Physiology IV: Somatosensory System 2 - Primary Sensory Neurons and their Modalities

Sensory Pathways: [blank_start]Dorsal Column/Medial Lemniscus System[blank_end] Discriminatory touch, pressure, vibration, proprioception [blank_start]Spinothalmic Tract[blank_end] Pain, Thermosensation, itch, tickle

Third order neurons of the sensory pathways tend to originate in the [blank_start]Thalamus[blank_end] and project to the [blank_start]Primary Somatosensory Cortex[blank_end] (AKA the [blank_start]Postcentral[blank_end] Gyrus)

Label the parts of the sensory and motor pathways shown below.

The Dorsal Column is split into 2 parts, the fasciculus gracilis and fasciculus cuneatus. Which is which and what do they innervate?

The vertebral level where sensory information stops travelling via the fasciculus cuneatus and starts travelling in the fasciculus gracilis is ...

In terms of the dorsal column medial lemniscus pathway, [blank_start]2nd[blank_end] order neurons cross collectively at the great sensory decussation and ascend in the [blank_start]medial lemniscus[blank_end] to the [blank_start]Ventral Posterior Lateral (VPL)[blank_end] nucleus of the thalamus

The Dorsal Column Medial Lemniscus pathway allows for Stereognosis. What is this?

[blank_start]Lateral Inhibition[blank_end] is the way in which an active neuron inhibits the activity of its neighbours via inhibitory interneurons

The somatosensory cortex has how many cell layers?

As information is conveyed from one neuron to the next in a sensory pathway, differences in the activity of adjacent neurones are amplified. This phenomenon is called [blank_start]contrast enhancement[blank_end]

Lateral inhibition allows a more focussed idea of where a sensation has occurred in the body and is facilitated by a certain type of neuron. These neurons are called [blank_start]interneurons[blank_end]