Nonverbal Learning Disabilitiess: an Endophenotype Across Neurodevelpmental Disorders

I started working with a student and kept finding they had a pattern of strengths and weaknesses academically that was familiar to a nonverbal disability that I had studied in many neurodevelopmental disorders. In talking to this student’s parents, I learned that what I saw made sense. The student has a genetic disorder similar to a disorder that fits that exact profile.

In my past research, I collaborated with researchers who were characterizing patterns of cognitive deficits in children and adolescents with different neurodevelopmental disorders; particularly fragile X-associated disorders–e.g., fragile X syndrome and the fragile X premutation, the 22q11.2 deletion syndrome (also called DiGeorge Syndrome and VeloCardioFacial Syndrome or VCFS), Turner syndrome, and Williams syndromes among others. These researchers characterized a difficulty or reduced resolution of spatial and temporal attention that they refer to as a spatiotemporal hypergranularity.

Two excellent papers from Tony Simon that is a helpful resource to understand this concept is Cognitive Characteristics of Children with Genetic Syndromes and A New Account of the Neurocognitive Foundations of Impairments in Space, Time and Number Processing in Children with Chromosone 22q11.2 Deletion Syndrome. Other research groups have developed similar ideas as well: Shared deficits in space, time, and quantity processing in childhood genetic disorders.

They defined the spatiotemporal hypergranularity or nonverbal learning disability across genetic disorders like this (emphasis mine):

While Turner Syndrome, Fragile X Syndrome, and Chromosome 22q11.2 deletion syndrome are all childhood genetic disorders, the different syndromes do have very different genetic etiologies, developmental trajectories, and physical manifestations. It is remarkable, therefore, that the syndromes appear to affect an overlapping set of cognitive processes. Mathematical ability is most probably one of the best known outcomes of the genetic syndromes. From the evidence reviewed in this paper, however, it also clear that the children suffer from a similar set of processing problems related to time and space. Although the link between mathematics and spatial/temporal processing is a subject of debate, recent work with children with developmental dyscalculia show that these children also have problems with temporal and spatial attentional processing. There is therefore tantalizing evidence suggesting a causal link between mathematical ability and spatial/temporal processing, which deserves further investigation.

The association between the functions most probably arises from damage to a common set of neural mechanisms. Turner Syndrome, Fragile X Syndrome, and Chromosome 22q11.2 deletion syndrome all appear to affect circuits located in the parietal and frontal cortices. Neural circuits lying in these same regions are also thought to play an important role in the ATOM model and provide a common code for numbers, space, and time. Variations in the extent and exact nature of the deficits may be related to the specific structures affected by each of the genetic disorders.

Collections of subclinical traits (traits not considered diagnostically relevant) across groups of people that correlate with genetic disorders are called endophenotypes. I have talked about my interest and previous work in identifying behavioral endophenotypes previously (my papers can be found here).

As Tony Simon stated in the first paper referenced above:

The visuospatial, visuomotor and numerical impairments in Williams, Turner, full mutation Fragile X (i.e. FXS) and chromosome 22q11.2 deletion syndromes are both striking in their degree of overlap, and puzzling in that other commonalities are limited. Because of the intimate connection between space and time, one prediction that flows from the above findings is that impairments should also be found in temporal processing. In fact, the two interdependent domains of function are often described with a single label, that of spatiotemporal cognition.

I feel that knowledge about these patterns of cognitive impairments are essential types of information to have as a special educator. If there is a consistent(ish) pattern of educational strengths and weaknesses in students that have different disabilities, I want to know.

More to the point, I want to use this information to design an intervention.

EDUCATIONAL ENDOPHENOTYPES

Since I did not know what else to do to help this student maximize their learning, I set up an experiment. Designing an experiment of some sort seems to be my solution to everything.

Experiments are basically my sonic screwdriver.

I wanted to determine if this student demonstrated a spatiotemporal hypergranularity that I could then target with specific, individualized instruction. I decided to do my experiment using educational resources available in the classroom since I was working 1:1 with the student anyway given they were on a different academic and functional level than other students in the classroom.

MY APPROACH

found materials that were designed to teach basic skills I felt this student needed to learn anyway. Most of these materials were based on discrete trial training from an old ABA-based life skills curriculum. These tasks were provided to me as photocopies and not as an overall curriculum.

Typically, I do not approve of the discrete trial as an educational method (testing is not teaching after all), but it was convenient for both myself and the student to use discrete trial methods that facilitate data collection, provide for high levels of reward for on-task behavior, and can be very fast.

METHODS

PRECURSOR SKILLS

Before we started any discrete trial training, I verified the student was capable of all the pre-requisite behaviors they needed to do the task.

Attending

The student was able to learn the attending program in ten days. This involved teaching in sequence: feet down, feet down with eyes on educational materials, feet down with eyes on materials and hands in learning position, and finally all of the above with mouth quiet. The student was able to independently apply attending in class when presented with the following verbal prompt, “[student name], Get Ready!”

Note: The Attending Curriculum is available upon request

Single Step Instructions

The student was able to follow simple one-step directions. Skills were modeled, and the student repeated the action when asked to do so. Within a week of training, the student was able to follow verbal instructions involving a single or two sequential directions with >95% fidelity and 3-4 step directions with >75% fidelity.

Ability to remain “on task”

Based on data collected during training sessions, the student was able to stay on task for 8 ± 2 minutes (range= 1-15 minutes). In most situations, the student asked to use the restroom (student said, “Potty”) or to get a drink (student said, “water”) to get a break from the task.

“Give me” commands

The student understood without prior training how to hand the instructor a preferred toy when asked, at which point the teacher immediately returned it as the reward and verbally praised the student for giving the item when asked. As such, there was no training provided.

During task training, “give me”, “show me”, and “hand me” were interchangeably used to increase flexibility and vocabulary skills.

Discrete Trial Training

Given their skills in understanding how to give a teacher a requested object and mastery of all other precursor skills, the student was able to learn how to perform a Discrete Trial Training session within a single day of training. The task structure was as follows: The student was asked to sit across the table from the the instructor. They put their hands on the table and the stimuli were presented. They awaited instruction and responded within five (5) seconds to teacher requests.

Most often the student preferred to point to the stimulus rather than pick it up. Sometimes they would hover their hand over incorrect answers and then rapidly move their hand to the correct one and say, “tricked you”.

The student’s preferred primary reinforcer (food reward) was ½ a piece of Froot Loop cereal, the second preferred was skittles, then M&Ms, and lastly Nerds candy. If they did not want a food reward they would push it away and say, “No” in a clear voice, followed by turning away and crossing their arms dramatically and pursing their lips. When the instructor would ask what they wanted instead, they would verbalize their desire. Most often they named their overall preferred reinforcement, which was access to tangibles with a preferred adult/peer (i.e., toys with a preferred adult).

When the student lost interest in the session they would ask to use the restroom or to get a drink using a 1 word verbal mand. If these mands were ignored and the student was instead asked to wait, they would cease to demonstrate effort during the task and would start to only select the item to their left until they were allowed to leave the table. If pressed, they would hide the stimulus cards under the table and ask, “Where it go?” with their hands up in a shrug and head shaking “I don’t know”.

Use of 5-item Token Chart

The student was able to understand and effectively use a 5-item token chart within 10 days of training. They would select an item to work for as a reward independently from a menu velcroed to a cabinet.

The student understood that 5 stars on their chart earned the reward. The student reported this knowledge in two ways: first, they would notify the teacher when their chart was full by saying the name of the reward and showing us the chart. Secondly, the student also would remind teachers that they were not marking the token chart enough by showing them the remaining boxes, handing the teacher a dry erase marker, and asking to be given a star.

VISUOSPATIAL TASKS

GENERAL TASK PROTOCOL

For all behavioral tasks that used discrete trial training, the tasks were carried out using the following procedure:

The student was invited to the table to participate in a learning session using the following script: “[student name], please come to the table so we can work on your goals” The student was 100% compliant with this initial request.
When at the table, a clear space was defined in front of the student using an overturned half-sheet jellyroll pan. The student was told, “[student name], we are going to work on choosing options from this tray. Is that okay with you?” Trials did not begin until the student responded affirmatively.
Each trial was started by saying, “[student name], are you ready?” and started when the student said, “yes” or shook their head affirmatively.
To start the trial (Study Session), the student was shown a card identical to the rewarded target stimulus for 2 seconds, and the card was placed face down on the table.
For each trial (Test Session), two cards with pictures, numbers, dots, or letters (depending upon the task) were placed in front of the student on the tray separated by at least 15 cm. The cards were placed simultaneously. In all cases the rewarded target stimulus was the card that was identical to the one seen during the Study Session.
The student was given a prompt to choose by saying, “[student name], show/give/hand me the [rewarded target stimulus]”
- If the student chose correctly, they were rewarded by the tester saying “correct” and handing them a reward immediately and marking a star on their star chart.
- If the student chose incorrectly, they were shown the correct card and the tester labeled the card by name and showed it to the student for 2 seconds. The student had a tendency to spontaneously echo the name of the item on the card and point to the card.
After a 15 second inter-trial interval, Steps 3-5 were repeated for up to 20 trials in a given day.

I also designed “control” tasks that did not require memory (i.e. did not require the student to remember the card from the study session). For the control versions of these tasks, the above steps were followed with the following modification: During Step 5 (Test Session), the student was presented the two cards 15 cm apart. But, immediately after this, the card shown during the Study Session was handed to the student and they were asked, “[student name], show/give/hand me the card that is the same as this one”.

This control was included to demonstrate that the student was able to perceive the stimuli correctly as demonstrated by an intact ability to match cards. If the student was able to match cards but unable to perform the same task when memory was required, it could be inferred that the student had difficulty disambiguating or discriminate among similar memory/stimulus representations. Such data would support theories that suggest individuals with genetic disorders often display a fundamental difficulty in mentally representing numbers, time, and space (i.e., the spatiotemporal hypergranularity described above).

SPECIFIC TASKS

MIDLINE ESTIMATION

For midline estimation, the student was asked which of two identical blocks were closer to the middle of a 45 cm (18 inch) masking tape line on the table. The middle of the line was clearly marked with a thick, red sharpie. The prompt given to the student was, “[student name], which of these two blocks is closest to the middle (instructoir pointed to and touched the mark at the midpoint of the tape line)”. The student responded by pointing and saying, “this one”.

There was no nonspatial control for this task.

ENUMERATION

For this task, the discrete trial procedure was followed with cards containing 1 cm diameter dots in recognizable patterns made up of 0-9 dots, reflecting the numbers 0-9.