**Author details**

90 Sexual Dimorphism

and females.

system [42].

[36]. A study of rhesus macaques has demonstrated that intact animals display less prepulse inhibition than animals given prepubertal castration [28]. This study also reveals that testosterone levels are correlated with tyrosine hydroxylase levels in the putamen among intact animals, suggesting the attenuation of PPI by gonadal sex hormones is mediated by dopaminergic activity in striatal regions. In addition, methamphetamine increases latent inhibition in male rats while this agent decreases this behavior in female rats, suggesting that presynaptic dopaminergic function shows a sex difference [37]. Hence, striatal DA function, especially presynaptic DA function may be different intrinsically between males

The reduced DA and DOPAC in the striatum can be interpreted as a decreased total DA contents in presynaptic DA terminals that imply decrement of the number in DA presynaptic terminals or reduced DA synthesis rates. Ineffectiveness of DA receptor antagonists on hyperlocomotion found in BrdU-rats also supports abnormality in presynaptic function rather than postsynaptic DA receptors. In rodent, DA agonists usually facilitate locomotor activity. This study indicated opposite changes in striatal DA between males and females as an effect of prenatal BrdU while hyperlocomotion was obviously detected in both sex. Hence, the hyperlocomotion may be attributed to DA abnormality in

Schizophrenia includes multiple pathology in brain functions. Striatal dysfunction is thought to be a fundamental element in schizophrenia [13]. A study using functional magnetic resonance imaging (fMRI) in schizophrenic patients has demonstrated that increased coherent intrinsic activity in the dorsal striatum during psychosis is predictive for delusion and hallucination and increased activity during psychotic remission in the ventral striatum is predictive for blunted affect and emotional withdrawal [38]. A positron emission tomography (PET) study has indicated an increased DA D2/D3 receptor density in a restricted area in the striatum [39]. A double-blind PET study has indicated that D2 blockade in the striatum predicts antipsychotic response better than frontal, temporal, thalamic occupancy [40]. In addition, an involvement of the striatum in the cognitive impairment in schizophrenia has been proposed [41]. Furthermore, a study using recent molecular technique has shown that D2 receptor overexpression in the striatum results in a functional deficit in the GABAergic system and this result suggests that the postulated deficit in GABAergic function in schizophrenia could be secondary to alterations in the striatum DA

It is hypothesized that psychosis is viewed as a process of aberrant salience [43] and a central role of DA is to mediate the salience of environmental events an internal representations [44]. A study using resting-state functional MRI has indicated increased that coherent intrinsic activity in the dorsal striatum during psychosis is predictive for delusion and hallucination, and that increased activity during psychotic remission in the ventral striatum is predictive for blunted affect and emotional withdrawal [38]. A meta-analysis of imaging studies using PET or single-photon emission computed tomography (SPECT) has indicated that the locus of the largest dopaminergic abnormality in schizophrenia is

the frontal cortex because the change was same in males and females.

Katsumasa Muneoka *Showa University School of Medicine, Department of Anatomy 1,Tokyo, Japan* 

Makiko Kuwagata *Hatano Research Institute, Food and Drug Safety Center, Toxicology Division, Kanagawa, Japan* 

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**Chapter 6** 

© 2013 Moreno-Gómez, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

and reproduction in any medium, provided the original work is properly cited.

**Sexual Dimorphism in Human Teeth from** 

Based on the referenced literature and from a holistic and integrating viewpoint, dental anthropology is seen as an interdisciplinary field that integrates knowledge of anthropology, dentistry, biology, paleontology and paleopathology in order to study all the information provided by the human dentition, such as anatomical, developmental, pathological, cultural and therapeutic variations in consideration of the conditions of life, culture, food and adaptation processes of the past and present human populations, through

Basically, dental anthropology is concerned with the study of morphological variation (dental morphological features) and metrics of the dentition of human populations over time (prehistoric and modern) and space (ethnic influences) and their relation with the processes of adaptation and dietary changes that led to the evolution of the dental system and the human race [3]. This is possible because the enamel is the hardest tissue of the human body and has a high capacity to preserve itself even in extreme conditions of pH, moisture, salinity and high temperatures, which is recognized in the archaeological taphonomic field as resistance, that dental morphology is expressed to be genetically unique and unrepeatable in each tooth [4], and the tooth structure (metric and morphological) formed histoembryologically does not change or remodel itself as with the bone, excluding mechanical wear or attrition and accumulation of secondary dentine [1], and teeth, in many cases have become the only element to be able *per se* to provide biological and cultural information of an individual or a human population, which is possible due to: 1. High heritability and strong genetic control of dental morphology; 2. Little environmental influence; 3. Correspondence between the dental characteristics and geographical distribution; 4. Are easy to observe and record; 5. Permit to compare past with present

**Dental Morphology and Dimensions:** 

**A Dental Anthropology Viewpoint** 

Additional information is available at the end of the chapter

morphology, size, disease and modifications of teeth [1,2].

Freddy Moreno-Gómez

http://dx.doi.org/10.5772/55881

**1. Introduction** 

