Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

Bartlett viewed thinking as a high level skill exhibiting ballistic properties that he called its “point of no return”. This paper explores one aspect of cognition through the use of a simple model...

/pdf/orienting-of-attention-2bi7r8jak3.pdf

Orienting of attention

The two basic phenomena that define the problem of visual attention can be illustrated in a simple example. Consider the arrays shown in each panel of Figure 1. In a typical experiment, before the arrays were presented, subjects would be asked to report letters appearing in one color (targets, here black letters), and to disregard letters in the other color (nontargets, here white letters). The array would then be briefly flashed, and the subjects, without any opportunity for eye movements, would give their report. The display mimics our. usual cluttered visual environment: It contains one or more objects that are relevant to current behavior, along with others that are irrelevant. The first basic phenomenon is limited capacity for processing information. At any given time, only a small amount of the information available on the retina can be processed and used in the control of behavior. Subjectively, giving attention to any one target leaves less available for others. In Figure 1, the probability of reporting the target letter N is much lower with two accompa­ nying targets (Figure la) than with none (Figure Ib). The second basic phenomenon is selectivity-the ability to filter out un­ wanted information. Subjectively, one is aware of attended stimuli and largely unaware of unattended ones. Correspondingly, accuracy in identifying an attended stimulus may be independent of the number of nontargets in a display (Figure la vs Ie) (see Bundesen 1990, Duncan 1980).

Neural Mechanisms of Selective Visual Attention

: The concept of attention as central to human performance extends back to the start of experimental psychology, yet even a few years ago, it would not have been possible to outline in even a preliminary form a functional anatomy of the human attentional system. New developments in neuroscience have opened the study of higher cognition to physiological analysis, and have revealed a system of anatomical areas that appear to be basic to the selection of information for focal (conscious) processing. The importance of attention is its unique role in connecting the mental level of description of processes used in cognitive science with the anatomical level common in neuroscience. Sperry describes the central role that mental concepts play in understanding brain function. As is the case for sensory and motor systems of the brain, our knowledge of the anatomy of attention is incomplete. Nevertheless, we can now begin to identify some principles of organization that allow attention to function as a unified system for the control of mental processing. Although many of our points are still speculative and controversial, we believe they constitute a basis for more detailed studies of attention from a cognitive-neuroscience viewpoint. Perhaps even more important for furthering future studies, multiple methods of mental chronometry, brain lesions, electrophysiology, and several types of neuro-imaging have converged on common findings.

/pdf/the-attention-system-of-the-human-brain-w797wllpat.pdf

The Attention System of the Human Brain

Attention deficit hyperactivity disorder (ADHD) comprises a deficit in behavioral inhibition. A theoretical model is constructed that links inhibition to 4 executive neuropsychological functions that appear to depend on it for their effective execution: (a) working memory, (b) self-regulation of affect-motivation-arousal, (c) internalization of speech, and (d) reconstitution (behavioral analysis and synthesis). Extended to ADHD, the model predicts that ADHD should be associated with secondary impairments in these 4 executive abilities and the motor control they afford. The author reviews evidence for each of these domains of functioning and finds it to be strongest for deficits in behavioral inhibition, working memory, regulation of motivation, and motor control in those with ADHD. Although the model is promising as a potential theory of self-control and ADHD, far more research is required to evaluate its merits and the many predictions it makes about ADHD.

/pdf/behavioral-inhibition-sustained-attention-and-executive-3s4ta68l66.pdf

Behavioral inhibition, sustained attention, and executive functions: Constructing a unifying theory of ADHD.

Although neglect has been demonstrated in the horizontal, vertical, and radial planes of space and has been attributed to sensory-attentional, motor-intentional, and representational deficits, motor intentional neglect in the radial plane has not been previously described. A patient who had a right parietal infarct was tested with a modified cancellation task that uses a fixed window, thereby controlling attentional demands and allowing one to dissociate between intentional and representational neglect. This patient showed proximal (radial) intentional neglect (a failure to move towards or in proximal space). Unlike controls whose search times decreased with increasing window size, our patient showed no change in search time as a function of window size. This pattern of behaviour suggests that the patient's search strategy does not incorporate factors such as the relation between a fixed target space and a variably sized aperture, but rather was based on the allocation of a certain amount of resources for a fixed period of time after which, regardless of performance, the patient would stop searching.

https://jnnp.bmj.com/content/jnnp/57/11/1395.full.pdf

Proximal intentional neglect: a case study.

Creative innovation with temporal lobe epilepsy and lobectomy

/pdf/emotional-and-neuropsychiatric-disorders-associated-with-vgwbzv0n.pdf

Emotional and Neuropsychiatric Disorders Associated with Alzheimer’s Disease

In portraiture, subjects are mostly depicted with a greater portion of the left side of their face (left hemiface) facing the viewer. This bias may be induced by the right hemisphere's dominance for emotional expression and agency. Since negative emotions are particularly portrayed by the left hemiface, and since asymmetrical hemispheric activation may induce alterations of spatial attention and action-intention, we posited that paintings of the painful and cruel crucifixion of Jesus would be more likely to show his left hemiface than observed in portraits of other people. By analyzing depictions of Jesus's crucifixion from book and art gallery sources, we determined a significantly greater percent of these crucifixion pictures showed the left hemiface of Jesus facing the viewer than found in other portraits. In addition to the facial expression and hemispatial attention-intention hypotheses, there are other biblical explanations that may account for this strong bias, and these alternatives will have to b...

Which cheek did Jesus turn

Background and Objectives: With conventional solid radially oriented-line bisections (SLB), normal subjects tend to bisect distal to the true midpoint (distal bias). This bias is thought to reflect a distal attentional bias in the radial plane. Whereas the right hemisphere, which mediates distributed-global attention, has a distal bias, the left hemisphere, which mediates focal attention, has a proximal bias. When performing conventional radial-line bisections, participants might primarily use right hemisphere-mediated global-distributed attention and thus develop a distal bias. The character-line bisection (CLB) task consists of strings of target and nontarget characters (letters or symbols) that are linearly aligned, and subjects are required to bisect a character that is closest to the midline. Thus, when performing the CLB subjects must use focal attention and detect symbols and both these activities are mediated by their left hemisphere. This left hemisphere activation might either reduce or reverse the distal bias observed on the SLB. The purpose of this study is to test this hypothesis. Methods: Fifteen normal subjects performed CLB (letter-line and symbol-line) and SLB tasks. Results: Overall, the subjects revealed a distal bias in both tasks, but the attempted bisections in the CLB tasks were more proximal than those in the SLB tasks. Conclusions: These result are consistent with the hypothesis that the CLB task, which requires both focal attention and the detection of symbols, activates the left hemisphere that has a greater proximal bias than the right hemisphere, thus reducing the distal bias observed with the SLB task.

Kenneth M. Heilman

Papers

Proximal intentional neglect: a case study.

Creative innovation with temporal lobe epilepsy and lobectomy

Emotional and Neuropsychiatric Disorders Associated with Alzheimer’s Disease

Which cheek did Jesus turn

Radial character-line bisection.