Question

We have seen that our sensory systems seem to all use some form of hierarchical organization. In tactile perception, the first region in the sensory pathway with cells that selectively respond to the orientation of a stimulus (as was seen in simple cells in vision), is in the:

A. Dorsal root ganglion cells
B. Medial lemniscal pathway
C. Thalamus
D. Motor cortex
E. Somatosensory cortex

Answer 1

The first region in the sensory pathway that selectively responds to the orientation of a tactile stimulus is the somatosensory cortex. This area is part of the hierarchical organization of the sensory system where initial cortical processing of tactile information takes place.

Step-by-step explanation:

In the context of tactile perception and sensory processing within the human nervous system, we consider the hierarchical organization of these systems. Tactile and other somatosensory stimuli first activate receptors in the peripheral nervous system, such as in the skin, muscles, tendons, and joints. These stimuli are then conveyed via ascending pathways to the central nervous system, specifically to areas of the brain that process and interpret sensory information.

For tactile stimuli coming from most of the body (below the neck), these are carried to the brain via the spinal cord through the dorsal column system or spinothalamic tract. Within these pathways, there are neurons successively transmitting the signals to higher centers. The first region in the sensory pathway with cells that selectively respond to the orientation of a tactile stimulus, similar to the function of simple cells in the visual system, is in the somatosensory cortex. This is the area of the brain where the initial cortical processing of tactile information occurs, progressing to further associative and integrative areas for complex processing and response initiation.