Neurophysiology

Anatomic Bases of Event-Related Potentials and Their Relationship to Novelty Detection in Humans

ABSTRACT

Voluntary of involuntary detection of an infrequent stimulus generates a large scalp P300 response. This P300 ERP (P for positive; 300 for the approximate peak latency poststimulation) has been widely used to study phasic attention and memory mechanisms. The P300 phenomenon, first reported in 1965 (Desmedt et al., 1965; Sutton et al., 1965) has been the subject of extensive research in normal, neurologic, and psychiatric populations. P300-like potentials have been described in rats(Ehlers et al., 1991; Yamaguchi et al., 1993), cats(Katayama et al., 1985; O'Connor and Starr, 1985; Wilder et al., 1981), and monkeys(Arthur and Starr, 1984; Neville and Foote, 1984; Paller et al., 1988; Pineda et al., 1989) supporting a broad ethologic significance of this electrophysiological marker of cognition(Fig. 1) (Swick et al., 1994).Theorists have focused on attention and memory formulations to account for the cognitive basis of the P300, although no clear consensus has emerged(Donchin and Coles, 1988; Verleger, 1988). Some of this disagreement results from the fact that the P300 does not represent a unitary brain potential arising from a discrete brain region or cognitive process as initially proposed. Instead, scalp positivities generated in the 300- to 700-ms poststimulus delivery measure activation of multiple neocortical and limbic regions dependent on the degree of voluntary and involuntary attention allocated to a stimulus. Support for this contention is provided by scalp topographic studies in normal subjects(Courchesne et al., 1975; Squires and Hillyard, 1975; Ruchkin et al., 1990a, 1992; Yamaguchi and Knight, 1991a; Bruyant et al., 1993), intracranial recording in epileptic patients (McCarthy et al., 1989; Puce et al., 1991; Paller et al., 1992; Baudena et al., 1995; Halgren et al., 1995a,b) and lesion studies in neurologic patients(Knight, 1984, 1997a; Knight et al., 1989; Yamaguchi and Knight, 1991b, 1992; Scabini, 1992).





AUTHORS

  • Robert T. Knight

  • Donatella Scabini

Date: 1998

DOI: 10.1097/00004691-199801000-00003

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The effects of lesions of superior temporal gyrus and inferior parietal lobe on temporal and vertex components of the human AEP.

Authors:

  • Robert T. Knight

  • David L. Woods

  • Clay Clayworth

Date: 1988

PubMed: 2461284

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Abstract:

We recorded auditory evoked potentials (AEPs) to 1 kHz tone bursts in controls and patients with unilateral lesions centered in posterior superior temporal gyrus and adjacent caudal inferior parietal lobule (STG) or in rostral inferior parietal lobule (IPL). Controls generated a vertex maximal N94 (N1b) and P200 (P2) and additional P45, N78 and N127 temporal AEP components (P45, N1a, N1c). Similar to prior reports, in controls the N1a was most prominent over the left temporal lobe and the P45 was largest over the right temporal lobe consistent with behavioral and anatomical data indicating differential organization of left and right human temporal lobe. The N1c was recorded equally from both T3 and T4 electrodes and was enhanced in the temporal site contralateral to the ear of stimulation. The patient groups had differential effects on AEPs. Unilateral STG lesions resulted in bilateral reductions of the N1b and P45 and marked unilateral reductions of the N1a and N1c over lesioned hemisphere. IPL lesions resulted in bilateral but non-significant reductions of the N1b and N1c. The scalp topography results in normal subjects combined with the effects of unilateral STG lesions provide supportive evidence that the temporal maximal components of the human AEP (P45, N1a, N1c) are generated by radially oriented neuronal dipole sources located in STG. The bilateral reduction of the N1b vertex response by unilateral STG lesions is compatible with a unilateral disruption of a vertically oriented dipole situated in the posterior superior temporal plane. The results emphasize the critical role of the superior temporal plane and lateral superior temporal gyrus in generation of human long latency AEPs.