Blue: pay attention there’s something unique going on here, what do I do? Yellow: transforming senses into actions Red: Executive Control and Working Memory
motor system activation was functionally integrated with prefrontal and parietal regions frequently observed during goal-directed behavior involving motor attention and working memory.
Striatal regions typically recruited in response execution were not engaged This may reflect a breakdown of higher-order control on error trials. functional interpretation of mesiotemporal activity is that it could represent internal speech [Ryding et al., 1996], a literal or figurative sub-vocal ‘whoops!’ response made to errors.
which likely contributes affective salience to No-Go target stimuli [Holroyd and Coles, 2002]. Activity in these frontotemporal areas has been linked to internally-generated emotional response [Reiman et al., 1997], awareness of errors [Hester et al., 2005], and self-referential thinking [Vogeley et al., 2001], suggesting these regions may underlie awareness of and emotional reaction to errors.
Specifically, affective responses might signal the failure to reinforce stimulus-action-reward associations.
ADHD as a model for understanding neural network dynamics
Using ADHD as a model for
understanding neural networks
Dr. Laura Jansons
• Diagnosis made by behavior observation:
– 18 symptoms of ADHD, need to meet a
percentage of them to be diagnosed
– Diagnosed using behavioral checklists
– Problem for neuropsychologists:
• DSM-V is not based on NP test data
• DSM-V not based on Neuroanatomy
• DSM-V is based on “lesion” or disease model.
– Old: ADHD is dysfunction of frontal lobe
– New: abnormally functioning brain circuitry
– New: Several etiological influences, “common disease-
common variant model”
– New: ADHD is not one thing, there is not one place on
the brain we can map.
• Based on what we’ve learned from neuroimaging, we should
be thinking in terms of loops and connections, and not land
• Those loops recruited in ADHD:
7 brain networks involved in ADHD
Yeo and colleagues (2011)
• Frontal Parietal network: effortful cognitive tasks, esp. novel.
• Ventral attentional network : directs attn. to salient objects. “What” you are
seeing or “what” an object is used for.
• Dorsal attentional network : Where and How of spatial attn. “Where” is object
located and “how” do I use it.
• Visual Network: interacts with dorsal and ventral route
• Limbic network: anticipation of rewards, monitors errors and conflict resolution.
• Sensory-motor network: motor skills
• Default mode network: What you are imagining at rest.
• What this means for neuropsychologists is
that it is no longer appropriate to think of
ADHD as a simple ‘‘frontal-lobe disorder’’
• Need to replace the localizationist view, ADHD
is not just one thing from one place in the
brain with one trajectory.
• This is why there is no NP test available, ADHD
is heterogeneous, the symptoms are
Functionally mapping ONE symptom of
ADHD using one type of test
• Stevens and colleagues, 2007, provided the first description
of how multiple neural network dynamics are associated with
response inhibition in normal control adolescent and adult
subjects in the performance of a “Go-No-Go” task.
• There is not one region in the brain
responsible for inhibiting response.
• There are “loops” of communication that
leads to disinhibition, in fact there are three.
• We are always “idling” and anticipating. When
the light is red, the car is not “off”.
• There is a lot going on when you inhibit a
These loops can be mapped on the brain via
The following is the “blue”, “yellow” and “red”
Correctly rejected No-Go stimuli involved with
successful response inhibition:
Stevens, et al, 2007
Blue: pay attention there’s something unique
going on here, what do I do?
Yellow: transforming senses into actions. Object
recognition, salience/reward value
Red: Executive Control and Working Memory
Fig. 1. Brain regions in each component
associated with successful response inhibition.
(A) Fronto-striatal-thalamic indirect pathway
engagement consistent with
modulation of motor function (Blue); (B)
precentral gyri deactivation concurrent with
prefrontal and inferotemporal activation
(Yellow); (C) frontoparietal circuit
activity consistent with higher-order
presentations of No-Go’ response contingencies
(Red). Statistical results are thresholded at a low
of p < .001, corrected for
searching the whole brain.
Summary Stevens 2007
• Causal relationships among ensembles of
different brain regions.
• May help understand that there is no one
linear cause for disinhibition, alterations in
specific connections or brain region could
impact psychopathological conditions.
• Network dynamics supporting correct
responses and errors of commission
• NCs between 11 and 37
• Go/No-Go task
• The analysis found five distinct functional
networks related to correct hits and errors.
(1000 ms intervals)
85% Go stimuli
right index finger taps
Correct Button Pushes
A: a motor-execution neural circuit integrated with frontal, parietal, and
striatal regions (Orange),
B: the ‘default mode’ neural network (imagining a task as if you were doing
A: a motor-
absent or decreased
activity in brain
regions engaged for
(things are going on implicitly—without thought)
Car’s going down the road without a driver, disturbance in intention
program, start, stay stop. Connection between working memory and
Impulsivity—environment , stimulus, triggers behavior not thought
B: a low-probability
functional circuit that
has a greater response
amplitude to errors
C: the pregenual
possibly reflecting an
affective response to
• Why are NP task so inadequate?
Behaviorally defined criteria in ADHD
do not easily ‘‘map’’ on to functional
• With the advent of functional
neuroimaging, it was seen conclusively
that these sorting and planning tasks
should not fairly be considered
• assessment instruments were never designed
to evaluate the networks and interactions in
• CPT’S are not ADHD tests: they measure a
range of impulses and don’t correlate with
• Current: widely accepted belief of causal
heterogeneity in ADHD. ADHD is not one thing
with one cause.
• the challenge to functional neuroimaging is to
find a way to effectively ‘‘diagnose’’ ADHD.
• Neuropsychology can establish itself at the
‘‘ground floor’’ in developing methodologies
to explore these different dimensions of
• Challenge in the field today seems to need a
way to bring these two worlds together.