Neuroscience Chapter on Neurotransmitters

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Questions and Answers

What is the primary function of GABA in the central nervous system?

Stimulation of neuronal excitability

Inhibition of nerve transmission (correct)

Regulation of reward and pleasure

Control of parasympathetic functions

A deficit in dopamine is related to which of the following conditions?

Alzheimer's disease

Parkinson's disease (correct)

Depression

Epilepsy

Which neurotransmitter is identified as the principal excitatory neurotransmitter in the CNS?

Acetylcholine

Serotonin

Dopamine

Glutamate (correct)

What is the role of acetylcholine concerning muscle control?

It is involved in muscle control and parasympathetic functions. Signup and view all the answers

Too little serotonin is commonly associated with which condition?

Anxiety Signup and view all the answers

Which function is primarily associated with the rubrospinal tract?

Fine motor control, mainly of flexors Signup and view all the answers

Where does the tectospinal tract decussate?

Immediately at the midbrain Signup and view all the answers

How many neurons are involved in the reticulospinal tract pathway?

Two Signup and view all the answers

What is the primary role of the reticulospinal tract?

Influence alpha or gamma motor neurons for locomotion and postural control Signup and view all the answers

What type of movements does the tectospinal tract primarily facilitate?

Reflexive movements in response to environmental stimuli Signup and view all the answers

Which cell type in the granular layer is responsible for inhibitory neurotransmission?

Golgi Cells Signup and view all the answers

What is the primary role of the Dentate Nucleus?

Regulating fine control of voluntary movements and cognition Signup and view all the answers

Which neurotransmitter is commonly released by Climbing Fibers?

Glutamate Signup and view all the answers

In neural sharpening, what phenomenon occurs to neuron firing rates?

Repetition suppression Signup and view all the answers

Which structure represents the appendicular skeleton within the cerebellar organization?

Paravermis Signup and view all the answers

Which of the following statements about Stellate Cells is true?

They inhibit Purkinje Cells using GABA. Signup and view all the answers

Which of the following layers contains the somas of Purkinje Cells?

Purkinje Layer Signup and view all the answers

What is the function of Granule Cells in the cerebellum?

Transmit excitatory signals to Stellate and Basket Cells Signup and view all the answers

What term is used to describe the difficulty in performing rapid alternating movements?

Dysdiadochokinesia Signup and view all the answers

Which condition is characterized by a wider-base gait and difficulty in tandem gait?

Ataxia Signup and view all the answers

In which direction do the fast phases of nystagmus typically move in relation to a cerebellar lesion?

Away from the side of the lesion Signup and view all the answers

What occurs during the Rebound Phenomenon when a patient abruptly stops resisting force?

Exaggerated rebound occurs in the opposite direction Signup and view all the answers

How many pairs of spinal nerves are present in the human body?

31 pairs Signup and view all the answers

From which part of the spinal cord do sensory neurons primarily receive information?

Dorsal Horn Signup and view all the answers

Which spinal nerves exit the vertebral column above their corresponding vertebrae?

All cervical nerves except C8 Signup and view all the answers

What does scanning speech indicate?

Enunciation of individual syllables Signup and view all the answers

What type of paralysis is characterized by spastic paresis?

Spastic Paresis Signup and view all the answers

What is the primary effect of anterior spinal artery syndrome on sensory pathways?

Loss of pain and temperature sensation Signup and view all the answers

Which syndrome is directly associated with compression in the cauda equina?

Cauda Equina Syndrome Signup and view all the answers

What common clinical presentation is associated with tabes dorsalis?

Positive Romberg sign Signup and view all the answers

In which condition would you expect to see both upper and lower motor neuron lesions?

Amyotrophic Lateral Sclerosis (ALS) Signup and view all the answers

Which reflex is expected to be absent in lower motor neuron syndrome?

Deep Tendon Reflex Signup and view all the answers

What is a typical motor response in Central Cord Syndrome?

Upper limb weakness greater than lower limb weakness Signup and view all the answers

Which vascular structure supplies the posterior spinal cord?

Paired posterior spinal arteries Signup and view all the answers

What leads to cape-like loss of pain and temperature sensation?

Syringomyelia Signup and view all the answers

What is a hallmark of Brown Sequard Syndrome?

Ipsilateral loss of motor and proprioception Signup and view all the answers

Study Notes

Neurotransmitters and Their Functions

Specific receptors must be present on postsynaptic cells for neurotransmitter action.
Acetylcholine: Essential for somatic muscle control and parasympathetic functions; deficits linked to Alzheimer's and Myasthenia Gravis.
Dopamine: Involved in reward and movement regulation; deficits associated with Parkinson's disease.
Glutamate: Principal excitatory neurotransmitter in the CNS; excess linked to epilepsy/seizures, crucial for learning and memory.
GABA: Primary inhibitory neurotransmitter; low levels contribute to epilepsy/seizures and anxiety.
Serotonin: Stabilizes mood and regulates sleep; deficits related to depression.

Cerebellar Cortex Layers

Molecular Layer: Contains axons of granule cells, dendrites from Purkinje cells, and inhibitory stellate and basket cells.
Purkinje Layer: Composed of a single layer of Purkinje cell bodies with extensive dendrites extending into the molecular layer.
Granular Layer: Houses granule and Golgi cells, along with axons from mossy fibers.

Cerebellar Cell Types and Neurotransmitters

Climbing Fibers: Release glutamate (excitatory) affecting Purkinje cells.
Mossy Fibers: Use glutamate (excitatory) to influence granule and Golgi cells.
Granule Cells: Also release glutamate (excitatory) impacting stellate and basket cells.
Golgi Cells: Release GABA (inhibitory) affecting granule cells.
Stellate and Basket Cells: Release GABA (inhibitory) on Purkinje cells.
Purkinje Cells: Release GABA (inhibitory) impacting deep cerebellar nuclei.

Neural Sharpening Concept

Neural sharpening enhances object recognition through repetition, associated with reduced neuron firing rates termed repetition suppression.

Cerebellar Homunculus

Vermis: Represents axial skeleton (trunk, neck, head).
Paravermis: Represents appendicular skeleton (limbs).
Lateral Hemispheres: Represent posterior lobe functions.

Deep Cerebellar Nuclei

Dentate Nucleus: Main output; involves fine control of voluntary movements, cognition, language, and sensory processing.
Emboliform & Globose Nuclei: Functionally related to movement coordination.
Fastigial Nucleus: Coordinates trunk, head, and neck movements.

Clinical Presentation of Cerebellar Dysfunction

Balance problems and gait disorders (ataxia).
Uncoordinated movements (dysmetria).
Speech issues such as dysarthria.
Visual disturbances (nystagmus) and symptoms of vertigo.

Specific Movement Disorders

Dysdiadochokinesia: Difficulty with rapid alternating movements, may indicate MS or cerebellar issues.
Scanning Speech: Individual syllables pronounced distinctly.
Dysmetria: Assessed by nose-touch test; involves evaluation of movement smoothness.
Ataxia: Symptoms include wide-based gait and impaired tandem walking.

Reflex and Motor Response Assessment

Rebound Phenomenon: Examines spastic limb reactions when force is resisted and then abruptly stopped.
Pronator Drift: Assesses upper limb motor function; sign of possible neurological issues if hand pronates.

Spinal Cord Anatomy and Function

Dorsal Horn: Houses neurons for somatosensory information.
Ventral Horn: Contains motor neuron bodies; associated with muscle control.

Spinal Nerves

Total of 31 pairs; categorized into cervical, thoracic, lumbar, sacral, and coccygeal regions.
All spinal nerves carry both sensory and motor functions.
C1-C7 exit above vertebrae; all others exit below.

Blood Supply to Spinal Cord

Anterior Spinal Artery: Supplies the anterior two-thirds.
Posterior Spinal Arteries: Supply the posterior aspect; includes artery of Adamkiewicz.

Spinal Cord Lesions and Presentations

Anterior Spinal Artery Syndrome: Loss of pain and temperature sensation with intact vibration.
Tabes Dorsalis: Impairs dorsal columns; results in loss of vibration sense.
Cauda Equina Syndrome: Leads to saddle anesthesia and bladder dysfunction.
Spinothalamic Lesion: Causes contralateral loss of pain and temperature.
Syringomyelia: Results in bilateral pain and temperature loss, often associated with Chiari malformation.
Central Cord Syndrome: Characterized by cape-like loss of pain and temperature; common in elderly.
Amyotrophic Lateral Sclerosis (ALS): Features both UMN and LMN lesions, leading to progressive motor neuron degeneration.
Brown-Sequard Syndrome: Sudden unilateral spinal cord damage leads to specific sensory deficits on opposite sides of the body.

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Description

Explore the essential roles of neurotransmitters in communication between neurons. This quiz covers key neurotransmitters such as Acetylcholine, Dopamine, and Glutamate, along with their functions and associated deficits. Test your knowledge on these vital components of the nervous system.