primary somatosensory cortex

(noun)

The main sensory receptive area for the sense of touch.

Related Terms

Examples of primary somatosensory cortex in the following topics:

  • Mapping the Primary Somatosensory Area

    • A cortical homunculus is a pictorial representation of the anatomical divisions of the primary motor cortex and the primary somatosensory cortex, i.e., the portion of the human brain directly responsible for the movement and exchange of sensory and motor information of the body.
    • Typically, the area of the body corresponds to a point on the primary somatosensory cortex (postcentral gyrus).
    • Areas such as the appendages, digits, and face can draw their sensory locations upon the somatosensory cortex.
    • The idea of the cortical homunculus was created by Wilder Penfield and serves as a rough map of the receptive fields for regions of primary somatosensory cortex.
    • The postcentral gyrus is located in the parietal lobe of the human cortex and is the primary somatosensory region of the human brain.

  • Sensory Areas

    • Parts of the cortex that receive sensory inputs from the thalamus are called primary sensory areas.
    • The primary somatosensory cortex, located across the central sulcus and behind the primary motor cortex, is configured to generally correspond with the arrangement of nearby motor cells related to specific body parts.
    • For example, the right primary somatosensory cortex receives information from the left limbs, and the right visual cortex receives information from the left eye.
    • Neighboring points in the primary visual cortex, for example, correspond to neighboring points in the retina.
    • Similarly, there is a tonotopic map in the primary auditory cortex and a somatotopic map in the primary sensory cortex.

  • Motor Areas

    • The motor areas of the brain are located in both hemispheres of the cortex.
    • Primary motor cortex: Main contributor to the generation of neural impulses that control the execution of movement.
    • Premotor cortex: Located anterior to the primary motor cortex and responsible for some aspects of motor control.
    • It is located on the midline surface of the hemisphere anterior to the primary motor cortex.
    • Topography of the human motor cortex, including the premotor cortex, SMA, primary motor cortex, primary somatosensory cortex, and posterior parietal cortex.

  • Thalamus

    • It is generally believed to act as a relay between a variety of subcortical areas and the cerebral cortex.
    • For the visual system, for example, inputs from the retina are sent to the lateral geniculate nucleus of the thalamus, which in turn projects to the primary visual cortex in the occipital lobe.
    • Each of the primary sensory relay areas receives strong back projections from the cerebral cortex.
    • Similarly, the medial geniculate nucleus acts as a key auditory relay between the inferior colliculus of the midbrain and the primary auditory cortex.
    • The ventral posterior nucleus is a key somatosensory relay, which sends touch and proprioceptive information to the primary somatosensory cortex.

  • Somatic Sensory Pathways

    • A somatosensory pathway will typically have three long neurons: primary, secondary and tertiary.
    • One major target within the brain is the postcentral gyrus in the cerebral cortex.
    • Note that many ascending somatosensory pathways include synapses in either the thalamus or the reticular formation before they reach the cortex.
    • The primary somatosensory area in the human cortex is located in the postcentral gyrus of the parietal lobe.
    • This is a pictorial representation of the anatomical divisions of the primary motor cortex and the primary somatosensory cortex, i.e., the portion of the human brain directly responsible for the movement and exchange of sensory and motor information of the body.

  • The Brain

    • As a rule, the smaller the cerebrum, the less convoluted the cortex.
    • The cortex of a rat or mouse is almost completely smooth.
    • The cortex of a dolphin or whale, on the other hand, is more convoluted than the cortex of a human.
    • The left and right hemispheres of the cerebral cortex are nearly symmetrical.
    • This deep fold marks the line where the primary somatosensory cortex (main sensory receptive area for the sense of touch) and primary motor cortex (one of the principal areas of the brain involved in motor function) come together.

  • General Organization of the Somatosensory System

    • A somatosensory pathway will typically consist of three neurons: primary, secondary, and tertiary.
    • The primary somatosensory area of the human cortex is located in the postcentral gyrus of the parietal lobe.
    • The postcentral gyrus is the location of the primary somatosensory area, the area of the cortex dedicated to the processing of touch information.
    • The surface area of cortex dedicated to a body part correlates with the amount of somatosensory input from that area.
    • Brain: The postcentral gyrus contains Brodmann areas (BA) 3a, 3b, 1, and 2 that make up the somatosensory cortex.

  • Cutaneous Sensation

    • The somatosensory system is composed of the receptors and processing centers to produce the sensory modalities, such as touch and pain.
    • The somatosensory is the system of nerve cells that responds to changes to the external or internal state of the body, predominately through the sense of touch, but also by the senses of body position and movement.
    • Processing primarily occurs in the primary somatosensory area in the parietal lobe of the cerebral cortex.

  • Sensory and Motor Tracts

    • The spinothalamic tract is a somatosensory tract while the corticospinal tract conducts motor impulses from the brain.
    • Both sensory pathways use three different neurons to get information from sensory receptors at the periphery to the cerebral cortex.
    • These neurons are designated primary, secondary, and tertiary sensory neurons.
    • The primary purpose of the corticospinal tract is voluntary motor control of the body and limbs.
    • However, connections to the somatosensory cortex suggest that the pyramidal tracts are also responsible for modulating sensory information from the body.

  • Cerebral Lobes

    • The cortex is divided into four main lobes: frontal, parietal, occipital, temporal.
    • The precentral gyrus, forming the posterior border of the frontal lobe, contains the primary motor cortex, which controls voluntary movements of specific body parts.
    • For example, it comprises the somatosensory cortex and the dorsal stream of the visual system.
    • The temporal lobe is involved in primary auditory perception such as hearing and holds the primary auditory cortex.
    • The superior temporal gyrus includes an area where auditory signals from the ear first reach the cerebral cortex and are processed by the primary auditory cortex in the left temporal lobe.