Brain and Language Lab
Neurodevelopmental Disorders
We are interested in language and other domains such as music and math, as well as learning and memory more generally, in a variety of neurodevelopmental disorders. These include developmental language disorder (DLD, formerly known as specific language impairment), dyslexia, motor-speech disorders (e.g., apraxia of speech and stuttering), autism, Tourette syndrome, ADHD, math disability, and schizophrenia. Much of our work on neurodevelopmental disorders is related to the Procedural circuit Deficit Hypothesis and the Declarative Compensation Hypothesis.
DEVELOPMENTAL LANGUAGE DISORDER (DLD)
How can we best characterize language and its neurobiological bases in individuals with Developmental Language Disorder (DLD, formerly known as specific language impairment)? What parts of the brain are abnormal in DLD, and what language and other cognitive symptoms might these abnormalities explain? How do children with DLD compensate for their deficits, and which brain systems do they use for this compensation? What aspects of cognition might actually be enhanced in the disorder? Our research on DLD attempts to answer these and related questions.
We have proposed the Procedural circuit Deficit Hypothesis, which posits that the phenotype of DLD – including the language and other cognitive problems found in the disorder – can be largely explained by abnormalities of brain structures underlying procedural memory, in particular the basal ganglia, and that individuals with the disorder compensate with declarative memory (Ullman & Pierpont, 2005; Ullman & Pullman, 2015; Ullman et al., 2020).
Evidence suggests that DLD is indeed associated with abnormalities of brain structures underlying procedural memory (Ullman & Pierpont, 2005; Ullman et al., 2020; Ullman et al., 2024), in particular the anterior neostriatum within the basal ganglia (Ullman et al., 2024). Evidence also suggests that individuals with DLD have learning and consolidation deficits of procedural memory (Hedenius et al., 2011; Lum et al., 2012; Lum et al., 2014; Ullman et al., 2020); that grammar problems are linked to procedural memory impairments in the disorder (Hedenius et al., 2011); and that declarative memory is relatively spared (Lum et al., 2012; Lum et al., 2015) or even enhanced (Lukacs et al., 2017), and compensates for the grammatical difficulties (Lum et al., 2012; Conti-Ramsden et al., 2015; Ullman & Pullman, 2015).
Publications:
Ullman, M.T., Clark, G.M., Pullman, M.Y., Lovelett, J.T., Pierpont, E.I., Jiang, X., & Turkeltaub, P.E. (2024, online). The neuroanatomy of developmental language disorder: a systematic review and meta-analysis. Nature Human Behaviour. (Supplementary Information)
DEVELOPMENTAL DYSLEXIA
We are interested in the neurocognition of language and reading deficits in developmental dyslexia. We have proposed the Procedural circuit Deficit Hypothesis, which posits that dyslexia may be at least partly explained by abnormalities of brain structures underlying procedural memory (Ullman, 2004; Ullman et al., 2020), leading to reading and other problems, and that individuals with the disorder compensate, at least in part, with declarative memory (Ullman & Pullman, 2015; Ullman et al., 2020).
Evidence suggests that dyslexia is in fact associated with learning and consolidation deficits of procedural memory (Lum et al., 2013; Hedenius et al., 2013), that declarative memory may be enhanced in the disorder (Hedenius et al., 2013), and that declarative memory compensates for the reading and grammatical difficulties (Hedenius et al., 2013; Ullman & Pullman, 2015; Ullman et al., 2020).
Publications:
DEVELOPMENTAL MOTOR-SPEECH DISORDERS
We are interested in the roles of declarative and procedural memory in developmental motor-speech disorders, including articulation disorder, childhood apraxia of speech (CAS, or verbal dyspraxia), and developmental stuttering (Ullman et al., 2020)
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AUTISM SPECTRUM DISORDER (ASD)
We also investigate the neurocognition of language and memory in autism spectrum disorder (ASD). We have proposed the Procedural circuit Deficit Hypothesis of ASD, which posits that the language abnormalities in the disorder may be at least partly explained by abnormalities of brain structures underlying procedural memory (Ullman, 2004; Walenski et al., 2006) and that individuals with ASD may compensate for language and social deficits with declarative memory (Walenski et al., 2006; Ullman & Pullman, 2015).
Evidence suggests that ASD is indeed associated with abnormalities of grammar (Walenski et al., 2006), including impairments in some cases (Walenski et al., 2006) and speeded grammatical processing in others (Walenski et al., 2014). It is not yet clear why some findings suggest grammatical difficulties, while others suggest speeded and thus in some manner enhanced grammatical processing. Additionally, lexical abilities may be enhanced in children with ASD, perhaps because of underlying strengths in declarative memory (Walenski et al., 2008). Indeed, accumulating evidence suggests that declarative memory can show enhancements in the disorder (Ullman & Pullman, 2015).
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TOURETTE SYNDROME (TS)
We investigate the neurocognition of language and memory in Tourette syndrome (TS). We have suggested that, due to the nature of the frontal/basal-ganglia abnormalities in TS, procedural memory may be enhanced in the disorder (Ullman et al., 2008; Walenski et al., 2007). Evidence indeed suggests that, despite these brain abnormalities, learning in procedural memory is normal or enhanced in TS (Takács et al., 2017; Takács et al., 2018), and that rule-governed grammatical composition, which seems to depend on procedural memory, is speeded in both morphology (Walenski et al., 2007) and phonology (Dye et al., 2016). In contrast, declarative memory appears to play a compensatory role in the disorder (Ullman & Pullman, 2015).
Publications:
Takács, Á., Kóbor, A., Chezan, J., Éltető, N., Tárnok, Z., Nemeth, D., Ullman, M. T., & Janacsek, K. (2018). Is procedural memory enhanced in Tourette syndrome? Evidence from a sequence learning task. Cortex, 100, 84-94. (Supporting Information).
ADHD
We are interested in the neurocognition of language and memory in ADHD. We have suggested that procedural memory shows abnormalities (Ullman, 2004), while declarative memory plays a compensatory role in the disorder (Ullman & Pullman, 2015).
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MATH DISABILITY (MD)
Math disability (MD) is a neurodevelopmental disorder of math. We have proposed a new explanatory account of MD that may further our understanding of the disorder (Evans & Ullman, 2016). According to the Procedural circuit Deficit Hypothesis (PDH) of MD, abnormalities of brain structures constituting the procedural memory system should lead to difficulties with math skills learned in this system, as well as of other functions that depend on these structures (e.g., executive function). The account is motivated by the high comorbidity between MD and language disorders such as dyslexia (and possibly DLD) that may be explained in part by the PDH, and a likelihood that automatized math skills are learned in part in procedural memory. In Evans & Ullman (2016), we first lay out the PDH of MD, and then present specific predictions, examining the existing literature for each while pointing out weaknesses and gaps to be addressed by future research. Although we do not claim that the PDH is likely to fully account for MD, we do suggest that the hypothesis could have substantial explanatory power, and that it provides a useful theoretical framework that may advance our understanding of the disorder.
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SCHIZOPHRENIA
We are interested in the neurocognition of language, music and memory in schizophrenia. In one study we found evidence for grammatical impairments in the disorder, but spared lexical abilities (Walenski et al., 2010). Interestingly, in a case study of a musician with the disorder, we found impairments of idiosyncratic aspects of music but not of rule-governed aspects of music (Skelley et al., 2009). Further work is needed to elucidate these patterns.
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OTHER NEURODEVELOPMENTAL DISORDERS
We are also interested in language and memory in other neurodevelopmental disorders, including obsessive-compulsive disorder (OCD), Developmental Coordination Disorder (DCD), phenylketonuria, and Williams syndrome.