Frontal Anatomical Correlates of Cognitive and Speech Motor Deficits in Amyotrophic Lateral Sclerosis.

The goal of this study was to identify neurostructural frontal lobe correlates of cognitive and speaking rate changes in amyotrophic lateral sclerosis (ALS). 17 patients diagnosed with ALS and 12 matched controls underwent clinical, bulbar, and neuropsychological assessment and structural neuroimaging. Neuropsychological testing was performed via a novel computerized frontal battery (ALS-CFB), based on a validated theoretical model of frontal lobe functions, and focused on testing energization, executive function, emotion processing, theory of mind, and behavioral inhibition via antisaccades. The measure of speaking rate represented bulbar motor changes. Neuroanatomical assessment was performed using volumetric analyses focused on frontal lobe regions, postcentral gyrus, and occipital lobes as controls. Partial least square regressions (PLS) were used to predict behavioral (cognitive and speech rate) outcomes using volumetric measures. The data supported the overall hypothesis that distinct behavioral changes in cognition and speaking rate in ALS were related to specific regional neurostructural brain changes. These changes did not support a notion of a general dysexecutive syndrome in ALS. The observed specificity of behavior-brain changes can begin to provide a framework for subtyping of ALS. The data also support a more integrative framework for clinical assessment of frontal lobe functioning in ALS, which requires both behavioral testing and neuroimaging.

Older Adults With Hearing Loss Have Reductions in Visual, Motor and Attentional Functioning.

Evidence from epidemiological, laboratory and clinical research suggests a link between age-related auditory declines and domain-general cognitive declines. Nevertheless, few studies have experimentally compared measures of non-auditory cognitive functions in younger normal hearing adults (YN), older adults with typical hearing thresholds for their age (ONHA) and older adults with clinically significant threshold hearing loss (OHL). The current study investigated the differences between these groups on measures of attentional response selection and execution to visual stimuli. A visual reaction time (RT) paradigm involving four tasks with differing and hierarchical attentional demands was administered. RTs on trials with differing foreperiods (FPs; pre-stimulus waiting times) were analyzed to assess context-related slowing, error commission and related cognitive control and strategic and automatic neural preparatory processes. The OHL group demonstrated a general slowing that was most apparent on the simplest tasks. Although the number of errors was similar when comparing all three groups, the OHL group exhibited less control over recovery from an error compared to the younger and ONHA groups. Unlike the YN and ONHA groups, the OHL group also showed difficulties with both strategic and automatic response preparation, although automatic preparation was more affected across all tasks. This pattern of results suggests that in older adults with hearing loss there is an underlying difficulty in automatic temporal processing that can affect higher order cognitive functions, although there may not be a completely generalized decline in cognitive functioning that is associated with hearing loss.

Alpha span: A measure of working memory.

In the alpha span test, short lists of words are presented and the participant's task is to mentally reorder the words and give them back in correct alphabetical order. Alpha span is the longest list of words correctly recalled; the article also describes a scoring method in which credit is given for partially correct answers. Alpha span provides a quick and easily completed measure of verbal-numerical working memory (WM), and evidence is presented to show that it is also a valid and reliable measure. One purpose of the article is to present data on age-related differences in WM in participants 17 to 87 years of age. These data show that alpha span is highest in people in their 20s and then declines systematically from the 20s to the 80s. A 2nd purpose is to report data on the reliability of the alpha span measure and explore its relationships with other cognitive measures. The article concludes with some comments on the nature of WM as illustrated by alpha span; specifically, we suggest that WM reflects both domain-general executive functions and specific abilities in the domain tapped by the task in question. (PsycINFO Database Record

CE verbal episodic memory impairment in schizophrenia: a comparison with frontal lobe lesion patients.

Schizophrenia (SCZ)-related verbal memory impairment is hypothesized to be mediated, in part, by frontal lobe (FTL) dysfunction. However, little research has contrasted the performance of SCZ patients with that of patients exhibiting circumscribed frontal lesions. The current study compared verbal episodic memory in patients with SCZ and focal FTL lesions (left frontal, LF; right frontal, RF; and bi-frontal, BF) on a four-trial list learning task consisting of three lists of varying semantic organizational structure. Each dependent variable was examined at two levels: scores collapsed across all four trials and learning scores (i.e., trial 4-trial 1). Performance deficits were observed in each patient group across most dependent measures at both levels. Regarding patient group differences, SCZ patients outperformed LF/BF patients (i.e., either learning scores or scores collapsed across trial) on free recall, primacy, primary memory, secondary memory, and subjective organization, whereas they only outperformed RF patients on the semantically blocked list on recency and primary memory. Collectively, these results indicate that the pattern of memory performance is largely similar between patients with SCZ and those with RF lesions. These data support tentative arguments that verbal episodic memory deficits in SCZ may be mediated by frontal dysfunction in the right hemisphere.

Cognitive impairments due to focal cerebellar injuries in adults.

INTRODUCTION: It has been asserted that damage to the cerebellum produces a specific pattern of cognitive deficits, but clinical studies have had ambiguous results. There remains particular uncertainty about the effects of focal cerebellar injuries on cognition in adults. Clinical reports and anatomical connectivity studies have suggested a possible functional convergence of frontal lobes and cerebellum. This investigation was designed to assess whether focal cerebellar injuries in adults would cause impairment on tasks previously demonstrated to be sensitive to prefrontal lesions. METHOD: We investigated this question in 32 adults with either stroke or resection of benign tumours and 36 healthy control subjects. Patients underwent standard and experimental cognitive testing and an assessment of general health and well-being at least 3 months post onset. RESULTS: The group with right cerebellar lesions had lower performance on some tests of response control and verbal fluency than the controls and also the patients with left cerebellar lesions. On most tests, including most of the experimental tests sensitive to prefrontal lesions, the patients had no significant difference from the controls. The patient groups reported no health or functional decline. CONCLUSIONS: These results and the bulk of the clinical literature suggest that damage to some cerebellar sites may have specific cognitive consequences, but the cognitive impairment after focal cerebellar injury in adults is mild or transient. After the acute epoch, demonstration of deficits may require more demanding probes of specific domains of cognition.

Rehabilitation of executive functioning in patients with frontal lobe brain damage with goal management training.

Executive functioning deficits due to brain disease affecting frontal lobe functions cause significant real-life disability, yet solid evidence in support of executive functioning interventions is lacking. Goal Management Training (GMT), an executive functioning intervention that draws upon theories concerning goal processing and sustained attention, has received empirical support in studies of patients with traumatic brain injury, normal aging, and case studies. GMT promotes a mindful approach to complex real-life tasks that pose problems for patients with executive functioning deficits, with a main goal of periodically stopping ongoing behavior to monitor and adjust goals. In this controlled trial, an expanded version of GMT was compared to an alternative intervention, Brain Health Workshop that was matched to GMT on non-specific characteristics that can affect intervention outcome. Participants included 19 individuals in the chronic phase of recovery from brain disease (predominantly stroke) affecting frontal lobe function. Outcome data indicated specific effects of GMT on the Sustained Attention to Response Task as well as the Tower Test, a visuospatial problem-solving measure that reflected far transfer of training effects. There were no significant effects on self-report questionnaires, likely owing to the complexity of these measures in this heterogeneous patient sample. Overall, these data support the efficacy of GMT in the rehabilitation of executive functioning deficits.

Impaired list learning is not a general property of frontal lesions.

BACKGROUND: List-learning tasks are frequently used to provide measures of "executive functions" that are believed necessary for successful memory performance. Small sample sizes, confounding anomia, and incomplete representation of all frontal regions have prevented consistent demonstration of distinct regional frontal effects on this task. OBJECTIVE: To confirm specific effects of lesions in different frontal regions. SUBJECTS: Forty-one patients with chronic focal frontal lesions and 38 control subjects. There were no group differences in naming scores. METHODS: Two word lists were presented, one with unblocked words from related categories and one in a preblocked format. Standard measures of learning, recall, recognition, and strategies were obtained, first for the frontal group as a whole and then for large but defined frontal regions. For all measures with significant group differences, a lesion "hotspotting" method identified possible specific regional injury effects. RESULTS: The frontal group was impaired on almost all measures, but impairments on most measures were particularly identified with lesions in the left superior frontal lobe (approximately area 9s) and some deficits in learning processes were surprisingly more prominent on the blocked list. CONCLUSION: Difficulty with list learning is not a general property of all frontal lesions. Lesions in different frontal regions impair list learning through specific mechanisms, and these effects may be modified by manipulations of the task structure.

Mapping task switching in frontal cortex through neuropsychological group studies.

This paper considers evidence provided by large neuropsychological group studies and meta-analyses of functional imaging experiments on the location in frontal cortex of the subprocesses involved in the carrying out of task-switching paradigms. The function of the individual subprocesses is also considered in the light of analyses of the performance of normal subjects.

Effects of focal frontal lesions on response inhibition.

This study examined the performance of 38 normal subjects and 43 patients with focal lesions of the frontal lobes on a simple go-nogo task where the probability of the nogo stimulus was either 75% or 25%. Patients with lesions to the superior medial parts of the frontal lobes, in particular to the left superior portion of Brodmann area 6 (which includes the supplementary motor areas and the premotor areas for the right hand) had an increased number of false alarms (incorrect responses to the nogo stimulus). These results indicate that area 6 is specifically involved in the inhibition of response. Patients with lesions to the right anterior cingulate (areas 24 and 32) were slower and more variable in their reaction time. These findings could be explained by an inability to sustain stimulus-response contingencies. Lesions to the right ventrolateral prefrontal cortex (Brodmann areas 44, 45, 47) also increased the variability of response, perhaps by disrupting monitoring performance.

Multiple effects of prefrontal lesions on task-switching.

This study examined the performance of 41 patients with focal prefrontal cortical lesions and 38 healthy controls on a task-switching procedure. Three different conditions were evaluated: single tasks without switches and two switching tasks with the currently relevant task signalled either 1500 ms (Long Cue) or 200 ms (Short Cue) before the stimulus. Patients with Superior Medial lesions showed both a general slowing of reaction time (RT) and a significantly increased switch cost as measured by RT. No other prefrontal group showed this increased reaction time switch cost. Increased error rates in the switching conditions, on the other hand, were observed in patients with Inferior Medial lesions and, to a lesser extent, ones with Superior Medial lesions. Patients with left dorsolateral lesions (9/46v) showed slower learning of the task as indicated by a high error rate early on. Several different processes are involved in task-switching and these are selectively disrupted by lesions to specific areas of the frontal lobes.

Keeping time: effects of focal frontal lesions.

This study examined the performance of 32 normal subjects and 39 patients with focal lesions of the frontal lobes on two simple timing tasks-responding in time with a tone that regularly repeated at a rate of once every 1.5s, and then maintaining the same regular response rhythm without any external stimulus. The hypothesis was that lesions to the right prefrontal cortex would disrupt timing performance. The two main findings were (1) an abnormally high variability in the timing performance (both self-timed and tone-timed) of patients with lesions to the right lateral frontal lobe, particularly involving Brodmann area 45 and subjacent regions of the basal ganglia; (2) an increase in the variability of timing performance as the task continued in patients with lesions to the superior medial regions of the frontal lobe. These findings indicate that the right lateral frontal lobe is crucially involved in the ongoing control of timed behavior, either because of its role in generating time intervals or in monitoring the passage of these intervals. In contrast, the superior medial regions of the frontal lobe are necessary to maintain consistent timing performance over prolonged periods of time.