Lecture 7 NROB60 Question And Answer

Flashcards generated from the lecture notes focusing on the somatosensory pathways and principles of sensation, useful for exam preparation.

What is the main focus of Lecture 7 in NROB60?

Somatosensory pathways.

Which pathways are covered for touch and pain in this lecture?

Dorsal Column-Medial Lemniscus pathway for touch and Anterolateral System for pain.

What process converts the energy of a stimulus into an electrical signal?

Sensory transduction.

What is sensory transduction?

The process of converting the energy of a stimulus into an electrical signal.

What do afferent sensory signals activate?

Central neurons capable of representing qualitative and quantitative aspects of the stimulus.

What is the term for body sensation, particularly touch and pain sensation?

Somatosensory.

What two types of touch are distinguished in the somatosensory system?

Fine touch and crude touch.

What is fine touch?

Two-point discriminative touch; the ability to sense and localize where the stimulus touches the body.

What is crude touch?

Non-discriminative touch; the sense that something has touched you without localization.

What are proprioceptors responsible for?

Sensing the position of our own limbs and body parts in space.

What is meant by the concept of 'labeled lines'?

Each nerve input to the brain reports only a particular type of information.

Where are the cell bodies of pseudounipolar sensory neurons located?

In the dorsal root ganglia.

What kind of channels do stimuli alter to initiate sensory transduction?

Cation channels.

What is the result of the deformation of the skin in sensory transduction?

It stretches the afferent nerve membrane.

How does amplitude relate to action potentials in sensory neurons?

Action potentials are all-or-none responses; their amplitude cannot encode information about the sensory stimulus.

What are mechanoreceptors responsible for?

Detecting mechanical stimuli such as touch and pressure.

What are the four types of tactile receptors sensitive to light touch?

Pacinian afferents, Meissner afferents, Merkel cell afferents, Ruffini afferents.

What characterizes the adaptation of tactile receptors?

Progressive loss of receptor sensitivity as stimulation is sustained.

Where do sensory afferents convey information when they enter the spinal cord?

To the dorsal horn.

What does the dorsal column-medial lemniscus pathway transmit?

Touch information.

Which major synapse occurs at the dorsal column nuclei?

The first-order axons terminate onto second-order neurons.

At what level does sensory information cross midline in the dorsal column pathway?

At the level of the medulla.

What is somatotopy?

The spatial organization of the body represented in the cortex.

What is the role of the thalamus in sensory processing?

It relays sensory information to the cortex.

What do nociceptors respond to?

Stimuli that produce tissue damage or pose a threat of damage.

What is the difference between Aδ and C fibers?

Aδ fibers are myelinated and carry fast pain signals; C fibers are unmyelinated and carry slow pain signals.

What kind of information does the spinothalamic tract carry?

Discriminative (first pain) and affective-motivational (second pain) information.

Which types of pain pathways are there in the anterolateral system?

Sensory-discriminative and affective-motivational pathways.

What is the role of TRPV1 ion channels?

Detecting sudden increases in temperature and binding capsaicin.

What happens to the representation areas in the somatosensory cortex after significant sensory experience?

Functional remapping occurs, expanding areas related to frequently used digits.

What is a dermatome?

The strip of skin innervated by a particular spinal nerve.

What does the dorsal horn of the spinal cord primarily contain?

Sensory neurons.

What two tracts are distinguished in the dorsal columns at the cervical level?

Fasciculus Gracilis and Fasciculus Cuneatus.

How do the somatosensory pathways differ for touch vs pain?

Touch pathways involve different neural routes and points of decussation compared to pain pathways.

What is the significance of dorsal column nuclei's position in relation to the body region it processes?

Gracile nuclei handle the lower body and cuneate nuclei handle the upper body.

Which ion channel is associated with cool sensations?

TRPM8.

What is referred to when discussing the 'somatosensory homunculus'?

The mapping of body parts represented in the primary somatosensory cortex.

What determines the size of a neuron's receptive field?

The branching characteristics of the afferent within the skin.

What does the dorsal column convey?

Ascending sensory information primarily from somatic mechanoreceptors.

What type of chronic pain is typically associated with persistent stimuli?

Second pain, which is duller and burning.

What are Ruffini afferents especially sensitive to?

Skin stretching during finger movement.

What do the layers of the spinal cord indicate according to cytoarchitecture?

The organization of neurons into specific functional zones.

What is a characteristic of cutaneous mechanoreceptors?

They are morphologically distinct and respond to different forms of energy.

How does pain signaling enhance recovery behavior?

It promotes actions like rest and feeding, which aid recuperation.

What is the typical threshold for pain detection from heat?

43°C.

What type of receptor is the TRPV1?

A vanilloid receptor that responds to painful heat.

How does a lesion in the dorsal column manifest clinically?

As a loss of touch sensation on the contralateral side of the body.

How does the neural representation of different fingers in the somatosensory cortex reflect functional usage?

More sensitive and frequently used fingers occupy more cortical area.

What is the main function of the dorsal columns?

To carry sensory information from mechanoreceptors to the brain.

What factors contribute to the morphological specialization of free nerve endings in the skin?

Cellular structures and receptor proteins that define their function.

Where are the primary sensory neurons initiated for touch sensation?

In the dorsal root ganglia.

In the spinal cord, what are the ventral horns associated with?

Motor functions.

What is the relationship between the anterolateral system and pain processing?

It contains defined tracts that help process pain signals from the body.

How does the spinothalamic tract differ from the dorsal column pathway?

It decussates immediately at the spinal cord level while the dorsal column decussates at the medulla.

What is the purpose of sensory homunculus mapping?

To visually represent sensory area distribution for different body parts in the cortex.

What does adaptation in mechanical receptors refer to?

A decrease in firing rate despite continued stimulus application.

What leads to inflammation following tissue damage?

Release of various substances from damaged cells and immune cells.

What role do free nerve endings play?

They function as nociceptors detecting pain and temperature changes.

What are cutaneous mechanoreceptors primarily involved in?

Detecting different types of mechanical stimuli.

How is the first pain characterized in the sensory experience?

As a sharp and sudden sensation.

What region of the body is innervated by the Fasciculus Gracilis?

The lower body.

How are nociceptive signals processed within the spinal cord?

By entering the dorsal horn and synapsing with second-order neurons.

How does variation in skin type affect mechanoreceptor distribution?

Smooth and hairy skin host different mechanosensory properties.

What is the role of the anterior white commissure in the anterolateral system?

It facilitates the crossing of second-order neurons to the contralateral side.

What clinical implications arise from understanding dermatomes?

They help localize neurological lesions based on sensory loss patterns.

What neural process occurs when an afferent signal crosses to the opposite side of the body?

Decussation.

Which type of pain pathways can have overlapping functions?

Sensory-discriminative and affective-motivational pain pathways.

What type of stimuli activate TRPV1 receptors?

Painful heat and capsaicin.

What physiological phenomenon occurs when there is damage to the somatosensory pathways?

Changes in somatosensory perception, often leading to altered sensations.

What clinical symptoms may arise from lesions in the dorsal column-medial lemniscus pathway?

Loss of tactile discrimination and proprioception.

What determines the type of information the anterolateral system processes?

The specific pathways involved in pain and temperature sensations.

How does the nervous system differentiate between various modalities of sensation?

Through distinct neural pathways for touch, pain, and temperature.

What correction regarding frequency of action potentials occurs during increased stimulus intensity?

A change in firing pattern reflecting stimulus features.

What functions are associated with the medial lemniscus tract?

Carrying touch information from the contralateral side of the body to the thalamus.

Why is understanding receptor adaptation important for sensory processing?

It informs how stimulus changes are detected and processed.

What does the representation of sensory information in cortical maps indicate?

The degree of sensory input and usage of body parts.

What would damage to the spinoreticular tract impact?

The emotional aspects of pain perception.

Which thalamic nucleus is involved in somatosensory processing?

Ventral Posterior Lateral nucleus (VPL).

What characterizes the response of Pacinian corpuscles?

They are rapidly adapting and sensitive to high-frequency vibrations.

What defines the complexity of sensory processing in the cortex?

The integration and interpretation of signals from multiple modalities.

What is an example of a behavioral response to painful stimuli?

Withdrawal reflex.

What clinical strategies can be inferred from the anatomy of somatosensory pathways?

Identifying the location of lesions based on sensory loss.

What process follows the synapsing of second-order neurons in the dorsal column pathway?

Ascending to the thalamus and then to the cortex.

What type of pressure sensations do Ruffini ending afferents respond to?

Deep pressure and skin stretch.

What adaptations in the somatosensory cortex are associated with motor skill learning?

Reconfiguration and expansion of neural pathways associated with skilled tasks.

What is the significance of the spatial arrangement of sensory input in the cortex?

It reflects the importance and frequency of use of different body parts.

How does the anterolateral system represent pain information?

Through a series of tracts that carry different aspects of pain processing.

What triggers the activation of nociceptors?

Tissue damage or potentially harmful stimuli.

What two types of pain sensations are associated with Aδ and C fibers, respectively?

First pain (sharp) for Aδ and second pain (dull) for C fibers.

What is the consequence of adaptation for tactile sensations?

It allows a focus on significant changes in stimulus rather than constant stimuli.

Why is the dorsal column pathway critical for touch?

It allows for fine discriminatory touch and proprioceptive feedback.

How does the density of mechanoreceptors relate to sensory acuity?

More dense innervation leads to finer tactile discrimination.

What can the loss of dermatomes indicate clinically?

Potential nerve injury or neurological conditions.

Why is pain considered an adaptive response?

It helps protect from further injury and encourages healing behaviors.

What role does the thalamus have in sensory processing?

It acts as a relay station for sensory information before it reaches the cortex.

What are the layers of the spinal cord primarily composed of?

Gray and white matter, with organized neuronal structures.

What can excessive or abnormal activity in nociceptors lead to?

Chronic pain conditions.

What behavioral implications arise from the emotional component of pain?

Responses such as vocalization or withdrawal behaviors.

What is the key feature of mechanoreceptor adaptation over time?

The reduction in firing rate despite continuous stimulation.

What anatomical features characterize the dorsal root ganglia?

Contain the cell bodies of pseudounipolar sensory neurons.