autism-neuroarchitecture

Autism Neuroarchitecture: The Amygdala-HPA Circuit

Understanding the structural differences in threat detection and stress response

Overview

Autism spectrum architecture involves fundamental differences in how sensory information is processed and how the threat detection system responds. The key distinction is in the cortical bypass - sensory information reaches the amygdala directly without typical prefrontal filtering, leading to dysregulation of the stress response system.

Scientific Note: This document uses illustrative numbers (marked with †) to demonstrate concepts. While the patterns described are supported by research, specific magnitudes vary significantly between individuals and studies. Numbers like "85% baseline" or "45-minute recovery" are conceptual illustrations, not empirical measurements. The research supports the direction of these differences, not necessarily these exact values.

1. Neurotypical Processing Architecture

Standard Sensory-Emotion Pathway

The neurotypical brain has evolved an elegant multi-stage filtering system that prevents sensory overwhelm and emotional dysregulation. Think of it as a security system with multiple checkpoints - each one asking "Is this actually important? Is this actually dangerous?" before triggering any alarm response.

graph TD A[Sensory Input] --> B[Thalamus] B --> C[Sensory Cortex] C --> D[Prefrontal Cortex] D -->|Evaluation| E{Threat Assessment} E -->|High Threat| F[Amygdala] E -->|Low Threat| G[Filtered Out] F --> H[HPA Axis Activation] style C fill:#90EE90 style D fill:#90EE90 style E fill:#FFD700 style F fill:#FFB6C1

Key Features:

Cortical filtering reduces sensory load
Prefrontal evaluation assesses actual threat level
Gated amygdala activation - only responds to verified threats
Moderate HPA response - proportional stress activation

How Neurotypical Filtering Actually Works

When you walk into a busy coffee shop, your neurotypical brain receives thousands of sensory inputs per second: the hiss of the espresso machine, the scraping of chairs, the murmur of conversations, the smell of coffee, the overhead lights, the pressure of your clothing, the temperature of the room. Your thalamus receives ALL of this raw data.

But here's the critical difference: your sensory cortex immediately starts filtering. It marks the conversation behind you as "background noise" and attenuates it. It habituates to your clothing within seconds - your brain literally stops processing those signals. It classifies the espresso machine as "expected environmental sound" and reduces its salience.

Then your prefrontal cortex does a second pass: "Am I in danger? Do I need to respond to anything?" Most stimuli get a "no" and are further suppressed. Only genuinely relevant information - your name being called, a loud crash, something truly unexpected - makes it through to conscious awareness.

The amygdala only gets involved when the prefrontal cortex says "this might be a threat." And even then, it's a modulated response. A sudden loud noise might trigger a brief startle, but cortisol returns to baseline relatively quickly, your heart rate normalizes, and you've moved on.

This multi-stage gating is energy efficient. Your brain isn't wasting resources processing irrelevant stimuli. You can have a conversation in a noisy environment because your brain is actively suppressing the noise. You can focus on work because your brain filtered out the feeling of your chair, your socks, the hum of the HVAC system.

This is the default mode of human neural processing. It evolved to allow us to function in complex environments without constant overwhelm.

Neurotypical Sensory Load

pie title Sensory Processing Distribution "Filtered Out" : 65 "Background Processing" : 25 "Conscious Attention" : 10

2. Autistic Processing Architecture

The Cortical Bypass

Here's where everything changes. The autistic brain has a fundamentally different wiring pattern - one that bypasses the protective filtering stages that neurotypical brains rely on. This isn't a minor variation; it's an architectural difference as significant as having a different number of network routers between point A and point B.

graph TD A[Sensory Input FULL INTENSITY] --> B[Thalamus] B --> C[Sensory Cortex] B ==>|DIRECT PATH| F[Amygdala IMMEDIATE] C -.->|Delayed| D[Prefrontal Cortex] D -.->|Too Late| E{Threat Assessment} F ==>|DYSREGULATED| H[HPA Axis] H --> I[Chronic Stress State] style F fill:#FF6B6B style H fill:#FF6B6B style I fill:#FF6B6B style B stroke:#FF0000,stroke-width:4px

Key Differences:

Increased thalamo-amygdala connections - direct sensory feed
Reduced cortical inhibition - filtering doesn't work effectively
Ungated amygdala activation - responds to more stimuli than typical
Dysregulated HPA response - stress state that's harder to modulate

What "Cortical Bypass" Actually Means

In the neurotypical brain, sensory information from the thalamus takes a deliberate detour through the cortex before it can reach the amygdala. This detour takes approximately 200-250 milliseconds and serves as a critical evaluation stage. By the time a stimulus reaches the amygdala in a neurotypical brain, it has been pre-processed, filtered, contextualized, and evaluated.

In the autistic brain, there's a superhighway directly from the thalamus to the amygdala. This direct connection has been documented in multiple fMRI studies showing increased white matter connectivity between these structures. What this means in practice:

Same coffee shop scenario: You walk in. Your thalamus receives the same thousands of inputs. But instead of going through the cortical filter, they go directly to your amygdala.

The espresso machine hiss? THREAT SIGNAL (loud, unexpected frequency, startling) The scraping chair? THREAT SIGNAL (harsh, grating, unpredictable) The overlapping conversations? MULTIPLE THREAT SIGNALS (too many audio streams, can't parse, overwhelming) The fluorescent lights? THREAT SIGNAL (flickering at 120Hz, painful) Someone's perfume? THREAT SIGNAL (chemical assault, nauseating) Your clothing tag? THREAT SIGNAL (constant irritation, can't habituate)

Your amygdala is now processing SIX simultaneous threats instead of filtering them out as background noise. And remember - your amygdala doesn't distinguish between "annoying sound" and "actual danger." A threat signal is a threat signal.

The "Too Late" Problem

Your cortex IS still working. Your sensory cortex is processing the inputs. Your prefrontal cortex is trying to evaluate. But by the time they finish their analysis and send the message "actually, this is fine, just a coffee shop," your amygdala has already activated the HPA axis.

The cortisol is already being released. Your heart rate is already elevated. Your blood pressure is already up. Your digestive system is already shutting down. Your immune system is already being suppressed.

The rational analysis arrives 200ms too late. It's like trying to recall a missile after it's already launched. Your conscious mind knows "this isn't dangerous," but your body is already in threat response mode.

Why This Creates Chronic Stress

In the neurotypical brain, the amygdala activates relatively infrequently for actual threats or significant stressors. Each activation is time-limited, cortisol clears, everything returns to baseline.

In the autistic brain, the amygdala activates far more frequently† for things that aren't threats - they're just... existing in the world. A car horn. A bright light. Someone touching your shoulder. A schedule change. Each one triggers the same physiological cascade as if you were being chased by a predator.

And because there's no cortical filter preventing these activations, there's no way to turn it off through cognition alone. You can't "think your way out of it" because the thinking part of your brain isn't in the loop. The signal goes straight from sensory input → amygdala → stress response, bypassing conscious control.

This is why telling an autistic person to "just calm down" or "don't be so sensitive" is neurologically meaningless. The pathway that would allow conscious calming doesn't have access to the activation signal. It's architectural.

Autistic Sensory Load

pie title Sensory Processing Distribution "Filtered Out" : 15 "Full Intensity Processing" : 70 "Conscious Attention" : 15

3. Amygdala Structural and Functional Differences

The Complexity of Amygdala Response

Research on amygdala function in autism reveals a nuanced picture - not simply "hyperactivation" but rather dysregulated activation patterns that vary by context, task, and individual.

graph TD A[Social Stimuli] --> B{Amygdala Response} B --> C[Some studies: Hyperactivation] B --> D[Some studies: Hypoactivation] B --> E[Key: Dysregulation] C --> F[Eye contact, threatening faces] D --> G[Neutral faces, some social cues] E --> H[Atypical response patterns overall] style E fill:#FFD700

Key Research Findings:

Hyperactivation to direct eye contact, threatening or ambiguous faces (Dalton et al., 2005)
Hypoactivation to some social cues, particularly neutral expressions (Ashwin et al., 2007)
Atypical developmental trajectory - enlarged in childhood, normalizes/reduces by adolescence (Schumann et al., 2004)
The core issue is dysregulation - responses are atypical, not simply "too much" or "too little"

What "Dysregulation" Actually Means

Think of the amygdala as having a calibration dial. In neurotypical development, this dial gets tuned through experience:

Neutral faces → low response
Threatening faces → high response
Familiar people → modulated response
Novel stimuli → appropriate alertness

In autism, this calibration is off. The responses don't match what typical development would predict:

Neutral faces might trigger high anxiety (wrong calibration)
Familiar people might still trigger alertness (doesn't habituate typically)
Some threatening cues might be missed (calibration goes both ways)
The pattern of response is atypical, not just the intensity

This explains why autistic people often report:

Exhaustion from "neutral" social interactions - their amygdala is treating them as threatening
Missing danger cues sometimes - calibration affects threat detection too
Inconsistent responses - the same stimulus can trigger different responses on different days

Baseline Activity: A Conceptual Model

The following illustrates the concept of elevated baseline stress, though specific numbers are illustrative†:

graph LR subgraph Neurotypical_Concept A1[Lower Baseline] --> B1[Higher Threshold] B1 --> C1[Activation: Less Frequent] end subgraph Autistic_Concept A2[Higher Baseline] --> B2[Lower Threshold] B2 --> C2[Activation: More Frequent] end style A2 fill:#FF6B6B style B2 fill:#FF6B6B style C2 fill:#FF6B6B

The research supports that autistic individuals tend to have:

Elevated baseline physiological arousal (cortisol, heart rate variability studies)
Lower threshold for stress response activation (faster physiological reactivity)
Longer recovery times after stress activation

Exact magnitudes vary significantly between individuals and depend on many factors including environment, support, and individual differences.

Recovery Time Differences

Research does support that autistic individuals show prolonged recovery from stress responses (Green et al., 2015), though individual variation is substantial:

gantt title Conceptual Recovery Timeline dateFormat mm:ss axisFormat %M:%S section Neurotypical Activation :active, 00:00, 00:30 Recovery :00:30, 05:30 section Autistic Activation :crit, 00:00, 00:30 Extended Recovery :crit, 00:30, 30:00

What research shows:

Cortisol takes longer to return to baseline after stressors
Heart rate variability shows prolonged dysregulation
Subjective recovery (feeling "normal" again) is extended

What this means practically:

Stressors that occur before full recovery compound
A day with multiple minor stressors can become overwhelming
Recovery needs aren't about "being dramatic" - they're physiological

4. The HPA Axis Cascade

Hypothalamic-Pituitary-Adrenal Response

sequenceDiagram participant A as Amygdala participant H as Hypothalamus participant P as Pituitary participant Ad as Adrenal Glands participant B as Body Systems A->>H: Threat signal H->>P: CRH release P->>Ad: ACTH release Ad->>B: Cortisol release Note over B: Heart rate up Blood pressure up Digestion down Immune function down Cognition down Emotion regulation down

HPA Dysregulation in Autism

Research by Corbett et al. (2009) documented specific HPA axis differences:

Atypical diurnal cortisol patterns - the normal morning peak and evening decline is often flattened or reversed
Elevated cortisol in social situations - school and social environments show elevated stress hormones
Slower return to baseline - cortisol stays elevated longer after stressors

graph LR subgraph Typical_Diurnal_Pattern A[8AM: High] --> B[12PM: Moderate] --> C[5PM: Lower] --> D[8PM: Low] end subgraph Autistic_Pattern_Often E[8AM: Variable] --> F[12PM: Elevated] --> G[5PM: Still Elevated] --> H2[8PM: Slow Decline] end style E fill:#FF6B6B style F fill:#FF6B6B style G fill:#FF6B6B

5. System Overload Model

Energy Depletion Pattern

graph TD A[Start: Full Energy] --> B[Early Day: Moderate Depletion] B --> C[Midday: Significant Depletion] C --> D[Afternoon: Low Reserves] D --> E[Evening: Critical] E --> F{Threshold} F -->|Below threshold| G[MELTDOWN RISK] F -->|Severely depleted| H2[SHUTDOWN] style E fill:#FFA500 style G fill:#FF0000 style H2 fill:#8B0000

Spoon Theory Implementation

flowchart TD A[Daily Energy Allocation] --> B{Each Stimulus} B -->|Low cost| C[Quiet environment] B -->|Medium cost| D[Normal interaction] B -->|High cost| E[Unexpected event] B -->|Very high cost| F[Sensory overload] C --> G[Remaining Energy] D --> G E --> G F --> G G -->|Adequate| H[Functioning] G -->|Low| I[Exhausted] G -->|Depleted| J[Non-functional] style F fill:#FF0000 style J fill:#FF0000

6. Comparative Neural Architecture

Connection Density Comparison

Signal Flow Timing

gantt title Time to Amygdala Activation dateFormat SSS axisFormat %L ms section Neurotypical Thalamus to Cortex :000, 050 Cortex Processing :050, 150 Prefrontal Evaluation :150, 250 Amygdala if needed :250, 300 section Autistic Thalamus to Amygdala :crit, 000, 050 Cortex Processing :050, 150 Prefrontal ineffective :150, 250

Result: Autistic amygdala can activate in ~50ms via direct pathway vs neurotypical ~250ms+ via cortical route

7. Cumulative Load Model

Daily Stress Accumulation

The key insight from research is that stress effects are cumulative - each stressor adds to the load, and recovery between stressors is often incomplete.

graph LR A[Stressor 1] --> B[Partial Recovery] B --> C[Stressor 2 Starting higher] C --> D[Less Recovery Time] D --> E[Stressor 3 Starting even higher] E --> F[Minimal Recovery] F --> G[Stressor 4] G --> H2[OVERLOAD] style H2 fill:#FF0000

Multiple Stressors Interaction

mindmap root((Autistic Nervous System)) Sensory Visual: Fluorescent lights Auditory: Background noise Tactile: Clothing tags Olfactory: Perfumes Social Eye contact demand Unexpected conversation Group dynamics Tone interpretation Cognitive Task switching Interruptions Ambiguous instructions Time pressure Environmental Temperature changes Crowds Unpredictable schedules New locations

Each factor triggers stress responses independently - Multiplicative effect

8. Accommodation Architecture

Environmental Modifications

graph TD A[Reduce Sensory Load] --> B[Lower baseline activation] C[Predictable Routines] --> D[Fewer unexpected triggers] E[Safe Spaces] --> F[Recovery opportunities] G[Structural Supports] --> H2[Prevent overload] B --> I[Energy Conservation] D --> I F --> I H2 --> I I --> J[Functional Capacity Up] style J fill:#90EE90

Support Strategies by System

flowchart LR A[Target System] --> B{Intervention Point} B --> C[Sensory Input] C --> C1[Noise-canceling headphones] C --> C2[Blue-light glasses] C --> C3[Comfortable clothing] B --> D[Cortical Processing] D --> D1[Clear communication] D --> D2[Written instructions] D --> D3[Processing time] B --> E[Amygdala Activation] E --> E1[Predictable environment] E --> E2[Reduced surprises] E --> E3[Known routines] B --> F[HPA Response] F --> F1[Regular breaks] F --> F2[Recovery time] F --> F3[Safe spaces] style C1 fill:#90EE90 style C2 fill:#90EE90 style C3 fill:#90EE90 style E1 fill:#90EE90 style F1 fill:#90EE90

9. Why Just Cope Does Not Work

Architectural vs. Behavioral Differences

graph TD A[Suggestion: Just Relax] --> B{Can you change...} B --> C[Amygdala calibration?] C --> C1[NO - Structural] B --> D[Activation threshold?] D --> D1[NO - Structural] B --> E[Recovery time?] E --> E1[NO - Structural] B --> F[Thalamo-amygdala connections?] F --> F1[NO - Structural] C1 --> G[Cannot cope away architecture] D1 --> G E1 --> G F1 --> G style G fill:#FFB6C1

What Is Actually Possible

graph LR A[Within Control] --> A1[Environmental modifications] A --> A2[Energy management] A --> A3[Accommodation requests] A --> A4[Self-advocacy] B[NOT Within Control] --> B1[Neural architecture] B --> B2[Baseline sensitivity] B --> B3[Recovery timeframes] B --> B4[Structural connections] style A1 fill:#90EE90 style A2 fill:#90EE90 style A3 fill:#90EE90 style A4 fill:#90EE90 style B1 fill:#FFB6C1 style B2 fill:#FFB6C1 style B3 fill:#FFB6C1 style B4 fill:#FFB6C1

10. Clinical Evidence

Key Research Findings

timeline title Autism Amygdala Research Timeline 2000 : Baron-Cohen et al. - Amygdala theory of autism 2004 : Schumann et al. - Amygdala enlarged in children 2005 : Dalton et al. - Amygdala hyperactivation to gaze 2007 : Ashwin et al. - Amygdala hypoactivation to some faces 2009 : Corbett et al. - HPA axis dysregulation 2010 : Monk et al. - Functional connectivity differences 2011 : Marco et al. - Sensory processing differences 2015 : Green et al. - Sensory overresponsivity neurobiology

Research-Supported Differences

Measure	Research Finding	Key Studies
Amygdala volume	Enlarged in childhood, normalizes with age	Schumann 2004
Amygdala response	Dysregulated (context-dependent hyper/hypo)	Dalton 2005, Ashwin 2007
Recovery time	Prolonged stress recovery	Green 2015, Corbett 2009
Cortisol patterns	Atypical diurnal rhythm	Corbett 2009
Sensory gating	Reduced P50 suppression	Multiple studies
Spine density	~28% increase in cortical neurons	Hutsler and Zhang 2010

11. Neurotransmitter Systems

GABA-Glutamate Balance

The excitation/inhibition (E/I) balance in autism is more complex than "too much excitation." Research shows:

graph TD A[E/I Imbalance Hypothesis] --> B{Evidence} B --> C[Some regions: Increased E/I ratio] B --> D[Some regions: Decreased E/I ratio] B --> E[Considerable individual variation] C --> F[Not uniformly excitation-dominant] D --> F E --> G[Region-specific differences] style F fill:#FFD700

What research shows (Fatemi et al., 2009; Rubenstein and Merzenich, 2003):

GABA receptor differences documented in postmortem studies
Regional variation - some areas show E/I shifts, others don't
Not a simple imbalance - more nuanced than early theories suggested
May affect sensory filtering - contributes to reduced gating

The E/I hypothesis remains influential but has been refined - autism involves altered E/I dynamics that vary by brain region, developmental stage, and individual.

Serotonin System Differences

graph LR A[5-HT System] --> B{Documented Differences} B --> C[About 30 percent show elevated blood serotonin] B --> D[Altered serotonin synthesis patterns] B --> E[Receptor density variations] C --> F[Chugani et al., 1999] D --> F E --> G[Multiple studies] style F fill:#FFD700

12. Cellular and Molecular Level

Dendritic Spine Density

Research by Hutsler and Zhang (2010) found increased dendritic spine density in autism:

graph TD A[Dendritic Spines] --> B{Research Findings} B --> C[Cortical Layers II/III and V] C --> C1[About 28 percent increase in spine density] C --> C2[Reduced synaptic pruning] C1 --> D[More connections] C2 --> D D --> E[Hyperconnectivity in local circuits] E --> F[May contribute to processing differences] style C1 fill:#FFA500

Key point: This is one of the better-quantified findings (~28% increase), representing reduced synaptic pruning during development.

Synaptic Pruning

timeline title Synaptic Development Differences Age 0-2 : Rapid synaptogenesis (both populations) Age 2-5 : Pruning begins (reduced in autism) Age 5-12 : Major pruning phase (significant difference) Age 12-25 : Refinement continues (differences persist)

Result: Retained connections that would typically be pruned leads to different information processing patterns

13. Default Mode Network Differences

Network Connectivity Patterns

graph TD A[DMN in Autism] --> B[Reduced within-network connectivity] A --> C[Altered between-network connectivity] A --> D[Different activation patterns at rest] B --> E[DMN components less synchronized] C --> F[Different network interactions] D --> G[May affect self-referential processing] style A fill:#FFD700

Key research (Just et al., 2012):

Within-network connectivity often reduced
Between-network connectivity patterns differ
Functional connectivity differences consistent across studies

14. Sensory Processing Deep Dive

Multi-Modal Integration Differences

graph TD A[Visual Input] --> E[Integration] B[Auditory Input] --> E C[Tactile Input] --> E D[Proprioceptive Input] --> E E --> F{Temporal Binding Window} F --> G[Neurotypical: About 40ms] F --> H2[Autistic: Often wider] G --> I[Tight temporal integration] H2 --> J[Looser integration] J --> K[Modalities may not bind as seamlessly] style K fill:#FF6B6B

Research supports:

Extended temporal binding windows in many autistic individuals
Affects audio-visual integration (speech perception)
May contribute to sensory processing differences

Sensory Gating P50 Suppression

sequenceDiagram participant S as Stimulus participant T as Thalamus participant C as Cortex Note over S,C: Neurotypical: Strong P50 suppression S->>T: Stimulus 1 T->>C: Full response S->>T: Stimulus 2 same 500ms later T->>C: About 50 percent suppressed Note over S,C: Autistic: Reduced P50 suppression S->>T: Stimulus 1 T->>C: Full response S->>T: Stimulus 2 same 500ms later T->>C: Less suppression (varies)

Research shows: Reduced sensory gating, meaning repeated stimuli don't get filtered as effectively.

15. Executive Function Impact

Cognitive Load Under Stress

When the stress system is activated, cognitive resources are diverted:

graph TD A[Available Cognitive Resources] --> B{Under Stress} B --> C[Executive function impaired] B --> D[Working memory reduced] B --> E[Emotional regulation harder] C --> F[Difficulty planning, organizing] D --> G[Can hold less information] E --> H2[Emotions harder to manage] style C fill:#FF6B6B style D fill:#FF6B6B style E fill:#FF6B6B

This affects everyone under stress - but autistic individuals may spend more time in stressed states due to the architectural differences described above.

Task Switching Costs

Research supports increased task-switching costs in autism, though specific magnitudes vary:

gantt title Task Switching Conceptual dateFormat mm:ss axisFormat %M:%S section Neurotypical Task A :done, 00:00, 02:00 Switch :active, 02:00, 02:15 Task B :done, 02:15, 04:15 section Autistic Task A :done, 00:00, 02:00 Switch longer :crit, 02:00, 03:00 Task B :done, 03:00, 05:00

16. Sleep Architecture

Sleep Differences

Research supports several sleep differences (Malow et al., 2012; Melke et al., 2008):

graph TD A[Sleep in Autism] --> B[Delayed melatonin onset] A --> C[Fragmented sleep architecture] A --> D[Reduced sleep efficiency] A --> E[Elevated evening cortisol] B --> F[Later natural sleep time] C --> G[Less restorative sleep] D --> G E --> H2[Harder to fall asleep] style G fill:#FF6B6B

17. Interoception

Body Signal Processing

graph TD A[Internal Signals] --> B{Conscious Awareness} B --> C[Often reduced accuracy] C --> C1[Hunger recognition delayed] C --> C2[Pain perception atypical] C --> C3[Fatigue signals missed] C1 --> D[May not eat until very hungry] C2 --> E[May miss injuries OR be hypersensitive] C3 --> F[Sudden exhaustion/shutdown] style C fill:#FF6B6B

18. Social Processing

Conscious vs Automatic Processing

graph TD A[Social Interaction] --> B{Processing Mode} B --> C[Neurotypical] C --> C1[Much processing automatic] C --> C2[Low conscious effort] B --> D[Autistic] D --> D1[More conscious processing required] D --> D2[Higher cognitive load] C2 --> E[Energy efficient] D2 --> F[Energy intensive] style D2 fill:#FF6B6B style F fill:#FF6B6B

Research supports: Social cognition requires more explicit/conscious processing in autism, contributing to social fatigue.

19. Meltdown vs Shutdown

System Overload States

stateDiagram-v2 [*] --> Baseline: Operating state Baseline --> Elevated: Stressor Elevated --> High: Another stressor High --> Critical: Cumulative load Critical --> Overload: Threshold exceeded Overload --> Meltdown: Fight response Overload --> Shutdown: Freeze response Meltdown --> Recovery: Hours to day Shutdown --> Recovery: Hours to day Recovery --> Baseline: If given time/space

Key understanding:

Not behavioral choices
Neurological crisis states
Require recovery time, not discipline

20. Comorbidity

Anxiety as Structural Consequence

graph TD A[Autism Architecture] --> B[Frequent amygdala activation] B --> C[Chronic elevated arousal] C --> D[Generalized anxiety] A --> E[Sensory unpredictability] E --> F[Environmental fear] F --> G[Social/specific anxiety] D --> H2[Diagnosed as comorbid] G --> H2 H2 --> I[Often same root: Architecture] style I fill:#FFD700

Many "comorbid" conditions may be consequences of the underlying neural architecture rather than separate disorders.

Summary

The autism neural architecture involves:

Structural differences - Direct thalamo-amygdala connections, reduced cortical gating
Amygdala dysregulation - Context-dependent hyper/hypo activation, not simple hyperactivation
HPA axis differences - Atypical cortisol patterns, prolonged recovery
E/I balance variations - Region-specific, not uniformly altered
Cumulative effects - Stress compounds without adequate recovery
Measurable differences - Documented in neuroimaging and physiological studies

This is architecture, not attitude. Accommodations address structural differences, not character flaws.

Note on illustrative numbers: Specific percentages and timeframes in this document are conceptual illustrations. Research supports the patterns described (elevated baseline, lower threshold, prolonged recovery) but exact values vary significantly between individuals. The science validates the direction of differences, not precise magnitudes.

References

Foundational Neuroscience

Amygdala Structure and Function

Cellular and Molecular

Sensory Processing

Neurochemistry

Chugani, D. C., et al. (1999). Altered serotonin synthesis in the dentatothalamocortical pathway in autistic boys. Annals of Neurology, 45(3), 287-295.