Are callous unemotional traits all in the eyes?
May 07, Organisms with a bilaterally symmetric nervous system face a problem — how to integrate functions across the two sides so that behavioural outputs can be coordinated for the entire body.
These patients, first studied by Roger Sperry and colleagues, end up in essence with two brains inside the same skull, and it could be argued, two largely independent minds.
The importance of bilateral integration is also evident and very well understood in the control of movement, where motor commands have to be tightly and dynamically coordinated across the two sides of the body.
The integration of the two sides of the nervous system is mediated by nerve fibres that project from one side to the other. Some neurons project axons across the midline and others do not — the binary nature of this choice has made it a favourite model system of developmental neurobiologists to investigate how growing axons are guided along specific pathways to their appropriate targets.
As a result, a great deal is known about the cellular and molecular processes that control whether an axon will cross the midline.
- Epidemiology of Schizophrenia Schizophrenia is a chronic debilitating disease to the individuals and families it affects. Despite the incidence of schizophrenia being relatively low schizophrenia is also a major contributor to the global burden of disease. Organisms with a bilaterally symmetric nervous system face a problem – how to integrate functions across the two sides so that behavioural outputs can be coordinated for the entire body. Group therapy most effective treatment for anxiety in young people. Group-based talking therapies shown to be most effective treatment for young people with anxiety disorders.
The process is mediated by attractive and repulsive signals made by specialised cells which reside at the midline of the nervous system. These signals are detected by dedicated receptor proteins expressed on the surfaces of growing axons.
The signals at the midline include two major families of secreted proteins: Netrins, which function to attract some neurons towards and across the midline, while repelling others, and Slits, which repel axons that normally do not cross the midline and which also prevent axons from re-crossing the midline multiple times.
How each neuron responds to these cues depends on which receptors it expresses: Amazingly, all these proteins are very highly conserved, as are their functions in controlling axonal projections across the midline, which were discovered and elucidated in great detail in nematodes, fruit flies and mice.
A number of studies have shown that their functions are also conserved and equally crucial in humans. This syndrome is characterised by an inability to coordinate the lateral movement of the eyes in the horizontal plane.
Lateral eye movements are controlled by the abducens-oculomotor nerves, one on each side of the head. The coordination of these movements of the two eyes is mediated by a set of interneurons which normally project across the midline of the hindbrain, where the cell bodies that form these nerves are located, and coordinate the activity of the nerves on the two sides.
As the ROBO3 gene is known to be required for axons to cross the midline, the implication was that the defect resulted from a failure to connect these cranial nerve nuclei on the two sides. A recent study by Alain Chedotal and colleagues modeling the effects of Robo3 mutations in mice strongly supports this explanation — deletion of the gene in just that part of the hindbrain did indeed disrupt connectivity between the two sides and resulted in similar defects in horizontal eye movements in the mice.
This is true for the other two Robo genes — Robo3 performs a different role, down-regulating the responses of the other Robo proteins and so mutating it has the opposite effect. Another study just published by Guy Rouleau and colleagues shows that the function of DCC in establishing trans-midline connectivity is also essential in humans.
They found mutations in this gene in patients with Congenital Mirror Movements. These are involuntary movements of one side of the body that occur in response to voluntary movement of the other side — i. The mirror movements could be caused by a failure to project across the midline of interneurons in the spinal cord that normally inhibit movement of one side when the other side is moving.
These studies provide a dramatic example of the importance of bilateral integration in the control of movement. It will be interesting to investigate whether patients with these disorders also show any differences in cognitive domains which might relate to subtly altered connectivity of the two cerebral hemispheres.
Mutations in DCC cause congenital mirror movements. Science New York, N. Genetic dissection of the function of hindbrain axonal commissures.Schizophrenia Schizophrenia is a debilitating mental disorder characterized by a dysfunctional thinking process and withdrawal from the outside world.
The word schizophrenia comes from two Greek words schizo . The epidemiology of schizophrenia has progressed from descriptive accounts to a surge in analytic epidemiologic findings over the last two decades.
This article reviews the epidemiology of schizophrenia, concentrating on results which are most credible methodologically and consistent across studies. Aug 01, · Wild swings in weather may be what led to the fall of the once mighty Aztec Empireand not, as is commonly held, the invasion of European colonialists.
This reference list was compiled by Robert Hare for personal use. Most, but not all, of the articles listed on these pages discuss or evaluate the PCL-R, the PCL:SV, the PCL:YV, and other Hare lausannecongress2018.com to available abstracts, and when available, links to the full text on the Journal web sites are provided (search for [full text] on the page below).
Schizophrenia Case Study; Schizophrenia Case Study. Epidemiology According to the WHO World Health Report depression is very common and considered one of the oldest clinical mood disorders responsible for morbidity worldwide. Approximately 9 million American adults aged 18 or over experience depression at some point in their.
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious or recessive traits resulting from incestuous sexual relationships and consanguinity.