Response Times

Discussion & Implications   History of MHI did not differentially disrupt general cognitive performance, self-perceived behavioural tendencies, or overall decision-making

  MHI group was capable of physiologically responding to the testing feedback environment, but only in a reactive way

  MHI group is significantly less aroused when anticipating consequences13 indicating differential physiological input when making decisions

  Exploratory analyses demonstrate potential differences in stability of emotional markers in maintenance of associative learning

  MHI group is faster to commit to a decision and do not discriminate differentially on the basis of punishment magnitude when risk is more probable

  Poor decision making could result from lack of anticipatory emotional markers, less stable learning patterns and faster response times in certain risky situations

  Lack of anticipation could produce exaggerated reactivity to outcomes (i.e. unexpected), and with limited self-control, behaviour may be deemed socially incompatible

  These results obtained in a university sample encourages accepting MHI on a continuum of brain injury severity given this neurophysiological profile emulates features of more traumatic cases

4000

4200

4400

4600

4800

5000

5200

5400

5600

Less Probable Punishment (Magnitude: Deck A > Deck C)

More Probable Punishment (Magnitude: Deck B > Deck D)

Response Time (ms)

Relative Risk of Punishment

IGT Response Time Background

  Head trauma introduces affective, behavioural, and cognitive complications across the lifespan with approximately 57 million hospitalizations annually1

  Mild Head Injury (MHI) producing an altered state of consciousness may be sufficient to produce neuropsychological dysfunction2, 3

  MHI reports in university students are associated with limits in neuropsychological performance 4, 5

  The orbitofrontal cortex (OFC) is highly susceptible to impact injury and mediates cause-effect/associative learning in decision-making, and controlling social behaviour 6, 7

  Decision outcomes/consequences produce (physiological/somatic) reactions which, in turn, bias future decisions/choices (learning)

  OFC injury interferes with this learning in terms of attenuated activation of somatic markers (“gut feeling”) when anticipating potential consequences8, self-control and regulation

Purpose: To investigate the relationship between

neuropsychological performance, physiological arousal, and decision-making in university students

with and without a history of MHI.

Hypotheses

1)   There will be no difference in general cognitive performance between the MHI and non-MHI groups.

2)   The MHI group will self-report a higher propensity of disinhibited and antisocial behaviours.

3)   Decision-making performance will be significantly worse for those reporting a history of MHI.

4)   Both groups are expected to physiologically respond to feedback/decision outcomes, but the MHI group is expected to present with significantly lower physiological arousal when anticipating future consequences.

Acknowledgments   Katie Chiappetta, BSc (Hons.) Candidate, Brock University

  Brock University/Neuropsychology Cognitive Research Lab (BUNCRL)

  Ontario Neurotrauma Foundation (ONF)

  McMaster University

References 1 Langlois, J. A., Rutland-Brown, W., & Wald, M. M. (2006). The epidemiology of traumatic brain injury: A brief overview. Journal of Head Trauma Rehabilitation, 21, 375-378.2 Kay, T., Harrington, D. E., Adams, R., Anderson, T., Berrol, S., Cicerone, K, et al. (1993). Definition of mild traumatic brain injury. Journal of Head Trauma Rehabilitation, 8(3), 86-87. 3 Giza, C., & Hovda, D. A. (2001). The neurometabolic cascade of concussion. Journal of Athletic Training, 36, 228-235. 4 Segalowitz, S. & Lawson, S. (1995). Subtle symptoms associated with self reported mild head injury. Journal of Learning Disabilities, 28, 309-319. 5 DeBono, A., & Good, D. (2008). The social consequences of mild head injury and executive dysfunction. Master of Arts Thesis, Psychology. Brock University: St. Catharines, Ontario, Canada. 6 Wallis, J. D. (2007). Orbitofrontal cortex and its contribution to decision-making. Annual Review of Neuroscience, 30, 31-56. 7 Wheeler, E.Z., & Fellows, L.K. (2008). The human ventromedial frontal lobe is critical for learning from negative feedback. Brain, 131, 1323-1331. 8 Bechara, A. (2004). The role of emotion in decision-making: Evidence from neurological patients with orbitofrontal damage. Brain and Cognition, 55, 30-40. 9 Delis, D. C., Kaplan, E., & Kramer, J. H. (2001), Delis Kaplan Executive Function System. San Antonio, TX: Psychological Corporation. 10 Bechara, A. (2007). Iowa Gambling Task. Florida Avenue: Lutz, Florida: Psychological Assessment Resources, Inc. 11 Patton, J. H., Stanford, M. S., & Barratt, E. S. (1995). Facture structure of the Barratt impulsiveness scale. Journal of Clinical Psychology, 51(6), 768-774. 12 Paulhus, D. L., Hemphill, J. D., & Hare, R. D. (in press). Self-Report Psychopathy scale. Version III. Toronto: Multi-Health Systems. 13 Bechara, A., Tranel, D., Damasio, H., & Damasio, A.R. (1996). Failure to respond autonomically to anticipated future outcomes following damage to prefrontal cortex. Cerenral Cortex, 6, 215-225.

0

3

6

9

12

15

MHI Non-MHI

Accuracy (Error %)

Group

Design Fluency Error Accuracy Score

Hypothesis 3: Decision-Making

Hypothesis 4: Physiological Arousal

Exploratory Analyses: Maintenance of Learning

0

10

20

30

MHI Non-MHI

Score

Group

Self-Report Antisocial Behaviour

Score

0

10

20

30

MHI Non-MHI

Score

Group

Self-Report Disinhibition Score

0 10 20 30 40 50 60 70 80

MHI Non-MHI

Percentile Rank

Group

IGT Final Percentile Rank

0

0.05

0.1

0.15

0.2

Reward Punishment

EDR Amplitude

(Inches)

Type of Feedback

Average EDR Amplitude To Choice Feedback

MHI Non-MHI

Feedback: F (1, 35) = .01, p = .90, ns Feedback * MHI: F (1, 35) = .82, p = .37, ns

t(42) = 0.12, p = .91, ns

t(42) = 0.47, p = .64, ns t(42) = 1.23, p = .23, ns

t(41) = 0.15, p = .88

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

MHI Non-MHI

EDR Anticipation Amplitude

(inches)

Group

Average EDR Amplitude Prior To Choice Selection

t(32) = 1.53, p < .05, sig

-6

-4

-2

0

2

4

6

8

Block 1 Block 2 Block 3 Block 4 Block 5

Risky vs. Good

Decisions

IGT Blocks

IGT Learning By Block

MHI

Non-MHI

MHI Non-MHI

A

A

C

C

D

B

B D

Main Effect (MHI): F (1, 42) = 4.03, p = .05, ns

Interaction (MHI*Frequency): F (1, 42) = 2.87, p = .10, trend