**3. Results**

#### **3.1 Findings of magnetic resonance studies applied to sex stimuli processing in paedophilia**

The detailed procedure gave a total of only 7 documents that were complying with the criteria of incorporation. All the documents were articles published in scientific journals. All these works was gathered in two different principal subject matters:


The structural studies were 3 and functional studies 4. The works that study regions of interest was 6 and works that study of the brain in total was 1. Respect to the design, the total of the studies have an experimental design. The type of sample has been organized on the basis of a two category:


In all the works the sex of the participants was masculine. The works that include group control (of healthy controls and not offenders) was 6 and the works that include other groups of delinquents (non sex offenders) was 1. On the other hand, the works that included homosexuals sample was 1, heterosexuals 2 and both (homosexuals and heterosexuals) was 4. The principal results obtained in every work are described of general form immediately afterwards (a brief summary of the same ones can observe in the table 3).


Table 3. Brief description and % of the studies included in the review.

#### **3.2 Structural magnetic resonance studies**

78 Neuroimaging for Clinicians – Combining Research and Practice

3. Works that were using as variable of interest the results of the structural and functional techniques to compare paedophiles with other groups (group of control or groups of

4. Works that were contributing empirical original information published in English, rejecting theoretical previous works, neuropsychological studies and studies of clinical

The search was realized during September, 2010. Once recovered all the works was reviewed with the aim to analyze if they are complying with the criteria of incorporation.

2. Sample and Groups. From that was extracted the number of participants, sex and groups in which was divided the sample (in case such that division is existing). 3. Magnetic renonance technique used. It was gathered information about the technique of

4. Type of design used for the study. It was gathered information about the type of design used in the study, for example if they were experimental, quasi-experimental, and

5. Principal obtained findings. Were extracted the principal results contributed by the

The detailed procedure gave a total of only 7 documents that were complying with the criteria of incorporation. All the documents were articles published in scientific journals. All

The structural studies were 3 and functional studies 4. The works that study regions of interest was 6 and works that study of the brain in total was 1. Respect to the design, the total of the studies have an experimental design. The type of sample has been organized on

In all the works the sex of the participants was masculine. The works that include group control (of healthy controls and not offenders) was 6 and the works that include other groups of delinquents (non sex offenders) was 1. On the other hand, the works that included homosexuals sample was 1, heterosexuals 2 and both (homosexuals and heterosexuals) was 4. The principal results obtained in every work are described of general form immediately

**3.1 Findings of magnetic resonance studies applied to sex stimuli processing in** 

these works was gathered in two different principal subject matters:

2. The sexual orientation of the people included in the sample.

afterwards (a brief summary of the same ones can observe in the table 3).

2. Works that study regions of interest or brain in total.

other sexual aggressors and delinquents in general).

They were checked also by the aim to extract the pertinent information.

From each of the works the following information was extracted:

case.

**2.3 Procedure** 

work.

**3. Results** 

**paedophilia** 

**2.4 Codification of the results** 

1. Authors and year of publication.

neuroimage used in the study.

descriptive, among others.

1. Structural or functional studies.

1. The type of groups that they include.

the basis of a two category:

The results of the structural magnetic resonance studies that study regions of interest, as frontal and temporo-limbic structures, showed that paedophiles had a lesser volume of gray matter in the frontostriatal circuits and the ventral striatum, which extended into the nucleus accumbens and orbitofrontal cortex (Schiffer et al., 2007).


Table 4. Brief summary of the different sMRI studies in paedophilia.

Magnetic Resonance Techniques in Study of Sexual Stimuli Processing in Paedophilia 81

prefrontal cortex, hypothalamus and periaqueductal gray matter. However, in no erotic emotional processing, they exhibited a less marked functional response in structures such as the amygdala, hippocampus and dorsomedial prefrontal cortex (Walter et al., 2007). A later research studies specifically the amygdale. Since the amygdala activation is central for emotional valuation, arousal, and salience this study investigate the amygdala activation, with functional magnetic resonance, in response to pictures of adults and children in paedophiles (exclusively attracted to boys) and in a control group (heterosexual). The controls showed less amygdala activation to pictures of children compared to adults. The activation profile was reversed in subjects with paedophilia, who exhibited significantly

Another research compare if the cerebral response of the heterosexual paedophiles to heteropaedophilic visual stimuli are comparable to the cerebral response of heterosexual men to heterosexual stimuli. This response included the activation of different limbic structures (amygdala, cingulated gyrus and hippocampus), substantia nigra, caudate nucleus, anterior cingulated cortex, different thalamic nuclei and association cortex. However, heterosexual men of the control group exhibited a cerebral response in the orbitofrontal cortex during visual sexual stimulation; this frontal response was not similar in the paedophiles that showed an abnormally reduced activity in the dorsolateral prefrontal cortex (Schiffer, Paul et al., 2008). Finally, other research studied of the pattern of cerebral activation in homosexual paedophiles and homosexual controls, during visual sexual stimulation. For this purpose was using photographs that are sexually stimulating and emotionally neutral to the two groups. In both groups finding that the sexually arousing images activated cerebral areas involved in the visual processing of emotional stimuli (occipitotemporal and prefrontal cortexes), but during the presentation of these images, there was a significant activation of areas such as the thalamus, globus pallidus and striata

**Authors-year N Groups (n) Sex orientation MRI Study Findings in paedophiles** 

Reduced activation in hypothalamus and lateral PFC

amygdala

Reduced activation of OFC and dorsolateral PFC

Increased activation of thalamus, globus pallidus and striatum

fMRI of ROI Increased activation in

(14) Heterosexuals fMRI of ROI

(12) Heterosexuals fMRI of ROI

(12) Homosexuals fMRI of ROI

HC = Healthy Controls Group, N = Total Sample, NO = Nonsexual Offenders Group, OFC = Orbitofrontal Cortex, P = Paedophiles Group, PFC = Prefrontal Cortex, ROI = Regions of

Hetero (HC) Homosexuals (P)

more activation to children than adults (Sartorius et al., 2008).

only in the group of paedophiles (Schiffer, Krueger et al., 2008).

20 P (10), HC (10)

20 P (8), HC

23 P (11), HC

Table 1. Brief summary of the different fMRI studies in paedophilia.

Walter *et al*. (2007) 27 P (13), HC

Sartorius *et al*. (2008)

Schiffer, Paul *et al*. (2008)

Schiffer, Krueger *et al*. (2008)

Interest.

Another study also looks for differences in specific areas. This investigation study portions of the limbic system, such as the amygdala, and in the gray matter of structures related to the development of sexual behaviour, such as the hypothalamus. In paedophiles, there was a significant decrease in the volume of the right amygdala and a bilateral reduction of the gray matter of the hypothalamus, septal regions, substantia innominata and bed nucleus of the stria terminalis (Schiltz et al., 2007) (A brief summary of this studies can be seen in table 4).

The study with more statistical power realized up to the date, and that compares the brain in your totality; find negative associations between paedophilia and the volumes of bilateral white matter of the parietal and temporal lobes. The regions with the lowest volume of white matter were adjacent to two major groups of fibres: the superior frontooccipital fasciculus and the right arcuate fasciculus. No difference was observed in the gray matter or in the volume of cerebrospinal fluid (Cantor et al., 2008) (Figure 1 shown a schema of brain white matters tracts. In this figure can observed the tracts of white matters affected in paedophilia, according to the Cantor et al., 2008).

Brain White Matter Tracts: 1) Arcuate Fasciculus (Short Fibres), 2) Superior Fronto-Occipital Fasciculus, 3) Cingulum, 4) Corpus Callosum, 5) Uncinate Fasciculus, 6) Inferior Longitudinal Fasciculus, 7) Perpendicular Fasciculus and 8) Superior Longitudinal Fasciculus. The white matter fibres affected in paedophilia are structures 1 and 2 (Cantor et al., 2008).

Fig. 1. Brain White Matter Tracts.

#### **3.3 Functional magnetic resonance studies**

On the other hand the functional neuroimaging studies during emotional and erotic stimulation find the following results. In a one o this studies is compared a group of paedophiles and a control group using emotional and erotic pictures. It was observed that the paedophiles responded less to visual erotic stimulation in three regions: dorsolateral

Another study also looks for differences in specific areas. This investigation study portions of the limbic system, such as the amygdala, and in the gray matter of structures related to the development of sexual behaviour, such as the hypothalamus. In paedophiles, there was a significant decrease in the volume of the right amygdala and a bilateral reduction of the gray matter of the hypothalamus, septal regions, substantia innominata and bed nucleus of the stria

The study with more statistical power realized up to the date, and that compares the brain in your totality; find negative associations between paedophilia and the volumes of bilateral white matter of the parietal and temporal lobes. The regions with the lowest volume of white matter were adjacent to two major groups of fibres: the superior frontooccipital fasciculus and the right arcuate fasciculus. No difference was observed in the gray matter or in the volume of cerebrospinal fluid (Cantor et al., 2008) (Figure 1 shown a schema of brain white matters tracts. In this figure can observed the tracts of white matters affected in

Brain White Matter Tracts: 1) Arcuate Fasciculus (Short Fibres), 2) Superior Fronto-Occipital Fasciculus, 3) Cingulum, 4) Corpus Callosum, 5) Uncinate Fasciculus, 6) Inferior Longitudinal Fasciculus, 7) Perpendicular Fasciculus and 8) Superior Longitudinal Fasciculus. The white matter fibres affected in

On the other hand the functional neuroimaging studies during emotional and erotic stimulation find the following results. In a one o this studies is compared a group of paedophiles and a control group using emotional and erotic pictures. It was observed that the paedophiles responded less to visual erotic stimulation in three regions: dorsolateral

terminalis (Schiltz et al., 2007) (A brief summary of this studies can be seen in table 4).

paedophilia, according to the Cantor et al., 2008).

paedophilia are structures 1 and 2 (Cantor et al., 2008).

**3.3 Functional magnetic resonance studies** 

Fig. 1. Brain White Matter Tracts.

prefrontal cortex, hypothalamus and periaqueductal gray matter. However, in no erotic emotional processing, they exhibited a less marked functional response in structures such as the amygdala, hippocampus and dorsomedial prefrontal cortex (Walter et al., 2007). A later research studies specifically the amygdale. Since the amygdala activation is central for emotional valuation, arousal, and salience this study investigate the amygdala activation, with functional magnetic resonance, in response to pictures of adults and children in paedophiles (exclusively attracted to boys) and in a control group (heterosexual). The controls showed less amygdala activation to pictures of children compared to adults. The activation profile was reversed in subjects with paedophilia, who exhibited significantly more activation to children than adults (Sartorius et al., 2008).

Another research compare if the cerebral response of the heterosexual paedophiles to heteropaedophilic visual stimuli are comparable to the cerebral response of heterosexual men to heterosexual stimuli. This response included the activation of different limbic structures (amygdala, cingulated gyrus and hippocampus), substantia nigra, caudate nucleus, anterior cingulated cortex, different thalamic nuclei and association cortex. However, heterosexual men of the control group exhibited a cerebral response in the orbitofrontal cortex during visual sexual stimulation; this frontal response was not similar in the paedophiles that showed an abnormally reduced activity in the dorsolateral prefrontal cortex (Schiffer, Paul et al., 2008). Finally, other research studied of the pattern of cerebral activation in homosexual paedophiles and homosexual controls, during visual sexual stimulation. For this purpose was using photographs that are sexually stimulating and emotionally neutral to the two groups. In both groups finding that the sexually arousing images activated cerebral areas involved in the visual processing of emotional stimuli (occipitotemporal and prefrontal cortexes), but during the presentation of these images, there was a significant activation of areas such as the thalamus, globus pallidus and striata only in the group of paedophiles (Schiffer, Krueger et al., 2008).


Table 1. Brief summary of the different fMRI studies in paedophilia.

Magnetic Resonance Techniques in Study of Sexual Stimuli Processing in Paedophilia 83

comparison with control subjects, the results of these latter studies appear to demonstrate that, in the presence of stimuli that are sexually relevant for each group, the central processing of these stimuli is comparable in the two groups, while the pattern of cerebral

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**6. References** 

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<www.dsm5.org>

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43.
