LECTURE 9

Question 1

Please name major brain regions that form the neural systems involved in the functions that are most impacted by the core features of autism – two brain regions associated with social impairment, two brain regions associated with communication deficits, two brain regions associated with repetitive behavior.

Answer 1

Social impairment
orbital frontal cortex
Anterior cingulate cortex
Fusiform gyrus
Posterior parietal cortex
communication deficit
Broca area
Substantia nigra
Repetitive behavior
Basial ganglia
Thalamus

Question 2

What evidence is available in support of a key role of corpus callosum alterations in autism spectrum disorder? What speaks against it?

Answer 2

Corpus callosum smaller/density is lower in people with autism. First used mouse model with lack of corpus callosum. This mouse model showed social deficits, Communication deficits and Stereotypies / repetitive behavioural patterns like would be expected from an autism model. However it seems that the corpus callosum is not the reason for this difference in behaviour. When an other mouse strains corpus callosum is severed in early life they do not show the same deficits.

Question 3

Please describe two localizations and two functions of specific neuroligin proteins (e.g. neuroligin 3

Answer 3

Neuroligin 3 is localized at the postsynaptic membrane of excitatory synapses and can also be found in extra synaptic regions. Its functions include promoting synapse formation and modulating synaptic function and plasticity.

Question 4

What evidence is available in support of the idea that the Nlgn3 R451C mutation leads to alterations in synaptic transmission?

Answer 4

NEUROBIOLOGY
* Reduced neuroligin 3 protein levels due to destabilization of mutant protein.
* Enhanced inhibitory but unchanged excitatory synaptic transmission.
* Imbalance between excitation and inhibition.

Question 5

Describe the neuronal and behavioral phenotype displayed by the Nlgn3 R451C knockin mouse model.

Answer 5

NEUROBIOLOGY
* Imbalance between excitation and inhibition.
BEHAVIOR
* Moderate alterations in social behavior, but intact social memory.
* Improved performance in the „Morris“ water maze for spatial and reversal learning.
* Intact locomotor activity and habituation.
* No alterations in anxiety-related behavior.