neurolin quiz 1

trepanation

Drilling a hole in the skull as treatment for language loss, languag was believed to be caused by a god or spirit sending its spirit into the brain, causing the person to become ‘silent in sadness’

hemiparesis

observed by Hippocrates, semi paralysis or muscle weakness on the contralateral side

Galen

completed the first lesion studies, believed that if the lesion was deep enough to get to the brain ventricles you lose consciousness.  Further developed the view that different abilities are localized in different ventricles  

Herophilus

localized intelligence in the ventricles of the brain which was the dominant view until the 18th century

Johann Gesner

viewed speech disorders as memory disorders, caused by inertia in brain connections

Franz Joseph Gall

the first to locate mental faculties in the cortex, explored and mapped the surface of the brain.  stated that the cortex was the highest level of organization in the brain

Jean-Baptiste Bouillard

examined patients with frontal lesions and found two types of language disorders:

disorders of ‘speech movements’

disorders of ‘word memory’

Ernest Aubertin

examined a patient who shot himself in the head and had access to his intact frontal lobes.  When pressed on, the patient couldn’t speak

Paul Broca

Localized speech production to the inferior frontal gyrus by observing patients  Leborgne (‘Tan’) and Lelong

Carl Wernicke

differentiated between patients who could no longer produce language and those who had lost the ability to understand language. associationism hypothesis that there is a ‘language gyrus’ connecting Broca and Wernicke’s areas, fibers connect different cortical areas and create associations between visual, auditory and tactile representations

Korbinian Brodmann

Created Brodmann’s areas, dividing the cortex into 52 distinct parts based on the characteristics of their neurons

unitarism

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

localism

there are different centers in the brain for various language functions 

Gall and Broca

associationism

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

Wernicke, Lichtheim, and Geschwind

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

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

handedness and language dominance, individual experiences and socioeconomic status, language abilities pre injury

cerebrum

largest part of the brain, includes the cortex and subcortical structures

cerebellum

coordination and control of voluntary movements

brainstem

breathing, heart rate, and blood pressure

midbrain

vision, hearing, sleep/wake cycles, motor movements

bilateral

affecting both sides/hemispheres

ipsilateral

that which affects the same side

contralateral

that which affects the opposite side

gray matter

comp

composition: mostly neuronal cell bodies, dendrites, unmyelinated axons, glial cells and capillaries

color: gray/brown due to lack of myelin

function: processing and integration of information, decision making, synaptic activity

location in brain: found in the cerebral cortex, basal ganglia, thalamus and hypothalamus

location in spine: central butterfly shaped region

white matter

composition: mostly myelinated axons, some unmyelinated axons and glial cells

colour: white due to myelin covering the axons

function: transmission of signals between different brain regions and between the brain and spinal cord

location in brain: found in inner layers beneath the cortex, connecting gray matter regions

location in spine: surrounds gray matter in the spinal cord

the insula

located beneath the operculum, near the frontotemporal cortical language areas , gateway for sensory information.  Projects fibers directly to areas dedicated to hearing complex sounds, damage can result in general auditory agnosia

the rostrum

part of the corpus callosum that connects the frontal lobes and part of the temporal lobes

the genu

part of the corpus callosum that connects the left and right frontal lobes, also called the forceps minor

the trunk/body

part of the corpus callosum that connects parts of the frontal, temporal and parietal lobes

the splenium

part of the corpus callosum that connects the two occipital lobes, also called the forceps major

dura mater

outer meninge, stiffest layer, covered by the skull

arachnoid mater

middle layer of the meninges containing blood vessels and cerebrospinal fluid in the space below it

pia mater

inner layer of the meninges, directly covers the brain, with cerebrospinal fluid on top of it

projection pathway

connects distant areas in the superior/inferior direction

commissural pathway

connects the hemispheres

association pathway

ipsilateral connections

auditory cortex

BA 41 and 42, allows you to recognize sounds which is essential for understanding oral language

visual cortex

BA 17 and 18, helps read words, lips, signs, and recognize objects as a first step to naming them

pars opercularis

BA 44, involved in phonological processing and language production. Likely facilitated by its position near the motor centers of the tongue and mouth

posterior Broca’s area

pars triangularis

BA 45, involved in the syntactic and semantic aspects of language, like selection and manipulation of semantic elements

Anterior Broca’s area

planum temporale

heart of wernicke’s area in the upper part of BA 22

implicated in several aspects of language:

• speech comprehension, i.e. phoneme perception

• lexical access, i.e. retrieving word meaning

• sentence building, i.e. building constituents 

inferior parietal lobule

‘geschwind’s territory’

has two regions:

BA 39 - angular gyrus

BA 40 - supramarginal gyrus

Together they constitute a multimodal association area:

• the neurons of this lobule can simultaneously process various stimuli

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

one of the last brain structures to evolve and mature in children, is rudimentary in primates

angular gyrus

part of the inferior parietal lobule, is involved in complex language processes like reading and writing

supramarginal gyrus

involved in phonological/articulatory processing and verbal working memory

arcuate fasciculus

a large bundle of nerve fibers located in the left hemisphere of about 90% of right handers and 70% of left handers, and is found in the same place among those who use sign language.  Is located around the lateral sulcus and is a neural loop involved in both the comprehension and production of spoken language

the basal ganglia

participates in circuits with the cortex and thalamus to mediate aspects of motor control such as:

• selection of the response to perform or inhibit movement

• suppression of unwanted motor behaviours

• integration of sensations and movement

• ‘smoothing’ of fine motor behaviour

degeneration impacts motor movements

important for timing of speech and affects muscle tone

putamen

part of the basal ganglia involved in phonological processing and rhyming

caudate

part of the basal ganglia involved in syntactic and phonological anomaly detection, and lexical processing of real vs pseudowords

thalamus

receives and organizes sensory information, connected to the limbic system and is involved in memory:

• input into memory

• inhibition of memory retrieval

left ventrolateral thalamus

involved in verbal recall:

if stimulated when an individual receives verbal input that they must remember, the individual shows fewer recall errors

if stimulated when an individual tries to retrieve verbal input there are more recall errors

electrical stimulation in right handed patients can produce deficits in language processing because it disrupts the relay from the basal ganglia to broca’s area

lesions may result in:

• difficulties with verbal recall

• difficulties with naming, repetition, and syntactic processing

choroid plexus

produces cerebrospinal fluid in the ventricles via its network of capillaries and glial cells with a specialized epithelial lining to gently push the cerebrospinal fluid through the ventricular system

cerebrospinal fluid

99% water but also contains proteins, glucose and ions.  Found in the ventricles, subarachnoid space and surrounding the spinal cord.

functions:

protection - cushions and attenuates the impact of a blow to the head

excretion - its unidirectional flow carries potentially harmful substances away from the brain

buoyancy - reduces net brain weight by making it float

transportation - hormones released into it can be transported far away from the brain

its health appears to be linked to our memory abilities?

cerebral flood flow

blood supply to the brain, typically 750ml/minute and 15% of our cardiac output

arteries

provides oxygenated blood from the heart, glucose and other nutrients to the brain

veins

carries deoxygenated blood back to heart, and removes carbon dioxide, lactic acid and other metabolic products

circle of willis

provides emergency circulation if an artery becomes occluded because it connects the internal carotid to the basilar artery in multiple ways to supply blood to brain tissue that would otherwise be ischemic

however, is only fully formed in 40-50% of people

internal carotid artery

left and right branches enter the skull to connect to the anterior and middle cerebral arteries to supply blood to the mid and forebrain

vertebral artery

its two divisions merge into the basilar artery, which branches into the posterior cerebral artery to supply blood flow to the hindbrain and cerebellum

hyperemia/hemorrhage

too much blood circulating and being absorbed into surrounding brain tissue created high intracranial pressure, causing brain tissue to become compressed and damaged

ischemia

not enough blood circulating to brain tissue, blood flow to the brain is less than 18ml/100g per minute, tissue death occurs if blood flow is less than 8ml per 100g per minute