Welcome to From the Spectrum Podcast. This is a podcast about autism. It is my goal to explain what is autism.
I plan to use a mixture of scientific literature, personal experience, and opinion.
With opinion, I will explain why. I will provide links to various references for each episode.
For each episode, we will discuss various aspects of autism.
The From the Spectrum Podcast will mostly avoid causes of autism, and I will try to avoid the increase of diagnoses of late.
This is like playing tug-of-war with barbed wire, and I don't think I want to travel down that path.
Before we get into the episode, I want to remind, I want to say, never underestimate a human's capacity to think.
Never underestimate the infinity, the infinite amount of possibilities that can come from human thought.
Human thought is very powerful.
For today's episode, we will discuss two areas. One is the so-called network, and one is a brain region.
We will expand on the Autism and Adaptive Responses episode, and we will also talk more in depth about the Reward Hub.
We've discussed this network before, and this brain region before.
The first network is the silence network, and the brain region is the nucleus accumbens.
We have discussed both of these, but today we will expand this discussion for a better understanding and connections to autism,
and to prepare to discuss differences between sex, female, male, or girl, boy, and diagnosing differences, autistic versus non-autistic.
First, the silence network was discussed in the Autism and Adaptive Responses episode.
However, we did not define it or mention it much because of the heavy biology discussion already built in to that episode.
The ancilla, that unique region that is a hub for brain states, such as memory, remembering what happened in that environment,
or whenever I do that, what happens then, or how we think and feel in that moment.
Also, bodily states, the signals coming up from the body, such as heart rate activation, the rate and depth of our breath,
or are we sweating, are we feeling tingly, are we excited, nervous, etc.
And how we, as the living organism, is integrated into the environment.
Is what I'm doing in this moment appropriate for the environment, appropriate for my task?
Do I want more of what I'm experiencing in that moment, in that environment? Do I like that feeling?
Do I want, and do I like, or do I not want, or like?
How we learn and build from experiences, from memory, from learning, remember neuroplasticity.
What we desire from the environment, what we desire out of our body, so we can have thoughts and feelings.
Those are three crucial sources of data being interpreted in the insula.
Remember research by Lucena Euden.
The Salient Network detects and coordinates neural and behavioral responses to salient stimuli, what is considered most important right now.
In other words, what is needed in that moment as we, as the living organism, is navigating society, navigating our life and this world.
And if you remember Autism and Adaptive Responses episode, a lot of this was discussed.
The insula works side by side here with the interior cingulate cortex and then that medial prefrontal cortex is heavily involved too.
I also want to define Salient's Detection.
Salient's Detection is attention and or perceptual grabs.
How and what determines the most important resources for learning and survival.
And remember the medial prefrontal cortex and the ACC leads the way during normal or healthy or adaptive responses.
And in large part it's receiving information from the insula.
Also remember when we make unhealthy or maladaptive responses, when we're overtaking by anxiety or depression, the insula kind of leads the way.
We get overtaken by that interpretation of those other factors such as bodily states or environmental states that external stimuli.
That can feed forward up to the insula and overpower all of our thoughts, all of those adaptive responses, even when we're capable of doing it, even when we have previously done it.
We can get kind of hijacked, they say.
Also consider the metabolic bank account and determining if we have enough metabolic resources for the demand.
Those bodily states and those powerful thoughts, those rapid and constant thoughts that follow, they're very energizing.
They take a lot of metabolic resources to process.
And remember the medial prefrontal cortex at resting states is one of the most metabolically demanding areas of the brain.
And let's not forget, we mustn't forget a typical autistic response with the outside world.
It's common that it's considered the outside world, it's chaotic for the autistic person, it's chaotic for the biology that gives us autism.
Also remember in the Autism and Adaptive Responses episode when discussing the insula.
A study by Lucena Uden, the foremost of the insula showed the hyperfunction of the insula to and from sensory and other limbic areas, thus causing errors in attentional resources and subsequent guiding of adaptive responses during socialness.
That sounds familiar with autism, that sounds like autism.
So this episode will parse out key findings between sex differences and primarily implications into socialness.
We covered in the Autism and Adaptive Responses episode the study released in Communications Biology not long ago, I believe April in 2024, that asked if brain connectivity and mechanisms altered brain connectivity in early development.
The study using six-week-old infants, this is brilliant, distinguished between high likelihood based on family history of autism, so a six-week-old considered high likelihood to have autism, versus typical likelihood.
This was using the silence network. The high likelihood have a stronger connection from the silence network, primarily the insula and ACC, to sensory motor regions, whereas the typical likelihood group have stronger connections from the silence network to the prefrontal regions.
Remember, the medial prefrontal cortex, along with other areas of the prefrontal and the human cortex, lead that way, they make the appropriate decisions and responses.
Those areas that make us the dominant species on earth is the prefrontal cortex and that human cortex. The areas that make our head extend up and full above the eyes unlike any other species.
Remember, if we had to just simply define the overarching goal or the overarching role of the prefrontal cortex, it quiets things so that we can properly evaluate things.
And that's huge. That's huge with autism and even without autism, maybe it's just social anxiety or essentially everyone can get hijacked in different moments, just rare occurrences to something that's pretty common or pretty debilitating in life.
People can range in this, but if you think about autism, there's some key things to remember. We love rules. The prefrontal cortex is essentially, if we want to expand the definition, it's a flexible rule setting machine.
You encounter different environments and you know how you're going to act or how you plan to act or how you typically react. You like that. People like that because we're essentially a predicting machine.
If we want to eliminate that external stimuli, autism prefers eliminating all of that outside noise and we can do this. Essentially, as we get older, we can better control the environment and that helps.
Children that can't, they typically have others, they have adults that can control their environment, make it less chaotic. And if you think about education and now the smaller classrooms or scheduled breaks, giving more breaks even.
And if you remember my examples of elementary school being put into smaller groups for reading and comprehension and all the way up through my senior year with the pathways to success, that little group, that alternative school, when it was me and essentially maybe four other students, that was very manageable.
These connections, these bi-directional connections or connections to and out of the prefrontal cortex is huge here and it's huge for human beings.
Okay, now that we kind of refreshed, had a refresher on the prefrontal cortex and the predicting machine and the preferences, the routines, the external stimuli and so forth, let's consider that as we examine these connections with the silence network.
Further, the high likelihood not only had an altered connection to sensory motor regions, they show a hypo-connection to that prefrontal area.
Remember an earlier episode, an earlier discussion, it was long ago, it was one of the first episodes about the brain connections, about the differences between, let's say, a gravel road and a paved highway.
How things, how vehicles maneuver and travel down these different roads. The gravel road has a poor connection in this case. The highway, the paved highway has that strong connection.
The biology that gives us autism downstream, we have autism from these biological components, these gene expressions and DNA sequencing, etc.
That gives us this trade-off. This is what is happening. This is what autism is biologically.
Something nature and evolution has given us for perhaps a sense of protection. It prevents us, it prevents autistics from orienting towards that external stimuli, that outside world.
This is seen at six weeks old. This is such a brilliant study. Remember autism and anxiety episode. Avoidance is one of the three features of anxiety.
And again, in that episode, we were processing bodily states, brain states and the environment.
Now, the question I have is, does this exist because autism gives us the ability to be comfortable within ourselves and provide us a path towards extreme fixation and interest.
That path for superpowers or does or did that chaotic world and this biology creation, that perception of the outside world, cause this creation of comfort within ourselves that then gave us opportunity to prefer the ability and develop the comfort of staying within ourselves.
Lastly, on the study using six week old inference based on the silence network connections.
This connection predicted subsequent individual trajectories and social attention to faces using eye tracking from three months old to 12 months old.
Using the same group, they show differences in eye tracking with that social attention that is very common with autism.
And autistic traits at 12 months old using the autism observation scale for infants. They pick this up.
Okay, now after extending the review on the previously mentioned six week old infants, followed until 12 months, they follow them all the way up to one year old.
Let's review the current topic for us. Sex and diagnosis differences.
A study on the relationship between polygenic or polygenic risk, which is some sort of calculation based off of each individual's genetic variance that will help determine their chance or risk, heritable risk of developing a disease, a condition.
We will discuss more sex and diagnosing differences and polygenic risk in a future episode.
So this episode used polygenic risk for autism and silence network connectivity between males, females, with and without autism.
So four different groups here. Autistic males, autistic females, non-autistic males, non-autistic females.
Between the ages of 8 and 17. Interestingly, this is from Gendar.
So four satellite locations used Harvard Medical School, Seattle's Children's Research Institute, UCLA and Yale.
We will discuss much more about Gendar in a future episode.
Some key findings include, one, sex dependent effect on genetic load with silence network connectivity to sensory motor, thereby altering sensory processing and implicating repetitive behaviors.
So the study used the silence network connectivity to sensory motor.
Similar to the study we just reviewed.
Sensory processing and repetitive behaviors. That sounds a lot like what people know about autism.
This silence network is critical.
Example, remember, serotypy is a misnomer. It is not.
Purpose-less behavior. There is a purpose behind those repetitions or that stimming, those types of movements.
It's relieving something, something built up.
Saying it's purpose-less is a human thought. It's a very human creation.
It doesn't fit in to the social norms. The social norms.
Can you fit in or not? And are you like the so-called normal people or not?
Humans love to group and categorize people.
The second key finding, females in comparison to males show lower levels of restricted repetitive behaviors.
That is, this protective female effect, which we will discuss more in a future episode.
This protective female effect in regards to the silence network connection.
This potentially explains the bias diagnosis of boys with autism.
Our silence network orientes away from the outside world.
OK, the nucleus accumbens.
The nucleus accumbens is in the ventral striatum and is the hotspot for reward processing.
The striatum is part of the basal ganglia, our go-no-go area.
A lot of motivation and motor movements converging here.
Just briefly on the nucleus accumbens.
Major roles of the nucleus accumbens includes processing, motivation, aversion, reward,
subjectively liking something and learning about that stimuli or the stimulus.
Is it good or bad?
If good, how much more of it do I want?
Do I like it?
There is a lot of dopamine and serotonin action in the nucleus accumbens.
Remember, dopamine is wanting.
Serotonin is having.
Lastly, the nucleus accumbens is two parts.
It is important for us to understand the nucleus accumbens in a future episode we discuss between
autistic girls and autistic boys.
The two parts are the shell and the core.
The shell contains glucocorticoid receptors called cortical steroids,
which is one of the two receptors for glucocorticoids.
Remember how dopamine works alongside hormones.
The shell also contains a lot of inhibitory actions.
Remember excitation and habitation.
A lot of GABA.
GABA in the shell controls dopamine and acetylcholine, the molecule for focus.
Also, there are abundant serotonin in the shell.
The core contains some glutamate.
We discussed glutamate with excitation and inhibition balance.
Glutamate is excitation.
GABA is inhibition.
And remember part two of the excitation and inhibition episode.
We discussed two glutamate receptors.
NMDA and AMPA receptors.
These are post-symnaptic.
Remember from that discussion NMDA are connected to repetitive type behaviors.
As AMPA are connected to social implications.
These will come into play when discussing the differences of autistic boys and autistic girls.
And non-autistic boys and non-autistic girls.
Overall, the nucleus contents is approximately 95% GABA.
And I believe that is on normal brains.
I am not sure the breakdown for autistics.
But most mostly remember this.
The connections to subjective things we like and want.
Which is two different things lacking in wanting or two different things.
I'm just going to say.
I'm not going to go into detail about sex differences with the nucleus accumbens.
And autism versus non-autism just yet.
But the data are very fascinating.
Oxytocin and the nucleus accumbens are major regions of interest here.
Remember it's shown.
Oxytocin and serotonin must converge into the nucleus accumbens.
For reward is motivating.
Reward is enjoyable.
Socialness is enjoyable.
So we will need to know about oxytocin.
Which we discussed last episode.
The nucleus accumbens.
Which we discussed here.
The silence network.
Also discussed here.
And just socialness. A broad scope of socialness.
Some things to consider.
Autistic girls fit more into the so called social norms.
So that sounds like a critical point of the entire assessment process.
It's a critical distinguishing of diagnosing autism.
Second is girls have more opportunity to develop social norms.
And three, data suggests boys have altered connections for processing both neutral and negative social stimuli.
So they use neutral and negative social stimuli.
And so boys have altered connections for processing such.
And four, autistic girls, non-autistic girls and non-autistic boys show similar social processing abilities.
Is this accurate?
We will find out.
And I'm looking forward to that.
This is what I know.
Autistic girls have more activity in the nucleus accumbens, including oxytocin and more connectivity through whole brain reward processes.
Which includes previously discussed regions.
The striatum.
Remember the ventral side, the nucleus accumbens we just discussed.
And the dorsal side, the dorsal striatum.
Stimulus responses.
The thalamus, which is central to all sensory processing.
All senses come through the thalamus.
And the medial prefrontal cortex.
Mostly areas covered in autism and adaptive responses.
Get it?
Girls are equipped to navigate and adapt the so-called adaptive responses.
Autistic girls have increased reward processing and silence detection and social understanding.
Lastly, using eye tracking measures, girls have increased volitional social attention.
Boys have increased attention to objects.
So in comparison group.
Girls, more social attention. Boys, more attention to objects.
Sounds like what people know about autism.
Girls have decreased attention to the objects.
As we wrap up today, we covered the silence network and the nucleus accumbens.
Differences such as autistic boys, autistic girls, non-autistic boys, non-autistic girls.
And this will be key for a future discussion with one of the leading researchers at UCLA and a part of GENDAR.
We will discuss these in depth.
So for today, it is very important that we have some background information for this discussion.
I'm looking forward to it.
In addition, she will explain polygenic score and protective female effect.
What this looks like for the female, the girl, and we'll explore the sex biases.
Why?
The lopsidedness with diagnosing autism in boys versus girls.
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