The Role of Specific Brain Areas in Autism Spectrum Disorders PSY- 725 Biological Bases of Behavior Unit 3 Project.

The Role of Specific Brain Areas in Autism Spectrum Disorders

The Role of Specific Brain Areas in Autism Spectrum DisordersPSY- 725Biological Bases of BehaviorUnit 3 Project

Autism Spectrum Disordersaccording to the DSM IV- TR(I) A total of six (or more) items from (A), (B), and (C), with at least two from (A), and one each from (B) and (C) (A) qualitative impairment in social interaction, as manifested by at least two of the following: 1. marked impairments in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body posture, and gestures to regulate social interaction 2. failure to develop peer relationships appropriate to developmental level 3. a lack of spontaneous seeking to share enjoyment, interests, or achievements with other people, (e.g., by a lack of showing, bringing, or pointing out objects of interest to other people) 4. lack of social or emotional reciprocity ( note: in the description, it gives the following as examples: not actively participating in simple social play or games, preferring solitary activities, or involving others in activities only as tools or "mechanical" aids )

(B) qualitative impairments in communication as manifested by at least one of the following: 1. delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime) 2. in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others 3. stereotyped and repetitive use of language or idiosyncratic language 4. lack of varied, spontaneous make-believe play or social imitative play appropriate to developmental level

(C) restricted repetitive and stereotyped patterns of behavior, interests and activities, as manifested by at least two of the following: 1. encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus 2. apparently inflexible adherence to specific, nonfunctional routines or rituals 3. stereotyped and repetitive motor mannerisms (e.g hand or finger flapping or twisting, or complex whole-body movements) 4. persistent preoccupation with parts of objects

(II) Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years: (A) social interaction (B) language as used in social communication (C) symbolic or imaginative play

(III) The disturbance is not better accounted for by Rhett's Disorder or Childhood Disintegrative Disorder

(APA, 2000)

So what is autism?The WHO says it is a spectrum of psychological conditions which is characterized by pervasive abnormalities in social interactions and communication as well as restricted interests and repetitive behavior.

Today, an estimated 1 in every 110 children is diagnosed with autism. An estimated 1.5 million people in the U.S. and tens of millions worldwide are affected by autism. Government statistics suggest the prevalence rate of autism is increasing 10-17% annually. Improved diagnosis and environmental influences have been given as two reasons for this marked increase. Studies suggest that boys are more likely than girls to develop autism and will receive the diagnosis three to four times more frequently. Current estimates are that in the US, one out of 70 boys is diagnosed with autism.

Exact causes of autism spectrum disorders are unknown. There is no conclusive evidence that vaccinations are responsible. Evidence does suggest that there are multiple genetic and neurologic components to the disorder.

(Autism Speaks, WHO)

Autism & ___________:The AmygdalaThe Anterior CingulateThe Basil GangliaThe Brain StemThe CerebellumThe Parietal LobesWernickes Area

The Amygdala

Located deep within the front of temporal lobe, just above hypothalamus gland.

Involved in emotions, memory, moderating approach/avoidant activities.

Plays key role in regulating fear, motivation, pleasure responses.

Plays key role in social responses and perceiving emotions in others.

The Amygdala & AutismPart of the social brain: made up of the amygdala, the orbito-frontal cortex (OFC), and the superior temporal sulcus and gyrus (STG).

Processes all types of visceral input and is specifically related to drive related behavior

Impairment and neuropathology has shown that there is an impaired fear response in these monkeys with abnormal amygdala functioning- and individuals with autism that experience abnormal fear responses and subsequent anxiety due to an inability to regulate normal fears and anxieties.

is essential for normal social interaction, such as facial expression and body postures

MRI studies showed that individuals with autism show very little to no activation in the amygdala while interacting with others (i.e. making eye contact, interpreting others' behavior), while individuals without autism had activity in the amygdala area during the MRI scans and while trying to interpret others' behavior

Size has been the focus of studies which have determined that amygdala enlargement was correlated with autism and joint attention

(Amaral, 2003; Baron-Cohen et al., 2000; Brothers, 1990; Bachevalier, 1991; Mosconi, 2009)Muris et al, 1998)

The Anterior Cingulate CortexInvolved in the Limbic System

Regulates blood pressure and heart rate

Involved in emotional awareness of self and others

Typically involved in effort of a task, in early learning or problem solving, working memory, and information selection from working memory

Anterior Cingulate Cortex & AutismAlexithymia (and low emotional intelligence) are likely associated with a deficit in ACC activity during emotional arousal.

Anterior (agrandular) insula shares extensive, reciprocal anatomic connections with the amygdala & is involved in perceiving & organizing autonomic responses to aversive or threatening stimuli and to emotional behavior. Lesions in the ventral region of the ACC result in autism spectrum symptoms.

(Phillips, et. al 2003; Taylor, 1999)

The Basal GangliaShares close ties with cerebral cortex, prefrontal cortex and thalamus

Acts as a conduit for information to and from the cerebral cortex

Related to cognitive and emotional functioning

Associated with functions such as voluntary motor control, procedural learning related to routine behaviors or habits, eye movements, vision processing.

Implicated in action selection, and the decision on timing of the execution of several pertinent behaviors.

The Basal Ganglia & AutismElevated dopamine levels in the BG appear to be associated with unnaturally strong learning mechanisms in the BG which allow for the details to overwhelm the ability of the PFC to sort information into categories with the result that the details dominate.

The BG is implicated in the stereotyped behavior, social, communicative, and motor/gait dysfunction in Autism spectrum disorders. Boys with autism showed significant compression in the right anterior-ventral and posterior-dorsal putamen and in the right anterior caudate and caudate tail; they showed significant expansion in the mid-dorsal putamen, middle caudate, and posterior globus pallidus.

(Qui, et. al, 2010; Trafton, 2010)

The Brain Stem

Consists of a group of structures called the pons, medulla oblongata and midbrain

Plays an important role in homeostatis by controlling autonomic functions such as breathing, heart rate and blood pressure, etc.

Can aid in organizing motor movements such as reflexes and coordinating with the motor cortex and associated areas to contribute to fine movements of the limbs and face

Other areas are responsible for is alertness, sleep, balance, and the startle response

Both brainstem and cerebellum have connections with and affect the function of the limbic system

The Brain Stem & AutismBrainstem and cerebellar components of the brain were found to be significantly smaller in autistic patients

Suggesting that there were early alterations or failures in the development of these areas in the fetal stages rather than a progressive degenerative process

Physiologic studies such as auditory brainstem evoked potentials and short latency somatosensory evoked potentials have revealed some brain stem dysfuction in those with autism.

Neuroraudiologic studies have shown cerebellar hypoplasia (an incomplete or underdeveloped cerebellum) and/or a small brain stem including the midbrain, pons, and medulla oblongata in those with autism

Neurotransmitters -- serotonin and dopamine-- arise mainly in the brainstem and project into the limbic system, cortical areas, and basal ganglia, which may lead to the symptoms seen in autism

(Hashimoto, et. al, 1995)

The Cerebellum

Continuously folded layer of thin neural tissue which appears to be striated but is actually a single tissue folded like an accordion.

Thought to be primarily responsible for gross & fine motor control and motor learning

Role in motor learning is to adjust to changes in sensorimotor relationships and for regulating motor timing

Consists of numerous types of neurons, most notably Purkinje cells and granule cells.

Each Purkinje cell connects with as many as 500 to 1000 parallel fibers & receives two types of input from parallel fibers creating a massive action potential in the Purkinje cell which causes burst of action potentials from the cell

It is thought that this burst of action potentials creates a long lasting change in parallel fiber inputs and may be an indicator of new learning and new neural pathways being created

The Cerebellum & AutismDamage to the cerebellum may result in some behaviors seen in children with Autism and associated disorders such as lack of awareness of body and feet, lack of awareness of space, hyperactivity and poor coordination

The link between the hippocampus and the cerebellum is essential in learning conditioned responses and a deficit in the timing of the connection in the cerebellum may interfere with learning

Occupation or activation of the cerebellum through fine motor movement such as finger tapping may allow for children with autism to focus on learning new CR

The cerebellum may play a role in the interpretation of bodily sensations, evidence from PET scans has shown activation in areas of the cerebellum when individuals are read stories about bodily sensations.

(DeSchettuer & Steuber, 2009; Kotani, et at., 2003; Saxe & Powell, 2006; Woodruff-Pak, 1999)

The Parietal Lobes

Positioned above (superior to) the occipital lobe and behind (posterior to) the frontal lobe

Play important roles in integrating sensory information from various parts of the body

Involved in the understanding of numbers and their relations (like mathematics) and in the manipulation of objects

Portions are involved with visuospatial processing

Left parietal-temporal damage can effect verbal memory and the ability to recall strings of digits

Right parietal-temporal lobe is concerned with non-verbal memory

The Parietal Lobe & AutismMagnetoencephalographic readings obtained while administering performance of tasks dependent upon executive function showed that the children on the ASD continuum lacked the long range, fronto-parietal coordinated activity that was observed in the control group of children

Children with ASD tend to perseverate and show reduced brain flexibility to move from an old rule to a new rule, as demonstrated in a card sorting task

(Perez-Velasquez, J.L., et. al., 2009)

Wernickes Area

Located on the superior surface of the temporal lobe between the angular gyrus and the auditory cortex in the left hemisphere.

Specializes in storing the sounds that make up words, working closely with Brocas area (controlling mouth and lips in motor area).

Wernickes Area & AutismOne theory suggests that areas that support communication in autistic individuals do not coordinate well with each other. Difficulties in sentence comprehension and working memory contribute to the social challenges that autistic children experience.

(Kana, et al. 2006)

SummaryIt would appear that the aforementioned brain structures and areas are implicated in the myriad of symptoms that mark Autism Spectrum disorders. The pervasive nature of these symptoms is clearly illustrated in the extent to which the brain areas and structures are interconnected and affected by one another.

Research has found that the amygdala may contribute to autism via an impaired fear response due to the inability to regulate normal fears and anxieties. The anterior cingulate cortex plays a role in alexithymia. The basal ganglia is implicated in the stereotyped behaviors and the fixation on certain minutiae found in autism. The brain stem has been seen to be involved, as well as the cerebellum. Dysfunction in the parietal lobes interferes with the ability to integrate sensory information and to adapt to changes in the environment or to rules. And even Wernickes area has its part in the communication difficulties often found in autism.

Special Thanks To:The Amygdala: Adrian Kruer-ZerhusenThe Anterior Cingulate Cortex: Michelle MinnetThe Basal Ganglia: Margo TownleyThe Brain Stem: Steve MilburnThe Cerebellum: John PachecoThe Parietal Lobes: Jill ThompsonWernicke's Area: June Martinez

Slides and Narration by Margo TownleyPictures Courtesy of Google Images *This has been a brain-on-chocolate production.

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