SF2 Unit 4 Memorization Flashcards
Projection Neuron
Second-order neuron with axon in Ascending Spinothalamic Tract
Interneurons: Inhibit or Excite Projection Neurons
inhibit (when active)
Neurotransmitters used by Nociceptors on projection Neurons
Gluatamate
Substance P
Calcitonin Gene-Related Peptide (CGRP)
Classes of Endogenous Opioids
Enkephalins
Dynorphins
Endorphins
Type of Receptor: Opioid Receptors
G-Protein Coupled
C Sensory Fibers
from nociceptors
Type of Fibers from Non-Nociceptor Receptors
A-Alpha or A-Beta
Principle opioid in dorsal horn
enkephalin (mu receptor type)
High concentration of Mu-type Opioid Receptors
Periaqueductal Gray
Caused of Pain Wind-Up
Repeated firing of C-fiber nociceptors
Hyperalgesia
Abnormally increased sensitivity to pain
Released by Microglia during inflammation
Interleukins
Brain-Derived Neurotrophic Factor (BDNF)
Discussed Types of Non-Opiate Analgesic Drugs
Antidepressants
NMDA Receptor Antagonists (ex: Ketamine)
Anticonvulsants
Rostral portion of developing neural tube; precursor to Telencephalon and Diencephalon
Prosencephalon
Diverticulation
Process of Rostral Neural Tube differentating and expanding faster than caudal portion
Primary cell type in Neocortex
Pyramidal Cells
Apical dendrite of Pyramidal Cells is in the Cortex. Where does it send inferior axons?
Corpus Callosum (white matter tract)
Columns (Cortex)
Vertical organization / functional unit
Columnopathy
Disorder of columnar development in Cortex
ex: Autism Spectrum Disorder
Primary Center(s) for Olfaction in Cortex
Piriform and Entorhinal Cortices
Unimodal Association COrtical Area
Adjacent to primary cortical area; modality-specific
Heteromodal Association Cortex
Receive/process input from multiple modalities; “higher-order” function
Disconnection Syndromes
Impairments in fibers that connect cortical regions
Cortical Signs Associated with Dominant Hemisphere Damage
Agraphia
Acalcia
Alexia (Pure and other)
Acalcia
Inability to perform simple math (Parietal lobe lesion)
Alexia w/agraphia. Lesion?
Left angular gyrus (dominant parietal lobe)
Pure Alexia. Lesion?
Left occipital lobe and splenium of corpus callosum
Typical sign of Damage to Non-Dominant Cerebral Hemisphere
Neglect
Construction Apraxia is an early finding in…
Alzheimer’s Disease
Damage to this structure can typically cause Hypersexuality and Hyperaggression
Amygdala
Non-Cortical Lesion which can cause Homonymous Hemianopia
Damage to Internal Capsule or Lateral Geniculate Nucleus
Destructive Eye Deviation
Deviation toward lesion.
Lesioned Frontal Eye Field (Area 8)
Irritative Eye Deviation
Deviation away from lesion.
Cause: Seizure
Apraxia
Loss of ability to carry out voluntary movement despite intact primary sensory, motor, and language areas
Cause: Subcortical Apraxia
May occur due to damage to Subcortical Extrapyramidal Motor System or Thalamus
(Cause of false localization of Apraxia to cortex)
Frontal Release Sign
Unmasking of Infantile reflexes by Frontal Lobe
Palmar Grasp, Sucking, Glabellar, Snout, Rooting Reflexes (dont memorize)
Dorsal Stream of Visual Processing
“Where” Stream
Motion and spatial information travelling dorsally from primary visual cortex to parietal lobe. Area 17 (V1) to Parieto-Occipital Association Cortex (V5)
Ventral Stream of Visual Processing
“What” Stream
Information about size, shape, color, etc. Travels ventrally to Temporal Lobe. Area 17 (V1) to Occipitotemporal Association Cortex
Object Agnosia
“Classic Agnosia”. Loss of ability to recognize objects by sight
Cause: Object Agnosia
Damage to Ventral “What” Stream
Types of Visual Agnosia Associated with Left Occipital/Temporal Damage
Apperceptive - Failure of Perception
Associative - Failure of recognition despite accurate perception
Prosopagnosia
Loss of ability to subscribe identity to familiar faces
Cause: Prosopagnosia
Bilateral damage to Fusiform Gyrus (Occipitotemporal Gyrus)
Akinetopsia
“Motion blindness”
Cause: Akinetopsia
Damage to lateral part of occipital lobe
Other name for Deep White Matter of Cerebral Hemispheres
Centrum Semiovale
Main Types of Tracts in Deep White Matter of Cerebral Hemispheres
Association Fibers
Commissural Pathways
Projection Fibers
Associational Fibers
Travel within hemisphere only, connecting areas within the cortex
Arcuate Fibers (U Fibers)
Connect adjacent cortical areas (gyri)
Predominant Association Fiber
Superior Longitudinal Fasciculus
Superior Longitudinal Fasciculus
Associational Fiber; Travels from anterior of front lobe to posterior of occipital lobe
Arcuate Fasciculus
Subtract of Superior Longitudinal Fasciculus in Dominant Hemisphere
Connects Broca’s and Wernicke’s Areas
Conduction Aphasia
Can speak fluently but incoherent and inappropriate responses.
Result of lesion to Arcuate Fasciculus
Inferior Longitudinal Fasciculus
Associational Fiber connecting Temporal and Occipital Poles
Cingulum Fibers
Originate from Cingulate Gyrus
Connects emotion centers and Default Mode Network with memory structures (Limbic System/Hippocampus)
Default Mode Network
Provides abilities of internal cognition, thought and dialog.
“Theory of Mind”
Understanding that we and others have similar motivations. Adjust behavior accordingly.
Structure: Default Mode Network
Uncinate Fasciculus
Association Fiber that connects Temporal and Frontal Lobes. Role in empathy and recognition
Uncinated Seizures - emotional affect and olfactory changes
Commissural Pathways
Connect the two cerebral hemispheres
Predominant Commissural Pathways
Anterior Commissure
Posterior Commissure
COrpus Callosum
Anterior Commissure
Commissural pathway connecting temporal lobe, olfactory cortices, and olfactory bulbs.
Posterior Commissure
Commissural pathway connecting Pretectal structures (Rostral Midbrain)
Corpus Callosum
Commissural pathway which connecting homotypic (“same type”) areas of the cortices/hemispheres
What can a defect in development or resection of the Corpus Callosum lead to?
Disconnection Syndromes
Projection FIbers
Afferent and efferent pathways that carry information between the brain and spinal cord
Capsule (Cerebral Structure)
Fiber bundle traveling through space in cerebrum
Corona Radiata
Name for structure formed when fibers fan out to fill hemisphere after traversing capsules
Internal Capsule
(Projection) Fiber tract between Thalamus and Lenticular/Lentiform Nucleus
Parts of the Internal Capsule
Anterior Limb
Genu
Posterior Limb
Anterior Limb of Internal Capsule (tracts)
Most tracts to and from frontal lobe. Includes Frontothalamic and frontopontine tracts
Genu of Internal Capsule (tracts)
Corticobulbar Fibers
Posterior Limb of Internal Capsule (tracts)
Corticospinal, sensory, and visual/optic radiations. Auditory Radiations.
Retrolenticular portion is here somewhere visual/auditory
Blood Supply: Anterior Limb of Internal Capsule
ACA
Blood Supply: Genu of Internal Capsule
Lenticulostriate Branches of MCA
Blood Supply: Posterior Limb of Internal Capsule
Lenticulostriate Branches of MCA
This-walled arteries susceptible to stroke in brain
Lenticulostriate Branches of MCA
Blood Supply: Basal Ganglia
Lenticulostriate Branches of MCA
External Capsule
Lateral to Internal Capsule (separated by Lentiform Nucleus); Contains Cortico-Cortical Projections
Cortico-Cortical Projections
Cholinergic axons connecting basal forebrain to other cortical areas. Found in External Capsule
Extreme Capsule
Connects Claustrum with the Insular Cortex
Function: Claustrum
Conscious, sustained attention
Function: Insular Cortex
Consciousness, emotion, empathy, self-awareness, and also “Theory of Mind”
Principle Component of the Extrapyramidal Motor System
Corpus Striatum
Consists of structures surrounding the COrpus Callosum and the Upper Brainstem-Diencephalic Junction
Limbic Cortex
Function: Limbic System
HOME
Homeostasis, Olfaction, Memory, Emotion
Receives precortical input from all sensory systems except olfaction
Thalamus
Internal Medullary Lamina
White matter tract dividing Thalamus into 3 (medial, anterior, lateral nuclear groups)
Lateral-Posterior Nuclei of Thalamus
Ventral Posterolateral (VPL)
Ventral Posteromedial (VPM
Lateral Geniculate
Medial Geniculate
Medial-Posterior Nuclei of Thalamus
Lateral Posterior
Lateral Dorsal
Pulvinar
Functional Divisions of Thalamus
Anterior/Medial: Limbic
Anterior/Lateral: Motor
Posterior/Medial: Multimodal
Posterior/Lateral: Sensory
Ventral Posterolateral (VPL) Nucleus
Thalamic nucleus; sensory from body (medial lemniscus, spinothalamic tracts)
Ventral Posteromedial (VPM) Nucleus
Thalamic nucleus; Sensory from head (Trigeminal sensory pathway)
Lateral Geniculate Nucleus
(Thalamus) Target for retinal axons. Optic radiations to Primary Visual Cortex
Medial Geniculate Nucleus
(Thalamus) Sends auditory radiations to Primary Auditory Cortex
Typical trend with Thalamic syndromes
Association with sensation and pain
Paresthesia
Aberrant positive sensations (tingling/numbness)
Dejerine-Roussy Syndrome
Thalamic Pain Syndrome
Initial presentation complete contralateral lack of sensation. Progression to severe pain. Typically from stroke
Dysesthesia
Abnormal, unpleasant sense of touch.
Thalamic sign
Allodynia
Subtype of Dysesthesia. Painful sensation induced by normally-innocuous stimuli
Possible thalamic sign
Hemianesthesia
Contralateral loss of sensation
Could be from damage to VPL or VPM
Cortical area remodeled by chronic pain
Prefrontal Cortex
Catecholamin-o-Methyltransferase
Gene/protein involved in pain sensitivity. Regulates enkephalin and catecholamines
Frank Congeital Insensitivity to Pain
Complete lack of A-delta and C fibers. Lack affective component of pain
Congenital Indifference to Pain
Can distinguish sharp/dull pain. Indifferent to sensations. Lack emotional responses, discomfort, and normal withdrawal from pain.
Normal peripheral fibers
Congenital Insensitivity to Pain w/Anhydrosis
Lack pain fibers due to a receptor mutation (cannot bind Nerve Growth Factor). Mutated TRK Receptor makes carrying pain impulse difficult. Difficulty responding to tissue damage/infection
TRK Receptors
Nerve Growth Factor (NGF) receptor found on Nerve and Mast Cells.
Importance of Mu Opioid Receptor
Most analgesics require Mu activation to work
Naloxone
Antagonizes and block Mu opioid receptor
Mechanisms of the Placebo Effect
1) Decreased awareness in pain sensitive regions
2) Increased activity in areas involved in top-down pain suppression
Receives projections from Periaqueductal Gray. Abundants 5-HT neurons. Descending projections modulate response to noxious stimulus in Dorsal Horn neurons
Dorsal Raphe Nucleus
Nociceptive Pain
Pain transmitted to CNS from peripheral receptors
Neuropathic Pain
Pain likely derived from nerve injury in CNS/PNS
Phantom Pain
Pain memory. Continuing pain after amputation
Most prominent gray matter loss in Chronic Pain
Dorsolateral Prefrontal Cortex
Timeline of Behavioral Effects of Chronic Pain
Stage 1: Acute Pain
Stage 2: Learned Helplessness
Stage 3: Acceptance of “Sick Role”
FDA-approved SNRIs for peripheral diabetic neuropathy
Venlafaxine and Duloxetine
Stroke
Acute impairment of blood supply
Ischemic Stroke
Loss of blood supply to regions of brain, leading to infarction
Infarction
Tissue death (necrosis) from lack of blood supply
Broad categories of Ischemic Stroke
Embolic and Thrombotic Stroke
Embolic Stroke
Masses (cholesterol/plaques) travel through circulatory system to block small diameter brain vessels
Thrombotic Stroke
Build-up of Atherosclerotic plaques within vessel walls. Gradual occlusion (as opposed to sudden)
Treatment: Ischemic Stroke
Tissue Plasminogen Activator (tPA). Can break-up clots if administered within 3 hours
Hemorrhagic Stroke
Weakening of blood vessel walls leads to rupture then bleed
Intracerebral Hemorrhage
Internal bleeding in the brain
Subarachnoid Hemorrhage
Rupture of surface blood vessels and build-up of blood/pressure in subarachnoid space. Characterized by sudden onset and ‘Thunderclap Headache’
Neonatal Intraventricular Hemorrhage
Bleeding into the ventricles. Elevated risk in premature / low birth weight infants due to autoregulation difficulty
Presentation: Neonatal Intraventricular Hemorrhage
Seizure, altered consciousness, and coma
Epidural Hematoma
Occasionally follows spontaneous hemorrhage. Rupture of Middle Meningeal Artery. Hematoma does not cross suture lines
Subdural Hematoma
Rupture of bridging veins. May cross suture lines
Hematoma seen in Shaken Baby Syndrome
Subdural Hematoma
Intraparenchymal Hemorrhage
Result of systemic/chronic hypertension. Can be secondary to reperfusion injury after ischemic stroke. Commonly impacts putamen, pons, thalamus, and cerebellum
Defining Feature: Charcot-Bouchard Microaneuryisms
Intraparenchymal Hemorrhage
Typical rupture in Intraparenchymal Hemorrhage
Lenticulostriate Branches of MCA
Ischemic Core
Area immediately impacted by loss of blood flow. Difficulty maintaining ionic homeostasis. Neurons fire in massive bursts (anoxic depolarization)
Anoxic Depolarization
Massive bursts of neuronal activity in Ischemic Core
Ischemic Penumbra
Periphery of Ischemic core; can be recruited into necrotic area if blood supply not returned
Excitotoxicity from Ca2+ and Glutamate released by Anoxic Deplorization in core.
Peri-Infart Depolarizations
Ischemic Penumbral neurons undergo successive rounds of depolarization for hours/days after initial event. Due to local Calcium and Glutamate increase
Cortical Spreading Depression
Region outside of Ischemic Core+Penumbra. Shorter depolarizations, Can go without damage
Eosin
Pathognomic (condition-specific) stain for stroke-lesioned brain tissue. “Dead reds”
Immediate imagery in stroke
Non-Contrast CT scan. Used to rule out Hemorrhagic Stroke prior to tPA administration
Imagery to localized stroke
CT scan or Diffusion-Weighted MRI
Cause: Cerebral Hypoperfusion
Typically heart failure
Cause of Syncope (fainting)
Cerebral Hypoperfusion
Lacunar Infarct
Stroke at terminal point of small artery resulting in small infarcted area
Watershed Infarct
Occlusion between two major arterial distributions. Combined symptoms from both supplies.
Ex: MCA/PCA
Transient Ischemic Attack
Acute episode typically resolved within 30 mins or up to 24 hours. Predictive of major stroke
Amaurosis Fugax
“Veil” coming down over one eye. Occlusion of Central Retinal Artery. Indicative of Transient Ischemic Attack
Abulia
Loss of willpower / ability to act voluntarily
Akinetic Mutism
Slowed/absent body movement and/or speech
Cause: Urinary Incontinence
ACA Stroke (genital representation on homunculus)
Area of Hippocampus sensitive to Ischemic Hypoxia
CA1 (pyramidal excitatory neurons)
Reason for Macular Sparing in PCA stroke
That part of the occipital lobe receives dual MCA/PCA supply
Occlusions associated with Thalamic Stroke
1) Penetrating Branches of PCA
2) Posterior Communicating Artery
3) Anterior Choroidal Artery
Weber’s Syndrome
Basal Midbrain Sydrome
Claude’s Syndrome
Tegmental Midbrain Sydrome
Benedikt’s Syndrome
Weber + Claude’s Syndrome
Wallenburg’s Syndrome
Lateral Medullary Syndrome
Typical Signs in Cerebellar Stroke
Inabiltiy to walk and ataxia. Also: dizziness, headache, nausea, vomiting
Four Brain Waves
Alpha, Beta, Delta, Theta
Beta Waves
Smallest amplitude. 13-30 Hz Associated with mental activity, alert wakefulness, and REM sleep
Alpha Waves
8-13 Hz. Relaxed wakefulness. Most prominent over Parietal and Occipital Lobes.
Theta Waves
4-8 Hz. Most prominent in the young > adult. Awake, drowsy and non-REM sleep states
Delta Waves
0.5-3.5 Hz. Non-REM sleep
Current Sink
Transient, local excess of (-) charge
Current Source
Transient, local excess of (+) charge
Determinant of EEG amplitude
Synchronization of firing
Sensory Evoked Potential
Average of EEGs recorded during the sensory stimulus
Seizures
Caused by abnormal patterns of neuronal activity
Epilepsy
Set of diseases characterized by chronic, repeated seizures
Partial Seizure
Restricted to one area of the brain
Simple Partial Seizure
Retain consciousness but may experience unusual feelings/sensations
Complex Partial Seizure
Change of consciousness, including dreamlike experience or loss of consciousness. May be accompanied by Automatisms
Automatisms (Seizures)
Repetitious behaviors such as blinking, twitches, mouth movements, walking in a circle
Aura
Sensation warning of impending seizure
Secondary Generalizations
Spreading of Partial Seizure from well-defined focal area to involve other brain areas
Generalized Seizures
Abnormal activation of many areas of the brain. Loss of consciousness. May trigger falls, loss of muscle tone, or massive muscle spasms.
Absence Seizures
Appear to be staring into space; may exhibit muscle jerking or twitching
Tonic Seizures
Stiffening of muscles esp: back, legs and arms
Clonic Seizures
Repetitive jerking movements of muscles on both sides of the body
Atonic Seizures
Loss of normal muscle tone; patient may fall down
Tonic-Clonic Seizures.
Stiffening of muscles esp: back, legs and arms. Repetitive jerking movements of muscles on both sides of the body (COMBINATION OF TWO)
Postictal Depression
Period of depression, with disorientation, drowsiness, or confusion, and altered EEG which may follow a seizure
Medication for Epilepsy
Approach 1: Barbiturates and Benzodiazepines. Attempting to enhance GABA neurotransmission
Approach 2: T-Type Ca2+ Channel and/or Use Dependent Voltage-Gated Na+ Channel Blockers. Reduce neuron ability to generate action potential bursts.
Surgery for Epilepsy
Temporal Lobe Resection. Most effective with focal epilepsy. Remove part or all of corpus callosum
Rare childhood epilepsys for which CBD is a treatment
Lennox-Gastaut Syndrome and Dravet Syndrome
Blood Supply: Inner Retina
Central Retinal Artery
Blood Supply: Choricocapillaris
Ciliary Arteries (branch of Opthalmic)
Muller Glia
Have cell bodies in Inner Nuclear Layer (Retina). Thought to be involved in synaptic formation
Primary Targets of Retinal Projections
Lateral Geniculate Nucleus
Superior Colliculus (midbrain)
Prectectum
Hypothalamus
Blood Supply: Lateral Geniculate Nucleus
Anterior Choroidal Artery + Small Branches PCA
Geniculocalcarine Tract
Primary visual pathway in brain. Connects LGN to Primary Visual Cortex. Tract fibers, known as optic radiations, travel through Retrolenticular Portion of the Posterior Limb of Internal Capsule
Divisions of Geniculocalcarine Tract
1) Upper Division (lower half of visual field); ends at Cuneus Gyrus (Upper Area 17)
2) Lower Division (upper half of visual field); ends at Lingual Gyrus (Lower Area 17)
Extrastriate Visual Pathways
Projections from Area 17 to Secondary Association Cortical Areas
Prestriate Cortex
Secondary Visual Cortex. V2. Both visual streams connect here to refine information from V1.
Superior Colliculus
Main player in Extrageniculate Pathway. Highly-sensitive to moving visual stimuli
Regulates control of Saccades (high velocity eye movements)
Superior Colliculus
Point of connection of Optic Tract to Superior Colliculus; Superior Colliculus to LGN
Brachium of Superior Colliculus
Extrageniculate Pathway
Retina -> Superior Colliculus -> Pulvinar -> Extrastriate Cortex
Works parallel to Geniculocalcarine Tract. Assimilates different types of information to construct objects in visual space
Regulates eye’s response to ambient light changes
Optic projection to Prectectum, then onward to Edinger-Westphal Nucleus
Edinger-Westphal Nucleus
Input from Pretectum. Regulates preganglionic parasympathetic fibers projection to eye.
1) Pupil Constriction
2) Lens Accomodation
3) Eye Convergence
Retinal projection to Hypothalamic
Goes to Suprachiasmatic Nucleus (Anterior Ventral Portion of Hypothalamus).
Involved in regulation of Circadian Rhythm and Hormonal Cycles
Progressive Encephalization
Evolutionary shift from retinal to primary cortical and then to higher-order visual processing
Binding Mechanism (Visual)
Combining multimodal sensation to create perception of external world
Cortical Blindness
Loss of conscious perception. Caused by lesion of Area 17 / V1
Blindsight
Ability to respond to visual stimuli even with Cortical Blindness. Thought to occur through Extrageniculate Pathway
Anton’s Syndrome
a.k.a. Visual Anosognosia
Patient denies losing vision despite Cortical Blindness
Achromatopsia
Disorder of color perception. Different from color agnosia/anomia because perception happens but failure to identify
Cause: Achromatopsia
Fusiform gyrus lesion (V4)
Metamorphosia
Distortion of size and shape. Lesion of Inferior or lateral visual association cortex
Balint’s Syndrome
Characterized by Simultagnosia, Optic Ataxia, and Ocular Apraxia.
Lesion: Bilateral lesion of Dorsolateral Parieto-Occipital Cortex (Dorsal Stream)
Simultagnosia
Perception of only a portion of visual field at a time; random shifting.
Optic Ataxia
Lack of coordination between visual input and hand movements. Inability to reach out and grab objects
Ocular Apraxia
Impaired gaze direction; difficulty initiating saccades
P-Type RGCs
(90% of RGCs) Small receptive field, sustained responses. Best suited for fine detail and color
M-Type RGCs
Large receptive field. Detection of motion
Non-M Non-P RGCs
Color-sensitive (???)
Relay Neurons in Lateral Geniculate Nucleus
Magnocellular LGN Neurons (correspond to M-Type RGCs)
Parvocellular LGN Neurons (P-Type RGCs)
Intralaminar LGN Neurons (Non-M Non-P RGCs)
Release glutamate at synapses
Stellate Cells (Visual)
Receive input from Lateral Geniculate Nucleus in Layer 4 of Primary Visual Cortex)
Blobs
Areas of high Cytochrome Oxidase concentration. Neurons in blobs have wavelength-sensitive repsonses to visual stimuli. Important in color discrimination
Channels for Information Processing in Primary Visual Cortex
1) M-Channel Neurons
2) Parvocellular, Interblob (P-IB) Channel Neurons
3) Blob Channel Neurons
M-Channel Neurons (Visual Processing)
Analyze motion.
Circular center-surround receptive fields; monocular; wavelength insensitive
Directionally Selective Cells
Allow for analysis of objects in motion
Simple Cells (Visual)
Orientation selective; respond to stimuli in specific angle in “on” zone
P-IB Channel Neurons
Analyze object shape/form. Contain Complex Cells
Complex Cells (Visual)
Highly orientation selective; No “on” and “off” zones; respond to stimulus anywhere in receptive field; small receptive field