Interaction between cognitive and affective processes
Name: Bob Rafal
Position: Professor of Clinical Neuroscience and Neuropsychology
Primary affiliation:School of Psychology, Univeristy of Wales, Bangor (see my UBangor webpage)
More Affiliations: Consultant Neurologist, North Wales Brain Injury Service
Postal address: Brigantia Building, Penrallt Road, Bangor LL572AS, UK
Voice: (+44) 124 838 3603
Facsimile: (+44) 124 838 2599
The goal of my research program is to understand the brain preparatory states and processes that determine whether a visual signal will be perceived or responded to. Selective attention allows the organism to respond to a given stimulus in one way under one set of circumstances, a different way under another, to not respond at all, or to delay a response pending further information. It is through such mechanisms that past learning, motivation, and emotion may influence behavior. The research employs two converging and complementary strands of inquiry involving normal adults and neurological patients. One approach is motivated by clinical observation in patients with classical neuropsychological disorders of visual attention, such as hemispatial neglect. We study deficits of perception, attention and eye movements in patients with focal brain lesions of frontal lobe, parietal lobe and thalamus. The second strand of inquiry involves experiments employing transcranial magnetic stimulation (TMS) in normal adults.
Key words: Neuropsychololgy; TMS; visual attention; eye movements; hemispatial neglect.
- 1973. M.D., Jefferson Medical College, Philadelphia, Pennsylvania.
- 1969 B.A., University of Delaware, Newark Biology.
Positions and Employment:
- 1999-to present. Professor of Clinical Neuroscience and Neuropsychology, University of Wales, Bangor.
- 1989. Associate Professor of Neurology, Brown University.
- 1989-1995. Associate Professor of Neurology, University of California, Davis.
- 1986-1989. Assistant Professor of Neurology, Brown University.
- 1985-1989. Professor of Neurology, University of California, Davis
- 1984-1986. Assistant Professor of Medicine, Brown University.
- 1980-1984. Clinical Assistant Professor of Neurology, University of Oregon HSU.
- 1977-1984. Private practice of Neurology, Hillsboror and Portland, Oregon.
- 1974-1977. Neurology Residency, Oregon Health Sciences University, Portland, Oregon.
- 1973-1974. General Medical Training (PGY1),Good Samaritan Hospital, Portland, Oregon.
1) Cortical control of eye movement reflexes
This research programme examines the integration of cortical and subcortical circuitry regulating a basic behaviour common to all vertebrates - visual orienting -and will help to explain how adaptive behaviour of the whole organism is generated to provide for a continuity of experience and coherent goal directed behaviour. Specifically it will examine how more phylogenetically recent regions of oculomotor cortex regulate archetypal midbrain mechanisms for reflexive visual orienting in order to co-ordinate strategic and environmental demands on the oculomotor system.
We employ a fixation offset effect (FOE) paradigm to measure the effect of strategic control of midbrain reflexes, and will identify the specific areas of cortex that exercise this control by transiently inactivating oculomotor cortex with TMS. Physiological studies have shown that the visual grasp reflex (VGR - reflexive eye movements toward a visual transient) is mediated by an opponent circuit within the superior colliculus. There are mutually inhibitory connections between movement cells that trigger the visual grasp reflex (VGR), and fixation cells that anchor the eyes when a visual signal is present at fixation. Our studies of the FOE in normals and neurological patients have indicated that: 1) there are separate neural systems for control of fixation for exogenous and endogenous saccades and; 2) these circuits can be modulated by strategic control. Currently we are conducting a series of experiments including:
(i) TMS studies of parietal and frontal lobe cortex on control of ocular fixation and voluntary and reflexive eye movements.
(ii) Effects of strategic oculmotor set and trace conditioning on the FOE in patients with Parkinson’s disease.
2) Neural Substrates for Saccade Remapping and Inhibitory Spatial Tagging
When we move our eyes the location of stationary objects is remapped on our retinae – but they stay at the same location in the world. To sustain a durable representation of objects in the world, therefore, the brain must 1) remap the location of objects to compensate for movement on the retina produced by the saccade; 2) maintain a record, within this remapped representation of space, of locations already examined. Our laboratory has helped identify the neural substrates for an inhibitory spatial tag (referred to as ‘inhibition of return’); and we are now studying how this inhibitory spatial tag is sustained in a durable representation of the external world across saccadic eye movements. In the coming year we plan to:
a) use TMS to identify the regions of cortex that are involved in spatial remapping.
b) study patients with lesion of the thalamus to specify the role of thalamic nucleii in saccade remapping and inhibitory spatial tagging.
1. Capizzi M, Correa A, Wojtowicz A, Rafal RD. Foreperiod priming in temporal preparation: testing current models of sequential effects. Cognition. 2015 Jan;134:39-49.
2. Van der Stigchel S, van Koningsbruggen M, Nijboer TC, List A, Rafal RD. The role of the frontal eye fields in the oculomotor inhibition of reflexive saccades: evidence from lesion patients. Neuropsychologia. 2012 Jan;50(1):198-203.
3. Song JH, Rafal RD, McPeek RM. Deficits in reach target selection during inactivation of the midbrain superior colliculus. Proc Natl Acad Sci U S A. 2011 Dec 20;108(51):E1433-40.
4. Van der Stigchel S, Arend I, van Koningsbruggen MG, Rafal RD. Oculomotor integration in patients with a pulvinar lesion. Neuropsychologia. 2010 Oct;48(12):3497-504.
5. van Koningsbruggen MG, Gabay S, Sapir A, Henik A, Rafal RD. Hemispheric asymmetry in the remapping and maintenance of visual saliency maps: a TMS study. J Cogn Neurosci. 2010 Aug;22(8):1730-8.
6. Bultitude JH, Rafal RD, List A. Prism adaptation reverses the local processing bias in patients with right temporo-parietal junction lesions. Brain. 2009 Jun;132(Pt 6):1669-77.
7. Snow JC, Allen HA, Rafal RD, Humphreys GW. Impaired attentional selection following lesions to human pulvinar: evidence for homology between human and monkey. Proc Natl Acad Sci U S A. 2009 Mar 10;106(10):4054-9.
8. Danziger S, Rafal R. The effect of visual signals on spatial decision making. Cognition. 2009 Feb;110(2):182-97.
9. Rafal RD. Oculomotor functions of the parietal lobe: Effects of chronic lesions in humans. Cortex. 2006 Jul;42(5):730-9.
10. Berger A, Henik A, Rafal R. Competition between endogenous and exogenous orienting of visual attention. J Exp Psychol Gen. 2005 May;134(2):207-21.