and Brain Sciences
Dr. William Hetrick
whetrick [at] indiana.edu
office: PY 126 | (812)855-2620
lab: Psychopathology & Neuropsychometry Lab
Cognitive neuroscience of schizophrenia and related psychological disorders; Clinical translational psychopathology approaches to understanding risk factors and "illness" mechanisms using both human and animal models; Temporal processing, cerebellar function, and brain micro-state measures of cognitive discoordination; Methods utilized in the lab include fMRI, EEG, ERPs, rTMS, EMG, and clinical-neuropsychological assessment.
- 1999 - Ph.D., The Ohio State University, Clinical Psychology
- 1993 - M.A., California State University, Experimental Psychology
- 1987 - B.A., Point Loma Nazarene College, Psychology
Areas of Study
- Clinical Science
- Neural Science
- Brain-behavior relationships that underlie perceptual and attentional anomalies associated with schizophrenia and related disorders
- Intra-subject response variability, including neural frequency and phase synchronization
- Role of endogenous opiods in the self-injurious behavior
- Relevent methods include human brain (EEG, ERP) and skeletomotor (EMG) recordings, and clinical-neuropsychological assessment.
Dr. Hetrick's research focuses on brain-behavior relationships in psychopathology, including schizophrenia, bipolar disorder, and autism.
One compontent of Dr. Hetrick's research investigates the origins and correlates of perceptual, attentional, and cognitive aberrations in schizophrenia and related psychotic disorders. Sensory gating hypotheses assert that these aberrations arise from deficits in gating, or filtering, or exteroceptive input by the central nervous system. It is speculated that this inability to gate or filter sensory inputs underlies information processing deficits - such as hyper-vigilance and poor selective attention - and might contribute to a psychotic state in which patients with schizophrenia are disorganized by an overabundance of irrelevant sensory stimulation. In other words, inundation of the central nervous system by irrelevant inputs may disrupt ongoing cognitive processes, resulting in cognitive fragmentation and disorganization. Dr. Hetrick's laboratory is examining this process, termed sensory gating, across levels of analysis, including both neurophysiological and phenomenological/symptom levels.
TEMPORAL PROCESSING DYSFUNCTIONS IN SCHIZOPHRENIA
Another line of research concerns deficits in the temporal coordination of information processing throughout the brain in schizophrenia. Much research to date into the causes of schizophrenia has focused on identifying the structures in the brain that give rise to the disorder. In contrast, Dr. Hetrick's research examines the extent to which impairments in the timing of neural responses and time-dependent communications between brain areas underlie schizophrenia. Dr. Hetrick's functional, rather than strictly structural approach, hypothesizes that neurons in the brain do not appropriately synchoronize their activity with each other. In turn, neural centers in the brain, referred to as nuclei, fail to encode, manipulate, and pass along information in a timely manner. These failures cause inconsistent interactions in time between neural centers, which may impair perceptual, affective, cognitive, and motor processes; widespread failures of this sort may lead to disturbances of consciousness which characterize schizophrenia. This work began with the previously mentioned observation of within-subject, trial-by-trial P50 peak latency variability in schizophrenia, which suggested a neural deficit in response timing and neural synchrony (Jin et al., 1998; Patterson et al., 2000).
There is accumulating theoretical and empirical support for the hypothesis that schizophrenia is associated with a fundamental disturbance in the timing of neural processes (Andreasen et al., 1998; Tononi & Edelman, 2000; Paulus & Braff, 2003; Phillips & Silverstein, 2003). Deficites in the temporal coordination of information processing in the brain may lead to disturbances of consciousness as well as poor coordination of perceptual, affective, cognitive, and motor processes similar to classic symptoms of schizophrenia such as thought disorder, and disorganized and contextually inappropriate behavior (Andreasen et al., 1998). Support for these conceptualizations is emerging with evidence that brain structures (e.g., cerebellum & basal ganglia) and neurotransmitter systems (e.g., dopamine & glutamate) that are directly linked to neural timing processes are also impaired in schizophrenia. Andreasen and her colleagues (1998) conceptually organized some of these theories and findings by suggesting that "cognitive dysmetria," or poor coordination of cognitive processes, is a fundamental problem in schizophrenia. Andreasen postulated that a cortico-cerebellar-thalamic-cortical (CCTC) brain circuit - believed to be responsible for fluid, temporal coordination of sequences of behavior - is a likely source of timing anomalies. This conceptualization is intriguing given the evidence for the essential role of cerebellum in cognitive and affective functions (e.g., Leiner et al., 1993; Schmahmann, 2001), and is being rigorously examined in my laboratory. Dr. Hetrick is examining the functional integrity of neural timing circuits in schizophrenia using three well-estabished timing tasks: eye-blink conditioning (EBC), time estimation (e.g., temporal bisection task), and time production and reproduction (e.g., free and paced finger tapping).
ERROR-RELATED NEGATIVITY, TASK SWITCHING, AND THE COMORBIDITY OF SCHIZOPHRENIA AND ALCOHOL DEPENDENCE
In view of the fact that schizophrenia is associated with multiple information processing deficits, Dr. Hetrick employs several other electrophysiological indices tailored to the study of higher-order cognitive functioning. One of these indices, referred to as error-related negativity (ERN), assesses the ability of the brain to monitor its output and very quickly detect response errors. Another of these indices, referred to as the P300 brainwave, assesses the brain's ability to identify task-relevant stimulus cues in the environment and switch the focus attention between cues to maximize performance in a dynamic task. In addition, Dr. Hetrick is studying the comorbidity of schizophrenia with alcohol dependence in an effort to determine shared and unique electrophysiological endophenotypes, or neurobiological markers, that may contribute to their comorbidity; this work is funded by a grant from the National Institute of Mental Health (NIMH).
NOTE: asterisks indicate advisee under Dr. Hetrick's direct supervision.
in Press - Kruschke, J. K., Kappennman, E.S., Hetrick W.P. Eye gaze and individual differences consistent with learned attention in associative blocking and highlighting. Cognitive Psychology.
*in Press - Johannesen, J.K., Kieffaber, P.D., O'Donnell, B.F., Shekhar, A., Evans, J.D., Hetrick W.P. Auditory ERP gating depends on schizophrenia subtype and frequency band of analysis. Schizophrenia Research
in Press - Krishnan, G.P., Vohs, J.L., Carroll, C.A., Hetrick W.P., Shekhar, A., Bockbrader, M.A., O'Donnell, B.F. Steady State Visual Evoked Potential Abnormalities in Schizophrenia. Clinical Neurophysiology.
in Press - Davis, R.A.O., Wilt, M.A., Murphy, R.R., Hetrick, W.P., O'Donnell, B.F. Subjective Perceptual Distortions and Visual System Dysfunction in Children with Autism. Journal of Autism and Development Disorders.
*2005 - Brown, S.M., Kieffaber, P.D., Vohs, J.L., Darroll, C.A., Tracy, zj.S., Shekhar, A., O'Donnell, B.F., Steinmetz, J.E. & Hetrick, W.P. Eye-blink conditioning deficits indicate timing and cerebellar abnormalities in schizophrenia. Brain and Cognition, 58, 94-108.
*2005 - Kieffaber, P.D. & Hetrick, W.P. Event-Related Potential Correlates of Task Switching and Switch Costs. Psychophysiology, 42, 56-71.
2004 - O'Donnell, B.F., Krishnan, G.P., Vohs, J.L., Bockbrader, M., Hetrick, W.P., Shekhar, A. Probing Neural Synchronization in psychiatric Disorders. Proceedings of the CAITA Conference, "Advances in Internet Technologies and Applications," July 8 - 11, Purdue University, Lafayette, IN.
2004 - O'Donnell, B.F., Hetrick W.P., Vohs, J.L., Krishnan, G.P., Carroll, C.A., Shekhar, A. Neural Synchronization Deficits to Auditory Stimulation in Bopolar Disorder. NeuroReport, 15, 1369-1372.
*2004 - Brenner, C.A., Edwards, C.R., Carroll, C.A., Kieffaber, P.D., & Hetrick W.P. P50 and Acoustic Startle Gating Are Not Related in Healthy Participants. Psychophysiology, 41, 702 - 708.
2004 - O'Donnell, B.F., Vohs, J.L., Hetrick, W.P., CArroll, C.A., Shekhar, A. Auditory Event Related Potential Abnormalities in Bipolar Disorder and Schizophrenia. International Journal of Psychophysiology, 53, 45 - 55.
*2004 - Zirnheld, P.J., Carroll, C.A., Kieffaber, P.D., O'Donnell, B.F., Shekhar, S., & Hetrick, W.P. Haloperidol Impairs Learning and Error-Related Negativity (ERN) in Humans. Journal of Cognitive Neuroscience, 16, 1098-1116.
*2004 - Carroll, C.A., O'Donnell, B.F., Shekhar, A., & Hetrick, W.P. The Effects of Olanzapine on Sensory Gating in Healthy Participants. Schizophrenia Research, 66, 197-198.
- IU Clinical Science Homepage
- IU Program in Neuroscience
- Dr. Hetrick's Neurocience Homepage
- IU Stars
- Dr. Hetrick's Laboratory Website