neurolin final

Gall

the first to locate mental faculties in the brain cortex

explored and mapped the surface of the brain, sees the cortex as a morphologically uniform and continuous layer

stated that the cortex was the highest level of organization in the brain

assumptions underlying Gall’s theory

• some human abilities are innate

• 27 human abilities mapped onto the cortex

• development of the skull depended on the size of the cortex under it

Leborgne

called “tan”, only thing he could say

studied by Broca, called it aphemie

lost the ability to speak at 30yo

displayed no other comprehension problems

other mental functions not affected

lesions localized specifically to the inferior frontal gyrus of the left hemisphere

Broca

his brain area has revolutionized our understanding of language in the brain and speech production

shows its possible to localize specific functions in the cerebral convolutions (gyri)

his research led others to discover the locations of other areas

wernicke

differentiated between patients who could no longer produce language, and those who had lost the ability to understand language

patients with reduced language comprehension had lesions in the temporal lobe of the left hemisphere (superior temporal gyrus)

model of the relationship between linguistic functions and brain structure

hypothesis that fibers connect different cortical areas and create associations between visual, auditory, and tactile representations

wernicke - lichtheim model

depending on if lesions are before or between broca’s motor area, wernicke’s auditory speech area, or lichtheim’s “concept center” you get different language deficits

Korbinian Brodmann

divided the cortex into 52 distinct regions based on the characteristics of their neurons (density, size, layers)

still in use today

unitarism

the soul is one and cannot be divided, we cannot therefore divide cognitive/cerebral functions

localism

there are different centers in the brain for various language functions

associationism

language depends on the connections between the different areas of the brain

holism

language functions are managed by the brain in general, extensive areas must work together

dynamic localization

language subfunctions are located in different parts of the brain. These must be combined in several different ways in order to obtain more complex functions

the human brain and cortex

an extension of the spinal cord, grew as our species evolved

cortex is the most recent structure that varies a lot between species

the cortex is the primary structure governing language in humans

this supports the idea that our brain makes us particularly attuned to language, compared to other species

early brain development

one of the first structures to form and develop in the human fetus, around 3 weeks

brain development week 24

the brain has a basic structure resembling an adult brain

brain development week 36-40

brain reaches about ¼ of adult size

human brain convolutions

our cortex has the greatest number of convolutions 0.12m²

human brain number of neurons and connections

80+ billion neurons, 14-16 billion in the cortex alone

one to 10,000 connections with other neurons

human brain weight

compared to the size of our bodies, we have the heaviest brains

individual factors influencing the degree to which an injury will affect language

handedness, language dominance, individual experiences, socioeconomic status, age, gender, language abilities pre injury

bilateral

affecting both sides (of the brain)

ipsilateral

that which affects the same side (as the lesion)

contralateral

that which affects the opposite side (of the lesion)

central fissure

separates the frontal from parietal lobes

lateral (sylvian) fissure

separates the temporal lobes from the frontal/parietal lobes

frontal lobe

decisions, judgements, problem solving, emotions

temporal lobe

hearing, perception, recognition, several aspects of language

parietal lobe

movement, orientation, recognition and perception of stimuli

occipital lobe

vision/some visual processing

the insula

located beneath the operculum, near the fronto-temporal language areas

gateway for multiple sensory information

projects fibers directly to areas dedicated to hearing complex sounds, damage can induce general auditory agnosia

dendrites

receives messages from other cells

soma

cell body, which maintains the neuron

axon

transmits messages from the cell body to other neurons

myelin sheath

covers the axon of some neurons and helps speed up the electric signal

made up of lipids, proteins, and water for electrical insulation, allowing the impulse to jump quicker from one node of Ranvier to the next

its production occurs during early childhood and continues into adolescence

axonal endings/terminal boutons

form junctions with other cells

nerve impulse

electrical signal propagating along the axon towards the dendrites of another neuron

synapse

small gap between two neurons that enables chemical signals to transfer for communication

the chemical: neurotransmitters

neuron communication

neurons receive information from other neurons and they make a “decision” about this information by changing their own activity, that can then be passed on to other neurons

gray matter

outermost layer of the brain (as the neocortex)

also found deep in the brain, brainstem and spine

involved almost everywhere

correlation between gray matter volume and cortical thickness with many cognitive process implies that…?

specific well preserved cognitive functions are explained by gray matter volume in older adults

gray matter is made up of

1. capillaries

2. neurons (cell bodies)

3. glial cells)

auditory cortex

BA 41 and 42

allows you to recognize sounds, an essential prerequisite for understanding oral language

visual cortex

BA 17 and 18

helps read words, read lips/signs, and recognize objects as a first step to identifying them by name

broca’s area

inferior frontal gyrus

generally defined as BA 44 and 45

originally “the center for language production”

now: part of a complex network involved in semantic, syntactic, and phonological processing, and even non language tasks

some evidence it is the neural substrate underlying chomsky’s “universal grammar”, active when learning grammar rules in a new (must be real!) language

BA 44, posterior inferior frontal gyrus

pars opercularis

phonological processing, language production

likely facilitated by its position near the motor centers of the mouth and tongue

BA 45, anterior part of the inferior frontal gyrus

pars triangularis

syntactic and semantic aspects of language, selection and manipulation of semantic elements

wernicke’s area

superior temporal gyrus, upper part of BA 22

implicated in several aspects of language:

speech comprehension (phoneme perception)

lexical access (retrieving word meaning and phonology)

sentence building (combining constituents)

strategically placed between the primary auditory cortex and inferior parietal lobule

BA 22, the heart of wernicke’s area

the planum temporale

geschwind’s territory

two distinct regions of the inferior parietal lobule, BA 39 and 40

angular gyrus

BA 39

complex language processes, semantics, reading, writing

supramarginal gyrus

BA 40

involved in the phonological/articulatory processing, verbal working memory

inferior parietal lobule

together, the angular and supramarginal gyrus constitute a multimodal associative area

the neurons of this lobule can simultaneously process various stimuli in different modalities

very well positioned for capturing the multiple properties of the written and oral word

one of the last brain structures to evolve, only in primates, one of the last structures to mature in children

arcuate fasciculus

large bundle of nerve fibers

in the left hemisphere of ~90% of right handers and ~70% of left handers

found in the same place among people who use sign language

around the lateral (Sylvian) fissure in the left hemisphere of the brain is a neural loop involved in both the comprehension and production of spoken language