The somatosensory cortex receives information from the general senses (touch,
temperature, pressure, pain, vibration). Behind this area, the somatosensory
association area interprets the stimuli. A lesion (such as that resulting
from a stroke) in the somatosensory cortex prevents you from feeling that
body part while a lesion in the association area prevents you from interpreting
stimuli there (such as recognizing what you hold in your hand without looking).
When an area of the somatosensory cortex is activated by sensation in the
contralateral region of the body, the corresponding ipsilateral region of
the somatosensory cortex is inhibited (perhaps via a projection from the
contralateral SII region through the corpus callosum) (Kastrup, 2008). Degeneration
of the somatosensory cortex is one of the first signs of multiple system
atrophy (Mochizuki, 2008).
The secondary somatosensory cortex (SII) responds to bilateral inputs
of general sensations, unlike the primary somatosensory cortex which only
responds to contralateral stimuli. SII is located above the lateral sulcus.
Painful and nonpainful stimuli are separated into distinct regions of
SII (Chen, 2008). The SII region plays a role in the recognition of an
object's orientation (Hsaio, 2002). It is believed that different regions
of the brain function in focusing attention, depending on the nature of
stimulus. The SII region is involved in selective attention of somatosensory
stimuli (Fujiwara, 2002).
The special senses include sight, smell, taste, and hearing. This sensory
information is recognized at specific areas: the visual, auditory, and
olfactory cortices. After each cortex recognizes the incoming stimuli,
the information is then interpreted and meaning is attached at the association
areas near these cortexes (the visual association area, auditory association
area, olfactory association area).
Lesions in the cortices for the special senses can obliterate that sense
(cortical blindness occurs after damage to the visual cortices although
the eyes and their input are still normal). Lesions in the association
areas might prevent you from recognizing familiar faces or sounds, for
example. The auditory association area (Wernicke's area) also translates
sounds into thoughts. Those with lesions here can have trouble comprehending
speech. Lesions in some areas of the visual association area can cause
colorblindness; large lesions result in someone who can see but doesn't
know what they're looking at.
A substantial amount of processing of sound information occurs in the
brainstem, midbrain, and thalamus before it reaches the auditory cortex.
Regions of the auditory cortex respond most strongly to human voice (as
opposed to animal vocalizations and other sounds). This is an example
of species-specific stimulus processing (Fecteau, 2004).
Schizophrenia, a disorder characterized by auditory hallucinations, is
associated with abnormal structure of the auditory cortex and a progressive
deterioration of this, and other, regions of the brain (Kasai, 2004).
In blind individuals, the visual cortex may adopt alternate processing
functions, such as a monitoring of auditory stimuli or language processing
(Kujala, 2004; Gilbert, 2004).
During ejaculation, virtually all of the cerebral cortex undergoes decreased
activity while certain areas, such as the right prefrontal cortex, septum,
midbrain-diencephalon region, putamen, insula, and cerebellum, increase
their activity. The visual cortex shows increased activity even if a subject's
eyes are closed (Bianchi-Demicheli, 2007). Some studies have identified
gender differences in activated areas with the medial amygdala, hypothalamus,
preoptic area, and anterior cingulated being more active in women and
the visual cortex more active in men (Bianchi-Demicheli, 2007; Levin,
The recollection of memories of specific events can be associated with
activation of the hippocampus and olfactory cortex (Gottfried, 2004).