Lecture 71 - Reticular System Flashcards
The Reticular Formation is a central core of nuclei that run through the length of the brainstem from the ________ down to the ______ zone of the Spinal cord. For the most part, they’re located in the _______ (Tectum, Tegentum, or Basalis?)
Diencephalon
Inermediat zone
Tegmentum
The ______ (Rostral or Caudal?) end of the Reticular Formation is associated with Consciousness (projecting to the ________ nuclei of the Thalamus, Cerebral cortex, Hypothalamus, and Basal forebrain), while the ______ (Rostral or Caudal?) end - continuous with the _______ zone of the Spinal cord - of the Reticular Formation is assoiated with Motor and Autonomic functions.
Rostral
Intralaminar nuclei of the Thalamus
Caudal
Intermediate zone of the Spinal cord
Order the following Reticular Formation nuclei from Medial to Lateral and describe what they control:
Raphe Nucleus
Gigantocellular
Parvocellular
Raphe –> most medial and responsible for Mood and Wakefullness
Gigantocellular –> Lateral to Raphe and responsible for Motor function
Parvocellular –> Most lateral and responsible for Respiration
One of the Subsets of the Reticular Formation is the Reticular Activating System (RAS). It is comprised of nuclei in the _______ (so the Rostral portion of te Reticular Formation), and these nuclei are responsible for producing all the ______ of the Reticular Formation.
The RAS functions include:
_______ processing and integration.
Regulation of _______ and the ____-____ cycle.
Regulation of ______ behavior.
Thalamus
NTs (Noradrenerigic, Serotonergic, Cholinergic, and Dopaminergic)
Sensory processing and integration
Regulation of Consciousness and Sleep-wake cycle
Regulation of Emotional behavior
In the Rostral Pons, Noradrenergic (produce Norepi) neurons are in the _____ ______ (Near the 4th ventricle).
As you move from the Pons into the medulla, the Noradrenergic neurons are in the ______ ______ area.
Keep in mind these neurons project out to all areas of the brain, and their functions include regulating Attention, _____-_____ states, Mood, ______ modulation, and BP.
Locus Ceruleus
Lateral Tegmental Area
Sleep-wake states
Pain
Dopaminergic neurons of the RAS are located in the ______ ______ and _____ ______ area of the Ventral Midbrain.
Substantia Nigra (specifically in the pars compacta)
Ventral Tegmental area
The Substantia nigra Dopaminergic neurons project to Subcortical regions, particularly the ______ and ______, responsible for movement. This is considered the ________ dopaminergic pathway.
The Ventral Tegmental dopaminergic neurons comprise 2 dopaminergic pathways:
The _________ pathway neurons arise from the Ventral Tegmental area and project to the ______ system strucures (medial temporal cortex, amygdala, cingulate gyrus, nucleus accumbens) and are involved in ______ and ______, as well as the _______ (positive or negative?) symptoms of Schizophrenia.
The _______ pathway neurons arise from the Ventral Tegmental area and project to the prefrontal cortex (so involved with Working memory and _______ aspects of motor initiation, as well as _______ (positive or negative?) symptoms of Schizophrenia.
Caudate and Putamen
Mesostrial dopaminergic pathway
Mesolimbic
Limbic
Reward and Addiction
Positive (Hallucinations)
Mesocortical
Attentional aspects
Negative (anhedonia, flat affect, etc.)
Serotonergic neurons in the RAS are located in the ______ nuclei. Those from the Rostral end of these nuclei project to the _____, _____, and _____ _____. Those from the Caudal end project to the ______, _____, and _____ _____.
Raphe Nuclei
Rostral –> Cortex, Thalamus, and Basal Ganglia
Caudal –> Cerebellum, Medulla, and Spinal Cord
Serotonergic neurons in the RAS are involved in regulating _______ state, ________ modulation, _______, and ________.
Psychiatric state
Pain modulation
Breathing
Temperature
Cholinergic neurons of the RAS are located in the Brainstem within the _________ tegemental nuclei and the ________ tegmental nuclei. They are also located in the Basal Forebrain within the Medial ______ nuclei, Nucleus of _______ ______, and the Nucleus _______.
The Brainstem nuclei project to _______ (cortical or subcortical?) areas and the ____ ____.
The Basal Forebrain nuclei present to the Hippocampus and the Entire cerebral cortex. Which Basal Forebrain nuclei project to which?
Brainstem –> Pedunculopontine Tegmental nuclei and Laterodorsall Tegmental nuclei.
Basal Forebrain –> Medial Septal nuclei, Nucleus of diagonal band, and Nucleus Basalis.
Brainstem nuclei –> project to Subcortical areas and the Spinal cord
Basal Forebrain nuclei –> Medial septal + Nucleus of diagonal band project to the Hippocampus; Nucleus Basalis projects to the Entire cerebral cortex.
The Pontomesencephalic aspect of the Reticular Formation is responsible for regulating _______.
Is it located Rostrally or Caudally?
Where does it project to?
Consciousness
It is located Rostrally in the Reticular Formation
It projects to both Thalami, which then project to the Cerebral Cortex bilaterally.
What are the 3 areas in which Lesions would cause Loss of Consciousness?
Upper Brainstem Reticular Formation (Rostral)
Bilateral Thalami
Extensive Bilateral Cortex
Sleeping actually requires several active neural circuits.
- The Sleep-promoting regions in the _______ (i.e. the _______ Reticular Formation and the Nucleus ______).
- The Anterior ________ (i.e. the ________ nucleus)
- The Basal ________.
Medulla
Medullary Reticular Formation
Nucleus Solitarius
Anterior Hypothalamus
Suprachiasmatic Nucleus (SCN)
Basal Forebrain
________ inputs to the Thalamus have an arousal effect on the brain, as the Thalamus then projects to the cortex causing wakefullness.
Similarly, neurons in the Posteriolateral Hypothalamus cause wakefullness by exciting the _______ and Hypothalamic arousal systems with release of ________ (Hypocretins) and _______ (which is why Benadryl makes you sleepy).
Cholinergic
Brainstem
Orexins (Hypocretins)
Histamine
There are _______ neurons in the ______ of the anterior hypothalamus that inhibit the neurons in the RAS and the posterior thalamus.
What effect does this have on the Sleep-wake cycle?
GABAergic
VLPO
Inhibiting the RAS –> inhibit Orexin and Histamine –> promotes Non-REM sleep.
Inhibiting Posterior Thalamus –> Inhibits Cholinergic neurons –> so no ACh goes to the cortex –> Promotes Non-REM sleep.
Promotion of REM sleep requires activity from the _____-__ cells in the Pontine Reticular Formation. These cells secrete GABA that reduces the action of ______ and _____ –> this in turn Disinhibits the Cholinergic neurons in the Pontine tegmental area –> increased ACh to the Thalamus.
Keep in mind the ACh from the Pontine tegmental nuclei acting on the Thalamus is the key for REM sleep!
REM-on cells
Norepi
Serotonin
Modulation of pain requires input from the Hpothalamus, Amygdala, and the Cortex to the __________ _____ area –> this inhibits transmission in the dorsal horn via a relay called the ____ ____ ____ (at the pontomedullary junction) –> this projects _______ neurons from the Raphe nucleus to the Spinal cord (one mech of pain modulation) AND it sends Substance P to the _____ _____, which then sends Norepi to the Dorsal horn (another mech of pain modulation).
Periaqueductal gray area (PAG)
Rostral Ventral Medulla (RVM)
Serotonergic neurons
Locus Ceruleus
The __________ tracts in the Reticular Formation are responsible for modulating motor functions of _____, _____, and _____. These are ______ (ascending or descending?) tracts that _____ (do or do not?) decussate.
There are 2 main origins for these tracts. 1. _______ Reticular Nucleus. 2. Medullary reticular formation (specifically the ________ nucleus).
Which one Excites anti-gravity extensors and which one Inhibits axial extensors and controls Breathing?
Reticulospinal tracts
Posture, Tone, and Balance
Descending tracts
DO NOT decussate
- Pontine reticular nucleus
- Gigantocellular nucleus
Pontine Reticulospinal Tract (Medial RST) excites anti-gravity extensors.
Medullary Reticulospinal Tract (Lateral RST) Inhibits Axial Extensors and controls Breathing.
The Caudal portion of the Red Nucleus is comprised of ________ neurons that make up the _______ tract.
Inputs: _______ and ________ (contra or ipsilateral?) Motor cortex.
Outputs: Ipsilateral in ______, Contralateral _______ _______, and Contralateral ________ _____ (this one being the Rubrospinal tract.)
The Rubrospinal tract decussates in the Ventral ______ ______ and Terminates in the _______ (region?) Spinal cord. It is responsible for movements like contralateral arm swing when walking/running.
Magnocellular
Rubrospinal tract
Inputs: Cerebellum and Ipsilateral Motor Cortex
Outputs: Ipsilateral Inferior Olive, Contralateral Reticular Formation, and Contralateral Rubrospinal Tract
______ posture refers to posture with the Arms flexed at the elbow and pointing up.
_______ posutre refers to posture with the Arms extended at the elbow and pointing down.
What is the localization of the lesions that would lead to each of these?
Decorticate –> Lesion ABOVE Red Nucleus (knocks out the Reticulospinal tract)
Decerebrate –> Lesion BELOW Red Nucleus (knocks out the Rubrospinal tract)
Autonomic Regulation of Heart rate as part of the Reticular Formation structures occurs via inputs From CN ___ and CN ____ (they detect changes in _____) –> to the caudal _______ nucleus –> Nucleus _______ and Ventrolateral ________ ______ area –> change in heart rate to accomodate BP.
CN IX and CN X
BP
Caudal Solitary nucleus
Nucleus Ambiguous and Ventrolateral Medullary Depressor area
Which nucleus in the Medulla is responsible for regulating respiration?
Solitary Nucleus (Nucleus Solitarius)
