Cortico-subcortical contributions to executive control

The term "executive functions" refers to a range of cognitive processes, their common feature being the coordination of information processing and action control. Cortico-subcortical circuits which connect the prefrontal cortex (PFC), the basal ganglia and the cerebellum via the thalamus are believed to serve as neuroanatomical substrates of executive processing. This paper focuses on information processing related to executive functions by the PFC and related subcortical regions. Findings are mainly derived from neuropsychological investigations of brain-damaged patients but also from imaging studies in healthy subjects. There is evidence for subtle differences between these regions with respect to the cognitive mechanisms contributing to inhibition of habitual responses, task management/multitasking and set shifting, although the data base is sparse so far.     

Book Reviews

L uke , H elen M. Kaleidoscope: The Way of Woman and Other Essays.
P rétat , J ane R. Coming to Age: The Croning Years and Late-Life Transformation.
R yce -M enuhin , J oel . (ed.). Jung and the Monotheisms: Judaism, Christianity and Islam.
W hitmont , E dward C. The Alchemy of Healing: Psyche and Soma.
H orowitz , M ardi J., K ernberg , O tto F. and W einshel , E dward M. (eds). Psychic Structure and Psychic Change: Essays in Honor of Robert S. Wallerstein, M.D.
G oldman , D. In Search of the Real: The Origins and Originality of D. W. Winnicott.
L angs , R obert . Empowered Psychotherapy: Teaching Self-Processing: A New Approach to the Human Psyche and Its Reintegration.
R oazen , P aul . Meeting Freud's Family.     

The independence of positive and negative affect depends on the affect measure

This study examined the degree of independence between Positive Affect (PA) and Negative Affect (NA) within a given situation. The affective state was measured before and after an experimentally induced success or failure experience in an anagram task. Two types of affect measures were used to assess PA and NA: the Positive and Negative Affect Schedule (PANAS) and a Pleasantness-Unpleasantness scale. Consistent with our hypotheses, results show that PA and NA are independent when measured with the PANAS but are correlated when assessed with the other scale. These PA-NA correlations differed significantly from each other before and after emotion induction, respectively. Additional analyses indicate that both PA scales are differentially sensitive to the mood induction procedure. The findings are discussed with respect to circumplex models of emotion.     

‘The lesser of two evils…’ – views of persons with rheumatoid arthritis on medication adherence: a qualitative study

Objective: This study aimed to explore medication adherence among adherent and non-adherent persons suffering from rheumatoid arthritis (RA). A special focus was put on the reasons accounting for successful medication adherence and on potential barriers or facilitating factors.

Design: A qualitative study with semi-structured interviews was conducted. Eighteen participants were recruited through stratified purposive sampling according to their medication adherence level. Interviews were analysed by interpretative phenomenological analysis.

Results: Medication adherence behaviour was described on a continuum ranging from non-adherent to adherent. Participants’ current adherence level was represented as a result of inner negotiations between a variety of influential factors and the successful application of a range of strategies. The influential factors were: experiences with medication, outcome expectations, knowledge of therapeutic options, the traits ‘openness’ and ‘conscientiousness’, belief in medical progress, characteristics of the medication, level of trust in one’s physician, and perceived autonomy. Facilitating strategies were: establishing routines, using social support and the deliberate suppression of information about potential adverse events.

Conclusion: The experience of and the reasons for medication (non-)adherence from the perspective of people with RA were explored comprehensively. Participants’ ongoing negotiations between adherence and non-adherence emerged as a key finding with implications for health service providers.     

Curvature-specific color aftereffects

Adaptation to convex and concave arcs in different colored light results in curvature-specific color aftereffects when arcs are later viewed in white light. In three experiments, it was shown that these color aftereffects often are partial (restricted to limited regions of the test arcs) rather than uniform, and in addition that aftereffects induced by exposure to arcs transfer to straight-line displays of particular orientation, and vice versa. These data were interpreted as evidence that arcs are processed in the visual system in relation to the orientations of local straight line approximations instead of on a global basis. In these terms, curvature-specific color aftereffects are merely complex forms of the orientation-specific color aftereffects first described by McCollough (1965).     

Orientation-specific aftereffects and illusions in the perception of brightness

Orientation-specific brightness aftereffects were found when vertical and horizontal gratings of the same space-average luminance were viewed following alternate exposure to vertical and horizontal gratings that differed in space-average luminance. The vertical test grating appeared bright following exposure to a dim vertical grating, and dim after a bright vertical grating had been viewed. This aftereffect did not occur when the adaptation gratings had been seen by one eye and the test gratings by the other eye. An orientation-specific illusion in the perception of brightness was also found, with the white sectors of a vertical grating appearing brighter against a background of horizontal lines than they did against a background of vertical lines. Both distortions imply that there are detectors in the human visual system that are conjointly tuned to luminance and contour orientation.     

Spatial-frequency-contingent color aftereffects: Adaptation with two-dimensional stimulus patterns

The spatial-frequency theory of vision has been supported by adaptation studies using checkerboards in which contingent color aftereffects (CAEs) were produced at fundamental frequencies oriented at 45\dg to the edges. A replication of this study failed to produce CAEs at the orientation of either the edges or the fundamentals. Using a computer-generated display, no CAEs were produced by adaptation of a square or an oblique checkerboard. But when one type of checkerboard (4 cpd) was adapted alone, CAEs were produced on the adapted checkerboard and on sine-wave gratings aligned with the fundamental and third harmonics of the checkerboard spectrum. Adaptation of a coarser checkerboard (0.80 cpd) produced CAEs aligned with both the edges and the harmonic frequencies. With checkerboards of both frequencies, CAEs were also found on the other type of checkerboard that had not been adapted. This observation raises problems for any edge-detector theory of vision, because there was no adaptation to edges. It was concluded that spatial-frequency mechanisms are operating at both low- and high-spatial frequencies and that an edge mechanism is operative at lower frequencies. The implications of these results are assessed for other theories of spatial vision.