Biological Basis of Behavior Flashcards
(111 cards)
1
Q
Quadriplegia
A
Inability to move arms and legs
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Paraplegia
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Inability to move legs
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Paresis
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Muscle weakness
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Q
Dura mater
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Fibrous membrane that also forms the falx cerbri, which extends down longitudinal fissure that separates the 2 hemishperes
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Q
Arachnoid mater
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Thinner and more delicate membrane separated from the dura by the subdural space through which passes series of veins
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Pia mater
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Most delicate and highly vascular membrane, which closely follows the contours of brain
7
Q
Ventricular system
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Has open chambers and channels filled with CSF, which circulate thru 2 large lateral ventricles, to the centrally located 3rd and 4th ventricle, to the brain stem
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Q
Choroid plexus
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Linings of the lateral ventricles that form fluid
9
Q
CSF
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Maintains brain’s neural buoyancy in cranial vault and is important in protecting from infection and regulates blood flow in brain
10
Q
Cortex
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6 layers that forms the outer layer of the brain; aka gray matter
11
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Frontal lobe
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Largest, governs output, higher cortical and cognitive functioning.
Subdivisions include primary motor cortex, premotor cortex, orbitofrontal cortex, and prefrontal cortex – regions devoted to attention, cognition, reasoning, problem solving, and voluntary movement.
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Primary motor cortex
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Initiation of motor movements and isolated muscle groups are specifically represented along surface of gyrus.
Relative representation corresponds directly to the requisite accuracy of motor control.
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Premotor cortex
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Initiation and execution of limb movements in conjunction with input from other cortical regions.
Mirror neurons here associated with imitation and empathy.
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Q
Prefrontal and orbitofrontal regions
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Higher-level cognitive functions (executive functions) which includes reasoning, planning, and judgment
15
Q
Broca’s area
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In inferior lateral region of the left frontal lobe.
Fluent production of oral and written speech + grammar and comprehension of syntax. Damage here –> Broca’s (expressive) aphasia.
16
Q
Superior temporal gyrus
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Auditory processing where conscious perception of sound occurs. Aka Heschel’s convolutions.
Reception of stimuli in this region is considered tonotopic, which corresponds to individual frequencies detected at the level of cochlea. Stimuli arrive by way of vestibulocochlear nerves and medial geniculate nuclei of thalamus.
17
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Decussation
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Process by which incoming stimuli are transmitted to contralateral hemisphere for processing.
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Auditory association cortex
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Where sound is processed further.
19
Q
Wernicke’s area
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In language-dominant hemisphere. Dedicated to comprehension of language. Damage –> disruption of ability to comprehend and meaningfully express language. Aka Wernicke’s (receptive) aphasia.
20
Q
Parietal lobes
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Include site of primary somatosensory processing.
Process visual information along dorsal and ventral pathways from occipital lobes to help coordinate movement and behaviors with the environment.
Damage –> neglect syndromes like hemispatial neglect – inability to attend to features of environment in the space contralateral to lesion site.
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Heteromodal cortex
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Within parietal lobes where sensory modalities are integrated to construct a complete picture
22
Q
Primary somatosensory processing
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Somatotopic detection of touch, pressure, pain, and temperature takes place.
23
Q
Occipital lobes
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Visual processing.
Primary visual processing located in region of occipital pole. Phototopic in nature, receiving stimuli from retina and optic nerve by way of lateral geniculate nucleus of the thalamus.
24
Q
Primary visual striate (cortex)
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Color and movement processed here. Then send for further processing and integration along dorsal stream to parietal regions for object location and ventral stream to temporal regions for object identification.
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Hippocampus
Region in inferior temporal lobe. Critical for memory formation (i.e., transfer of memories to LT stores).
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Amygdala
Processes emotions. Its connections to midbrain structures make it essential component of fight-or-flight response.
Also processes olfactory stimuli.
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Thalamus
Performs critical relay functions b/w the cortex and brain stem.
Specific nuclei or nerve cells form specific transmission sites in thalamus to and from specific cortical regions.
Also performs important attention and perceptual functions.
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Basal ganglia
Network of complex loops involved in motor output (i.e., descending motor pathways), emotions, cognition, and eye movements.
Includes caudate nucleus, putamen, global pallidus, subthalamic nucleus, and substantia nigra.
Cerebral cortex provides most of the input to basal ganglia, and primary outputs of basal ganglia to thalamus.
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Extrapyramidal syndromes
Abnormalities in basal ganglia of coordination and rhythm of movement.
Parkinson's and Huntington's result from abnormalities in basal ganglia.
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Bradykinesia
Slow movements
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Brain stem
Inclusive of medulla, pons, and midbrain.
Pons (or bridge), followed by medulla, is essentially contiguous with spinal cord.
As a unit, brain stem is involved in control and regulation of autonomic functions and maintaining homeostasis - including breathing, HR, temperature, and BP.
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Reticular formation
Includes reticular activating system. Plays role in alertness, consciousness, and pain. Also role in regulating respiratory and CV systems.
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Cerebellum
Comprises gray matter cortex and subcortical white matter with interconnections to cortical regions of other hemispheres of brain. Associated w/ regulation of movement (automatic and rhythmic), coordination of limbs, and postural control.
Divided into superior, middle, and inferior cerebellar peduncles.
Middle cerebellar peduncle: only structure visible on surface of brain.
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Neuron
Consists of cell body (contains nucleus), dendrites, and axons. Most neurons are multipolar - multiple dendrites and axons.
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Myelin sheath
Insulating fatty later that surrounds axon and speeds up transmission.
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Synapse
Space b/w 2 neurons where chemical/electrical communication occurs.
Mostly, the axon from one neuron communicates with the dendrites of another.
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Neurotransmitter
Chemicals released presynaptically by axon terminal of one neuron and bind to NT receptors on postsynaptic neuron --> postsynaptic excitation or inhibition.
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Action potential
When postsynaptic excitation reaches minimum threshold and causes neuron to send signal down its axon.
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All-or-nothing phenomenon
Firing of neuron; strength of firing doesn't vary in response to strength of input.
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Biogenic amines
Smaller molecular messengers that include acetylcholine and serotonin
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Catecholamines
Smaller molecular messengers that include dopamine, norepinephrine, and epinephrine
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Amino acids
Smaller molecular messengers that include gamma-aminobutryic acid (GABA) and glutamate
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Neuropeptides
Larger molecules including vasopressin, oxytocin, and substance P
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Norepinephrine (NE)
Functions as hormone and NT. Formed in brain stem at the locus coeruleus and is found in the sympathetic NS and CNS. Underlies fight-or-flight response and is released into blood by adrenal gland in response to stress or arousal. Primarily excitatory.
Regulates mood, memory, alertness, hormones, and ability to feel pleasure.
Low levels = depression
High levels = anxiety
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Dopamine (DA)
Both excitatory and inhibitory. Majority of neurons in the substantia nigra. Pathways extend to frontal lobes, basal ganglia, and hypothalamus.
Role in emotions, movement, endocrine functioning, attention, sociability, motivation, desire, pleasure, and reward-driven learning.
Overactivity of DA in frontal lobes implicated in schizophrenia. Loss of DA-producing neurons in basal ganglia pathway underlying cause of PD. Underactivity also implicated in ADHD.
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Serotonin (5-HT)
Primarily inhibitory. Widely distributed throughout brain and originates in raphe nuclei in brain stem. Pathways extend to limbic system.
Associated with regulation of mood, anger, aggression, anxiety, appetite, learning, sleep, sexual functioning, level of consciousness and pain.
Low levels = depression, OCD, anxiety.
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Acetylcholine (ACh)
Major role in PNS and ANS. Primary NT at the neuromusclar junction (synapse b/w neuron and muscle cells). Involved in movement.
Activates brain through reticular activating system and regulates alertness and attention.
Degeneration of ACh in striatum associated with movement d/o like Huntington's disease.
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Gamma-aminobutryic acid (GABA)
The major inhibitory NT of the CNS. Widely distributed throughout CNS but mostly concentrated in striatum, hypothalamus, spinal cord, and temporal lobes.
Associated with emotion, balance, and sleep patterns.
Low levels = high anxiety and agitation, epilepsy
High levels = reduction in anxiety
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Glutamate
Brain's primary excitatory NT. Widely distributed through CNS. Basic building block of proteins.
Important for learning and memory.
Excessive glutamate --> excitotoxicity (cell death d/t excessive stimulation/excitation); implicated in cell death following TBI and stroke.
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Agonist
Chemical that binds to receptor site and mimics activity of a NT --> causes same downstream effect as the NT --> boosts its overall system.
Partial agonist: doesn't produce 100% of the effect of agonist.
Inverse agonist: binds to same receptor site as agonist but has opposite effect of full agonist by causing reduction in overall efficacy of a NT system.
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Antagonist
Blocks or reverses effect of agonist or inverse agonist. But when no agonist is present, antagonist have no effect on their own.
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Pharmacodynamics
Biochemical and physiological effects of drugs on the body.
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Pharmacokinetics
How body handles drug thru absorption, distribution, metabolism, and elimination.
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Absorption
Occurs when drug reaches bloodstream (mainly in small intestine). Results in drug's onset and degree of action.
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Distribution
Blood stream transporting the drug to site of action. Speed of distribution varies depending on how drug is administered.
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Metabolism
Body recognizes drug as foreign and attempts to eliminate it via chemical transformation. Mainly occurs in liver.
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Elimination
Function of renal and hepatic processes. Half-life of drug is time it takes for drug concentration to decrease by half d/t excretion and metabolic change.
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Therapeutic window
Range of drug dose that can result in desired clinical efficacy without unsafe side effects
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Anxiolytics
Used to treat anxiety and are classified into benzo and nonbenzo.
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Benzodiazepines
Include alprazolam (Xanax), clonazepam (Klonapin), diazepam (Valium), and lorazepam (Ativan).
Sometimes used as sleep agents or treatment for seizure disorders and alcohol withdrawal.
Act thru CNS and can cause muscle relaxation as well as sedative, anxiolytic, and anticonvulsant effects. Enhance action of GABA and block rapid release of stress hormones.
Side effects include drowsiness, confusion or feelings of detachment, dizziness, imbalance, and high potential for dependence. Increase effects of alcohol and other CNS depressants.
Must be tapered slowly.
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Nonbenzodiazepine
Buspirone (Buspar)
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Barbiturates
Formerly used for sedation but have been replaced by benzos.
Side effects include tolerance, physical dependency, and severe withdrawal sxs.
Also enhance function of GABA in CNS.
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Antidepressants
Have different mechanisms of actions and generally don't cause dependence, tolerance, or addiction. Include class of NT called monoamines (NE, 5-HT, and DA).
Used to treat depressive disorders, anxiety, ADHD, and eating disorders.
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Monoamine hypothesis
Depression caused by abnomral fx of NTs NE, 5-HT, and DA.
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Tricyclic antidepressants
Characterized based on chemical 3-ring structure. Include amitriptyline (Elavil), nortriptyline (Pamelor and Aventyl), imipramine (Tofranil), and desipramine (Norpramin).
Absorption occurs in small intestine and peak levels occur in 2-8 hours following ingestion. Block reuptake of 5-HT and NE.
Side effects including cardiac/autonomic, anticholinergic, and neurobehavioral changes
Orthostatic hypotension one of the most common reasons for discontinuing.
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Monoamine oxidase inhibitors (MAOIs)
Block reuptake of monoamine NTs (5-HT, NE, and DA) . Include phenelzine (Nardil) and tranylcyromine (Parnate).
Most dangerous side effect is hypertensive crisis.
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SSRI
Selective b/c they have weaker affinity for blocking action of other monoamines.
Include fluoxetine (Prozac), fluvoxamine (Luvox), sertraline (Zoloft), citalopram (Celexa), and escitalopram (Lexapro).
Less likely to cause anticholinergic and cardiac/autonomic side effects. But side effects include GI side effects, headache, sexual dysfx, insomnia, psychomotor agitation, and occasional extrapyramidal reactions.
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Norepinephrine-dopamine reuptake inhibitors (NDRIs)
Newer meds that include bupropion (Wellbutrin)
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SNRIs
Include venlafaxine (Effexor)
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Over-the-counter antidepressant products
Include St. John's wort, S-adenosyl methionine (SAME-e), 5-HTP, Omega-3 fatty acids, and folic acids.
Can take Omega-3s and folic acid with antidepressants.
Side effects: St. John's wort --> reduced effectiveness of oral contraceptives; Omega-3 --> risk of bruising and bleeding.
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Antipsychotics
All traditional meds block DA receptors, whereas atypical also block 5-HT receptors.
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Conventional (typical/first-gen) antipsychotics
Include haloperidol (Haldol), thioridazine (Mellaril), molinidine (Moban), thiothixene (Navane), fluphenazine (Prolixin), trifluoperazine (Stelazine), and chlopromazine (Thorazine). All have equal efficacy but differ in potency and side effects.
Side effects: extrapyramidal sxs including parkinsonism, acute dystonia, akathisia, and tardive dyskinesia. --> First 3 side effects result from early drug reactions. TD, results from LT-use. Also Neuroleptic malignant syndrome -- rare but life-threatening with catatonia, stupor, fever, and autonomic instability.
Other side effects: orthostatic hypotension, sexual dysfx, sedation, anticholinergic effects (dry mouth, constipation, difficulty w/ urination).
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Parkinsonism
Includes bradykinesia (slowed movements), tremor, and rigidity.
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Acute dystonia
Muscle spasms in tongue, face, neck, and back
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Akathisia
Restless movements and sxs of anxiety and agitation.
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Tardive dyskenisia
Abnormal involuntary, stereotyped movements of face, tongue, trunk, and extremities. May be irreversible
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Atypical (2nd-gen) antipsychotics
Block DA and 5-HT receptors. May produce milder extrapyramidal sxs but can have dangerous metabolic effects like weight gain, diabetes, and dislipidemia.
Include olanzapine (Zyprexa), quetiapine (Seroquel), ziprasidone (Geodon), aripiprazole (Abilify), paliperidone (Invega), iloperidone (Fanapt), asenapine (Saphris), clozapine (Clorazil), and risperidone (Risperdal).
Clozapine one of the more effective atypicals but most dangerous. Fatal agranulocytosis (low white blood cell count).
Risperidone is first-line tx for new onset schizophrenia + agitation and aggression in dementia and BP d/os. Also FDA approved to minimize self-harm in autism and disruptive bx d/os.
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Lithium
first mood-stabilizer approved for acute mania/hypomania. Effective in preventing relapse in BP d/o.
Suspected mechanism of action involves NE and 5-HT. Slow onset of action and narrow therapeutic index.
Side effects: nausea, diarrhea, vomiting, thirst, excessive urination, weight gain, and hand tremor. Plus reversible increase in white blood cell count.
Chronic side effects: hypothyroidism, goiter, and rarely kidney damage.
Toxicity may result in lethargy, ataxia, slurred speech, shock, delirium, coma, or death.
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Other mood stabilizers
Include antipsychotics and anticonvulsants. Atypicals like Zyprexa and Abilify approved for acute and maintenance tx of mania. Symbyax is FDA approved for tx of depression in BP.
Anticonvulsants include divalproex (Depakote), lamotrogine (Lamictal), carbamezepine (Tegretol), and topiramate (Topamax). Work by enhancing actions of GABA. Side effect of Lamictal is Stevens-Johnson syndrome -- potentially fatal skin rash.
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Opiates
Natural or synthetic compounds from opium poppy. Natural include opium, morphine, and codeine. Semisynthetic include morphine, heroin, Percodan (oxycodone hydrochloride and aspirin) and Dilaudid (hydromorphone hydrochloride).
Used to relieve pain and anxiety. LT use changes the way nerve cells work in brain which can lead to withdrawal sxs when discontinued suddenly (diarrhea, vomiting, chills, fever, tearing and runny nose, tremor, abdominal cramps, and pain).
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Opioids
Drugs with opium-like mechanisms of action.
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Psychostimulants
Increase prefrontal cortex levels of NE and DA and are primarily used to treat ADHD.
Amphetamine (Adderall), methylphenidate (Concerta), and modafinil (Provigil), also used for sleep disorders like narcolepsy.
Side effects include insomnia, headache, tics exacerbation, nervousness, irritability, overstimulation, tremor and dizziness, weight loss, abdominal pain or nausea, slow growth in children, and blurred vision.
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Computerized tomography (CT)
Uses x-rays to look at slices of brain, providing info on density of brain tissue + images of soft tissues, liquid, air, and bone.
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Hyperdense
Brighter areas on CT scan
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Hypodense
Darker areas on CT scan
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Isodense
Areas of intermediate density on CT
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Magnetic resonance imaging (MRI)
Uses magnetic fields that cause protons to align themselves in response to magnetic field's line of force. Described in terms of intensity or brightness of signal (hyper/hypointense areas).
Preferred for detecting small lesions like plaques in pts with MS, subtle tumor, or chronic hemorrhage.
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Neuroangiography
use to visualize lesions of blood vessels through radiographs and injection of contrast material in vasculature. Gold standard for eval of vascular diseases in head, neck, and spine like atherosclerotic plaques and other vessel narrowings, aneurysms, and arteriovenous malformation.
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Wada test
example of neuroangiography that helps localizing language fx and aids in presurgical planning, particularly in pts w/ epilepsy who are undergoing brain resection.
Amobarbital is selectively infused into each carotid artery while pt is awake, which puts other hemisphere to sleep so that various cognitive fxs can be assessed in that hemisphere.
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Electroencephalography (EEG)
Original method for measuring brain activity. Uses small metal disk that records electrical activity of neurons in brain area that is attached to scalp. Electrical impulses are amplified and displayed on paper using chart recorder.
Useful in detecting widespread abnormality in brain fx in sleep, anesthesia, coma, TBI, and epilepsy.
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Positron Emission Tomography (PET)
Uses small amounts of injected radioactive material to measure regional cerebral blood flow via glucose metabolism or oxygen consumption.
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fMRI
Detects functionally induced changes from blood oxygenation.
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Aphasia
Acquired disorder of language and can affect expressive or receptive speech, reading (alexia), and/or writing (agraphia).
Syndromes subdivided into 3 classifications
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Fluent aphasia
Speech is fluent but difficulties w/ comprehension and/or repetition of words/phrases spoken by others
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Nonfluent aphasia
Expressive speech notable for poor articulation or grammar but comprehension is relatively preserved
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Pure aphasia
Select aspects of language are affected such as reading and writing.
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Wernicke's aphasia
sensory aphasia or receptive aphasia where primary deficit is inability to understand language. Ability to repeat others also impaired. Lesion typically in left temporal lobe.
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Transcortical sensory aphasia
Comprehension is poor but person can repeat what others say.
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Broca's aphasia
(Motor or expressive aphasia) where person speaks slowly, with poor grammar, and limited prosody. Only keywords are used and use of verbs or connecting words is limited.
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Transcortical motor aphasia
Person able to repeat what others say.
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Conduction aphasia
Speak normally, name objects, understand speech, but repeat what others say.
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Anomic aphasia
Focal deficit in naming objects despite ability to produce meaningful speech, comprehend speech, and repeat speech.
Angular gyrus thought to be affected.
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Global aphasia
All aspects of language are impaired including expressive speech, comprehension, repetition, reading, and writing.
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Alexia
Acquired inability to read. Usually d/t stroke in posterior region of left hemisphere, affecting posterior region of corpus callosum, disconnecting visual centers of brain from language centers of the brain.
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Agraphia
Acquired disorder of writing. May affect spelling, grammar, letter formation, or visuospatial errors (e.g., poor spacing or orientation of letters).
Different types of agraphia are usually classified based on accompanying symptoms such as alexia, apraxia, or visuospatial disorders.
The site and extent of damage can range from
parietal lobe, frontal lobe, corpus callosum, and subcortical structures.
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Apraxia
Acquired disorder of skilled, purposeful movement not due to
a primary motor or sensory impairment such as paresis or paralysis.
In some cases, the action may be carried out accurately but in a clumsy manner, and in other forms of apraxia, the person may commit errors such as performing sequenced actions in the wrong order (such as sealing an envelope before placing the letter inside).
The lesion site may vary depending on the type of apraxia but is usually in the left hemisphere.
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Dementia
Umbrella term that refers to decline in 2 or more areas of cognitive fx resulting in significant impairments in ADLs.
In DSM-5, dementia is replaced by neurocognitive disorder.
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Alzheimer's disease (AD)
Most common dementia in 65 and older (approx. 10%). Nearly half of those 85 and older.
Decline in memory and at least one other cognitive domain; progressive, steady decline in cognition, and no evidence of mixed etiology.
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Cholinesterase inhibitors
Medications used to treat AD that prevent breakdown of ACh. Include galantamine, rivastigmine (Exelon), and donepezil (Aricept).
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Stages of AD
Early (1-3 years): mild impairments in memory, particularly new learning and retention of new memories over time. Also visuospatial fx (e.g., topographic disorientation and difficulty w/ construction) and language (e.g., word finding and naming).
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Pick's disease
Cortical dementia that is caused by degeneration of the frontal and temporal lobes of the brain. This and other FTDs characterized by personality changes like bx disinhibition and executive dysfx and language abnormalities.
Distinguishable on autopsy by Pick inclusion bodies found in cortical and hippocampal neurons in frontal and anterior temporal lobes.
