Exam 2 Neuro

Label the hypothalamus on a mid-sagittal slice

label the thalamus on a mid-sagittal slice

label the thalamus on a horizontal slice

label the thalamus on a coronal slice

1. Gatekeeper of sensory function

2. Integrates motor information

3. Regulates cortically-mediated functions

List the three functions of the thalamus

Mood, emotion, cognition, personality, and memory

Describe the function of the major thalamic nuclei: mediodorsal

Memory, emotion, and executive function

Describe the function of the major thalamic nuclei: anterior

Complex sensory integration

Describe the function of the major thalamic nuclei: lateral (dorsal and posterior)

motor integration and coordination

Describe the function of the major thalamic nuclei: ventral (lateral and anterior)

Sensory relay

Describe the function of the major thalamic nuclei: ventroposterolateral and ventroposteromedial

Language (reading and writing), visual processing (visual reflexes)

Describe the function of the major thalamic nuclei: pulvinar

Visual Processing

Describe the function of the major thalamic nuclei: lateral geniculate nucleus

Input: afferent spinal somatosensory neurons
Output: primary somatosensory cortex

What is the inputs/outputs for the following thalamic nuclei: Ventroposterolateral

Input: midbrain, visual cortex
Output: inferior parietal lobe

What is the inputs/outputs for the following thalamic nuclei: pulvinar

Input: Midbrain, brainstem nuclei along auditory pathway
Output: primary audiory cortex

What is the inputs/outputs for the following thalamic nuclei: medial geniculate nucleus

Input: Optic Nerve (CN2)
Output: Visual cortex

What is the inputs/outputs for the following thalamic nuclei: lateral geniculate nucleus

Aphasia
Dysarthria
Disorders of consciousness
Cognitives deficits
Motor deficits

What can happen if the thalamus is damaged?

maintain homeostasis in ANS, hormones, and regulatory systems

What is the primary function of the hypothalamus?

loss of homeostasis

What happens if the hypothalamus is damaged?

The pineal gland which is a part of the epithalamus secretes melatonin which controls the sleep/wake cycle

What is the relation between the pineal gland and the sleep/wake cycle (circadian rhythms)?

HOME
Homeostasis
Olfaction: sense of smell + association with memories and emotions
Memory: short and long term, declaritive and implicit
Emotion: emotional regulation, memory, and decision making

What are the functions of the limbic system?

Reulation of
hormones
temperature
blood volume
food intake
Thirst
circadian rhythm
pleasure

What is the specific function of this limbic system region: hypothalamus

sense of smell
emotion
memory and homeostatic structures

What is the specific function of this limbic system region: olfactory bulb

supports emotional regulation, decision making, memory, and reward system

What is the specific function of this limbic system region: amygdala

Memory (short,long, declarative, implicit)

What is the specific function of this limbic system region: hippocampus

Memory

What is the specific function of this limbic system region: mammillary bodies

Emotions, memory

What is the specific function of this limbic system region: cingulate gyrus

identify these regions on a mid-sagittal slice view of the brain: hypothalamus, olfactory bulb, amygdala, hippocampus, mammillary bodies, cingulate gyrus

identify these regions on an inferior view of the brain: hypothalamus, olfactory bulb, amygdala, hippocampus, mammillary bodies, cingulate gyrus

Working memory is a type of short-term memory that is important for higher level cognition and long term memory allows us to learn information and has a huge capacity; stored for a long duration

What is the difference between working memory and long-term memory?

Explicit memory refers to the conscious retrieval of past information or experiences, whereas implicit memory refers to an unintentional or unconscious form of retrieval

What is the difference between explicit and implicit memory?

Episodic memory involves highly personal details about yourself. Semantic memory involves facts about the world that have nothing to do with you.

What is the difference between episodic and semantic memory?

Tying laces of shoe or singing a familiar song

What are some examples of implicit memory?

Henry Molaison; Case Study of Anterograde Amnesia. H.M. had brain surgery in 1953 when he was 27 yrs. old. The surgery involved removal of part of the brain known as the hippocampus to alleviate the severe symptoms of epilepsy.

Who was HM?

Cracked his skull in an injury, so Dr. Skoville removed his hippocamus which as a result took away his ability to store long-term memory and past memories

What happened to HM?

From midbrain to medulla

Where is the reticular formation?

Responds to intensity/novelty of stimuli like when you hear a familiar sound at night vs unusual
Insensitive to modality

Describe how the reticular formation is involved in cortical arousal and consciousness

Integrates cranial nerve functions with respiratory center

Describe the integrated motor function of the reticular formation for swallowing

ANS (autonomic nervous system)
Respiratory system

Name at least 2 systems that must be coordinated for successful, safe swallowing

Sensation usually involves sensing the existence of a stimulus, whereas perceptual systems involve the determination of what a stimulus is.

Describe the difference between sensation and perception

Temperature, touch, pain, and proprioception

What are the types of somatosensation?

somatotopically

How is somatosensory cortex organized?

postcentral gyrus of parietal lobe

Where is somatosensory cortex?

DRAW THE CHART

First order (pseudounipolar neurons) (PNS)
• Dendrites (receptors) in periphery (e.g., skin) (key region)
• Cell bodies in dorsal root ganglion (DRG) (key region)
• Axons enter spinal cord through dorsal root & ascend to medulla through dorsal column (key region)

Second order (CNS)
• Cell bodies in nucleus gracilis or nucleus cuneatus in medulla (key region)
• Axons cross midline in medulla(cross over)
• Continue through contralateral brain stem in medial lemniscus (key region)
• Synapse in thalamus (VPL nucleus) (key region)

Third order (CNS)
• Cell bodies in thalamus (key region)
• Axons ascend to parietal lobe (primary somatosensory cortex, postcentral gyrus) (key region)

describe the paths of the somatosensory system: dorsal column-medial lemniscus

First order (pseudounipolar neurons) (PNS)
• Dendrites (receptors) in periphery (e.g., skin) (key region)
• Cell bodies in DRG (key region)
• Axons enter spinal cord through dorsal root (key region)
• Synapse in dorsal horn (key region)

Second order
• Cell bodies in dorsal horn (key region)
• Axons cross midline in spinal cord (crossover)
• Ascend in contralateral anterior spinothalamic tract (key region)
• Anterior and lateral tracts merge
• Multiple axon collaterals to reticular formation, hypothalamus, amygdala (key region)
• Synapse in thalamus (VPL nucleus) (key region)

Third order
• Cell bodies in thalamus (key region)
• Axons ascend to parietal lobe (primary sensory area), anterior cingulate, insula (key region)

describe the paths of the somatosensory system: anterior spinothalamic

First order (pseudounipolar neurons) (PNS)
• Dendrites (receptors) in periphery (e.g., under the skin) (key region)
• Cell bodies in DRG (key region)
• Axons enter spinal cord through dorsal root (key region)
• Synapse in dorsal horn (key region)

Second order
• Cell bodies in dorsal horn (key region)
• Axons cross midline in spinal cord (cross over)
• Ascend in contralateral lateral spinothalamic tract
• Multiple axon collaterals to reticular formation, hypothalamus, amygdala (key region)
• Anterior and lateral tracts merge
• Synapse in thalamus (VPL nucleus) (key region)

Third order
• Cell bodies in thalamus (key region)
• Axons ascend to parietal lobe (primary somatosensory area), anterior cingulate, insula (key region)

describe the paths of the somatosensory system: lateral spinothalamic

First order
• Dendrites (receptors) in periphery (e.g., skin) (key region)
• Cell bodies in spinal DRG (key region)
• Axons enter spinal cord through dorsal root (key region)
• Synapse in dorsal horn (key region)

Second order
• Cell bodies in dorsal horn (key region)
• Axons ascend in spinocerebellar tracts (key region)
• May cross over in spinal cord & then cross back over in medulla (crossover)
• Synapse in ipsilateral cerebellum (key region)

NO THIRD ORDER
• Final destination \= cerebellum

describe the paths of the somatosensory system: spinocerebellar

DCML
Lateral Spinothalamic tract
Anterior spinothalamic tract
Spinocerebellar Tract

Put the somatosensory system pathways in order

The somatosensory systems carry information about pain, touch, temperature, and proprioception from the body to the brain

What types of information are carried by the somatosensory system?

signals are carried to thalamus & then parietal lobe

What is the location of the crossover in the somatosensory system?

dorsal root ganglion

\

What is the location of the cell bodies and synapse in the somatosensory system?

?

What are the regions through which the axons travel in the somatosensory system?

Mechanoreceptive , Thermoreception, Nociception

What are the names of the neurons in the somatosensory system?

On the picture of the spinal cord, label the dorsal & ventral root fibers, dorsal & ventral horns, spinal nerve, and dorsal root ganglion.

Graphesthesia is the ability to determine shapes or let- ters drawn onto the skin solely based on the sensation of touch

What is graphesthesia?

Ability to recognize object through sense of touch only. Have pt close eyes and try to recognize STEREOtypical object like a key, coin or pen with touch

What is stereognosis?

inability to identify objects by touch

What is tactile agnosia?

areas innervated by afferent nerve

Explain what a dermatome is

complete transection: Bilateral loss of all sensory & motor below the lesion
hemi-section: Damage to 1 side of spinal cord (R or L)

Explain what kind of sensory loss would occur with a complete transection or a hemi-section of the spinal cord

Peripheral neuron regrowth → growth tip encounters scar tissue (stump) →forms hypersensitive neuroma →sensations "recorded" in brain as from missing limb

What is the cause of phantom limb pain?

Cornea (protection, refraction and focusing of light)
Pupil (opening through which light enters the eye)
Lens (refracting and focusing of light)

What role do the cornea, pupil, and lens play in vision?

shape, size, brightness
•Distributed through retina, but not in fovea

What is the function of the rods cells found in the retina?

color (r, g, b), fine detail
•Located primarily in fovea

What is the function of the cone cells found in the retina?

connect photoreceptors to ganglion cells

What is the function of the bipolar cells found in the retina?

•Action potentials
•Axons form optic nerve

What is the function of the ganglion cells found in the retina?

optic nerve leaves eye

What causes the blind spot?

Some fibers branch off from optic tract to synapse on suprachiasmatic nucleus of hypothalamus

Some fibers branch off from optic tract to synapse on superior colliculus

Label all regions of the visual pathway from the retina to the occipital lobe including where the synapses are.

occipital lobe

Where is primary visual cortex located?

retinotopically

How is the primary visual cortex (V1) organized?

•Visual field: external area visible to eyes without movement
•Retinal field: focused representation of visual field

What is the difference between visual and retinal fields?

Damage to either optic nerve will result in ipsilateral monocular blindness, or blindness in one eye

Label and explain the visual field defects caused by damage to the optic nerve

Bitemporal heteronymous hemianopsia
•Creates tunnel vision

Label and explain the visual field defects caused by damage to the optic chaism

Homonymous hemianopsia
•Loss of same visual half (R/L) in each eye

Label and explain the visual field defects caused by damage to the optic tract

Homonymous hemianopsia
Loss of same visual half (R/L) in each eye

Label and explain the visual field defects caused by damage to the LGN

Homonymous quadrantanopia
•Interruption of portion of geniculocalcarine fibers

Label and explain the visual field defects caused by damage to the geniculocalcarine fibers

Homonymous hemianopia with central sparing
•Blindness in opposite field of vision in each eye

Label and explain the visual field defects caused by damage to the primary visual cortex

form

What kind of information is processed in V3?

color and form

What kind of information is processed in V4?

Motion

What kind of information is processed in V5?

Where" pathway: Dorsal
•To parietal lobe
•Topographic abilities
•Map reading, navigation

Describe the dorsal visual pathways

•"What" pathway: Ventral
is responsible for processing shape, color, and size

Describe the ventral visual pathway

Damage -\> inability to localize items

What kinds of deficits can occur with damage to dorsal visual pathway?

Damage -\> agnosias: inability to recognize objects, words, faces

What kinds of deficits can occur with damage to ventral visual pathway?

difficulty recognizing an object due to perceptual deficit

Define/describe apperceptive agnosia

difficulty recognizing or attaching meaning to an item with preserved perception

Define/describe associative agnosia

difficulty recognizing colors (severe \= no color vision)

Define/describe achromatopsia

difficulty recognizing movement

Define/describe akinetopsia

•Bilateral damage to V1
often can sense and follow light but cannot process any other visual information.

Define/describe cortical blindness

the ability to respond to visual stimuli without consciously perceiving them

What is blindsight?

Sound waves creates vibration/pressure which moves the tympanic membrane creating mechanical energy via movement of ossicles

Explain mechanical energy created in the auditory system from the external auditory meatus/tympanic membrane to the auditory nerve (cranial nerve VIII).

The hydraulic energy is created because of the movement of fluid in cochlea

Explain hydraulic energy created in the auditory system from the external auditory meatus/tympanic membrane to the auditory nerve (cranial nerve VIII).

electrical energy (nerve impulses) is caused by the movement of hair cells in cochlea

Explain electrical energy created in the auditory system from the external auditory meatus/tympanic membrane to the auditory nerve (cranial nerve VIII).

Neurochemical energy is created (an action potential) by glutamate release exciting the auditory nerve (CN VIII)

Explain neurochemical energy created in the auditory system from the external auditory meatus/tympanic membrane to the auditory nerve (cranial nerve VIII).

Organ of Corti - complex of structures located on the basilar membrane of the cochlea
Organ of Corti has a third type of cochlear fluid called cortilymph
Superior border of the organ of Corti is the tectorial membrane
• Outer hair cells (3 rows) -motor & sensory
• Inner hair cells (1 row) -sensory only

Describe how the Organ of Corti functions (Be sure to mention the basilar membrane, fluid, inner and outer hair cells, and tectorial membrane)

Basilar membrane displaced by perilymph fluid movement which creates mechanical displacement of cilia

Explain what happens when the basilar membrane moves, including what happens to the stereocilia in the organ of corti

Connect sterocilia in hair cells

what are tip-links in the organ of corti?

In the stereocilia on top of the hair cells; they're triggered by the kinocilium bending away from the other cilia and pulling on the tip-links (which causes the K+ channels to open)

Where are the potassium channels in the organ of corti?

•K+ moves into hair cell leading to depolarization causing it to open calcium channels

what causes opening of calcium channel in the organ of corti?

• Triggers release of neurotransmitter (glutamate)

what happens when calcium enters the hair cells in the organ of corti?

They convert the energy from efferent fibers to lengthen OHC

What are outer hair cell microtubules and how do they impact hearing?