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** Main emotions, manifested by face, can activate fusiform and extra striates.<ref name="pmid17400195">{{cite journal| author=Deeley Q, Daly EM, Surguladze S, Page L, Toal F, Robertson D | display-authors=etal| title=An event related functional magnetic resonance imaging study of facial emotion processing in Asperger syndrome. | journal=Biol Psychiatry | year= 2007 | volume= 62 | issue= 3 | pages= 207-17 | pmid=17400195 | doi=10.1016/j.biopsych.2006.09.037 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17400195  }} </ref>
** Main emotions, manifested by face, can activate fusiform and extra striates.<ref name="pmid17400195">{{cite journal| author=Deeley Q, Daly EM, Surguladze S, Page L, Toal F, Robertson D | display-authors=etal| title=An event related functional magnetic resonance imaging study of facial emotion processing in Asperger syndrome. | journal=Biol Psychiatry | year= 2007 | volume= 62 | issue= 3 | pages= 207-17 | pmid=17400195 | doi=10.1016/j.biopsych.2006.09.037 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17400195  }} </ref>
**Several neuropsychological studies have suggested the following problems:<ref name="pmid18563474">{{cite journal| author=Woodbury-Smith MR, Volkmar FR| title=Asperger syndrome. | journal=Eur Child Adolesc Psychiatry | year= 2009 | volume= 18 | issue= 1 | pages= 2-11 | pmid=18563474 | doi=10.1007/s00787-008-0701-0 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18563474  }} </ref>
**Several neuropsychological studies have suggested the following problems:<ref name="pmid18563474">{{cite journal| author=Woodbury-Smith MR, Volkmar FR| title=Asperger syndrome. | journal=Eur Child Adolesc Psychiatry | year= 2009 | volume= 18 | issue= 1 | pages= 2-11 | pmid=18563474 | doi=10.1007/s00787-008-0701-0 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18563474  }} </ref>
*** Difficulty in passing’ theory of mind tasks
*** Difficulty in passing theory of mind tasks
*** Executive dysfunction
*** Executive dysfunction
*** Tendency to interpret visual stimuli in parts rather than wholes (poor central coherence)
*** Tendency to interpret visual stimuli in parts rather than wholes (poor central coherence)
*** There are studies that suggest in patients with AS there is a Verbal IQ (VIQ) > Poor Performance IQ (PIQ) profile which shows strength on verbal skills relative to visuospatial skills and non-verbal problem solving (nonverbal learning disability)<ref name="LincolnCourchesne1998">{{cite journal|last1=Lincoln|first1=Alan|last2=Courchesne|first2=Eric|last3=Allen|first3=Mark|last4=Hanson|first4=Ellen|last5=Ene|first5=Michaela|title=Neurobiology of Asperger Syndrome|year=1998|pages=145–163|doi=10.1007/978-1-4615-5369-4_8}}</ref>
*** There are studies that suggest in patients with AS there is a Verbal IQ (VIQ) > Poor Performance IQ (PIQ) profile which shows strength on verbal skills relative to visuospatial skills and non-verbal problem solving (nonverbal learning disability)<ref name="LincolnCourchesne1998">{{cite journal|last1=Lincoln|first1=Alan|last2=Courchesne|first2=Eric|last3=Allen|first3=Mark|last4=Hanson|first4=Ellen|last5=Ene|first5=Michaela|title=Neurobiology of Asperger Syndrome|year=1998|pages=145–163|doi=10.1007/978-1-4615-5369-4_8}}</ref>
* There has been a report on developmental problems of neuronal migration in the cerebral cortex during pregnancy and fetal development in patients with AS which may result in problems in the connectivity of the brain cortex..


== Associated Conditions ==
== Associated Conditions ==

Revision as of 05:14, 20 June 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Pathophysiology

Functional magnetic resonance imaging provides some evidence for both underconnectivity and mirror neuron theories.[1][2]
  • Asperger syndrome appears to result from developmental factors that affect many or all functional brain systems, as opposed to localized effects.[3] Although the specific underpinnings of AS or factors that distinguish it from other ASDs are unknown, and no clear pathology common to individuals with AS has emerged, it is still possible that AS's mechanism is separate from other ASD.[4] Neuroanatomical studies and the associations with teratogens strongly suggest that the mechanism includes alteration of brain development soon after conception. Abnormal migration of embryonic cells during fetal development may affect the final structure and connectivity of the brain, resulting in alterations in the neural circuits that control thought and behavior.[5] Several theories of mechanism are available; none are likely to be complete explanations.[6]
  • The underconnectivity theory hypothesizes underfunctioning high-level neural connections and synchronization, along with an excess of low-level processes.[1] It maps well to general-processing theories such as weak central coherence theory, which hypothesizes that a limited ability to see the big picture underlies the central disturbance in ASD.[7] A related theory—enhanced perceptual functioning—focuses more on the superiority of locally oriented and perceptual operations in autistic individuals.[8]
  • The mirror neuron system (MNS) theory hypothesizes that alterations to the development of the MNS interfere with imitation and lead to Asperger's core feature of social impairment.[2][9] For example, one study found that activation is delayed in the core circuit for imitation in individuals with AS.[10] This theory maps well to social cognition theories like the theory of mind, which hypothesizes that autistic behavior arises from impairments in ascribing mental states to oneself and others,[11] or hyper-systemizing, which hypothesizes that autistic individuals can systematize internal operation to handle internal events but are less effective at empathizing by handling events generated by other agents.[12]

Associated Conditions

Pathophysiology

Asperger Syndrome (AS) causes some chemical, structural and functional abnormalities which include:[16]

  • Chemical markers:
    • Higher level of N-acetyl aspartate/choline (NAA/Cho) level at the right anterior cingulate.[17]
    • [18F] F-Dopa influx(k) increase in the striatum, putamen ,caudate nucleus and frontal cortex (affected dopaminergic system).[18]
    • Changes in NAA/Cho are positively correlated with the obsessive compulsive scale that is affected in AS.[16]
    • There is an association in cortical serotonin 5-HT2A receptor binding and social communication in patients with AS.[19]
    • Administration of oxytocin may improve performance facial emotion recognition task, affective speech comprehension, increase eye gaze, emotion recognition and social interaction.[20]
  • Brain structural changes
    • Lower grey matter volumes in the bilateral amygdala, hippocampus gyrus, prefrontal lobe, medial frontal gyrus, left occipital gyrus, right cerebellum, limbic striatal, bilateral caudate, left thalamus, putamen and precuneus.[21][22][23]
    • Greater grey matter volumes at the bilateral inferior parietal lobule and the left fusiform gyrus.[16]
    • Higher volume of white matter around the basal ganglia, left parietal lobe, but lower white matter volume at the right frontal region and corpus callosum.[24]
    • Lower fractional anisotropy in the short intracerebellar fibers and right superior cerebellar peduncle (bilateral and in the white matter in the internal capsule, frontal, temporal, parietal and occipital lobe, cingulum and corpus callosum).[25]
    • Abnormal volumes of hippocampus, amygdala and anterior cingulate cortex (ACC).[16]
    • Abnormality in the anatomy and structure of the brain cause the cognitive.
      • Abnormality in the ACC, amygdala and hippocampal areas in patients with AS contirbute to their difficulty with modulating of emotional reactivity[26]
      • Localized cerebral abnormalities discharge adaptive social behavior.[27]
    • Volumetric exes at the inferior parietal lobule is linked to synesthesia.[28]
    • Dysfunction of motor circuits in the frontostriatal and cerebellar reflect chaotic movement.[29]
    • There are lesions in the occipital lobe in areas responsible for visual/spatial reasoning.[23]
    • Several neuroimaging studies have found the following abnormalities:[30]
      • Abnormal activation in the inferior temporal sulcus.[31][32] 
      • Abnormal dysactivation of the frontal lobe while performing neuropsychological tests.[33][34][35][36]
      • Abnormal functional integration of the amygdala and parahippocampal gyrus.[28] 
      • Abnormal structures in the inferior temporal gyrus, entorhinal cortex and rostral fusiform gyrus.[37]  
      • Missing tissue area in each hemisphere at the part where the middle frontal gyrus and the precentral sulcus intersect.[38]
      • Lesion in the right middle temporal gyrus white matter.[39]
  • Brain functional changes
    • Executive dysfunctions are related disordered neural connectivity of the brain.[40]
    • Abnormal functions in cerebella, frontal and temporal lobes, and the limbic system.[41]
    • Abnormality in the functional integration of amygdala and parahippocampal gyrus.[28]
    • Neuroimaging patterns of AS patients are not affected by stimuli type (static and dynamic faces).[42] For example, story task and cartoon task activate the same region of the brain (medial prefrontal region).[43]
    • Main emotions, manifested by face, can activate fusiform and extra striates.[44]
    • Several neuropsychological studies have suggested the following problems:[30]
      • Difficulty in passing theory of mind tasks
      • Executive dysfunction
      • Tendency to interpret visual stimuli in parts rather than wholes (poor central coherence)
      • There are studies that suggest in patients with AS there is a Verbal IQ (VIQ) > Poor Performance IQ (PIQ) profile which shows strength on verbal skills relative to visuospatial skills and non-verbal problem solving (nonverbal learning disability)[45]
  • There has been a report on developmental problems of neuronal migration in the cerebral cortex during pregnancy and fetal development in patients with AS which may result in problems in the connectivity of the brain cortex..

Associated Conditions

Asperger Syndrome (AS) is associated with several conditions which include:

  • Attention deficit hyperactivity disorder (most common in pediatric patients) (ADHD)[46]
  • Depression (most common in adolescent and adult patients)[46][47]
  • Bipolar disorder[46][47]
  • Tourette’s syndrom[46]
  • Obsessive compulsive disorder[46][47]
  • Tic disorder[46]
  • Anxiety disorders[47]
  • Schizophrenia[48] 
  • Non-verbal learning disability[49]
  • Difficulty in falling asleep, sleepiness after awakening and during daytime and poor sleep quality[50]
  • There have been case-reports of Asperger Syndrome (AS) associated with aminoaciduria,[51] ligamentous laxity[52] and recurrent hypersomnia[53].

References

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  42. . doi:10.1016/j. rasd.2013.09.012 Check |doi= value (help). Missing or empty |title= (help)
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