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Neurobiology of Autism > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What were three early indications of neuroanatomical involvement in Autism?

A
  • Abnormal EEG’s
  • Increased prevalence of seizures
  • large head size
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2
Q

“Modular” approach - define it

A

particular functions are linked to specific neuroanatomical regions
-“islands”

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3
Q

“Integrative” approach - define it

A

Neuroanatomical regions are thought about in terms of networks of structures and regions subserving a particular type of behavior

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4
Q

What can neuroimaging be used to do?

A

assess structural and functional differences across groups of individuals

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5
Q

Structural imaging - what does it examine?

A

examines the underlying anatomy of the brain

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6
Q

Functional imaging - what does it examine?

A

examines changes in the activity of the brain while performing tasks

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7
Q

What happens in an sMRI?

A

Magnetic fields are applied in particular arrangements. These fields affect the behavior of atoms within the brain such that they will align themselves with the fields in the presence of the fields. When the fields are turned off, the atoms return to their normal position/behavior, and in doing so, they emit energy. This energy is transmitted to a computer that uses a bunch of mathematical algorithms to convert this signal to an image

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8
Q

What does DTI look at?

A

integrative networks by quantifying the structural connectivity between different brain structures

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9
Q

What does DTI measure? What is the most common reported value?

A

have measures that correspond to the connectivity between areas
-FA

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10
Q

What is the value FA?

A

estimation of the number of axons and how densely packed they are
-microstructure

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11
Q

What is the value RD?

A

myelination

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12
Q

Functional Imaging - what does it test for

A

Relation between structure/regions and function is established through correlations

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13
Q

Name 3 different methods that have been used to compare patient populations to normal controls
-what are the main differences btw these techniques?

A
  • EEG/ERP
  • PET
  • fMRI
  • –each technique assesses “activity” differently and each technique has it’s advantages and disadvantafes
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14
Q

EEG - what does it look for? what are the methods?

A

Looks at the principle waves

-Places electrodes on the scalp with a conductive gel to pick up population neuronal activity

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15
Q

ERP in EEG studies

A

different behaviors result in different waveforms

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16
Q

EEG/ERP in Autism and social factors

A

Individuals with autism or at risk for autism exhibit abnormal ERP responses in face processing

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17
Q

Advantages of MRI

A
  • non-invasive

- good spatial resolution

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18
Q

Disadvantages of MRI

A
  • Susceptible to movement

- Expensive

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19
Q

Advantages of EEG/ERP?

A
  • Great temporal resolution

- Low-cost

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20
Q

Disadvantages of EEG/ERP?

A
  • Poor spatial resolution
  • Only assesses surface activity
  • Limited task flexibility
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21
Q

PET imaging - what is it? what does it do?

A

Another way to assess the function of a region

-detects radioactivity

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22
Q

How does the PET scanner work?

A

Subjects are injected with a radioactively labeled form of glucose and asked to perform a particular task. After completing the task, the subject is then scanned, if a region was activated during the task, it would have taken in the radioactive glucose, which is detected in the PET scanner, transmitted to a computer for mathematical computations that produce an image

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23
Q

PET: Autism and cognitive factors

-what were the results?

A

When engaged in standard verbal learning test, ASD show lower glucose metabolism indicating a dysfunction of these areas associated with verbal learning

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24
Q

Advantages to PET?

A
  • good spatial resolution

- task is performed outside of scanner

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25
Q

Disadvantages to PET?

A
  • poor temporal resolution
  • radioactive material injected into subject
  • Subject must remain still during scan
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26
Q

Functional MRI - what does it entail?

A

-usually involves a task, comparing BOLD changes to a control task

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27
Q

What were the results from the fear-scramble fMRI testing with Autism and social factors?

A

emotional face processing recruits amygdala, pulivinar, FFA more in ASD than TD

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28
Q

Advantages of fMRI?

A
  • no radioactive ligand
  • good temporal resolution
  • good spatial resolution
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29
Q

Disadvantages of fMRI?

A
  • mechanisms and implications of patterns of activation not fully understood
  • subject must remain motionless
  • task must be performed in the scanner
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30
Q

What is required in order to carry out an fMRI test?

A

Implementation of appropriate control task/condition

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31
Q

What are the core structures of the “social brain”?

A
  • FFA
  • EBA
  • STS
  • AMY
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32
Q

What are the structures within the extended circuit of the “social brain”?

A
  • OFC
  • VLPFC
  • IPL
  • MPFC
  • TPJ
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33
Q

What has the orbitofrontal cortex been implicated in?

A

reward and social reinforcement

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34
Q

What is the medial prefrontal cortex?

A

reasoning about others’ beliefs, self-reflection, and autobiographical memory

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35
Q

Temporoparietal juction - what is it?

A

attributing beliefs to others and reasoning about those beliefs

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36
Q

Amygdala - what has it been implicated in?

A

Recognition of the emotional states of others through analysis of facial expressions

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37
Q

Posterior STS in the right hemisphere - what does it do?

A

analyzes biological motion cues to interpret and predict the actions and social intentions of others

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38
Q

Extrastriate body area - what happens here?

A

Visual perception of human bodies

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39
Q

Fusiform face area -what has it been implicated in?

A

face perception and recognition

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40
Q

What is emotion?

A
  • The affective aspect of consciousness

- The visceral aspects of a physiological response

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41
Q

What are the adaptive benefits of emotion?

A
  • Physiological fight or flight response.
  • More efficient decision-making
  • Better social interaction
  • Stronger memory
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42
Q

What does high arousal mean?

A

Excited

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43
Q

What does low arousal mean?

A

Calm

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44
Q

What does positive valence mean?

A

Approach

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45
Q

What does negative valence mean?

A

Aversion

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46
Q

Why is the amygdala important?

A

highly conserved across species

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47
Q

How does info come in to the amygdala?

A

via the Lateral nucleus and Basal nucleus

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48
Q

After the info gets routed into the amygdala, where does it go? What are the functions?

A

to the central nucleus, then to the hypothalamus and brainstem
-Flee, Freeze, Autonomic, Hormonal, Responses

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49
Q

The emotional valence attached to the inputs coming from the hypothalamus and brainstem go where? What does it do while there?

A

routed out from the accessory basal nucleus to the striatum

-Facial expressions, Body postures

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50
Q

Where do the inputs coming from the basal nucleus and accessory basal nucleus go? Why is this important?

A

routed back to the hippocampus

-hippocampus is important for memory and the amygdala helps to attach emotional meaning to those memories

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51
Q

How does info flow into and out of the amygdala?

A

The amygdala is made of unique subdivisions (nuclei), and these take incoming information in, emotionally process it, and send it out in a variety of structures so that the body can act on it.

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52
Q

What are the 5 general functions of the amygdala?

A
  • fear processing
  • emotional recognition
  • emotional modulation of memory
  • face processing
  • reward learning
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53
Q

What are the 6 symptoms of Kluver-Bucy syndrome?

A
  • Visual agnosia
  • hyperorality
  • hypermetamorphosis
  • hypoemotionality
  • dietary changes
  • excessive or aberrant sexuality
  • changes in social interactions
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54
Q

Hypoemotionality - define it

A

no longer fearful

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55
Q

hypermetamorphosis - define it

A

i.e. they took anything that came close to them non-stop

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56
Q

hyperorality - why did this symptom present itself? define it

A

because of the visual agnosia, they investigated the objects by mouth

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57
Q

visual agnosia - define it

A

also known as psychic blindness

-they could not recognize objects by sight

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58
Q

Fear processing: Animal literature: what were the takeaways?

  • Rodent literature
  • Monkey literature
A
  • Rodent literature: rats with amygdala damage are unable to associate neutral cues with an aversive outcome
  • Monkey literature: monkeys with amygdala damage also show deficits in fear learning
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59
Q

What is the human case study in fear processing? Who was the subject?

A

Patient SM

-a rare disease resulted in the calcification of both amygdalae

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60
Q

What is the fear circuitry? I.e. see a snake in the woods

A

First, extremely rapidly, the visual information of the snake coming from the eyes relays into:
visual thalamus (imprecise)->amygdala->striatum and brainstem
—heart beat and breathing increases
occipital cortex (precise)->amygdala->hippocampus->prefrontal cortex
—fight or flight then decided on

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61
Q

How did researchers test for emotion recognition?

A

set of pictures of people depicting different facial expressions
-faces presented one at a time and subject is asked to label the emotions

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62
Q

What is greater amygdala activation correlated with?

A

Better memory

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63
Q

Face processing - what does the amygdala help you do?

A

Look at the person in the eyes

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64
Q

What does fear learning help us do?

A

Helps us avoid dangerous situations

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65
Q

What impact does selective damage to the amygdala have?

A

very subtle effects on learning that involves rewards

-mainly changes our internal drives

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66
Q

Why is the amygdala important for reward learning?

A

guides our behavior based on our internal emotions

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67
Q

What is the evidence of morphological changes

in the amygdala in ASD?

A
  • Enlarged Amygdalae
  • Increased cell densities
  • Abnormalities in neuronal firing
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68
Q

Frontal lobe - why is it important? What cortex makes it up?

A
  • recently evolved
  • integrates info from many different regions
  • mediates goal-directed actions and controls decision making
  • implicated in emotional valence and reward association
  • —Neocortex -> 6 layers
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69
Q

Who is Phineas Gage?

A
  • Railroad worker

- survived, but sustained frontal damage due to steel tamping rod

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70
Q

Why was Phineas Gage important?

A

He experienced severe behavioral changes after the frontal damage

  • Before: well-loved, respected
  • After: irreverent, profane, obstinent
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71
Q

Medial OFC - what is it known for?

A

identification of items, creating new stimulus associations, story comprehension, sentence completion, risk

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72
Q

Lateral OFC - what is it known for?

A

Inhibitions, hypothesis testing, face perception, non match to sample (choosing the new), working memory, stimulus association

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73
Q

What is the striatum known for?

A

Habit learning

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74
Q

What is the hypothalamus known for?

A

Autonomic functions and arousal

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75
Q

What is the cingulate known for?

A

involved in detecting errors btw action/outcome

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76
Q

What is the temporal lobe known for?

A

vision

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77
Q

What is the insula known for?

A

taste

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78
Q

What does the OFC receive inputs from?

A
  • The olfactory, taste, and somatosensory cortices
  • temporal lobe visual area around the temporal sulcus (specifically tuned for face processing)
  • cingulate cortex, the striatum, and the hypothalamus
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79
Q

What is the job of the OFC?

A

not only involved in pairing the “what” aspects of sensory signals with reward expectations, but is also involved in coding for pleasantness of such stimuli

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80
Q

What is an example of something that is coded for in the OFC?

A

Facial identity and facial emotions are coded for in the OFC, as well as the relationship between facial expression and expected reward outcome

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81
Q

What does the OFC share bidirectional connectivity with?

A

The amygdala

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82
Q

What are the basic functions of the OFC? Describe them.

A 
Reward
-anticipation of reward
-evaluation of reward qualities
Flexibility
-updating contingencies
Social Function
-appropriate emotional response
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83
Q

Wernicke’s area - what is it important for?

A

speech production

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84
Q

What is the primary motor cortex involved in?

A

Actually moving your muscles

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85
Q

Everything before the central sulcus is involved in what?

A

acting upon the info

-organized from very basic (near central sulcus) to very complex (very front of the brain)

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86
Q

Everything happening after the central sulcus is doing what?

A

Is taking in info

-the parietal lobe is taking in info about your body and the occipital lobe is taking in visual info

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87
Q

Why was the cerebellum one of the most controversial sites of brain abnormality in ASD? What changed

A

-Recent evidence show that the cerebellum is also involved in cognitive functions, along with motor and equilibrium

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88
Q

What is the trend regarding the cerebellum across species?

A

It is highly conserved

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89
Q

What are the three main lobes of the cerebellum?

A
  • anterior
  • posterior
  • flocculonodular
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90
Q

What is the name of the most medial region of the cerebellum?

A

Vermis

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91
Q

What are the names of the lateral regions of the cerebellum?

A

the two lateral regions are the hemispheres

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92
Q

What is the cerebellum involved in?

A
  • voluntary movements
  • balance and equilibrium
  • muscle tone
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93
Q

What type of function is the cerebellum involved in?

A

Higher cognitive functions

94
Q

What is the main function of the frontal lobe?

A

Conscious motor actions just in front of the central sulcus) and executive functions (more anterior regions)

95
Q

What is the main function of the parietal lobe?

A

Somatosensory perception (just posterior to the central sulcus) and visual spatial organization (more posterior regions)

96
Q

What is the main function of the occipital lobe?

A

vision

97
Q

What is the main function of the temporal lobe?

A
  • vision
  • memory
  • audition (in the lateral fissure)
98
Q

Where does the cerebellum receive inputs from?

A

not only the motor areas, but also the prefrontal, parietal, and temporal cortex

99
Q

What is increased activity in the cerebellum associated with?

A

performance on tasks measuring executive functions, spatiotemporal skills, and language

100
Q

What is the main function of the vermis?

A

Regulation of affect and emotions

101
Q

What is the main function of the hemispheres of the cerebellum?

A

regulation of cognitive functions

102
Q

What is the main function of the anterior lobe?

A
  • Regulation of muscle tone

- coordination of skilled voluntary movements

103
Q

What is the main function of the posterior lobe?

A
  • planning

- monitory of voluntary activity

104
Q

What is the main function of the floculonodular lobe?

A
  • balance

- control of eye movements

105
Q

Be able to locate (cerebellum):

    - the primary fissure, 
- the posterior (or posterolateral) fissure, 
- the anterior lobe, 
- the posterior lobe
- the flocculonodular lobe
- the vermis
- the cerebellar hemispheres
A

look up photo

106
Q

Where does all info that comes out of the cerebellum come from?

A

cerebellar nuclei

-no other cells in the cerebellum send their axons outside the cerebellum

107
Q

What is the outermost layer of the cortex called? What does it contain?

A

Molecular layer, and it is occupied mostly by axons and dendrites

108
Q

What layer is directly below the molecular layer? What does it contain?

A

The Purkinje layer

-Purkinje cells

109
Q

What layer is directly below the Purkinje layer? What does it contain?

A

Granular layer

-dense layer of tiny neurons called granule and golgi cells

110
Q

What is in the center of each folium?

A

White matter

111
Q

What do the axons of the Purkinje cells do?

A

They synapse onto the deep nuclei and will not project outside the cerebellum

112
Q

Are Purkinje cells inhibitory or excitatory?

A

Inhibitory

113
Q

What is responsible for sending excitatory output?

A

The three deep nuclei

114
Q

info coming from the brain and the body enters the cerebellum by what two systems of fibers? Are they inhibitory or excitatory?

A

Mossy fibers and climbing fibers

-Excitatory

115
Q

Cerebellar injury will result in:

A
  • slow and uncoordinated movements
  • difficulty in judging distance and when to stop
  • staggering when walking, tendency to fall
  • abnormal eye-movements
116
Q

What is the main function of the premotor cortex?

A

Planning

117
Q

What is the main function of the motor cortex?

A

Execution

118
Q

What does the primary fissure of the cerebellum do?

A

divides the bulk of the cerebellum into anterior and posterior lobes

119
Q

What does the posterior fissure of the cerebellum do?

A

It separates the posterior lobe from the flocculonodular lobe

120
Q

What does the horizontal fissure of the cerebellum do?

A

It divides the posterior lobe into two regions (anterior and posterior)

121
Q

What are the characteristics of the cerebral cortex?

A
  • Unique to the mammalian brain
  • Highly convoluted with gyri and sulci
  • 2-4 mm thick
  • organized into 5 major lobes and 1 additional region
  • organized into layers
122
Q

What two domains can the cerebral cortex be divided into?

A
  • Functional domain

- Anatomical domain

123
Q

What is layer 1 of the neocortex? what is it made up of?

A

Molecular layer

-occupied by dendrites

124
Q

What is layer 2 of the neocortex? what is it made up of?

A

External granule cell layer

-granule cells

125
Q

What is layer 3 of the neocortex? what is it made up of?

A

External pyramidal cell layer

-variety of cell types , largely pyramidal cells

126
Q

What is layer 4 of the neocortex? what is it made up of?

A

Internal granule cell layer

-granule cells

127
Q

What is layer 5 of the neocortex? what is it made up of?

A

Internal pyramidal cell layer

-large pyramidal cells

128
Q

What is layer 6 of the neocortex? what is it made up of?

A

Polymorphic or multiform layer

-heterogeneous layer of cells that blends into white matter

129
Q

What are the two main cell types in the cortex?

A

Pyramidal cells (mostly excitatory) and small granular cells (mostly inhibitory)

130
Q

Paleocortex - define it

A

structures that comprise btw 4-5 layers

131
Q

Archicortex - define it

A

structures that comprises only 3 layers

132
Q

What does the layering of neurons in the neocortex provide?

A

an efficient means of organizing the input-output relationships of neocortical neurons

133
Q

Uncinate fasiculus - what is it

A

part of inferior occipitofrontal

-interconnects orbital frontal and anterior temporal

134
Q

Superior longitudinal fasciculus- what is it

A

Interconnects Broca’s and Wernicke’s areas

135
Q

What are the connections within the neocortical layer 4

A

Layer 4 is mostly stellate cells – where axons from thalamus come in and make synapses

136
Q

What are the connections within the neocortical layer 2/3?

A

send axons out to other cortical areas

137
Q

What are the connections within the neocortical layer 5/6?

A

send axons down to subcortical structures, and some to other cortical areas

138
Q

What is the minicolumn?

A

A vertical assembly of pyramidal neurons, their interconnections, and learning with the cortical column

139
Q

What is the function of the minicolumn?

A

To provide fine tuning of info processing and learning within the cortical column

140
Q

Cortical development can be broadly divided into what two phases:

A
  • genetically determined events occurring in utero

- cell death, connectivity, and pruning occurring both before and after birth

141
Q

What happens during postnatal development of the cerebral cortex?

A

Neuronal proliferation and migration continue after birth

142
Q

Disturbed neuronal migration could account for observations such as:
-Any significance in those with Autism?

A
  • thickened cortex
  • high neuronal density
  • minicolumnar alterations
  • neurons in molecular layer
  • irregular laminar patterns
  • poor gray-white matter boundaries
  • ectopic gray matter

—Most of these have been found in patients with ASD

143
Q

Microabnormalities of Cerebral Cortex in ASD:

A
  • alterations in cortical columns spacing and number
  • Polymicrogyria (too many gyri)
  • Macrogyri (large gyri)
  • Schizencephaly (abnormal slits or clefts in cerebral cortex)
  • Cortical thickening
  • Layering changes
144
Q

Microcephalia vera - define it

A

characterized by reduced brain size with normal gyral patterns

145
Q

Lissencephaly - define it. What is it composed of?

A

characterized by a brain with poor or no sulci

-cortex is composed of 4 layers

146
Q

Polymicrogyria - define it

A

characterized by too many abnormally small convolutions

147
Q

Heterotopias - define it

A

Gray matter heterotopias are collections of normal neurons in abnormal locations secondary to an arrest of radial migration of neurons

148
Q

Connectional specificity - define

A

Cytoplasm of one neuron is separate from the cytoplasm of another neuron

149
Q

Dynamic polarization - define

A

Some parts of neurons are specialized for taking info IN, whereas other parts send info OUT

150
Q

What are the two main classes of brain cells?

A
  • Neurons

- Glial cells

151
Q

Neurochemicals in the brain -

A
  • Highly variable in size
  • Display specific pattern of localization in the CNS
  • Mediates fast synaptic transmission and slow modulation of neuronal activity
152
Q

Agonist - define it

A

a molecule that binds to a receptor and activates it

—all neurotransmitters are agonists at their receptors

153
Q

Antagonist - define it

A

A molecule that binds to a receptor but does not activate the receptor
—prevents agonist binding

154
Q

Modulator - define it

A

A molecule that binds to a receptor at a site distinct from where agonists bind
—modulates receptor function

155
Q

If a person cannot grow new neurons, how does the brain change in order to accommodate new learning?

A

One mechanism by which the brain adapts to help you learn new information involves the structure on the next slide: the dendrites.

156
Q

How do brain tumors (cancer) occur?

A

Unlike neurons, glial cells can divide and grow new cells throughout one’s lifetime. Most brain tumors are limited to glial cells, not neurons.

157
Q

Soma (cell body)

A
  • contains the cell’s nucleus
  • contains DNA
  • controls protein manufacturing
  • directs metabolism
158
Q

Dendrites - what are they?

A

(usually) larger and tree-like. This area receives inputs from other neurons at locations called synapses. The dendrites are “post-synaptic” (with respect to information flow)

159
Q

Neuronal membrane - what is it?

A

composed of a lipid bilayer, contains the intracellular fluid. We will see more about the specific properties of this membrane in a minute

160
Q

Axon - what is it?

A

Represents the “output”. Electrical signals flow down towards the axon terminals where the synapses are located. This axon is “presynaptic” with respect to this synapse.

161
Q

What is an interneuron?

A

Anything that is not sensory or motor

162
Q

Glutamate - what is it known for?

A

Fast excitatory synaptic transmission

163
Q

GABA - what is it known for?

A

Fast inhibitory synaptic transmission

164
Q

What do GABA and Glutamate systems in ASD research show?

A
  • decreased brain levels of GAD (important to synthesize GABA)
  • Lower levels of Glutamate in cerebral cortex and cerebellum
  • Increased expression of glutamate transporter genes
165
Q

The neurotransmitter remains in the synapse until:

A
  • enzyme breakdown
  • presynaptic cell reuptake
  • glial uptake
166
Q

What impact can the different types of receptors have on NTs?

A

The have different functions that can increase or decrease the efficacy of NTs

167
Q

How can drugs alter the transmission speed of NTs?

A

Drugs may block reuptake or reabsorption, leaving the NT in the synapse for longer (more available) or speed up NT removal (making less available)

168
Q

What are the three main types of biogenic amines?

A
  • Norepinephrine
  • Dopamine
  • Serotonin
169
Q

What are the two main types of neuropeptides?

A

Oxytocin and vasopressin

170
Q

What are the two different types of other neurotransmitters? What is different about one of them?

A
  • Biogenic amines

- Neuropeptides (not a “true” neurotransmitter)

171
Q

Norepinephrine - what is it implicated in?

A

attention, memory, and physiological arousal

172
Q

Where is Norepinephrine produced? What is the precursor in the diet?

A

Produced in the locus coeruleus

-phenylalanine

173
Q

Norepinephrine - significance? ASD ties?

A
  • dysfunctional in depression and anxiety disorders

- not clearly associated with ASD

174
Q

Dopamine - what is it implicated in?

A

mood regulation, cognition, movement, and motivation

175
Q

Where is Dopamine produced?

A
  • Substantia nigra

- ventral tegmental area

176
Q

Dopamine - significance?

A

Is disrupted in disorders such as parkinson’s disease, depression, and addictive behaviors such as drug abuse and gambling

177
Q

Why can too much dopamine be bad?

A

It can lead to impulsivity and a lack of focus

178
Q

Dopamine in ASD

A

Increased DA metabolites in ASD

-Haloperidol (a DA receptor antagonist) has been used to treat some symptoms of ASD

179
Q

Serotonin - what is it implicated in?

A

Arousal, mood, sleep, and cognition
-decreases appetite
LIKING, CONSUMMATORY BEHAVIOR

180
Q

Serotonin - where is it produced?

A

Raphe Nucleus

181
Q

Serotonin - significance?

A
  • Variability in serotonin receptors may be related to increased anxiety behaviors
  • implicated in depression, anxiety, and OCD
  • –One of the most effective anti-depressant classes functions to increase extracellular serotonin
182
Q

Serotonin and ASD

A

-In children SER is naturally higher than adult levels early in development. In typical kids, this drops off in mid-childhood, but stays elevated in children with ASD

183
Q

Name an example of an SSRI

A

Prozac

184
Q

Serotonin - treatment

A

treatment with selective serotonin reuptake inhibitors (ie SSRIs) reduces hyperactivity, increases social competency in ASD

185
Q

Neuropeptides - what are they used for and how do they work?

A
  • Are used by cells for communication

- Peptides are released by neurons, are not recycled back into the cell, secretion is modulated by external peptidases

186
Q

Oxytocin and Vassopressin - where are they released? What are they associated with?

A

They are released from the posterior pituitary

-associated with social behavior

187
Q

What is Vasopressin specifically associated with?

A

Paternal behavior and territoriality

188
Q

What is Oxytocin specifically associated with?

A

Maternal behavior and bonding

  • “love drug”
  • released during birth, breastfeeding, sexual intercourse, etc. to promote bonding
189
Q

Oxytocin and ASD

A
  • OT receptor density is decreased in ASD
  • Children with ASD have lower levels of circulating OT than typical children
  • OT may be a potential treatment avenue for social dysfunction in ASD
190
Q

Environment - define it and give some examples

A

all non-genetic factors

-ie virus/bacteria, medications, chemicals, diet, etc

191
Q

Epidemiology - define it

A

the study and analysis of the patterns, causes, and effects of health and disease conditions in a defined population

192
Q

What are some commonly studied environmental risk factors?

A
  • childhood vaccines
  • nutrition and diet
  • meds taken during pregnancy
  • chemicals in the environment
  • infections that cause inflammatory responses
  • sociodemographic factors
193
Q

What type of disorder is ASD?

A

Multi-factor with multiple etiologies

194
Q

What are the 5 types of study designs when looking at environmental risk factors?

A
  • Case series
  • Ecologic
  • Cross-sectional
  • Cohort
  • Randomized Clinical Trial
195
Q

Case series - define. Strength of evidence?

A

Studies on a group of patients with a similar disease and epidemiology and describes their characteristics
-very weak

196
Q

Case series - pros and cons?

A 
Pros:
-easy to carry out (can use patients from a clinic)
Cons:
-no control group
-often retrospective analyses
197
Q

Ecologic studies - define. Strength of evidence?

A

Divide population into group (often by geography or time range) and compare rates of exposure with rates of disease and look for correlations
-weak

198
Q

Ecologic studies - pros and cons

A

Pros: can use pre-existing data from many sources (e.g. census records, health data)

Cons: no individual data, does not control for confounds at the ecological level (i.e. SES), assumes factors not examined remain constant

199
Q

Cross-sectional studies - define. Strength of evidence?

A

Select the study population irrespective of exposure or disease. Calculate prevalence of exposure and disease. Compare disease rate among exposed and non-exposed, and/or by level of exposure
-moderate

200
Q

Cross-sectional studies - pros and cons

A

Pros: collect data from participants in one visit, individual data collected on health outcomes and confounding variables.

Cons: cannot determine temporal (causal) relationship between exposure and outcome.

201
Q

Cohort studies - define. Strength of evidence?

A

Study population is free of the disease at the start of the study. Rates of disease incidence are monitored over time and compared for those with and without exposure
-strong

202
Q

Cohort studies - pros and cons

A

Pros: information about exposure is collected prior to occurrence of disease outcome (permitting causal inferences), exposure data is collected without influence of knowledge of the disease status of the individual, able to collect information on confounds.

Cons: depending on the length and number of follow-ups, subject retention can be difficult

203
Q

Randomized clinical trial - define. Strength of evidence?

A

Participants are randomly assigned into exposure groups or placebo. Experimenter and participant are blind to which condition they are in. Compare health outcomes in exposed vs placebo groups
-very strong, especially w/large sample size

204
Q

Randomized clinical trial - pros and cons

A

Pros: provides basis for causal inference, if sample size is large enough then random assignment protects against confounds.

Cons: not ethical to study an exposure with significant harm, some participants will refuse to be in a study if they can’t choose a treatment or know what group they are assigned to.

205
Q

Sociodemographic factors - what are the 3 main ones?

A
  • Level of parental education
  • Race/ethnicity
  • Parental age
206
Q

Sociodemographic factor: Level of parental education

-describe it in terms of ASD

A
  • Widely reported positive correlation between education level of parents and incidence of ASD diagnosis
  • –diagnosis x2 with postgrad education
  • Possible confounds: underassessment in families with less parental education, and differences in access to healthcare.
  • –In countries with universal healthcare (e.g. Denmark) these correlations are NOT found.
207
Q

Sociodemographic factor: Race/ethnicity

-describe it in terms of ASD

A

No consistent reports of differences in ASD prevalence by race or ethnicity

208
Q

Sociodemographic factor: Parental Age

-describe it in terms of ASD

A
  • Older parental age (either parent) has been consistently linked to increased risk of ASD via cross-sectional studies
  • Cannot determine causality, but it can be interpreted that age is a biomarker of processes yet to be determined
209
Q

Infections that cause inflammation: list one that was once believed to be related to ASD
-why?

A

Rubella
-Given the heterogeneity of the kinds of viruses associated with neurodevelopmental illness, current thought is that the specific microorganism is less important than the inflammatory/immune response it provokes

210
Q

Infections that cause inflammation: Mechanism of Action

-what is it? what happens?

A
  • Neuroinflammation modulates brain function through the activation of microglia and astrocytes
  • when activated, these glia secrete cytokines
211
Q

During development, when and what does glia secrete within infections that cause inflammation?

A

When activated, these glia secrete cytokines

212
Q

What happens with excess or chronic activation of cytokines?

A

With excess or chronic activation, the same cytokines become desstructive

213
Q

Air pollution - how does it relate to ASD?

A

Most studies have reported a modest increases in risk for ASD in individuals with higher estimated exposure to air pollution

214
Q

Air pollution: What are some challenges when looking at this factor?

A
  • Air pollution is a highly complex and variable mixture of compounds that are highly correlated, so it is difficult to determine the impact of specific chemicals.
  • It is still difficult to accurately measure/quantify exposure to air pollution over time.
  • Difficult to account for confounds (e.g. noise pollution from traffic could cause sleep disturbances)
215
Q

Air pollution - what is the mechanism of action?

A
216
Q

When does oxidative stress occur?

A

Oxidative stress occurs when excess oxygen radicals are produced in cells, which could overwhelm the normal antioxidant capacity

217
Q

What can oxidative stress result in?

A
  • The presence of xenobiotics
  • The activation of the immune system in response to invading microorganisms (inflammation)
  • Radiation, which makes oxidative stress a common denominator of toxicity or stress.
218
Q

Mercury - how does it relate to ASD?

A

Few studies to date have found robust differences in Hg levels among ASD individuals and appropriately matched controls (particularly on geographic and dietary variables)

219
Q

Mercury: describe this environmental factor

-where does it come from? how is it measured?

A
  • Mercury exposure comes from several sources: industrial emissions in air and water, dental amalgams, in fish/seafood, and as a preservative in certain vaccines
  • Hair absorbs Hg, and measurements of Hg concentrations in hair are primarily used as a way to estimate exposure
220
Q

Mercury - what is the mechanism of action?

A

When Hg enters a neuron, it:

  • interferes with ion currents involved in the action potential
  • damages the Blood Brain Barrier by altering the cell membranes of astrocytes
  • damages tubulin, a protein important for the integrity of microtubules
221
Q

How do some believe that Mercury impacts ASD?

A

Some hypothesize that ASD involves alterations in the body’s ability to detoxify, and thus accumulation of toxins, like Hg, are likely to follow

222
Q

Medications taken during pregnancy

-list two that have been believed to be related to ASD

A
  • Thalidomide

- Valproic acid

223
Q

Valpoic acid - what is it? what does it do?

A

Medication used to treat seizures and migraines

-causes birth defects

224
Q

Thalidomide - what is it? what does it do?

A

Originally prescribed as a sedative, but then used as an anti-nausea med for morning sickness

225
Q

Mechanism of action of thalidomide on the fetus? what is sig about it? Relation to ASD?

A
  • MoA is very specific: specific physical changes correspond directly to when the med was taken during gestation
  • ASD characteristics were present only in cased with the Opthalmological changes (20-24 post conception)
  • —provides evidence for a very specific critical period
226
Q

Nutrition/diet - a factor for ASD?

A

GI symptoms and food allergies are common among individuals with ASD, and so dietary factors are also worth considering

227
Q

Nutrition/diet - Mechanism of Action?

A

Allergies = immune activation

-“Leaky Gut” hypothesis

228
Q

What is the “Leaky Gut” hypothesis?

A
  • Intestinal lining is damaged (or maldeveloped), leading to increases in GI permeability
  • Increased GI permeability allows toxic proteins to enter the bloodstream and subsequently accumulate in the CNS
229
Q

Maternal nutrition - describe this factor. Why is it important?

A

Proper nutrition during pregnancy is essential for fetal brain development, and maternal nutrient deprivation is associated with increased risk for neural tube defects, schizophrenia, and other adverse neurological outcomes
-Folic acid!!! (protects unborn babies against serious birth defects)

230
Q

Maternal nutrition - how does it relate to ASD?

A

-study found a trend of decreasing risk for ASD as daily folic acid intake increased

231
Q

Maternal Nutrition - Mechanism of Action?

A
  • During early stages of gestation, mammalian embryos undergo extensive DNA demethylation, followed by a re-establishment of new methylation patterns
  • Folate provides a major source of methyl (carbon) groups, and so low levels could impact mechanisms involving methylation and hence expression or activity of genes, proteins, and neurotransmitters

Neurobiology of Autism (2 decks)

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