Week Six:
ADHD and Development Lab

Carhart Fellow in Clinical Psychology

ADHD and Development Lab, University of Iowa | Iowa City, Iowa

July 8, 2015

This past week was a little slow for because of the holiday weekend. The lab visit on Monday, the 29th had to reschedule, so I was left spending my week catching up on data entry from our visits at the Lab, as well as archival data collected from collaborators at the University of Minnesota.

During our weekly meeting, Dr. Nikolas and I discussed three more articles. These articles were of a more theoretical nature, as opposed to empirical as were the articles that I had written about last week.

To better understand the conceptualization of attention based on the current literature, I read Chen, Golomb, and Turk-Browne (2011) in which a taxonomy of external and internal attention were delineated. Throughout the article, the terminology was classic of the tradition of cognitive psychology, where the work of Dr. Nikolas and other contemporary ADHD researchers elsewhere more write in lieu of neuropsychological or neuroscience perspectives. Nonetheless, the terminology is only of marginal significance because the terms are often synonymous with terminology used in the contemporary literature on ADHD. We focused mainly on aspects of the taxonomy that we found to be most relevant to ADHD.

Credit: Chen, Golomb, & Turk-Browne (2011).
Credit: Chen, Golomb, & Turk-Browne (2011).

In their taxonomy, Chen, Golomg, and Turk-Browne (2011) divided attentional processes into two categories: external attention and internal attention. External attention is involved in the selection and modulation of perceptual information from sensory inputs, spatial awareness, and temporal elements. Internal attention is tasked with selection and modulation of mentally generated information, which implies cognitive control mechanisms (e.g. executive functioning) implicated in response and task selection, working memory, and long-term memory. Unfortunately, the article did not enumerate further processes within internal attention, as one would notice these are only a handful. Considering the large body of literature on executive functioning deficit in ADHD, internal attention is perhaps most relevant to ADHD as cognitive control mechanisms are involved in regulating internally generated information, as well as information from external attention processes. Figure 1 illustrates the taxonomy proposed.

Next we discussed the behavioral neuroenergetics theory of ADHD put forth by Killeen, Russell, and Sargeant (2013). While the theory is rather complicated and touches on decades of neuroscience research, Killeena, Russell, and Sargeant argue that due to neurogenic deficits in neurotransmission and energy resupply to neurons in essential brain systems, ADHD is best described as a disorder characterized by deficits in sustained attention. To put in different words, reduced neurotransmission of essential excitatory and inhibitory neurotransmitters and depreciated energy transport leads to the cognitive and behavioral deficits we find in ADHD.

Credit: Nigg & Casey (2005).
Developmental pathways of ADHD. Credit: Nigg & Casey (2005).

Nigg & Casey (2005) put forth a cognitive-emotional theory of ADHD defining the disorder that has much to do with reward and approach systems, which are mediated by executive functions. Understanding the neurodevelopment of ADHD, namely the underinvolvement of effortful control and affective response systems, Nigg and Casey focus on the frontostriatal (behavioral inhibition, goal-directed behavior), frontolimbic (emotional self-regulation, avoidance and approach), and frontocerebellar (temporal processing) systems of the brain. By extension, the theory emphasizes the development of impulsivity that we often see in individuals with the ADHD subtype predominantly hyperactive-impulsive. Figure 2 summarizes this theory.

This coming week I hope to have plenty to share with you, as I have four lab visits scheduled, including more discussion of theoretical and empirical works.

Chen M. M., Golomb J. D., & Turk-Browne N. B. (2011). A taxonomy of external and internal attention. Annual Review of Psychology, 62(1), 73-101. doi: 10.1146/annurev.psych.093008.100427

Killeen P. R., Russell V. A., & Sargeant J.A. (2013). A behavioral neuroenergetics theory of ADHD. Neuroscience and Biobehavioral Reviews, 37(4), 625-657. doi: 10.1016/j.neubiorev.2013.02.011.

Nigg J. T. & Casey, B. J. (2005). An integrative theory of attention-deficit/hyperactivity disorder based on the cognitive and affective neurosciences. Development and Psychopathology, 17(3), 785-806. doi: 10.10170S0954579405050376

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Andrew Crow '16

Andrew is a Psychology and Philosophy major from Milwaukee, Wisconsin.