Bio Quiz 5 Flashcards
ADHD: Genetics
Genetics plays major role in ADHD
Occurs in families
- Twin studies suggesting heritability factor as high as 0.91
Several genetic pathways
- Polymorphisms on dopamine D4 receptor gene, serotonin, and noradrenergic genes
ADHD: Neurotransmitters
Overproduction of dopamine in striatum
- Hyperactive symptoms
- Movement
- Role in attention (with norepinephrine)
Catecholamine dysregulation
Decreased serotonin
- Responsible for mood states
ADHD: Neuroimaging
Frontal parietal system & Somatomotor networks have hyperactivation
Prefrontal and Parietal networks demonstrate hypoactivation
Reduction in Cortical and Subcortical volumes in children diagnosed with ADHD
- Reduced basal ganglia
- Reduced caudate and putamen
- Cerebellum
- Reduction in frontal lobes
- Corpus callosum
- Some suggest volumetric differences occur primarily in right hemisphere
Feedback loops- motor loop
Motor loop:
- Takes in sensory input, consolidates, decides correct motor output
- Fluid, Efficient, and Target-oriented movement,
Integration of motor output:
- Afferens from motor and sensory cortex
- Reach the putamen (information is processed here)
- From putamen to thalamus
- Direct pathway
- Indirect pathway
- Projections from thalamus to motor cortex result in measured and coordinated output
Cognitive/association loop
Learning and cognition
Higher cortical functions and motor learning
Active in hours of training: trying different things and deciding
Afferens from various cortical areas to caudate nucleus and nucleus accumbens which contains reward-affirming dopaminergic connections
Projections from N Acc and Caudate to Thalamus via direct and indirect pathways
From Thalamus, projections back to cortical areas
Consulting services streamlines cognitive processes by separating the successful ones from the unsuccessful ones during motor learning
Limbic circuit
Emotional aspects of behavior
- Links basal ganglia with areas of the brain that process emotionality
- Motor expression of emotions: postures, gestures, facial expressions
- Hippocampus, amygdala, and limbic lobe project to caudate and N Acc (reward)
- Direct and Indirect from caudate and N Acc to thalamus, communicating what behaviors to facilitate and what to inhibit
- Thalamus projections back to cortical areas (limbic lobe)
Fmri Review Article
Hypoactivation of “social brain” during social processing tasks:
- Prefrontal cortex
- Posterior superior temporal sulcus
- Amygdala
- Fusiform gyrus
What functions are these areas associated with Dorsal prefrontal cortex & Basal ganglia?
Dorsal Prefrontal Cortex: Exceutive functioning
Basal Ganglia: Motor Control, balance, coordination, etc.
Where is reward system
In autism, anomalous mesolimbic responses to social and nonsocial rewards
ASD: Genetics
Heritability estimated to be as high as 90%
No ONE genetic mutation accounts for the majority of ASD
- De novo mutations- 15%
- 200-400 different genes can cause ASD
- Chromosome 15
- Serotonin transporter gene
Many diagnosed have no identifiable etiology
In some, it’s completely genetic, in some it’s genetic plus other factors
ASD: Neurotransmitters
Serotonin dysregulation
Endorphin Elevations
Intellectual Disability
Smaller brain and hippocampal volumes
Typically, ventricle volume is increased
Down syndrome: larger parietal gray matter
Fragile X: increased caudate gray matter
Prader-Willi syndrome and Angelman syndrome: chromosome 15
Childhood Maltreatment & Genetics
Functional polymorphism in the monoamine oxidase (MAOA)
- Moderates the effects of antisocial problems that are common in children who were abused
- Warrior gene
Childhood Maltreatment & Neurotransmitters
Serotonin, Aamma-Aminobutyric Acid (GABA), and noradrenaline dysregulation
- Difficulties with social attachment, mood disorders
Childhood Maltreatment & Neuroimaging
Earlier age and longer duration = greater structural brain changes
Hippocampus: is volumetrically normal at time of maltreatment, but later seen to be smaller
Prefrontal cortex: most susceptible to maltreatment
- Also decreased metabolic activity
Amygdala
