselves
closed class words
Prepositions, conjunctions, helping verbs
-> “closed class” because they rarely change within a language
Wernickes Aphasia
- Fluent Aphasia
- damage in left temporal cortex (near auditory cortex)
- > can articulate themselves but make little sense
- > omit nouns and verbs (open class words)
- have anomia: difficulties recalling object names
- > make up names or describe it in other words
- have struggles with language comprehension of any form because sentences without nouns and verbs make little sense
anomia
difficulties recalling object names
-> seen in patients with Wernickes Aphasia
open class words
- nouns and verbs
- > often changed within a language ( add new open class words)
- open class words are not used by patients with Wernickes Aphasia-> makes it hard to understand them
relationship between music and language
- music as well as language relate to detecting small changes in sound
- > high correlations between detection of changes in pitch of sounds and tone of voice
- evolutionary process that helped us develop language also helped us develop music
- we prefer music that resembles our language in tone and rhythms which suggests that they are related
Dyslexia
- reading impairment in people who have adequate vision, motivation, cognitive skills and educational opportunity
- more common in boys
- more common in English because it has a large number of irregular, nonphonetic spellings
- results out of difficulty converting symbols into sounds
brain anomalies in Dyslexia
- patients with dyslexia are more likely to have bilateral symmetry (no enlarged planum temporale in left hemisphere)
- brain areas in parietal and temporal lobe have lower than average gray matter
- > can be cause as well as consequence of poor reading
dysphonetic dyslexics
- trouble sounding out words so they try to memorize words a whole
- > when they don’t recognize a word, they infer it from context (read ‘laugh’ as ‘funny’)
dyseidetic dyslexics
- can sound out words but fail to recognize words as a whole
- > read slow and struggle with irregular spellings
explanations and treatment for dyslexia
- dyslexia might result from:
- > poor auditory memory
- > difficulties detecting order of sounds
- > attention focus problems
- can be treated with teaching them to focus on one word at the time (with a cut out sheet of paper)
- > but this changes their attention strategy in other activities too: are then not able to multitask anymore
3 kinds of monism
- materialism = everything is matter, the mind doesn’t exist
2. mentalism = the outside world doesn’t exist unless a mind perceives it
3. identity position = mental processes ARE brain processes (consciousness = brain activity)
=> monism is generally widely accepted nowadays
-> brain activity and experience are inseparable
easy and hard problems concerning consciousness (Chalmers)
- easy: difference between sleep and wakefulness
- hard: why does consciousness exist at all? why does info-processing feel like something at all?
–>today we are limited to easy problems before we can get to the hard one
flash suppression
experiment: a dot on screen, followed by a flashing ring around it
- > makes people unable to see the stationary dot
- > strong response to flashing stimulus decreases the response to the steady stimulus (steady dot)
Consciousness
when we are conscious, we see and recognize things
- > gamma waves (precisely synchronized in several areas) are evoked and spread widely
- > being conscious of a stimulus means that it evokes more overall brain activity
masking and backward masking
- masking: brief visual stimulus is preceded and followed by by longer interfering stimulus (often a pattern)
- backward masking: only brief stimulus followed by final stimulus
– > when stimuli are masked, we have no consciousness of them
binocular rivalry
perception switches between the two stimuli that are presented to each eye independently.
-> are competing for consciousness
experiments using binocular rivalry
- some stimuli (e.g. facial expressions) hold attention longer than neutral ones (stripes)
- > using a pulsating stimuli on one eye results in distinct brain activation for the pulsating and stationary stimulus
- > shifts are evident in fMRI scans
- > large scale activation in differing brain areas
- > conscious stimuli virtually take over brain activity
unattended stimuli and consciousness
- much of our brain activity is unconscious and even unconscious activity can influence behavior
- > binocular rivalry experiments: when a word or even your name appears in the unattended field, the attention switches rapidly to that eye
- ->means that unattended stimuli are still somehow attended to and that the brain detects it before you become conscious
Consciousness as a Threshold Phenomenon
- consciousness of a stimulus seems to be a yes-or-no thing
- when a stimulus activated enough neurons to some extend, activation magnifies and spreads over much of the brain
- if a stimulus fails to reach that level it just fades away
- fMRI support: brains response is either weak or strong, not intermediate
phi phenomenon
dots appearing one by one later seem as if they were one dot that moves in a circle (inferred that movement afterwards)
- > intepretation/consciousness depends on timing and context: also with words that sounds half way like dent or tent
- > depending on which sentence it appears in, you will perceive it as either one or the other
- -> we are capable of becoming conscious of something after it is gone
anaesthetic patients
- loosing consciousness marked by decreased overall activity
- > especially between cerebral cortex and subcortical areas
- > consciousness returns with increased activity between cerebral and subcortical
- > further alertness returns with increased cortex activity
- > loss of connectivity leads to a stimulus that cannot spread = reach consciousness
- people in a vegetative state can sometimes show wilful brain responses to verbal instructions (indicating some consciousness)
- brief magnetic stimulation of one area results in spreading activation in conscious people and only brief, local activation in sleeping, anesthetized or vegetative people
attention
- attention is not a synonym of consciousness but closely related
- > we can be conscious without paying attention but we cannot pay attention without being conscious
inattentional blindness
(change blindness) =
when something changes slowly or changes while you blink you don’t notice the change
Brain Areas Controlling Attention
- bottom-up: stimulus dependent attention
- top-down: intentional attention
- > top-down depends on PFC and parietal cortex
- > evident in stroop task: hard to suppress reading (top down interfering with bottom up)- > fluctuation makes you resist distraction
Spatial neglect
- often in people with right hemisphere damage
-> ignore left side of body and visual field - mainly loss of attention!! rather than loss of sensation
- we can make these people aware of their neglected side
-> telling them to pay attention or crossing over left (neglected) arm under right arm increases attention for neglected arm
social neuroscience
study how genes, chemicals and brain areas contribute to social behavior
Love related brain activity
pictures of the person you love result inn increased brain activity in :
- reward area = similar to that of drug addicts
- hippocampus and other areas for memory and cognition => what we call love combines motivation, emotions, memories and cognitions
oxytocin
- is a hormone that is released during and after child birth -> stimulates breast to produce milk
- > promotes bonding in general
- > both men and women release it during sex -> called “love enhancing, magnifying hormone”
- > in studies it increased attraction to partner not just everyone and made men stand further away from other attractive women
- > results in greater attention to facial expressions
- > increases conformity of opinions in in-group
- > can increase attention to threats
empathy
- ability to identify with other people (often towards people who are similar to us)
- > helpfulness depends on empathy
- > stronger in humans than in other species
varying degrees of empathy and altruism are reflected in brain activity
–> psychopaths show less empathetic brain activation
