Aphasia History and Neuroanatomy Flashcards
What do localizatinionists believe?
Language is housed in subcomponents in the brain.
There are distinct processors that handle language
What do unitarianists believe?
Brain functions as a unified organ
Language is not distinct from any other aspect of cognitive processing
Who was the first localizatinist?
Plato
Descartes
Mind/body problem. Primarily a dualist (believed the mind and brain could coexist. Mind influences the body through the pineal gland but the body could not influence the mind.
Gall was an advocate of….
Localization! Brain had three major divisions: brainstem, basal ganglia, cortex
Flourens
Experimental localizer but against localization of cerebral function.
Who is given credit to this day for the localization principle?
Broca- he demonstrated that a lesion in the left frontal lobe caused a speech problem but not an impairment in comprehension
What are some things about Hughlings-Jackson?
He was the founder of neuropsychology.
Neither a unitarianist or a localizationist
What did Brodmann do?
Categorized the brain into 52 distinct areas based on cellular organiation of the cortex in the respective regions.
Tissue stains to visualize different cell types
Organization of cells is called architectonics
Some stuff about Freud. Tell me!
Theories of unconscious mind
Mechanism of repression
Dreams as a window into unconscious desires
Penfield
Localizationist that mapped the motor cortex using electronic stimulation
Geschwind
Introduced classical model of aphasia and brought discussion to boston. BDAE. Behavioral neurology.
Introduced idea of connectionism
What is connectionism?
Lower level or primary sensory/motor functions are strongly localized but higher level functions like object recognition, memory, and language are the result of interconnections between brain areas.
Parallel distributed processing. What are the three principles?
Representation of information is distributed (not local)
Memory and knowledge for specific things are not stored explicitly, but stored in connections between units
Learning can occur with gradual changes in connection strength
CT Scan Adv and Disadv
Provides detailed image of the brain
Differentiates between tissues of different densities.
Short imaging time
Widely available
Cheaper than other tests
Disadvantages: possible health risks from radiation
MRI
Disadvantages between soft tissues
Can be used to study disordered or normal structures
High degree of spatial resolution
Disadv:
Longer imaging times than CT
Cannot be used with metal devices
More costly than CT
fMRI
Assess how the brain changes over time.
Safe and noninvasive
Can be used in conjunction with MRI
Basic functions of nervous system
Sensation (monitors changes/events occuring outside the body), integration (parallel processing and interpretation of sensory information to determine appropriate response), reaction(motor output)
Basic structures of the NS
Peripheral nerves Spinal cord Cerebellum Subcortical gray matter Subcortical white matter Cortex
Two basic nerve cell types
Neurons- Functional, signal conducting cells
Neuroglia- Supporting cells
Neurons. What are they?
The basic functional and structural unit of the nervous system.
Receive, integrate, and transmit information
Operate through electrical impulses
Specialized to conduct information from one part of the body to another
Most have certain structural and functional characteristics in common
Components of neurons
Cell body, dendrites, axon, neurotransmission, synapse
What is the soma?
Contains nucleus
Round, centrally located structure.
Controls protein manufacturing
Directs metabolism
What are the dendrites and what do they do?
Thin, branched processes whose main function is to receive incoming signals
Increase surface area of a neuron to increase its ability to communicate with others neurons.
Convey info towards the soma
Axons
Most neurons have a single axon
Originates from a special region of the cell body called the axon hillock
Covered with myelin
Afferent impulses are
Sensory
Efferent impulses are
Motor
Other kinds of cells in the nervous system
astrocytes, schwanna cells, microglia, oliodendroglia
What do glial cells do?
Do not propagate neural impulses Support neurons (literally, provide physical support as well as nutrients) Cover neurons with myelin Clean up debris Housekeepers
What do astrocytes do?
Provide a structural matrix for cell bodies in CNS; Maintain environment or neural function; Allow for neural plasticity to help adapt to injury
What do microglia do?
Perform scavenger functions such as cleaning debris after nerve celle damamge. Are specialized immune cells that act to defent the CNS
Schwann cells. What kinds of stuff do they do?
Provide myelin insulation to axons in the PNS
What do oliodendrocytes do?
Produce the myelin sheath which provides the electrical insulation for certain neurons
What is the synapse?
Space between axon terminal and dendrites
Formed when an axon of a presynaptic cell “connects” with the dendrites of a postsynaptic cell
What is an action potential?
An electric signal that is sends a molecular mess
What are neurotransmitters?
Any group of substances that are released on excitation from the axon terminal of a pre-synaptic neuron
acetylcholine, adrenaline, dopamine, endorphins and serotonin
What is gray matter made up of?
Nerve cell bodies and processes
What is white matter made up of?
Nerve cell axons
/Users/kcohen729/Pictures/iPhoto Library/Previews/2013/12/06/20131206-141500/k09zwwSWRxifb1r%srRf7A/IMG_0002.jpg
/Users/kcohen729/Pictures/iPhoto Library/Previews/2013/12/06/20131206-141534/E29Soo3NQ9uD8JCLRkG+jQ/IMG_0107.jpg
What are the components of the peripheral nervous system?
Autonomic and somatic nervous system
What are the components of the autonomic nervous system?
Sympathetic and parasympathetic nervous system
What are the components of the brainstem?
Reticular formation, medulla oblongata, pons, midbrain
What are the types of subcortical white matter?
Corpus callosum, cortico-cortical association fibers, cortico-subcortical association fibers
What does the midbrain do?
Visual and auditory reflexes, orienting reflexes
What does the pons do?
Relay of information from the cochlea and vestibular apparatus, control of movement and sensation from the face, control of mastication
What does the medulla do?
Integration of breathing and swallowing, control of respiration, control of blood pressure, control of cortical arousal
Reticular formation/reticular activating system
Clusters of gray matter intermixed with white found throughout the pons, midbrain, and medulla
Regulates balance and posture, sleep and conscious attention, relays info from eyes and ears to the cerebellum,
Injury leads to irreversible coma
What are the three components of the cerebellum and what are they made up of?
Cerebellar cortex- gray matter in the form of parallel folds called folia
Arbor vitae- tracts of white
Cerebellar peduncles- three pairs- superior, middle, and inferior
What does the cerebellum do?
Coordinate movements, regulate posture and balance. More specifically:
Evaluation of sensory input, predicting and scheduling tasks, learned motor skills and muscle tone, posture and smooth muscle contractions, compares intention to actual movement and sends signals to adjust
What makes up the brainstem and subcortical gray matter?
Pons, Midbrain, medulla oblongata, thalamus, hypothalamus, basal nuclei
What are the basal nuclei and what is their function?
Masses of gray matter deep to the cortex. Control highly practiced movements, starting and stopping movements, walking, dyskinesias and unwanted movements
What is the thalamus?
Relay station for the cortex that lies under the corpus callosum and can be seen across frontal sections. It is a major relay station for most sensory impulses
Which basal nuclei make up the basal ganglia?
Pallidus, putamem, caudate nucleus
Help initiate and terminate movement, suppress unwanted movement, regulate muscle tone
What is the extrapyramidal system?
Basal nuclei and their interconnections and transmitters
What does the extrapyramidal system do?
Influence motor instructions sent to the periphery
Has a role in stabilizing the large, complicated systems that control movement, Helps to direct action and interpret sensory information
What structures make up the limbic system and what do they do and where are they?
Amygdala, hippocampus, cingulate gyrus.
Play a role in emotion and memory. Pleasure and aversion centers. Also olfaction and memory.
Ring of structures on the inner border of the cerebrum and the floor of the diencephalon.
What are the three different types of cerebral white matter?
Commisural fibers, association fibers, and projection fibers.
What do commisural fibers do?
Connect corresponding areas of the two hemispheres.
What do association fibers do?
Connect different parts of the same hemisphere.
What do projection fibers do?
Enter and leave the cerebral hemispheres from and to lower structures
What is the arcuate fasiculus and what kind of cerebral white matter is it made up of?
Association fiber that connects Broca’s and Wernicke’s areas.
In general, the cerebral cortex plays a role in….
memory, attention, perceptual awareness, thought, language and consciousness.
Where is the perisylvian zone and what does it contain?
Cortex surrounding the fissure in the dominant hemisphere.
Contains major neural components for understanding and producing language.
What provides physical protection to the brain?
Skull, meninges, cerebrospinal fluid
What provides chemical protection to the brain?
Blood brain barrier
What is the blood brain barrier?
Tightly packed cells in blood vessel walls that prevent entry of many molecules
What is the skull
A bony structure that supports the structures of the face and protects the head against injury.
What are the meninges and how are they positioned?
Pia mater- thin vascular layer adherent to the contours of the brain
Arachnoid mater- spider web filamentous layer
Dura mater- outermost, tough membrane that lays against the bone
Subarachnoid bleed
Subarachnoid hemorrhages are typically acute. May follow a head injury or a rupture of a blood vessel in the CNS, for example, because of an aneurysm in the vessel.
Subdural bleed
Subdural hematomas are usually the result of a serious head injury. When this happens, it is called an acute subdural hematoma. Among the deadliest of all injuries.
What is the ventricular system and what are its components?
Connecting system of internal cavities filled with cerebrospinal fluid.
What are the functions of cerebrospinal fluid
Floats brain so it is naturally buoyant, cushions from hitting the inside of the skull, chemical stability(rinses away wastes)
What happens if CSF cannot circulate or drain properly?
Hydrocephalus
What happens when you have hydrocephalus?
Fluid buildup causes increased pressure on the brain, either internally or externally.
Ventricles must be surgically drained via an implanted shunt
What is the Blood Brain Barrier permeable to?
alcohol, O2, CO2, nicotine, anesthetics
What are the kinds of blood vessels that run through the brain?
2 internal carotid arteries
2 vertebral arteries
Where is the circle of Willis and what does it do?
Situated at the base of the brain. Functions as a safety valve. Joins anterior and posterior circulation. Most common site for congenital aneurysm.
What are the cerebral arteries
Anterior cerebral artery, middle cerebral artery, posterior cerebral artery
Gyri
Convolutions. Outwardly rounded ridges of cortex.
Sulci
Depressions. The grooves or fissures between the gyro.
What are the 4 primary cortices?
Primary auditory cortex, primary visual cortex, primary sensory cortex, primary motor cortex
What are the 4 association cortices?
Temporal association cortex, parietal association cortex, frontal association cortex, occipital association cortex
What functions do the frontal lobe association areas perform?
Concentrating, planning, complex problem solving
What functions do the temporal lobe association areas perform?
Interpret complex sensory experiences, store memories of visual scenes, music, and complex patterns
What functions do the parietal lobe association areas perform?
Understanding speech, choosing words to express thought
What functions do the occipital lobe association areas perform?
Analyze and combine visual images with other sensory experiences.
Primary motor cortex is also known as the…
Pre-central gyrus
What does the primary motor cortex do?
Initiation of skilled motor movements.
Lesion to primary motor cortex results in…
Paralysis to to the contralateral half of the body
What is the function of Broca’s area
Word formation, articulation, speech production
What is the location of Broca’s area?
Inferior third frontal gyrus of the frontal lobe
How does Broca’s area help us speak?
A vocalization program is formed and transmitted to the muscles of the face, tongue, vocal cords, and pharynx in order to form speech
Supplementary motor area. Where is it?
Anterior to the primary motor cortex
What does the supplementary motor area do
Temporal organization of movement, especially in sequential tasks such as speech
