Final Exam Flashcards
Where is language localized
Language is lateralized: for the vast majority of the people, language is almost entirely localized int he left hemisphere.
What is the role of the right hemisphere in language?
Relates more to how people use language, instead of what do words mean. The Prosody of speech: rhythm, tone or emphasis. Emotional state of the speaker. Recognizing people’s voices. Understanding metaphors.
What happens to language when the right hemisphere is damaged?
People get literal in their interpretation of language.
Phonagnosia
A disorder where people have great difficulty recognizing familiar voices. Result of damage to right hemisphere.
Posterior Language Area
It is near the junction of the temporal, occipital, and parietal lobes. It is a hub where the perception of a word is linked up to the concept it represents. It is critical for language comprehension.
Wernicke’s Area
Could also be called: posterior aphasia, sensory aphasia, receptive aphasia, or fluent aphasia. Location in the superior gyrus of the left hemisphere (region of the auditory association cortex). Involved in the analysis of speech sounds and in recognition of spoken words. Important for comprehending words and producing meaningful speech.
Broca’s Area
Could also be referred to as anterior aphasia, motor aphasia, expressive aphasia, or non-fluent aphasia. Location in the frontal lobe. Involved in speech production.
Disorders of language: Aphasia
Important for studying the neural basis of language in humans. Aphasia is the disturbance in understanding, repeating or producing meaningful speech, caused by brain damage. Difficulty patients experience cannot be due to sensory or motor deficits or lack of motivation. Not all language disturbances are aphasias.
2 broad categories of aphasia depending on the location of the brain damage:
- Damage to the frontal lobe:
anterior aphasia, motor aphasia, non-fluent aphasia, Broca’s aphasia, expressive aphasia (difficulty producing language). - Damage to the sensory association cortex: posterior aphasia, sensory aphasia, fluent aphasia, Wernicke’s aphasia, receptive aphasia (difficulty comprehending language).
Transcortical Sensory Aphasia
Caused by damage to the posterior language area. Patients fail to comprehend the meaning of words and they are unable to express their thoughts in meaningful speech. They are able to perceive and recognize words as well as speak fluently. They can repeat words back to you, read, and write without understanding. Suggests that there might be a direct connection between Wernicke’s area (recognizing words) and Broca’s area (speech production) that bypasses the posterior language area.
Conduction Aphasia
Caused by damage to and around the connections between Wernicke’s and Broca’s area known as the arcuate fasiculus. Patients are unable to repeat the words they hear. They have meaningful, fluid speech as well as intact speech comprehension. Especially impaired at repeating nonsense words or novel sounds. Disrupts short term working memory.
Pure Word Deafness
Caused by damage to Wernicke’s area or disruption of auditory input to this region. Patients are unable to recognize the words they hear. In addition, they are unable to comprehend or repeat spoken words. They speak intelligently at first but over time their speech becomes a bit awkward. They are able to hear, read lips, read and write and interpret non-speech sounds (door bell).
Wernicke’s Aphasia
Caused by damage to both Wernicke’s area and the posterior language area. Patients have features of both transcortical aphasia and pure word deafness. Patients have poor language comprehension. What they say is meaningless and filled with function words (a, the, in). Patients have natural and fluent speech, with intact prosody.
Brocca’s Aphasia
Caused by damage to Broca’s area. Patients are unable to express themselves. The speed is slow, laborious, and confluent. They understand language. They are well-aware of their deficits - makes them frustrated.
3 Distinct Issues of Broca’s Aphasia
- Articulation Problems: Patients have issues with engaging in the coordinated movements necessary to make appropriate speech sounds (moving lips, tongue, jaw). A related problem is sequencing the sounds properly (saying LIKSTIP instead of LIPSTICK).
- Agrammatism: Difficulty using and understanding grammar. Grammar is important to understand when the action is happening or who is doing it.
- Anomia: Patients have a hard time coming up with the appropriate word. They think about the word, but it remains at the tip of their tongue. They describe things in a roundabout way (circumlocution).
Facial Paresis: Volitional vs Emotion
Volitional: Difficulty moving facial muscles on command. Able to move muscles in response to emotion. Damage to primary motor cortex.
Emotional: Able to move facial muscles on command. Difficulty moving muscles in response to emotion. Damage to thalamus / insular cortex.
How are emotions measured? (Behavioural, Autonomic, Hormonal)
Behavioural: Movements, Facial expression, Body language.
Autonomic: Signalling through PNS, Fight or flight response.
Hormonal: Signalling through bloodstream, e.g., endorphins linked with relaxation and lower stress.
Common Sense Theory
Perceive emotional event / stimulus –> Emotion occurs –> Physiological response
James-Lange Theory
Perceive emotional event / stimulus –> Physiological response –> Emotion occurs
Limbic System
Group of brain structures involved in feeling, perceiving, and regulating emotion. Central nucleus of the amygdala: important for inducing fear, important for recognizing emotions in others. People with bilateral amygdala damage can still feel fear, it’s just much harder to find things that will induce this.
Ventromedial Prefrontal Cortex (vmPFC)
Important for regulation of emotion: inhibition of emotion expression, fear extinction learning depends on vmPFC. Damage to vmPFC: impulsive (sometimes violently), outwardly emotional, childlike. Serotonin inhibits emotional outbursts: riskier behaviour in rhesus monkeys with low serotonin.
Strokes
Sudden interruption of blood supply to the brain.
Cause: Atherosclerosis. Plaque buildup in arteries. Often form an internal carotid artery. Risk factors: Age, high blood pressure, high cholesterol. Decreases blood flow. Increases blood pressure.
Ischemic Stroke
Blocked artery: blocks blood flow in artery in brain. Thrombus: Clot forms within blood vessel. Embolus: Clot breaks away from origin & occludes artery.
Hemorrhagic Stroke
Ruptured artery: bleeding around the brain (i.e., hemorrhage). High blood pressure: pressure in artery builds up, causes wall of blood vessel to rupture.
Ischemic Stroke Treatments
- “Clot-busting” drugs (thrombolytics): Dissolve clot & restore blood flow. Tissue plasminogen activator (tPA). Short time window (3-4 hours).
- “Clot removal”: thrombectomy.
Hemorrhagic Stroke Treatments
- Surgery: Repair the blood vessel.
- Blood Pressure Management: Lowering blood pressure. Decreasing pressure in the brain.
Stroke: Prognosis & Recovery
Strokes often cause permanent brain damage: depends on size of blood vessel, time-lapse from blockage/rupture until treatment. Improvement of function over time: physical therapy, occupation therapy, speech therapy, constraint-induced movement therapy.
Closed-Head Injuries (Concussions)
Caused by a blow to head with blunt object: brain moves inside skull due to impact.
1. Coup: Brain contacts inside of skull on the same side as the impact. Direct injury at point of contact.
2. Countercoup: Brain contacts inside of skull on the opposite side of the impact. Secondary injury brain bouncing back.
Open-Head injuries
Caused by penetrating brain injuries. Damaged blood vessels, increases pressure, leads to inflammation.
Traumatic Brain Injuries Results cycle
Inflammation –> Glial Cells increase (esp. astrocytes) –> Pressure increases –> Apoptosis (neuron death) –> Scarring Plaque Residue –> Seizure Disorders, Alzheimer’s Disease, Parkinson’s.
TBIs: Treatment & Prognosis
Rest!. Avoid other hits in future. Multiple hits can lead to Mild TBI. Greater risk of developing brain problems: Seizure disorders, Neurodegenerative diseases. Alzheimer’s, Parkinson’s.
Seizure Disorders
Sudden, uncontrolled, electrical disturbances in the brain. Have many causes.
Causes of seizures
Scarring: Relates to stroke, injury, tumor. Can lead to: withdrawal or reduced function of GABA receptors. This leads to Withdrawal of GABA Agonist: GABA - regulate neuronal excitability by inhibiting neuronal firing. Example Cases: alcohol, barbiturates )(sleeping aids).
Idiopathic (unkown cause). Gene Mutations (causes neural network instability). High Fevers (in children).
Seizure Disorders - GABA & Alcohol: Alcohol consumption
Higher activity of GABA receptors –> Higher inhibition in the brain –> Neurons less likely to fire
Seizure Disorders - GABA & Alcohol: Long-term alcohol abuse
Brain adapts to constant increase in GABA activity.
Reduced GABA receptor activity –> Increased excitatory neurotransmitters –> Counteract sedative effects; maintain normal brain function.
Seizure Disorders - GABA & Alcohol: Alcohol withdrawal
GABA system no longer overstimulated; compensatory changes remain. Decreased GABA receptor activity –> Increased excitatory neurotransmitters –> Imbalance (hyper-excitable state).
Partial Seizures
Begins & remains in an identifiable part of the brain (clear focus/focal area). A simple one does not lead to loss of consciousness, but a complex one does.
Generalized Seizures
Begins & involves most of the brain (no clear focus/focal area).
Grand Mal (tonic-clonic): Aura (sensation preceding seizure), Tonic (Loss of consciousness, Intense muscular contraction), Clonic (Violent, rhythmic contractions).
Petit Mal (absent): ‘Less violent’, ‘Spells of absence’ (stare into distance, blinking repeatedly), Short, More common in children.
Seizure Disorders: Treatment & Prognosis
Anticonvulsant Drugs: Benzodiazepines - increase GABA’s inhibitory effects on the brain (increases inhibitory synapses).
Most respond well to medications.
In few cases, medication doesn’t work: surgery (if seizure foci located).
Non-Malignant Brain Tumours
Has a distinct border: “Benign”. Encapsulated: Can be removed. Cannot metastasize (spread).
Malignant Brain Tumours
Does not have distinct borders. Is cancerous. Infiltrates surrounding tissues: difficult to remove, remaining cells with reproduce. Can metastasize (ie., spread).
Brain Tumours damage brain tissue in two main ways
Compression and Infiltration
Meningioma Brain Tumours
Non-malignant. Arise within tissues of the meninges. Dura mater. Arachnoid membrane - easier to remove.
Glioma Tumors
Malignant. Arise from neural stem cells that give rise to glial cells. Grow & Divide quickly: difficult to remove. More resistant to: chemotherapy and radiation. Poor prognosis: aggressive, treatment resistant.
Infections of the Brain
Certain bacteria & viruses circumvent the blood-brain barrier. This can cause encephalitis and/or meningitis. Both are brain infections, but they affect different parts of then brain.
Meningitis
Inflammation of the meninges. Due to: Bacteria, Virus. First symptoms: Headache, Stiff neck.
Encephalitis
Inflammation of the brain itself. Due to: Bacteria, Virus, Toxic chemicals, Allergic reactions. First symptoms: Headache, Nausea, Fever.
Polio, Rabies, Herpes Simplex.
Polio
Viral Disease. Causes: Destruction of motor neurone in the brain stem and spinal cord. Can lead to: muscle weakness, paralysis. Largely eradicated: vaccines.
Rabies
Viral Disease. Causes: Widespread brain damage - enter motor neurons, spread to brain. Transmitted through: Bite of infected animal.
Herpes Simplex
Common Virus (cold sores). Causes: rare cases - enters brain, causing encephalitis, and brain damage.
Developmental Disorders - Toxins, Viruses, Drugs
Insecticides, Heavy metals (lead, mercury). Impairs fetal development: intellectual disability. Fetal Alcohol Syndrome: alcohol consumption in 3rd & 4th week of pregnancy - born prematurely, smaller birth size, distinct facial features, delayed development.
Developmental Disorders: Inherited Metabolic Disorders
“Inborn errors in metabolism”. Caused by: Gene mutations that disrupt the code (‘recipe’) for enzyme synthesis - enzyme not produced. Phenylketonuria (PKU): Absence of enzyme that converts phenylalanine to tyrosine. Tay-Sachs Disease: Absence of enzyme in lysosomes - waste buildup, cell & brain swelling.
Developmental Disorders - Congenital
Present at birth. Down syndrome: caused by extra 21st chromosome, impairs fetal development - intellectual disability, distance facial features. Increased Risk Alzehimers: after age 30, extra chromosome: overproduction amyloid-beta, forms plaques, cognitive decline.
Autoimmune Disease: Multiple Sclerosis - Characteristics
Damages myelin sheath (white matter in brain & spinal cord). Leads to: Scarring, plaques, interrupts action potentials. Sporadic disease: no obvious genetic predisposition, more prevalent in northern climates. Two hypotheses:
1. Infections Hypothesis: Childhood infections trigger immune system disruption, causing it to later attack healthy myelin.
2. Hygiene Hypothesis: Lack of early viral/bacterial exposure leads to immune system confusion, causing it to later misinterpret own myelin as harmful.
Autoimmune Disease: Multiple Sclerosis - Symptoms
Remitting-relapse MS: Cycles - symptoms false up (get worse) and recede (get better); gradually worse over time.
Progressive MS: Slow, continuous increase in symptoms and disease progression.