Ronan, Ella

Shaw, Vivien

Winder, Isabelle C.

English

Cerebral torque has been described as a right-left asymmetry of the frontal and parieto-occipital regions of the brain. It is associated with an increase in inter-hemispheric connectivity and the subsequent development of language. T.J. Crow has postulated links between cerebral torque and functional psychoses; with a focus on schizophrenia. Connections between psychotic disorders and language have been made where disordered speech, auditory hallucinations, and functional or structural deficits in language areas of the brain are seen in diagnosed individuals.T.J. Crow hypothesises that cerebral torque arose after a genetic speciation event occurring 5-6 MYA – around the same time Homo sapiens diverged from the Pan lineage. This is thought to have triggered a chain of events mitigating the formation of the Xq21.2/Yp11.2 homology block, where a paracentric inversion occurred on the Y chromosome 160 KYA and cerebral torque is hypothesised to have formed. It is this timeline of genetic events that initially implies that torque is specific to Homo sapiens, as they only occur after the Homo-Pan split. However, contrary to Crow’s theory, asymmetries of the brain have been documented in nonhuman primates since the 1970’s as new technologies such as functional magnetic resonance imaging (fMRI) and computed tomography (CT) came into use for imaging the brain. Neurological asymmetries have been found in ape species Gorilla, Pan and Pongo, as well as monkey species Macaca mulatta; Macaca fascicularis; Saguinus oedipus, and Callithrix jacchus. If theorised correlations between hemispheric asymmetries and psychosis are to be believed, evidence for such asymmetry in nonhuman primates could point towards their possession of an anatomical foundation for developing psychotic-type behaviours. This research examines the genetic and anatomical precursors of psychosis through a meta-analysis of existing literature, genome comparison studies and examination of CT scans of human and primate brains. It further investigates the hypothesis that African great apes (Gorilla spp., Pan troglodytes, Pan paniscus) possess the neuroanatomical prerequisites for developing psychosis, and explores the question as to whether or not ancient human species (Neanderthals and Denisovans) also possessed them

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   PRIFYSGOL BANGOR / BANGOR UNIVERSITY  Cerebral Torque in Nonhuman PrimatesRonan, Ella; Winder, Isabelle C.; Shaw, VivienPublished: 18/12/2019Cyswllt i'r cyhoeddiad / Link to publicationDyfyniad o'r fersiwn a gyhoeddwyd / Citation for published version (APA):Ronan, E., Winder, I. C., & Shaw, V. (2019). Cerebral Torque in Nonhuman Primates.Hawliau Cyffredinol / General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/orother copyright owners and it is a condition of accessing publications that users recognise and abide by the legalrequirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of privatestudy or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal ?Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access tothe work immediately and investigate your claim. 24. Jul. 2020Cerebral Torque in Nonhuman Primates Ella Ronan, Dr Isabelle Winder, Vivien ShawIntroductionCerebral torque is asymmetry of the frontal andparieto-occipital regions of the brain. Torqueand related structural asymmetries have beenlinked to the development of schizophrenic andaffective type psychoses. Recent evidencesuggests that cerebral torque is also present innonhuman primates, leading to the question-‘Do nonhuman primates also suffer frompsychosis?’The aim of this project is to investigate theinstance of cerebral torque in apes andmonkeys. We have previously tested thehypothesis that these species display apparentpsychotic behaviours both in captivity, and inthe wild. We are therefore assessing whether ornot non human primates also have the sameassociated anatomical variation in the brain.MethodsCranial morphometrics will use CT scans oftarget species crania. The midline betweencrista frontalis and confluence of sinuses will befound. MorphoJ software will be used tomeasure scans for torque.Predicted ResultsWe predict that nonhuman primates will showevidence of torque at the population level.DiscussionIf cerebral torque exists in ape brains, thisshows that associated psychosis is possible.This would imply an ape origin for psychosisthat predates Homo sapiens.Cerebral torque present innonhuman primates. Abnormal formationsuggests psychosis susceptibility.Figure 1 Cerebral torque in healthy vs schizophreniapatient. Image from Oertel-Knochel and Linden (2011).Author(s) Species/Method ResultsGroves & Humphrey (1973)21 mountain gorillas/skull lengthLeft half of skull longerGannon et al. (1998) 18 chimpanzee cadavers/planum temporale areaLarger left planum temporale Hopkins et al. (1998) 21 apes MRI/planum temporale volumeLarger left planum temporalHopkins and Marino (2000)19 chimpanzees MRI/frontal and occipital widthLeftward occipital; rightward frontalHolloway & De La Coste-Lareymondie(1982)135 ape endocasts/qualitative score of petalias65 leftward, 26 rightward occipital; 53 rightward, 12 leftward frontal petaliaLeMay (1976) 28 great ape cadaver photos/occipital petalia and widthRightward occipital petalia; leftward widthZilles et al. (1996) 9 chimpanzee cadavers/differences in chimerics of hemispheric petaliasNo differences in petaliasYeni-Komishan & Benson (1976)25 chimpanzee cadavers/sylvian fissure lengthLeft sylvian fissure longerTable 1 Cerebral asymmetries in great apes. Adaptedfrom Pilcher, Hammock and Hopkins (2001).ella_ronan@hotmail.com @ellronan

Cerebral Torque in Nonhuman Primates

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Cerebral Torque in Nonhuman Primates

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