Quiz 3: Lecture: Medulla-Limbic System Flashcards
What does the medulla oblongata connect?
The brain to the spinal cord through the foramen magnum
What does the medulla oblongata do?
Relays information, Regulates autonomic functions
What autonomic functions do the medulla oblongata regulate?
heart rate, blood, pressure, respiration, digestion
Do we have control over autonomic functions?
No (can modify but don’t have much say)
Most of the functions in the brainstem are _____ functions.
visceral (more voluntary as we go higher)
Autonomic centers (4) in the brainstem (medulla oblongata):
Reticular formation, Cardiovascular centers, Respiratory rhythmicity center, Solitary nucleus
Relay stations in the brainstem (medulla oblongata):
Olivary nucleus, Nucleus cuneatus, Nucleus gracilis
Where is the fourth ventricle located?
Posterior region of pons and medulla, Anterior to the cerebellum, Extends from cerebral aqueduct superiorly, Extends inferiorly into central canal of brainstem and spinal cord
The medulla oblongata does these 3 things:
Allows brain and spinal cord to communicate, Coordinates complex autonomic reflexes, Controls visceral functions
Types of nuclei in the medulla and what they do
Autonomic nuclei: control visceral activities
Sensory and motor nuclei: of cranial nerves
Relay stations: along sensory and motor pathways
Autonomic nuclei of the Medulla Oblongata consist of these two parts:
Reticular formation; Reflex centers
What is the reticular formation and what is its function?
Gray matter with embedded nuclei; Regulates autonomic functions
What do reflex centers do and what do they consist of?
Control peripheral systems
Cardiovascular centers; Respiratory rhythmicity centers
What are cardiovascular centers and what are their function?
Cardiac center
Control blood flow through peripheral tissues
What is the function of respiratory rhythmicity centers?
Sets pace for respiratory movements (can be modified)
What is the Pre-Botzinger complex?
“Originate signals that control normal breathing”
Neurons that will fire action potentials on their own regularly to help set pace for respiratory movement (don’t need stimuli coming in to generate action potential)
Where do the neurons of the Pre-Botzinger complex exit the brain?
They exit through the phrenic nerve (which is the sole innervation for the diaphragm)
The breathing rhythm is relayed to the _____ _____ from the pre-Botzinger complexes.
hypoglossal nuclei
What are the 3 Relay Stations of the Medulla Oblongata?
Nucleus gracilis and nucleus cuneatus, Solitary nucleus, Olivary nuclei (olives)
How many Nucleus gracilis and Nucleus cuneatus do we have?
Two, one in each hemisphere (Nucleus gracilis inward and Nucleus cuneatus outward)
What is the function of the Nucleus gracilis and Nucleus cuneatus? Which structure does it go to next?
Pass somatic sensory information to thalamus
Primary somatosensory cortex located in postcentral gyrus
What is the function of the Solitary nucleus?
Receives visceral sensory information
What is the function of the Olivary nuclei (olives)?
Relay information about somatic motor commands (Have control over these)
Ascending pathway of relay stations of the Medulla Oblongata
fasciculus gracilis, fasciculus cuneatus (S-2, L-3, T-4, C-3), receptors, primary afferent neuron, (decussation), medial cuneate nucleus, nucleus gracilis
Descending pathway of relay stations of the Medulla Oblongata
Medulla oblongata, Pyramid, pyramidal decusation, lateral corticospinal tract, ventral corticospinal tract, motor end plates, spinal cord, ventral root
The medulla oblongata regulates:
blood pressure; respiration
What do the pons connect? What does this link to?
Cerebellum to brainstem (bridge)
Links to mesencephalon, diencephalon, cerebrum and spinal cord
What is the pons involved in?
Somatic and visceral motor control
Damage to the _____ or _____ may result in _____ _____ of _____ _____
cerebellum; pons; poor coordination; limb movement
The job of the cerebellum is to:
Prepare motor movements with the plan of a motor movement with the actual execution of the motor movement
The pons have these 2 nuclei:
Nuclei involved with respiration, Nuclei and tracts
What are the nuclei involved with respiration and what are their function?
Apneustic and pneumotaxic center
Modify respiratory rhythmicity center activity
What is the function of nuclei and tracts and what are they?
Process and relay information to and from cerebellum
Ascending, descending, and transverse tracts
What are ascending, descending, and transverse tracts and what is their function?
Transverse fibers (axons)
Link nuclei of pons with opposite cerebellar hemisphere
The Pons contains:
sensory and motor nuclei for four cranial nerves
nuclei concerned with the control of respiration
tracts that link the cerebellum with the brain stem
Cranial Nerve #1, function, and direction
Olfactory nerve (sense of smell)
olfactory bulb > olfactory tract > olfactory cortex
What is the only sensory sensation that doesn’t have to go to the thalamus before being processed?
Cranial nerve 1- olfactory nerve (sense of smell)
Goes directly to its primary center- olfactory cortex
Cranial nerve #2, function, direction
Optic nerve
Processing visual information from the eye
Axons lead to ganglion cells that forms optic nerve > optic chiasm > thalamus > occipital lobe
Cranial nerve #3, function, direction
Oculomotor nerve, Respond to light
Sympathetic: Fight or flight (eyes dilate, slow digestion, saliva production stops, urinary stops)
Blood supply to muscle increase (increased heart rate), increased respiration, tense up
Parasympathetic after: eyes constrict, let everything go
Mnemonic to remember cranial nerves 1-12
Some= (S) Olfactory
Say= (S) Optic
Marry= (M) Oculomotor
Money= (M) Trochlear
But= (B) Trigeminal
My= (M) Abducens
Brother= (B) Facial
Says= (S) Vestibulocochlear
Big= (B) Glossopharyngeal
Brains= (B) Vagus
Matter= (M) Accessory
Most= (M) Hypoglossal
Structures in brain on slide 45
Medulla, pons, midbrain, third ventricle, cerebral aqueduct (in midbrain- mesencephalon), fourth ventricle, then behind septum pellucidum is lateral ventricle.
Corpus callosum looks like upside down Nike check
Colliculi (bumps) called corpora quadrigemina (4)
Two bumps on top: Superior colliculi
Two bumps on bottom: Inferior colliculi
The inferior colliculi are involved in:
Auditory reflexes
The superior colliculi are involved in:
Visual reflexes (at most basic level)
Not developing a conscious perception
Red nucleus function
Involved in subconscious positioning of upper limbs
What are the two parts of the substantia nigra? What are their functions?
Pars compacta; Pars reticulara
Pars compacta: dopaminergic neurons
Pars reticula: GABAminergic neurons
Pars compacta function
Dopaminergic neurons
In the synthesis of dopamine, these cells create neuromelanin which creates the pigmentation we see in the brain
In Parkinson’s disease, area is pale due to:
Pars compacta (dopaminergic neurons lead to neuromelanin)
They selectively die off then develop Parkinson’s (initially motor disorder- no cognitive disorder, just can’t initiate movement)
Substantia nigra function
Structure that is part of the basal nuclei (also known as basal ganglia)
What is the part that selectively degenerates in Parkinson’s disease?
Substantia nigra (basal ganglia)
What is the mesencephalon and what is its functions?
Midbrain
Processes sight, sound, and associated reflexes, Maintains consciousness
A superior view of a transverse section at the level of the midbrain (Slide 45) includes which structures?
Cerebral peduncle, Substantia nigra, Red nucleus, Cerebral aqueduct, Superior colliculus, Tectumn; Tegmentum; Cerebellum
What are the 3 structures of the Mesencephalon?
Tectum; Tegmentum; Cerebral peduncle
What is the tectum made up of?
Two pairs of sensory nuclei (corpora quadrigemina)
- Superior colliculus (visual)
- Inferior colliculus (auditory)
What is the Tegmentum made up of?
Red nucleus (many blood tests), Substantia nigra (pigmented gray matter)
What does the pineal gland do?
Secretes melatonin involved in sleep
What is a Sagittal section made/ what’s it separating?
Separating right and left so looking at midbrain
What are cerebral peduncles and what do they contain?
Nerve fiber bundles on ventrolateral surfaces
Contain descending fibers to cerebellum, motor command fibers
What is the function of reticular formation? What is the direction?
Involved in general sense of arousal. When stimulated, increases awareness
Runs good length of brainstem so ignore boundaries between midbrain, pons, medulla
What happens during superior colliculi visual reflex (blowing air into eyes)?
Visual process coming in through eyes, goes to LGN first, then branch goes to superior colliculus, then comes back to muscles in the eye, eye closes to protect them (before cognitively aware)
Inferior colliculus function
Auditory reflex
Going to hijack brain and pay attention to some potentially threatening sound (Orient all senses so you pay attention to it)
Phenomenon called blindsight is what?
Condition that can develop in a patient when they have a lesion in their visual pathways beyond the superior colliculus (so where between LGN and occipital lobe)
Legally blind due to pathways being disrupted from primary visual cortex, can’t develop conscious perception of vision but visual tract is intact
What can a person with blindsight do?
Can navigate through an obstacle course and avoid the obstacles without a conscious perception of it
Damage to the left superior colliculi would interfere with the reflex ability to _____.
turn the head to the right (its contralateral fibers)
Cerebellum function and location; 3 lobes
Coordinates repetitive body movements
Two hemispheres; Covered with cerebellar cortex
Anterior, flocculonodular, posterior
What is the first and second largest part of brain?
First: Cerebrum (cortex)
Second: Cerebellum
Anterior lobe function
Receiving info from spinal cord muscles, joints, tendons
Arbor vitae:
white matter (tree of life)
Flocculonodular lobe function:
Helps with body position/ perception or actual changes in gravity
Posterior lobe function:
Getting information from cortex
How do you achieve movement?
Think of it with cerebellum, execute through motor cortex, Substantia nigra pars compacta helps initiate movement
In Parkinson’s patients who lost Substantia nigra, what happens?
Have problem initiate movement, have resting tremor but once start moving, don’t have shaking so much anymore
Unlike in Substantia nigra, lesion in cerebellum causes what?
Intentional tremor (hands fine at rest but shaky when moving)
Brain structure selectively vulnerable to alcohol:
Cerebellum; Posterior pituitary with secretion of ADH
Which two structures work in synchrony to help regulate movement of limbs?
Basal ganglia, Cerebellum
Functions of the Cerebellum (from slide):
Adjusts postural muscles
Fine-tunes conscious and subconscious movements
Compare motor commands with actual execution to detect errors
The _____ _____ and the cerebellum act in synchrony to regulate the movements of the limbs.
Basal ganglia
Structures of the cerebellum:
Folia (surface of cerebellum; highly folded neural cortex)
Anterior and posterior lobes (separated by primary fissure)
Cerebellar hemispheres (separated by midline by vermis)
Vermis (narrow band of cortex)
Flocculonodular lobe (below fourth ventricle)
More structures of cerebellum:
Purkinje cells (large branched cells- biggest in brain)
Found in cerebellar cortex; Receive input from up to 200,000 synapses
Arbor vitae (Highly branched internal white matter of cerebellum)
Cerebellar nuclei embedded in arbor vitae (relay info to Purkinje cells)
The peduncles (superior, middle, inferior)
What is the main way cerebellum connects with brain?
Middle cerebellar peduncles (links cerebellum with pons)
What is a disorder of the cerebellum and what are some causes?
Ataxia
Damage from trauma or stroke; Intoxication ( temp. Impairment); Disturbs muscle coordination
Cerebellum facts from slide:
10 percent of human brain mass
Contains more than half of our 85 billion neurons
Surface area is 80 percent of that of cortex
2.8x larger than primates
What is the cerebellum-cerebral cortex loop?
Start in cortex > Send axons to pons > Send it down to the cerebellum (sensory info) > and what is thought to come out is motor (Now we know only motor is NOT true)
Direct pathway from the cerebellum and VTA (a, b, c, d)
a) Technique: optogenetics (can activate single channel)
behavior being driven by cerebellar activation
TTX: puffer fish toxin (paralyzes you by blocking sodium channels- voltage gated; at axon hillock)
b) hooked up mice to wander freely through box (4 quadrants). Spent 70% time in happy quadrant
c) 3 chambers divided to 5 (social vs. nonsocial)
d) Cb-VTA is not prosocial on its own
Newly recognized ones for the cerebellum:
Cognition, Emotion, Social behavior
Overseeing the postural muscles of the body and making rapid adjustments to maintain balance and equilibrium are functions of the _____.
Cerebellum
The diencephalon connects which two structures?
Links cerebrum with brain stem
Location of diencephalon:
Located under cerebrum and cerebellum
Borders the 3rd ventricle
Two divisions: Thalamus and Hypothalamus
Thalamus function
Relays and processes sensory information
Filters ascending information for primary sensory cortex; Relays information between basal nuclei and cerebral cortex
Hypothalamus function
Hormone production, Emotion, Autonomic function
Pituitary gland location and function:
Major endocrine gland (connected to hypothalamus via infundibulum (stalk))
Interfaces nervous and endocrine systems
What separates the left and right thalamus?
Third ventricle
What is interthalamic adhesion (intermediate mass)?
Projection of gray matter; Extends into ventricle from each side
What are thalamus nuclei?
Rounded masses that form thalamus
Relay sensory information to basal nuclei and cerebral cortex
No sensory information, with the exception of _____, reaches the cortex without prior processing in the thalamus.
Olfaction (smell)
What are the five groups of thalamus nuclei?
Anterior group, Medial group, Ventral group, Posterior group, Lateral group
Anterior group function
Anterior nuclei; Part of limbic system (emotions)
Medial group function
Provides awareness of emotional states
Ventral group function:
Relays sensory information from basal ganglia and cerebellum
Posterior group consists of:
Pulvinar nucleus (sensory), Lateral geniculate nucleus (visual), Medial geniculate nucleus (auditory)
Lateral group function:
Affects emotional states; Integrates sensory information
Parts of hypothalamus:
Mammillary bodies, Infundibulum, Tuberal area
Mammillary bodies location and function:
Located in posterior hypothalamus
Process olfactory and other sensory information, Control reflex eating movements, Recollective/ episodic memory, Wernicke-Korsakoff (anterograde amnesia)
What is the Infundibulum and its function?
A narrow stalk
Connects hypothalamus to pituitary gland
Tuberal area location and function:
Located between Infundibulum and mammillary bodies
Helps control pituitary gland function
What are eight functions of the hypothalamus?
- Provides subconscious control of skeletal muscle
- Controls autonomic function
- Coordinates activities of nervous and endocrine systems
- Secretes hormones (Antidiuretic hormones (ADH) and Oxytocin)
- Produces emotions and behavioral drives (feeding center- hunger, third center- thirst)
- Coordinates voluntary and autonomic functions
- Regulates body temperature (preoptic area of hypothalamus)
- Controls circadian rhythms (day-night cycles- Suorachiasmatic nucleus)
What hormones do the hypothalamus secrete?
Antidiuretic hormone (ADH) by supraoptic nucleus
Oxytocin (OT, OXT) by paraventricular nucleus
A 37-year old man comes to the office due to difficulty sleeping. He says that his new job as a business executive is very stressful and requires considerable travel. During the past 3 months, the patient has made numerous trips between the United States and France. He experiences insomnia and daytime sleepiness for several days after these trips, but his sleep then improves significantly. Which of the following hypothalamic nuclei is most likely responsible for this delayed improvement in his symptoms?
Suprachiasmatic (day-night cycles)
JoJo begins to experience mood swings and disturbed thirst and hunger. Imaging studies indicate that a brain tumor is the likely cause of these disorders. In what part of the brain is the tumor most likely located?
Hypothalamus
Limbic system is a functioning group that:
- Establishes emotional states
- Links conscious functions of cerebral cortex with autonomic functions of brainstem
- Facilitates memory storage and retrieval
The limbic system (aka the limbic lobe) comprises several phylogenetically older structures centered around the brainstem (7):
• Cingulate gyrus
• Parahippocampal gyrus
• Hippocampus (hippocampal formation)
• Amygdaloid complex
• Parts of Hypothalamus
• Nucleus accumbens (part of ventral striatum)
• Orbitofrontal cortex
What are the 7 limbic system components shown in the picture?
Amygdaloid complex, Hypothalamus, Fornix, Corpus Callosum, Cingulate gyrus, Lateral ventricle (occipital horn), Hippocampus
Amygdaloid body function
Acts as interface between the limbic system, the cerebrum, and various sensory systems
Limbic lobe of cerebral hemisphere contains these 3:
Cingulate gyrus, Dentate gyrus, Parahippocampal gyrus
Hippocampus function
storage and recall of long-term memories
What is the Fornix and its function?
Tract of white matter; Connects hippocampus with hypothalamus
Anterior nucleus of the thalamus function:
Relays information from mamillary body to cingulate gyrus
Reticular formation function
Stimulation or inhibition affects emotions (rage, fear, pain, sexual arousal, pleasure)
Cingulate gyrus location and limitation:
Lies on the medial aspect of the cerebral hemisphere, above Corpus callosum (separated by Sulcus of corpus callosum)
• CG is limited superiorly by the Cingulate sulcus; inferiorly, it is contiguous with Indusium griseum (a thin layer of primitive cortex covering the Corpus callosum)
Anterior Cingulate function
Role in empathy, impulse control, emotion, and decision making.
• Connected to the emotional limbic system and the cognitive prefrontal cortex (helps us manage uncomfortable emotions)
• Ventral region connected to: amygdala, nucleus accumbens, hypothalamus, anterior insula
Hippocampus location
Depth of the temporal lobe; on coronal sections (shape resembles sea horse)
Hippocampus insists of the following sub structures:
Dentate gyrus, Hippocampus proper (Amon’s horn), Subiculum and Entorhinal cortex
What is the Uncus and where is it located
Anterior, enlarged portion of Hippocampus
Tail of the Dentate gyrus separates the inferior portion of the Uncus into Uncinate gyrus (anterior) and Intralimbic gyri (posterior)
Hippocampus plays a major role in what?
Encoding of long-term memory
(contrary to earlier views, not processing of emotions)
What happened to Patient KC?
Semantic (facts) memory intact but lost episodic (emotional content memory)
If he could memorize facts without his hippocampus, then memory in some cases, us the able to bypass this part
Amygdaloid complex location and function
Group of subcortical nuclei located in front of the Hippocampus
• Receives input from subcortical areas concerned with the somatic expression of emotions (Hypothalamus and brain stem nuclei) via Basolateral nucleus. Sends output to cortical areas concerned with the cognitive aspects of emotion via the Central nucleus
• Acts as an interface between the limbic system, the cerebrum, and various sensory systems
Part of our brain that constantly looks for threats?
Amygdaloid complex
Responds to physical or emotional threats by releasing cortisol, adrenaline, and noradrenaline.
PATIENT SM (URBACH-WIETHE DISEASE)
Born with normal amygdala > degeneration of amygdala > unable to pick up social cues, positive disposition, no fear, lost perceived threat and sense of personal space
The ___ theory of emotion describes an event followed by a physiological response (fight or flight) which is then interpreted as a particular emotion and then the emotion is perceived.
Schachter-Singer (stimulus→autonomic arousal→appraisal→ conscious feeling e.g., fear)
The ___ theory of emotion describes an event which elicits simultaneous physiological response (fight or flight) and perception of an emotion (fear)
Cannon-Bard (stimulus→subcortical brain activity→simultaneous conscious feeling and autonomic arousal, ex. Dog makes you tremble, and you feel afraid)
The ___ theory of emotion describes an event which elicits physiological response (fight or flight).
James –Lange (stimulus→autonomic arousal→conscious feeling e.g., fear)
The ___ theory of emotion requires that interpretation must happen before arousal or emotion, which happen simultaneously.
Lazarus [stimulus→appraisal of threat (fear, 1st response)→bodily response (2nd response)]
Nucleus accumbens location and function
Convergence between head of Caudate nucleus and Putamen (lateral to Septum pellucidum)
Role in addiction and reward; regulated by VTA through mono synaptic pathway
The histology and connectivity pattern of the _____ is very similar to that of the other components of the Striatum
NACC
The majority of the _____ neurons are _____ medium spiny neurons
NACC; GABA-ergic
(Sends inhibitory stimuli)
Major input to the NACC originates which 4 places?
Ventral tegmental area (Dopaminergic), prefrontal cortex, Amygdaloid complex and Hippocampus
The NACC projects back to the _____ _____ via the _____ _____ _____
prefrontal cortex; Dorsomedial thalamic nucleus
Orbitofrontal cortex location
Lies above orbital roof, at base of frontal lobe
The olfactory and the orbital sulci divide the surface of the OFC into four gyri:
Gyrus rectus, Medial orbital gyrus, Anterior orbital gyrus, Posterior orbital gyrus and Lateral orbital gyrus
Decrease of _____% cell firing when removal or damage of this structure:
30; Orbitofrontal cortex
Alzheimer’s disease starts selectively in the _____.
hippocampus
_____ binds to _____ receptors and lacks _____ _____ effects.
Psilocybin; serotonin; rewarding dopamine
MRI measures _____ _____ and ______ decreased with _____ over placebo in regions other than the striatum, including areas involved in association and “constraining the experience of the world”
blood flow and oxygenation; psilocybin
What is more susceptible to aschemia and which is more resistant?
CA 1; CA 3
Which part is involved in empathy, impulse control, negative emotions?
Anterior cingulate
What is the mammillary body connected to?
Singular axon gyrus
Direction of flow in limbic system:
Cingulate gyrus > Mamillary body > Parahippocampal gyrus
Which of the following is not a function of the limbic system?
Functions in maintaining homeostasis in cold weather (hypothalamus)
What is the cerebral component of limbic system?
Cingulate gyrus
