1. Cognitive and Discriminative Somatosensory Cortical Networks Overlap
Parminder Kaur, Alexandra Borstad, Petra Schmalbrock, Deborah S. Nichols-Larsen
School of Health and Rehabilitation Science , The Ohio State University
Introduction
Results
Rt SMA , z-63
SMG, z -56
Lt precentral gyrus, z-51
R – Middle
Frontal Gyrus
R - Supplementary Motor Area
L - Angular Gyrus
L & R frontal operculum
Post stroke cognitive and somatosensory impairments are related to poor long term functional outcomes.1,2
Up to 89% of people with hemiparesis demonstrate upper extremity somatosensory deficits3 and cognitive impairments varies from 40-60%.1
Discriminative sensory loss is the most common impairment experienced post stroke.2,3
Functional MRI data showed a significant area of overlap for cognitive and somatosensory networks. One sample T-test (using single group average) showed significantly diffuse area of activation for stroke group, for both somatosensory and cognitive (fMRI) tasks.
Matched T-test showed significant differences between affected/ unaffected hand of stroke subjects versus the matched hand of the controls for almost all the measures.
HASTe strongly correlated with PASAT (r=.722, p<.0001). PASAT strongly correlated with BBT (r=.685, p <.001). HASTe moderately correlated with BBT (r=.431, p <.05).
R – Angular Gyrus
L-Precentral
Gyrus
R – Supramarginal
Gyrus
Orange –Cognitive networks
Blue –Sensory networks
Cognitive task – Paced Visual Serial Addition Test
Purpose
To determine the cortical overlap of cognitive and somatosensory networks. Also, if the cortical activity in these networks varies in post-stroke subjects compared to controls.  
To determine how cognitive, somatosensory and motor function are related post-stroke.
Post stroke group
Control group
Single-Group Average (One-Sample T-Test) for cognitive task. With 12 subjects, all in one group and the mean group effect measured. The group activate on average z > 3.0, p -0.05
Sensory task - Right Brush Discrimination Test
Conclusion
Networks supporting somatosensory discrimination and working memory overlap in various cortical areas. Post-stroke subjects demonstrated disruption of both networks, associated with decrements in performance on sensory discrimination and cognitive testing. 
In our sample, discriminative sensations were affected bilaterally .
Lower performance on somatosensory and cognitive measures were associated with poorer performance on the BBT.
The somatosensory and cognitive dysfunction influences motor function and should be included in the standard testing of the stroke subjects.
Methods
A convenience sample of 12 controls and 12 chronic post-stroke subjects, age and gender matched, was recruited. After meeting the inclusion and exclusion criteria, subjects were tested in a single behavioral and imaging session.
Functional MRI testing was done for somatosensory (right brush discrimination) and cognitive ( PVSAT- Paced visual serial addition test) tasks.
Cognition tests - Paced Auditory Serial Addition Test (PASAT; 2 & 3 sec), Choice Reaction Test (CRT), N-back (1 back and 2 back)
Sensory tests - Hand Active Sensation Test (HASTe), Brief Kinesthesia Test (BKT), Form Perception Test (FPT).
Motor tests - Box and Blocks (BBT), 9 Hole Peg (9NP).
Post stroke group
Control group
Single-Group Average (One-Sample T-Test) for right brush discrimination. With 12 subjects, all in one group and the mean group effect measured. The group activate on average Z > 3.0, p
Individuals are matched for age, gender and handedness - Matched T tests
Somatosensory Task
Affected hand of stroke subjects vs matched hand of controls
Unaffected hand of the stroke subjects vs matched hand of controls
Monofilament (index and pinky finger)
Not significant
Brush discrimination
p =
Form Perception Test
p = 0.005
p =
Brief Kinesthesia
p =
Hand Active Sensation Test
References
Cognitive Task
Reaction time
p =
PASAT – 2 seconds
p =
PASAT – 3 seconds
p =
2 – back (accuracy)
p =
1 – back (accuracy)
p =
Vakhnina NV, Nikitina L Yu. Post stroke cognitive impairments. Neuroscience & Behavioral Physiology. 2009;39 (8):
Kim JS, Choi- Kwon S. Discriminative sensory dysfunction after unilateral stroke. Stroke 1996;27:
Borstad AL, Bird T, Choi S, Goodman L, Schmalbrock P, Nichols-Larsen DS. Sensorimotor training induced neural reorganization after stroke. JNPT March;37(1):27-36.
Carey LM, Matyas T. Frequency of discriminative sensory loss in the hand after stroke in a rehabilitation setting. J Rehabil Med 2011;43:
Motor Task
Affected hand of stroke subjects vs matched hand of controls
Unaffected hand of the stroke subjects vs matched hand of controls
Box and blocks test
p < 0.000
p =