Replace Psychometric Inferences with Direct Brain Measurements: LORETA Reflects Traditional Cerebral Loci for Neuropsychological Tests

Paula L Corradini,Michael A Persinger

doi:10.4236/nm.2015.63018

Abstract

Inferences of subtle cerebral injury and dysfunction have been historically dependent upon psychometric tests from which clinical neuropsychological profiles are generated. In addition to being secondary, over-inclusive and crude indicators of cerebral activity, psychometric tests are subject to economic incentives to “re-norm” traditional methods under the pretense of “ensuring” contemporary representations that are sanctioned by regulating organizations dominated by agendas of control over the interpretations of clinicians. The validity of neuropsychological tests is essential for their perspicacious application and interpretations. We measured the quantitative electroen-cephalographic profiles and calculated s-LORETA (standardized Low Resolution Electromagnetic Tomography) profiles in real time for normal men and women while they engaged in both traditional and novel neuropsychological tests that were employed to infer localized brain injury. Conspicuous alterations in source current density within specific frequency bands occurred within various regions of the right prefrontal region during performance of the Category, Design Fluency and Conditioned Spatial Association Test, the prefrontal medial surface during Toe Graphaesthesia, the caudal medial surface during Toe Gnosis, the left temporal region during Speech-Sounds, and within the right retrosplenial-parahippocampal region for Seashore Rhythms. Results supported the well established regional associations with the classic neuropsychological tests, verified the cerebral localization with more recent procedures, and emphasized the utility of modern real-time, direct cerebral imaging procedures.

Highlights

The performance-based procedures (“tests”) by which clinical neuropsychologists have inferred the integrity of neuronal function within regions of the human cerebrum have progressed through several stages of constructvalidity
We present compelling evidence that s-LORETA profiles of normal volunteers engaged in different classic and novel neuropsychological, performance-based procedures support the construct validity of these tests and reveal a realistic perspective of the volume and variations involved with task execution
According to traditional interpretations the accuracy or speed, compared to normative data, by which a subject completes each test reflects the integrity of function within the right prefrontal region for the Category Test [14] [15] the right superior temporal cortices for the Seashore Rhythm Tests [16], the left superior temporal cortices for the Speech Sounds Test [17] [18], the right orbital frontal region for the Conditioned Spatial Association Test and the right more rostral prefrontal region for the Design Fluency Test [19]

Summary

Introduction

The performance-based procedures (“tests”) by which clinical neuropsychologists have inferred the integrity of neuronal function within regions of the human cerebrum have progressed through several stages of constructvalidity. The development of CT (Computerized Tomography) and MRI (Magnetic Resonance Imaging) permitted more temporally contiguous comparisons between quantitative measurements of specific behaviours and more detailed alterations of signal organization within the cerebral volume. These measurements were indicators of structural correlates rather than direct functional or dynamic contributions. Concurrent measurements of the specific class of behaviors and the activity within correlative regions within the cerebrum required the development of the functional tools of imaging such as fMRI, PET (Positron Emission Tomography) and SPECT (Single Photon Emission Computed Tomography). Remarkably precise in their differentiation of the location of cerebral activity, reflecting perfusion or a highly correlated metabolic product of neuronal and glial activity during specific tasks, the equipment is largely static, cumbersome and expensive [1]

Methods

Results

Conclusion