Me or We?

A poem written many years ago that captures the mind-body and depersonalization

Me or We?

 If I were a math expression I’d be

Irrational Number Body

 Perfect Square Mind

A body that acts quite on its own

A mind that can only watch and mourn

Body, the numerator, mere flesh and bone

Irrational number like, a math anomaly

Visible to all, pure absurdity

Mind, the denominator, profound and wise

Perfect square like, just ecstasy

Hidden from sight, pure tragedy

Body just limited by space, movement and time

Mind without boundaries, infinite times

Two seeming identities in one unreasonable body

Perchance, I should be a 'We' and not 'Me.'

I crave the 'Me' and not the 'We'

How do I go from 'We' to 'Me'?

Interaural differences

[Concepts in Sensorimotor Research]

Interaural differences refer to the differences between the sound signals that reach each ear. These differences are caused by the time delay and the amplitude difference of the sound waves that reach each ear.

• ITD (interaural time difference): time delay between the arrival of sound at each ear. ITD is greatest for sounds coming from the side of the head and is zero for sounds coming from directly in front or behind the listener.
• ILD (interaural level difference): amplitude difference between the sound waves arriving at each ear. ILD is greatest for sounds coming from directly to one side of the listener and is zero for sounds coming from directly in front or behind the listener.

The brain processes these interaural differences to determine the location of the sound source and create a spatial auditory image, which helps us to perceive the world around us in three dimensions.

Some studies have reported differences in how autistics process interaural differences, including reduced ability to integrate auditory and visual information, as well as altered auditory and multisensory temporal processing. 

The caveat being, more research is needed in this area for better understanding. Nothing is set in stone when it comes to autism. 

Interoception and exteroception

[Concepts in Sensorimotor Research]

Interoception and exteroception are two types of sensory perception.

Interoception refers to the sense of the internal state of the body. It helps us understand and feel what's going on inside our bodies, like feeling hungry, thirsty, or perceiving our heartbeat. Interoceptive awareness contributes to emotional regulation and self-awareness.

Exteroception refers to the perception of the external environment through our senses like vision, hearing, touch, taste, and smell. These senses help us navigate and interact with the world around us.

Research findings  in autism:

Autistics often exhibit differences in sensory processing, which may include atypical interoceptive and exteroceptive perception. Findings (examples below) suggest that atypical interoceptive and exteroceptive processing may be significant factors in understanding the behavioral and sensory symptoms in individuals with autism.

• This review explores the role of oxytocin in interoception and its potential implications for autism. The authors propose that atypical interoceptive processing, potentially linked to altered oxytocin functioning, could contribute to the social and emotional difficulties experienced by autistics. (1)
• This study found that adult autistics exhibited significantly lower interoceptive awareness compared to NT adults. The authors suggest that this might be related to the difficulties in social and emotional processing seen in autism (2).
• This review discusses various neurophysiological findings in sensory processing, including exteroception, in autistics. The authors highlight that altered sensory processing may contribute to the core features of ASD, such as social communication and repetitive behaviors (3) 

Temporal Binding Window and Autism

[Concepts in Sensorimotor Research]

Temporal binding window (TBW) refers to the specific time frame during which the brain integrates and processes information from different sensory modalities. It is the period in which the brain combines and links stimuli occurring close in time and attributes them to a single event. This window is crucial for the perception of synchrony and the formation of coherent perceptual experiences.

In autistics, research suggests alterations in the TBW due to difficulties in accurately perceiving and integrating sensory information across different modalities, leading to difficulties in forming a unified perception of the world.

One aspect of the TBW that has been extensively studied in relation to autism is audiovisual integration. Typically, individuals are sensitive to the relative timing of auditory and visual stimuli and can perceive them as belonging to a single event when presented within a certain temporal proximity. However, studies have shown that autistics may have a broader or more extended TBW. This means that they require a longer temporal proximity between auditory and visual stimuli to perceive them as synchronized.

This winder TBW has implication in terms of social communication and interaction since the perception of synchrony is crucial for understanding and interpreting non-verbal cues such as facial expressions, gestures, and vocal intonations. Difficulties in integrating sensory information across different modalities can also contribute to sensory processing issues commonly observed in individuals with autism, such as hypersensitivity or hyposensitivity to certain stimuli.

TBW may also influence higher-level cognitive processes such as attention, perception of causality, and the ability to predict and anticipate events. Disruptions in these processes can impact the ability to understand the temporal structure of events and may contribute to difficulties with executive functioning.

Ventriloquism Effect in Multisensory Integration

[Concepts in Sensorimotor Research]

The ventriloquism effect is a fascinating example of multisensory integration, the process by which the brain combines information from different senses to create a unified percept. The brain is integrating information from the visual and auditory senses to create the perceive that the sound is coming from a location (the dummy's mouth) that is different from the actual source of the sound.

The ventriloquism effect can also occur in other situations where there is a mismatch between the visual and auditory information, such as when watching a movie with dubbed audio, or when hearing a person speak on a phone or speaker. The brain uses contextual cues to determine the location of the sound source and can be influenced by visual information, leading to the perception of the sound coming from a different location.

There is some evidence to suggest that autistics may process sensory information differently than neurotypicals, including the processing of auditory information and less fooled by the ventriloquism effect which may suggest that autistics have difficulty integrating information form different senses (which has implication in terms of social interactions).

Other studies have suggested that individuals with autism may have heightened sensitivity to certain auditory stimuli and may experience difficulty in filtering out irrelevant sounds. This hypersensitivity to sound could potentially interfere with the integration of visual and auditory information, leading to a weaker ventriloquism effect.

However the caveat is that research on the relationship between autism & ventriloquism effect is ongoing and not fully understood. So nothing is set in stone.

Alexithymia

Alexithymia is characterized by difficulty in recognizing and expressing one's emotional experiences.

The term was first used in the 1970s by psychotherapist Peter Sifneos to describe a group of people who had difficulty expressing their emotions. They may also be more prone to stress-related issues and have difficulties coping with stress in general.

Studies find the prevalence of alexithymia in autistics to range from 50% to 66% compared to a 10% prevalence in the neurotypical population (1,2).

1. Alexithymia in autistics has been associated with several negative outcomes.Social communication difficulties: Difficulty expressing emotions and interpreting the emotions of others, can interfere with social communication; which may be particularly pronounced in autistics, who already experience social communication difficulties (3).
2. Reduced quality of life due to the negative impact on social relationships (4)
3. Increased anxiety and depression: One study found that alexithymia was a significant predictor of depression in autistic adults (5).
4. Greater risk for negative outcomes: In a longitudinal study of autistic children those with higher levels of alexithymia were found to have a higher risk for negative outcomes such as anxiety, depression, and behavioral problems over time (6).

Propagnosia and Autism

There is some research suggesting a possible link between prosopagnosia  and autism. However studies are correlational in nature and do not establish a causal link between prosopagnosia and autism

What is Propagnosia

Propagnosia (face blindness), is a neurological condition that affects a person's ability to recognize and remember faces. There is difficulty recognizing familiar faces, such as those of family members, friends, or colleagues. They may also have difficulty recognizing faces in photographs or on television.

Noise Cancelling Headphones and Autism

Noise Cancelling Headphones are often seen as the solution to sensory overstimulation in autistics. 

Pop on a pair of headphones. And Voila, the autistic problem is solved like magic (sarcasm intended).

Are they really the solution they are touted to be? The answer may surprise you. 

He et al 2023: Taxonomy of Sensory Differences in Autism

 

The authors (Vanderbilt study) propose a hierarchical taxonomy to describe and refer to various sensory features of autism, which will help researchers to better understand the nature and impact of the sensory differences of autism and place future research targets at appropriate levels of analysis.

The 5 levels of proposed taxonomy are.

 

MAST - The Maastricht Acute Stress Test

[concepts in Sensorimotor Research] 

The Maastricht Acute Stress Test (MAST) is a research laboratory procedure that is used to induce stress in research participants. It is used to study the effects of stress on a variety of physiological and psychological processes, including heart rate, blood pressure, cortisol levels, anxiety, and depression. The MAST combines elements from two of the most common experimental paradigms measuring stress, the Trier Social Stress Test (TSST) and the Cold Pressor Test (CPT).

The Test: 
There is a 5-minute preparation phase, during which the participant is seated in a comfortable chair and is given instructions about the task. The participant is then asked to put their right hand into a bowl of ice water for 60-90 seconds. In between each hand immersion trial, the participant is asked to complete a series of mental arithmetic problems. The participant is given negative feedback if they make a mistake or take too long to answer a question.

The test takes approximately 20 minutes to complete. During the procedure, the participant's heart rate, BP, and salivary cortisol levels are measured. The participant is also asked to rate their subjective feelings of stress on a scale of 1 to 10.

Benefits

• It is a simple and easy-to-use procedure.
• It is non-invasive and does not pose any risk to participants.
• It is effective at inducing stress in participants.
• It can be used to measure a variety of stress-related outcomes.

Limitations

• Laboratory-based procedures may not be representative of real-world stress.
• It can be stressful for participants and may not be suitable for everyone. (will autistics even agree to do this?)
• It is not a diagnostic tool and cannot be used to diagnose any medical conditions.

https://www.frontiersin.org/articles/10.3389/fpsyg.2017.00567/full

Maffei et al 2023: Oromotor skills in Autism

Based on review of research published between 1994 and 2022 on oromotor functioning in autistic individuals, 

key takeaways: 

• Oromotor functioning plays a foundational role in spoken communication and feeding.
• 81% of included 107 studies report a significant oromotor challenges related to speech production, nonspeech oromotor skills, or feeding 
• Studies used various methods to investigate oromotor functioning in autistics
• Behavioral measures -  tasks such as tongue protrusion, lip closure, and oral diadochokinesis. 
• Parent report measures - questionnaires and interviews. 
• Medical record review - examining medical records for information on feeding / swallowing difficulties. 
• Neuroimaging techniques -  fMRI & MEG.

• The findings suggest that oromotor challenges are common in autistics, but more research is needed to better understand the nature / extent and their impact on communication and feeding.

Some limitations of this paper include

• numerous inclusion and exclusion criteria, which may have excluded relevant studies eg: non-English publications, pre 1994 studies etc
• wide variation in studies re sample characteristics, behaviors analyzed, and research methodology, which makes it difficult to draw definitive conclusions. 
• did not include a meta-analysis, which would have allowed for a quantitative synthesis of the findings across studies. 

Maffei MF, Chenausky KV, Gill SV, Tager-Flusberg H, Green JR. Oromotor skills in autism spectrum disorder: A scoping review. Autism Res. 2023 Apr 3. doi: 10.1002/aur.2923. Epub ahead of print. PMID: 37010327.

Vestibular, Proprioception in Autism

Lay summary:  Go to any Occupational Therapist and you are bound to hear the words vestibular and proprioception, sensory diet at least a few times.  

Why is this important: Understanding the role of sensory processing difficulties and the sensory systems involved (such as vestibular, proprioception, and somatosensory body mapping) can be helpful in developing effective interventions and support strategies for autistics.

Constant Overload

Being bombarded by the sensory system

A constant overload, it never ends
Sensory overwhelmed, a feeling of prison
Trapped in my own mind, with no friends.

Poor somatosensory body mapping
A constant confusion, a foggy haze
I struggle to understand my own body
A feeling of being lost, in a daze

Words get stuck, inside my head
Apraxic, struggles to speak
A feeling of frustration, so very unique
As talking eludes me, instead

It can be a struggle, to navigate
This world that's full of sensation

I need to find a way
… with determination

The brain is a Giant Prediction Machine

Poem follows Prof Mark Wallace's comment in class "The Brain is a giant prediction machine" after a discussion on the growing popularity of Bayesian Statistical Models in research. 

The brain is a giant prediction machine

Bayesian model-like, it constantly schemes

Past experiences and memories in its grasp

Current sensory input, processed in a flash.

 

TBI Regressive Autism

Ameliorating Hemianopia with Multisensory Training (Rowland et al., 2023)

Quick Summary of paper . An  visual-auditory stimulation therapy was used on two older males  who has loss of vision in the left hemifield (hemianopia). The cause was brain trauma (TBI) rather than lesion.  Prior to joining the study both had been referred to PT and OT as rehabilitation measures. 

• 64 year old JM joined the study 14 months after stroke  (2 infracts)
• 74 year old CW joined the study ~18 months after 1 infract (better sighted field compared to JM). 
• Therapy took place over 8 months /10 sessions 

The results were dramatic. Both patients recovered the ability to detect and describe visual stimuli throughout their formerly blind field within a few weeks. They could also localize these stimuli, identify some features, and perceive multiple visuals simultaneously in both fields. (more detail on paper here link)

Relating all this back to Autism

So impressive about being able to restore sight in a matter of 8 months, given therapy was started 14-18 months after infract and not immediately and it was in older adults. 

Why is regressive autism not thought to be TBI at 18 mo, where there is a sudden loss of learned skills. 

• If TBI --> can those lost skills not be regained through targeted therapy. If you can restore skills in 60-70 yr old, should be able to, in a younger more plastic brain. 
• If TBI -->  is this related to CW & JM having practice with vision for 60-70+ years vs toddlers who only have practice with the skills for 18 mo.

Rethink Traditional Therapies

• CW & JM  had PT/OT for 14-18 mo before joining study; implication these therapies not that useful for regaining lost skills. 
• Autistics kids are in insane amounts of therapy (childhood stuffed with ABA/speech/OT every waking hr with little advances to show for it other than the $$$ spent and lots of career advancement for therapists). 
•  Maybe we need rethink early childhood therapy to be more targeted to restore lost skills. Even regaining that level of lost skills improves quality of life, let alone moving beyond.

Fidget Stim Toys and Autism

Many autistics have sensory processing difficulties and may be hyper- or hypo-sensitive to environmental stimuli. 

Fidget stim toys (eg: stress balls or fidget spinners) have been associated with autism.

Do Fidget toys help ALL autistics? The answer may surprise you.

Local vs Distributed Information

[Concepts in Sensorimotor Research]

Class Discussion  in my Multisensory Processing seminar class, see details of paper here. 

Implications for autism. Application and interventions is my big thought always.

I think by now it is pretty established that there are glitches in multisensory processing in autistics.

Past studies indicate TBW (Temporal Binding Window) larger in autistics - individual cortical columns were strong, but not talking to columns in other domains.

I want to highlight that this paper says that this balance between distributed vs local information can be a tool to explore differences in multisensory processing. The paper also goes on to say that this can be used to develop effective interventions aimed at improving performance on tasks requiring coordination between different sensory modalities.

So how exactly can we start to do this. What kind of experiment design can we set up so that we get to big goal of interventions. Do we first check for what regions of the brain are involved in autistics, while we do a task.

Apraxia, dyspraxia, oral-motor apraxia, Aphasia

[Concepts in Sensorimotor Research]

Pretty much every SLP I've been to over the years, has mentioned these terms. So what exactly are they. 

Apraxia, dyspraxia, and oral-motor apraxia are all related to deficits in motor planning and execution, but they differ in their specific manifestations and underlying neural mechanisms.

Stimulus Value Gates Multisensory Integration

[Concepts in Sensorimotor Research]

Application to Autism. 

The advantage of a good filtering system is less getting overwhelmed by your sensory environment in the real world, but the disadvantage was that you could lose out on critical information. This almost automatic value-based filtering ability is, I think, an issue many autistics like me struggle with. But even with extensive experience, value-based filters could vary around task domain, context-specific or even things like predictability.  Which is still, i think, why we still face challenges in trying to understand what exactly is going on in the non-neurotypical populations. 

Bean, N. L., Stein, B. E., & Rowland, B. A. (2021). Stimulus value gates multisensory integration. European Journal of Neuroscience, 53(9), 3142-3159.

Summary of the paper we discussed in my Multisensory Integration seminar this week. 

Synesthesia and Autism

[Concepts in Sensorimotor Research]

Paper was for my Systems Neuroscience Class this semester was on Synesthesia and Autism. 

(I got an A+ both for this essay and the final grade for the course.)

Instructor Feedback: you wrote an excellent essay! Your essay was engaging to read and provided compelling insight into synesthesia and autism. You succeeded to find intriguing papers at each level of understanding and used those references effectively. The concise way of writing reveals a true talent to distill the key messages from complex papers from (very) diverse fields and to use them for your argument. This was overall very impressive to see! you wrote an excellent essay ! Overall, we grade your essay with an A+ Keep up this good work.