Final project neurobiology final

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Final Project Submission for Understanding The Brain: The Neurobiology of Everyday Life Autism Spectrum Disorder: The Neurobiological Factors

Transcript of Final project neurobiology final

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Final Project Submission for Understanding The Brain: The Neurobiology of Everyday Life

Autism Spectrum Disorder: The Neurobiological Factors

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Introduction

• Autism Spectrum Disorder (ASD) is a range of complex neurodevelopmental disorders characterised by difficulties in communication, social skills and inflexible and repetitive behaviours.

• These difficulties are known as the Triad of Impairments.

• Autistic people often have additional challenges such as intellectual disability, sensory issues, perceptual difficulties or dyspraxia.

• ASD is also often coupled with another medical condition, particularly epilepsy.

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Examples of ASD traits

• Difficulties in initiating and/or sustaining conversations.

• Unusual or impoverished use of language.

• Absent or unusual eye contact with others.

• Unable to understand jokes or irony.

• Strong preference for rigid routines.

• Obsessional interests and behaviours.

• Adverse reactions to unfamiliar environments.

• Scattered skill sets.

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What Causes ASD?

• To date scientists have been unable to ascertain the exact cause of ASD.

• Research points to there being a combination of genetic, neurobiological and possibly environmental factors involved.

• Since ASD has a broad impact on cognitive and neurological functioning and has different expressions and severities in each individual with the condition, multiple parts of the nervous system are implicated in it’s cause.

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Larger Brains?• Studies have shown that, on average, young children with ASD have

larger brains than typically developing children of the same age.

• Later in development the brain growth in children with ASD stops at a time when the brains of typically developing children are still growing.

• Ultimately the brain volumes of both groups are equalised.

• These findings indicate an atypical brain development in individuals with ASD.

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Synapses and Neurotransmitters

• Many researchers believe that the functioning of synapses may be impaired in ASD.

• However, synaptic dysfunction is likely to effect all areas of cognition and behaviour.

• Individuals with ASD typically have both strengths and deficits in cognition rather than an overall deficit.

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Synapses and Neurotransmitters

• It is more probable that abnormal amounts of specific neurotransmitters are involved in ASD such that only the cognitive functions and behaviours involving synapses receptive to those particular neurotransmitters are effected.

• For example: Glutamate levels in the blood of some people with ASD have been found to be abnormal.

• Glutamate has an excitatory effect on the postsynaptic neuron and is thought to be crucial in neural plasticity and in cognitive functions such as learning and memory. It is also believed to be important in the development of the cortex.

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Brain Areas Implicated in ASD

Amaral,  D.G., Schumann, C. M., Nordahl, C.W. (2008). Neuroanatomy of autism. Trends in Neurosciences 

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Some Brain Regions for ASD Research• The Amygdala – located deep within the temporal lobes of the

brain, this is the brain area most associated with emotions. It is involved both in the processing of incoming emotional information AND producing an associated response.

• The Fusiform Gyrus – forms part of the temporal lobe and the occipital lobe. This area is thought to be essential for the recognition of faces and the perception of emotions in facial stimuli.

• The Cerebellum – responsible for coordination and regulation of motor control including movements with a social function i.e. gestures and expressions.

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Some Brain Regions for ASD Research• The Frontal Lobes – responsible for articulation of speech,

emotions and reasoning. This area is associated with all executive functions including mental flexibility.

• The Basal Ganglia – involved in a variety of functions including learning and routine behaviours. It’s core function is one of action selection not just of motor movements but also of thought, perceptions, moods and emotions. It both receives and sends out information to many other brain regions and particularly the cerebellum, thalamus and the brain stem.

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Further Hypotheses• Many neurobiological hypotheses have been put forward to explain

ASD.

• One of the most prominent, and controversial, is the ‘broken mirror’ hypothesis.

• Mirror neurons are active during the observation, imitation and understanding of the intentions of other’s actions.

• The ‘broken mirror’ hypothesis contends that there is a mirror neuron dysfunction in ASD giving rise to the difficulties autistic people have in relating to and interacting with other people.

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My experience with this course.

I took this course purely because of my general interest in Neurobiology. I already had a basic knowledge of the brain and it’s functions but this course has really expanded the scope of my understanding to include the entire nervous system.

The constant references to everyday life examples throughout the lecture series helped reinforce the learning process for me and bring the subject alive. Since learning about things like central pattern generators, visual perception and the vestibuloocular reflex I find myself automatically analysing the everyday events in my life in neurobiological terms. For example, when I’m at the gym I am thinking about things like fast fatigueables and the gamma reflex loop.

As a mother it has made me more aware of certain critical periods in the development of my children’s nervous systems. I am now making my children look into the distance more often to calibrate their eye length. I am also armed with the argument for my saying “practice, practice, practice” to them; you have to keep practicing an instrument to close the cerebellar loop!

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My experience with this course.

One of the main things I will be leaving this course with is not only an improved understanding of how the nervous system works but also an understanding of the signs and symptoms of it going wrong. Unfortunately we are all likely to encounter impairments to our nervous system across our lifetimes in one way or another and I feel more likely to see the signs of things like macula degeneration having taken this course.

I really appreciated the lab videos in this course as well. To be able to see real brains both whole and in parts was really helpful to me in understanding some of the topics covered.

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References

The Autism Spectrum in the 21st Century. Exploring Psychology, Biology and Practice – Ilona Roth