Reticular Formation and diffuse neuromodulatory systems

Question 1

Reticular Formation functions:

Answer 1

The functions of the reticular formation include the sleep-arousal cycle, perception of pain, control of movement, and the regulation of visceral activity

Question 2

what is the function of the median reticular formation?

Answer 2

The median reticular formation comprises the raphe nuclei which are the major source of SEROTONERGIC projections through the CNS

Question 3

What is t he function of the paramedian reticular formation?

Answer 3

The paramedian reticular formation is a predominately efferent system (motor). It has relatively long axons. Some axons ascend to synapsee in the midbrain reticular formation or in the thalamus. Others have both ascending and descending branches that contribute to the polysynaptic network. The magnocellular component receives corticoreticular fibers from the premotor cortex and gives rise to the PONTINE AND MEDULLARY RETICULOSPINAL TRACTS

Question 4

what is the function of the lateral reticular formation?

Answer 4

The lateral reticular formation is mainly afferent (sensory) in nature. It receives fibers from all of the sensory pathways including the sensory pathways

Question 5

Parabrachial area

Answer 5

Visceral pain, respiratory control, taste

Question 6

Nucleus reticularis pontis oralis

Answer 6

sleep-awake cycle, reticulospinal pathway

Question 7

Nucleus reticularis pontis caudalis

Answer 7

Mastication, reticulospinal pathway

Question 8

Nucleus gigantocellularis

Answer 8

inhibatory pain pathway

Question 9

what is the function of the Rostral reticular formation?

Answer 9

The rostral reticular ormation of the midbrain and pons functions with the THALAMUS, BASAL FOREBRAIN AND HYPOTHALAMUS to maintain an alert conscious state in the forebrain.

Question 10

What is the function of the caudal reticular formation?

Answer 10

The caudal reticular formation of the pons and the medulla function with the cranial nerves and spinal cord to control motor and autonomic crucial life support functions including respiration and HR and BP

Question 11

Neuromodulatory pathways:

functions:

Answer 11

Neuromodulatory pathways are diffuse projection pathways that originate from a single region but project “diffusely” to many CNS structures.

These pathways do not elicit AP, but they regulate a broad range of cellular mechanisms involving signaling cascades that regulate synaptic transmission, neurona growth, and other functions. This neuromodulation can either facilitate or inhibit the subsequent signaling properties of the neuron

Question 12

Norepinephrine Pathways

Nucleus locations:

Answer 12

Norepinephrine pathway:

Nucleus location: Locus ceruleus (rostral pons) and lateral tegmental area (pontine and medullary reticular formation)

Question 13

Norepinephrine Rostral Projections

nucleus location:

projection:

function:

Answer 13

NE Rostral Projection

nucleus: locus ceruleus
projection: entire forebrain, cortex and basal ganglia, and the amygdala and thalamus

Function: modulation of attention, sleep-wake states, and mood.

**NE plays a roll in central pain modulation, and mood disorders like depression, bipolar, and anxiety.

Question 14

Norepinephrine- Caudal Projections:

nucleus location

projection:

function

Answer 14

NE- Caudal projections:

nucleus location: lateral tegmental area (pontine and medullary reticular formation)

projection: brainstem and spinal cord
function: sympathetic functions such as blood pressure control

Question 15

Dopamine:

Locations of the neurons:

3 projection systems

Answer 15

Neurons containing dopamine are located in the substantia nigra pars compacta and the ventral tegmental area

There are three dopamine projection systems: mesostriatal, mesolimbic, and mesocortical

Question 16

Mesostriatal Pathway

arises from:

projects to:

lesions produce:

Answer 16

Mesostriatal Pathway

the mesostriatal pathway (nigrastriatal) arises from the substanti nigra pars compacta and projects to the caudate and putamen.

Lesions of this pathway produce movement disorders (Parkinson’s) and are often treated with dopaminergic agonists.

Question 17

Dopamine- mesolimbic pathway

arises from:

projects to:

function:

Answer 17

The dopamine mesolimbic pathway arises from the VTA and projects to limbic structures including the prefrontal and temporal cortex, amygdala, cingulate gyrus, and nucleus accumbens.

This pathway plays a role in reward circuitry and addiction

Overactivity in this pathway is involved in positive symptoms of schizophrenia (hallucinations) and respond to dopamine antagonists

Question 18

Serotonin- rostral projection

nucleus location:

projection:

function:

lesions:

Answer 18

Neurons the contain serotonin are found in the raphe nuclei (rostral pons) and rostrally they project to the entire forebrain.

The function of the serotonin rostral pathway is the awareness of pain and sleep pattern and mood modulation.

lesions in this pathway are believed to play a role in many psychiatric syndromes

Question 19

Dopamine- Mesocortical pathway

arises from:

projects to:

functions:

lesions produce:

Answer 19

The dopamine- mesocortical pathway arisses from the VTA and projects to the frontal cortex.

the mesocorticl pathway plays a role in working memory and attention aspects of motor initiation.

Lesions of this pathway may be responsible for the cognitive defects and hypokinesia seen in Parkinsons.

**hypofunction of this pathway may be responsible for the negative symptoms and cognitive symptoms of schizophrenia

Question 22

Serotonin- Caudal projections:

nucleus location:

project to:

functions:

Answer 22

the Caudal raphe nuclei of the caudal pons and medulla projects to the cerebellum, medulla, and spinal cord.

functions of the caudal projections of serotonin are involved in pain modulation, breathing, temperature regulation, and motor control.

deficits in this pathway play a role in SIDS

Question 23

Histamine Pathway:

location of neurons:

projections to:

functions:

Answer 23

Histamine is released from neurons in the tuberomammillary nucleus (in the posterior hypothalamus and midbrain reticular formation) and projects to the forebrain. it is important for maintaining the awake state.

Histamine is also involved in circadian rhythms, the sleep-wake cycle, thermoregulation, neuroendocrine regulation, food and water intake, locomotion, sexual ehavior and memory and learning

Question 24

Acetylcholine: Brainstem projection

locations:

project to:

function:

Answer 24

Ach: brainstem projection

location of nucleus: pedunculopontine nuclei and laterodorsal tegmental nuclei

brainstem projections travel throu the thalamus and thne to the cortex

projections from the pedunculopontine plays a role in motor systems. Stimulation results in coordinated movements

these projections have a role in arousal

Question 25

Ach- Forebrain Projections nucleus location: project to: function:

Answer 25

Ach- neurons are located in the **nucleus basalis** and project to the **cerebral corte**x. they are responsible for **arousal**. The **medial septal nuclei** and the **nucleus of the diagonal band** that project to the **hippocampus** play a role in **declarative memory** functions

Question 26

Orexin nuclei location: projects to: function:

Answer 26

Orexin: nucle are located in the **posterior lateral hypothalamu**s and projectto the **frontal cortex, limbic systems, and brainstem nuclei** Orexin regulates **arousal, wakefulness, and food intake**