Lecture 17 - Somatosensory System: Touch and Proprioception

These flashcards cover key terms and concepts related to the somatosensory system, its functions, and the mechanisms involved in touch and proprioception.

A network of sensory pathways that processes information related to touch, temperature, pain, and proprioception, enabling the perception of various tactile stimuli.

What is the somatosensory system?

The ability to identify two distinct points of stimuli applied simultaneously on the skin, dependent on the density of sensory receptors and the size of receptive fields.

What is two-point discrimination?

The specific area of skin where sensory neuron activation occurs in response to a stimulus, crucial for touch perception.

What is a somatosensory receptive field?

The internal sense that provides awareness of body position and movement, essential for coordination and balance.

What is proprioception?

The electrical change in a sensory neuron's membrane potential triggered by a stimulus, initiating sensory signaling.

What is a receptor potential?

Sensory receptors that respond to mechanical forces such as pressure, vibration, and touch.

What are mechanoreceptors?

Unencapsulated nerve endings that respond to pain (nociception) and temperature changes.

What are free nerve endings?

A sensory pathway transmitting mechanosensory information (pressure, vibration) from the body to the brain.

What is the dorsal column-medial lemniscal pathway?

A neural pathway that carries tactile and proprioceptive information from the face to the brain.

What is the trigeminothalamic system?

The process of converting external stimuli into electrical signals in sensory receptors.

What is sensory transduction?

The minimum stimulus intensity required to activate a sensory neuron and elicit a response.

What is threshold in sensory systems?

An area of skin primarily supplied by a single spinal nerve root, important for sensory mapping.

What is a dermatome?

The brain's ability to adapt and rearrange its neural connections in response to injury or new experiences.

What is functional reorganization in the brain?

Mechanoreceptors that provide different sensory information; slowly adapting respond to sustained stimuli, while rapidly adapting respond to changes.

What are slowly and rapidly adapting mechanoreceptors?

To process sensory information from the body related to touch, pain, temperature, and proprioception, with increased representation for sensitive areas.

What is the function of the somatosensory cortex?

Higher density of sensory fibers typically results in smaller receptive fields, leading to greater sensory acuity.

What is the relationship between receptive field size and density?

The ability to detect two closely spaced points on the skin as distinct sensations, indicating tactile acuity.

What is two-point discrimination of the skin?

They determine receptive field size and density, impacting the brain's ability to distinguish between closely applied stimuli.

How do somatosensory afferents influence two-point discrimination?

It adjusts its receptive fields in response to sensory experience or injury to accommodate changes in input.

How does the somatosensory cortex remap based on experience?

Mechanoreceptors detect pressure and vibrational changes, providing the necessary input for distinguishing two touch points.

What role do mechanoreceptors play in two-point discrimination?

Regions like fingers and lips, with smaller receptive fields, enable greater tactile resolution and discrimination.

How does surface area affect two-point discrimination?

A visual representation illustrating the relative size of body areas based on sensory innervation, highlighting sensitivity variations.

What is the significance of the homunculus in the somatosensory cortex?

The process of sensory adaptation can decrease sensitivity to constant stimuli, impacting the ability to detect closely spaced stimuli.

How does adaptation of sensory receptors affect two-point discrimination?

Factors include genetics, skin type, age, and sensory experiences, all affecting tactile acuteness.

What factors contribute to individual differences in two-point discrimination?

It integrates sensory input with motor controls and emotional responses, facilitating coordinated actions.

How does the somatosensory cortex interact with other brain regions?

Injury can lead to sensory deficits, including loss of proprioception and impaired tactile processing.

What is the impact of injury to the somatosensory cortex?

Acts as a relay, processing sensory information before transmitting it to the somatosensory cortex.

What is the role of the thalamus in somatosensory processing?

Development arises from sensory stimulation and experiences, shaping responsiveness to touch.

How does tactile sensation develop in infants?

It aids in diagnosing neurological conditions and tracking recovery during rehabilitation.

What are the clinical implications of understanding two-point discrimination?

Using calipers to find the minimal distance at which two distinct points are perceived.

How can two-point discrimination be tested clinically?

Higher sensory acuity corresponds to improved ability to discriminate between two close points on the skin.

What is the relationship between sensory acuity and two-point discrimination?