**2. Clinical state and cognitive dysfunction in Parkinson's disease**

Parkinson's disease (PD) causes tremors of the hands, stiffness, akinesia, or inability to maintain posture. Patients with PD have decreased levels of dopamine in the striatum, which consists of the putamen and caudate nucleus, which are a part of the basal ganglia [11]. They may further develop protein-related disorders,

**117**

**Figure 3.**

*counts on the striatum per pixel.*

*Cross-Modality Dysfunction between the Visual and Olfactory Systems in Parkinson's Disease*

such as the presynaptic dopamine transporter (DaT), which is responsible for the incorporation and transmission of dopamine components [12]. DaT scanning is performed with ioflupane (123I-FP-CIT), a radio-iodinated cocaine analogue [13, 14]. It has a high affinity for the DaT protein located on presynaptic nerve endings in the striatum. These nerve endings are projections of dopaminergic neurons from the substantia nigra. Binding of a radiopharmaceutical agent to DaT reflects number of striatal dopaminergic neurons. The accumulation of DaT is expressed in proportion to the occipital lobe (**Figure 3**). The degree of DaT deficit is associated

The principal symptoms of PD are related to movement, although the nonmotor symptoms are also noteworthy. For example, attention function, which demands a response speed or switching [16]; executive function, which is related to action planning or problem solving [17]; working memory function, which holds information temporarily and allocates attentional resources [18, 19]; social cognition function, which involves interpreting emotions based on others' facial expressions [20, 21]; and temporal function, which estimates duration [22, 23] were

Impairment of olfaction has also been reported in patients with PD and may be a biomarker for cognitive dysfunction and early PD [24–26]. Olfactory information is projected directly to the limbic system, including the piriform (PIR), amygdala (AMG), hippocampus (HI), and entorhinal cortex (ENT). These areas determine odor detection, its emotional evaluation (pleasant or unpleasant), and memory retrieval [27]. Olfactory information finally ascends to the orbitofrontal cortex (OFC). The OFC participates in the identification or recognition of odor, filtered through emotion and memory via activation of the AMG and HI [28]. Olfactory dysfunction in PD may occur due to deficiency of dopamine and pathological changes in the ENT, AMG and HI, especially in the areas affected by early onset of

Furthermore, the striatum is involved in various functions, which include an integration of sensory information [30–32]. Studies have demonstrated that the striatum (putamen and caudate) acts as a "hub," with specialized functional roles for different neuron types in mice [33] and humans [34, 35]. However, it was

*Striatal DaT deficit in Parkinson's disease (coronal view). The left panel shows a binding radiopharmaceutical agent accumulation in a healthy person. The right panel shows a binding radiopharmaceutical agent accumulation in a patient with Parkinson's disease. The numbers indicate binding radiopharmaceutical agent* 

*DOI: http://dx.doi.org/10.5772/intechopen.90116*

with the severity of the movement disorder [15].

unclear whether PD affects cross-modal function.

shown to be impaired in PD.

PD [29].

## *Cross-Modality Dysfunction between the Visual and Olfactory Systems in Parkinson's Disease DOI: http://dx.doi.org/10.5772/intechopen.90116*

such as the presynaptic dopamine transporter (DaT), which is responsible for the incorporation and transmission of dopamine components [12]. DaT scanning is performed with ioflupane (123I-FP-CIT), a radio-iodinated cocaine analogue [13, 14]. It has a high affinity for the DaT protein located on presynaptic nerve endings in the striatum. These nerve endings are projections of dopaminergic neurons from the substantia nigra. Binding of a radiopharmaceutical agent to DaT reflects number of striatal dopaminergic neurons. The accumulation of DaT is expressed in proportion to the occipital lobe (**Figure 3**). The degree of DaT deficit is associated with the severity of the movement disorder [15].

The principal symptoms of PD are related to movement, although the nonmotor symptoms are also noteworthy. For example, attention function, which demands a response speed or switching [16]; executive function, which is related to action planning or problem solving [17]; working memory function, which holds information temporarily and allocates attentional resources [18, 19]; social cognition function, which involves interpreting emotions based on others' facial expressions [20, 21]; and temporal function, which estimates duration [22, 23] were shown to be impaired in PD.

Impairment of olfaction has also been reported in patients with PD and may be a biomarker for cognitive dysfunction and early PD [24–26]. Olfactory information is projected directly to the limbic system, including the piriform (PIR), amygdala (AMG), hippocampus (HI), and entorhinal cortex (ENT). These areas determine odor detection, its emotional evaluation (pleasant or unpleasant), and memory retrieval [27]. Olfactory information finally ascends to the orbitofrontal cortex (OFC). The OFC participates in the identification or recognition of odor, filtered through emotion and memory via activation of the AMG and HI [28]. Olfactory dysfunction in PD may occur due to deficiency of dopamine and pathological changes in the ENT, AMG and HI, especially in the areas affected by early onset of PD [29].

Furthermore, the striatum is involved in various functions, which include an integration of sensory information [30–32]. Studies have demonstrated that the striatum (putamen and caudate) acts as a "hub," with specialized functional roles for different neuron types in mice [33] and humans [34, 35]. However, it was unclear whether PD affects cross-modal function.

#### **Figure 3.**

*Sino-Nasal and Olfactory System Disorders*

*more pleasant odor than the green strawberry on the right.*

is that of "ga-ga", most people experiences an illusory sound "da-da". For the double flash illusion, if one dot flashes on the display when two beeps are sounded, most people reports experiencing two flashes. Thus, vision dominates the other senses in many cases. Although the mechanism of cross-modality has become increasingly clear in healthy persons [1–10], a function in disease states remains unclear.

*Diagram representing the effective relationship among the five senses. Vision is often prioritized over the other* 

*An example of the effect of color effect on smell recognition. The red strawberry on the left may seem to have a* 

**2. Clinical state and cognitive dysfunction in Parkinson's disease**

Parkinson's disease (PD) causes tremors of the hands, stiffness, akinesia, or inability to maintain posture. Patients with PD have decreased levels of dopamine in the striatum, which consists of the putamen and caudate nucleus, which are a part of the basal ganglia [11]. They may further develop protein-related disorders,

**116**

**Figure 2.**

**Figure 1.**

*senses during integration.*

*Striatal DaT deficit in Parkinson's disease (coronal view). The left panel shows a binding radiopharmaceutical agent accumulation in a healthy person. The right panel shows a binding radiopharmaceutical agent accumulation in a patient with Parkinson's disease. The numbers indicate binding radiopharmaceutical agent counts on the striatum per pixel.*
