Kenneth Manzel

Neuroanatomical correlates of the Benton Facial Recognition Test and Judgment of Line Orientation Test

Two of the most successful and widely used tests developed by Arthur Benton and colleagues are the Facial Recognition Test (FRT) and Judgment of Line Orientation Test (JLO), which probe visuoperceptual and visuospatial functions typically associated with right hemisphere structures, especially parietal, occipitoparietal, and occipitotemporal structures. Taking advantage of a large database of focal lesion patients (the Iowa Neurological Patient Registry), we used a new lesion–deficit mapping technique to investigate the neuroanatomical correlates of FRT and JLO performance. For the FRT, there were 201 patients with relevant data; of these, 38 were impaired on the FRT, and failure was most strongly associated with lesions in the right posterior-inferior parietal and right ventral occipitotemporal (fusiform gyrus) areas. For the JLO, there were 181 patients with relevant data; of these, 23 were impaired on the JLO, and failure was most strongly associated with lesions in the right posterior parietal region. These findings put new empirical teeth in the localizing value of the FRT and JLO tests, and they extend and sharpen previous work that had pointed to right posterior structures as being important for FRT and JLO performance.

Detecting poor effort and malingering with an expanded version of the Auditory Verbal Learning Test (AVLTX): Validation with clinical samples

Three studies describe the development and validation of a new procedure (AVLTX) to detect inadequate effort or malingering by adding 60-min delayed recall/recognition trials and identifying “impaired” memory performances that are highly inconsistent with performances of brain-damaged (BD) individuals. In Study I, AVLTX performances of 25 probable malingerers (PMs) were compared with those of 43BD and 40 psychiatric patients (PSYs). Seven inconsistencies were identified and converted to scaled inconsistency scores, yielding the exaggeration index (EI). Study II reported cross-validation in an independent sample of 34 PM, 70BD and 89 PSY, showing sensitivity of 0.59 and specificities of 0.97 (BD) and 0.92 (PSY). Study III compared the diagnostic accuracy of the EI with two well-established effort assessment paradigms, exemplified by the RMTand DRT (a symptom validity test). The RMT showed excellent sensitivity and poor specificity; the DRT showed poor sensitivity and excellent specificity; the EI showed good sensitivity and excellent specificity. Adding a second delayed trial to list-learning tests can be a time-efficient procedure to detect inadequate effort.

Dimensions of personality disturbance after focal brain damage: investigation with the Iowa Scales of Personality Change.

This study employed a multistep, rational–empirical approach to identify dimensions of personality disturbance in brain-damaged individuals: (a) Five dimensions were hypothesized based on empirical literature and conceptual grounds; (b) principal components analysis was performed on the Iowa Scales of Personality Change (ISPC) to determine the pattern of covariance among 30 personality characteristics; (c) when discrepancies existed between principal components analysis results and conceptually based dimensions, empirical findings and clinical considerations were weighed to determine assignment of ISPC scales to dimensions; (d) the fit of data to the refined dimensions was assessed by examination of intercorrelations; (e) differential predictions concerning the relationship of dimensions to ventromedial prefrontal cortex (vmPFC) damage were tested. This process resulted in the specification of five dimensions: Disturbed Social Behavior, Executive/Decision-Making Deficits, Diminished Motivation/Hypo-Emotionality, Irascibility, and Distress. In accord with predictions, the 28 participants with vmPFC lesions, compared to 96 participants with focal lesions elsewhere in the brain, had significantly more Disturbed Social Behavior and Executive/Decision-Making Deficits and tended to have more Diminished Motivation/Hypo-Emotionality. Irascibility was not significantly higher among the vmPFC group, and the groups had very similar levels of Distress. The findings indicate that conceptually distinctive dimensions with differential relationships to vmPFC can be derived from the Iowa Scales of Personality Change.

Is the prefrontal cortex important for fluid intelligence? A neuropsychological study using Matrix Reasoning.

Patients with prefrontal damage and severe defects in decision making and emotional regulation often have a remarkable absence of intellectual impairment, as measured by conventional IQ tests such as the WAIS/WAIS-R. This enigma might be explained by shortcomings in the tests, which tend to emphasize measures of “crystallized” (e.g., vocabulary, fund of information) more than “fluid” (e.g., novel problem solving) intelligence. The WAIS-III added the Matrix Reasoning subtest to enhance measurement of fluid reasoning. In a set of four studies, we investigated Matrix Reasoning performances in 80 patients with damage to various sectors of the prefrontal cortex, and contrasted these with the performances of 80 demographically matched patients with damage outside the frontal lobes. The results failed to support the hypothesis that prefrontal damage would disproportionately impair fluid intelligence, and every prefrontal subgroup we studied (dorsolateral, ventromedial, dorsolateral + ventromedial) had Matrix Reasoning scores (as well as IQ scores more generally) that were indistinguishable from those of the brain-damaged comparison groups. Our findings do not support a connection between fluid intelligence and the frontal lobes, although a viable alternative interpretation is that the Matrix Reasoning subtest lacks construct validity as a measure of fluid intelligence.

A neuropsychological test of belief and doubt: damage to ventromedial prefrontal cortex increases credulity for misleading advertising

We have proposed the False Tagging Theory (FTT) as a neurobiological model of belief and doubt processes. The theory posits that the prefrontal cortex is critical for normative doubt toward properly comprehended ideas or cognitions. Such doubt is important for advantageous decisions, for example in the financial and consumer purchasing realms. Here, using a neuropsychological approach, we put the FTT to an empirical test, hypothesizing that focal damage to the ventromedial prefrontal cortex (vmPFC) would cause a “doubt deficit” that would result in higher credulity and purchase intention for consumer products featured in misleading advertisements. We presented 8 consumer ads to 18 patients with focal brain damage to the vmPFC, 21 patients with focal brain damage outside the prefrontal cortex, and 10 demographically similar healthy comparison participants. Patients with vmPFC damage were (1) more credulous to misleading ads; and (2) showed the highest intention to purchase the products in the misleading advertisements, relative to patients with brain damage outside the prefrontal cortex and healthy comparison participants. The pattern of findings was obtained even for ads in which the misleading bent was “corrected” by a disclaimer. The evidence is consistent with our proposal that damage to the vmPFC disrupts a “false tagging mechanism” which normally produces doubt and skepticism for cognitive representations. We suggest that the disruption increases credulity for misleading information, even when the misleading information is corrected for by a disclaimer. This mechanism could help explain poor financial decision-making when persons with ventromedial prefrontal dysfunction (e.g., caused by neurological injury or aging) are exposed to persuasive information.

Benefit of the doubt: a new view of the role of the prefrontal cortex in executive functioning and decision making

The False Tagging Theory (FTT) is a neuroanatomical model of belief and doubt processes that proposes a single, unique function for the prefrontal cortex. Here, we review evidence pertaining to the FTT, the implications of the FTT regarding fractionation of the prefrontal cortex, and the potential benefits of the FTT for new neuroanatomical conceptualizations of executive functions. The FTT provides a parsimonious account that may help overcome theoretical problems with prefrontal cortex mediated executive control such as the homunculus critique. Control in the FTT is examined via the “heuristics and biases” psychological framework for human judgment. The evidence indicates that prefrontal cortex mediated doubting is at the core of executive functioning and may explain some biases of intuitive judgments.

The cognitive and behavioral effects of meningioma lesions involving the ventromedial prefrontal cortex

OBJECT Anterior skull base meningiomas are frequently associated with changes in personality and behavior. Although such meningiomas often damage the ventromedial prefrontal cortex (vmPFC), which is important for higher cognition, the cognitive and behavioral effects of these meningiomas remain poorly understood. Using detailed neuropsychological assessments in a large series of patients, this study examined the cognitive and behavioral effects of meningioma lesions involving the vmPFC. METHODS The authors reviewed neuropsychology and lesion mapping records of 70 patients who underwent resection of meningiomas. The patients were drawn from the Neurological Patient Registry at the University of Iowa. Patients were sorted into 2 groups: those with lesions involving the vmPFC and those with lesions that did not involve the vmPFC. Neuropsychological data pertaining to a comprehensive array of cognitive and behavioral domains were available preoperatively in 20 patients and postoperatively in all 70 patients. RESULTS No change occurred in basic cognitive functions (e.g., attention, perception, memory, construction and motor performance, language, or executive functions) from the preoperative to postoperative epochs for the vmPFC and non-vmPFC groups. There was a significant decline in the behavioral domain, specifically adaptive function, for both the vmPFC and non-vmPFC groups, and this decline was more pronounced for the vmPFC group. Additionally, postoperative data indicated that the vmPFC group had a specific deficit in value-based decision making, as evidenced by poor performance on the Iowa Gambling Task, compared with the non-vmPFC group. The vmPFC and non-vmPFC groups did not differ postoperatively on other cognitive measures, including intellect, memory, language, and perception. CONCLUSIONS Lesions of the vmPFC resulting from meningiomas are associated with specific deficits in adaptive function and value-based decision making. Meningioma patients showed a decline in adaptive function postoperatively, and this decline was especially notable in patients with vmPFC region meningiomas. Early detection and resection of meningiomas of the anterior skull base (involving the gyrus rectus) may prevent these deficits.

Development and standardization of a reading test for brain‐damaged patients

We conducted 2 studies to assess the psychometric properties and clinical utility of a reading test, the Iowa‐Chapman Reading Test (ICRT), which was developed as a means of measuring reading capacities in patients with brain damage. We first collected normative data from 101 adults, then applied the test to 145 patients with focal cortical brain damage. Forty‐two patients performed defectively on the test, with impairments being evident in connection with a variety of different brain regions. Most important, nearly all (89%) of the 64 patients with lingering complaints of reading difficulties performed below expectations on the ICRT, despite generally normal performances on other standard reading tests. The results indicate that the ICRT provides an economical and sensitive index of reading and in particular, chronic subtle weaknesses in reading that are evident to the patient but not detected by many conventional tests.

Neural correlates of improvements in personality and behavior following a neurological event

Research on changes in personality and behavior following brain damage has focused largely on negative outcomes, such as increased irritability, moodiness, and social inappropriateness. However, clinical observations suggest that some patients may actually show positive personality and behavioral changes following a neurological event. In the current work, we investigated neuroanatomical correlates of positive personality and behavioral changes following a discrete neurological event (e.g., stroke, benign tumor resection). Patients (N = 97) were rated by a well-known family member or friend on five domains of personality and behavior: social behavior, irascibility, hypo-emotionality, distress, and executive functioning. Ratings were acquired during the chronic epoch of recovery, when psychological status was stabilized. We identified patients who showed positive changes in personality and behavior in one or more domains of functioning. Lesion analyses indicated that positive changes in personality and behavior were most consistently related to damage to the bilateral frontal polar regions and the right anterior dorsolateral prefrontal region. These findings support the conclusion that improvements in personality and behavior can occur after a neurological event, and that such changes have systematic neuroanatomical correlates. Patients who showed positive changes in personality and behavior following a neurological event were rated as having more disturbed functioning prior to the event. Our study may be taken as preliminary evidence that improvements in personality and behavior following a neurological event may involve dampening of (premorbidly) more extreme expressions of emotion.