Kenneth D. Pool

Infarction of the superior temporal gyrus: a description of auditory evoked potential latency and amplitude topology.

P1 and N1 of the cortical auditory evoked potential (AEP) were studied with multiple electrodes in 10 normal subjects and 6 patients with left middle cerebral artery infarction. Patients were selected based on neurological examination and on CT scans showing both (1) infarction limited to the vascular territory and (2) involvement of posterior portion of superior temporal gyrus. Waveforms recorded from C3, Cz, and C4 were examined for peak latency and amplitude of P1 and N1 on all subjects. Topographic displays of amplitude over P1 and N1 latency ranges were also examined. In normals, P1 was identified in 9 of the 10 subjects at all three electrode sites. In patients, P1 was identified at C3 in only 1 of the 6. N1 was present at all three electrodes in the 10 normal subjects and in 5 of the 6 patients. The remaining patient had N1 at C4 and Cz only. Examination of amplitude topology showed as asymmetric evolution of P1 and N1 in the patients. This asymmetry was not present in normals. The results of this study are consistent with theory that P1 arises from primary auditory cortex. Results further suggest multiple generators for N1. Additional study correlating topographic display from multichannel recordings with CT or MRI in brain-injured patients may bring more insight into N1 generators.

Linguistic performance deficits in stutterers : relation to laryngeal reaction time profiles

Abstract Converging evidence suggests that stuttering is associated with deficits in the planning and execution of speech. Evidence also suggests that the onset, development, and loci of stuttering are related to demands language places on speech motor planning and execution. We combined linguistic and vocal motor assessments to address two questions: 1) Can we identify a subgroup of adult stutterers who demonstrate linguistic deficits? and 2) Do linguistically normal and impaired stutterers show different patterns of laryngeal reaction time (LRT) as a function of response complexity? Linguistic performance was evaluated using tasks that assess relatively high-level production and comprehension processes. Responses used to record LRT differed in linguistic and motoric complexity. Only linguistically impaired stutterers showed significant increases in LRT for complex responses. Findings suggest that linguistic and motor processes affect the efficiency and fluency of speech motor control and that both processes be made explicit in models of stuttering.

Quantitative topographic electrophysiology and functional neurologic status in right middle cerebral artery infarction

SummaryThirteen patients with clinically and radiographically defined right middle cerebral artery infarction were studied using EEG, quantitative electroencephalographic (QEEG) spectra, and multi-channel evoked potentials. The purpose of this effort was to develop QEEG rules that related to the patients neurologic status. Three QEEG relative delta spectral patterns were identified in the right hemisphere which related to neurologic residua. These include limited perisylvian involvement, mixed involvement of perisylvian and extrasylvian regions, and extrasylvian involvement only. While there were parallels between QEEG spectral patterns and auditory, visual and somatosensory evoked potentials, there were modality specific features consistent with functional differences.

Quantitative electroencephalography and anatomoclinical principles of aphasia. A validation study.

No single technology in isolation can provide a full view of the anatomoclinical principles evident in the clinical populations we study. The dynamic nature of quantitative electrophysiology makes it an ideal complement to anatomic and metabolic imaging. The statistical conundrum it has presented may be resolved by the approach incorporated in CART. The intent of this study was to examine QEEG and CART in the evaluation of the neurologic bases of a well-defined behavioral disorder like aphasia. The combined power of QEEG and CART yielded objective electrophysiologic methods to predict aphasia that rival the reliability of the language examination. Such success is unprecedented. This success allows us to incorporate QEEG and CART into our technological armamentarium and to return to the evaluation of less well-understood disorders with confidence in both our findings and anatomoclinical principles we derive from them.

Brain Electrical Activity Mapping: Applications to Vocal Motor Control Disorders

Brain Electrical Activity Mapping (BEAM) is a recently developed analytic tool for examining both electroencephalographic (EEG) and evoked potential (EP) data. Specifically BEAM overcomes several of the limitations which have hampered full use of these approaches, especially as applied to disorders of speech motor control. This chapter discusses rationale for development of BEAM, briefly describes the technology, and presents findings from initial studies of patients with two vocal motor control disorders — spasmodic dysphonia (SD) and stuttering (ST).

Brain electrical activity mapping in adductor spasmodic dysphonia

Brain electrical activity mapping (BEAM) was employed to study ten patients exhibiting adductor spasmodic dysphonia. BEAM is a recent neural imaging technique which utilizes digital signal processing and color graphics capabilities to generate mappings of the scalp distribution of ongoing cortical EEG activity, as well as cortical evoked response amplitudes to sensory stimulation. The technique provides data for EEG eyes open, EEG eyes closed, and auditory, visual and somatosensory evoked potentials. Patient responses were compared with normative data previously established for the BEAM technique, and significance probability mappings of patient‐to‐normal deviations generated. Results suggest diverse neurophysiologic abnormalities among the spasmodic dysphonic patients. Specific findings varied from patient to patient but included abnormal EEG activity and abnormal evoked responses in a significant proportion of patients tested. Regions of frequent “lesion” overlap were also present. Relationships of BEAM...