Now you see it,now you don't: statistical and methodological considerations in fMRI

We illustrate the effects of statistical threshold, spatial clustering, voxel size, and two approaches to multiple comparison correction on fMRI results. We first analyzed fMRI images obtained from a single subject during a noun-verb matching task. Data were analyzed with Statistical Parametric Mapping (SPM) using two different voxel sizes, and results were displayed at three different levels of statistical significance. At each statistical threshold, results were first uncorrected for multiple comparisons and spatial extent and then presented using a spatial extent cluster of 20 voxels. We then statistically controlled the Type I error rate associated with multiple comparisons by using the false discovery rate and by the random field adjustment for false-positive rate used by SPM. We also examined group results from language and graphesthesia paradigms at three levels of statistical significance. In all circumstances, apparent random activations decreased as more conservative statistical approaches were employed, but activation in areas considered to be functionally significant was also reduced. These issues are important in the choice of analytic approach and interpretation of fMRI results, with clear implications for the surgical management of individual patients when fMRI results are used to delineate specific areas of eloquent cortex.     

The attentive homunculus: now you see it, now you don't

The nature of the neural system that directs our attention toward selective items in the extrapersonal world is a longstanding and interesting puzzle. The ability to image the human brain at work non-invasively using positron-emission tomography or functional magnetic resonance has provided the means to investigate this issue. In this article, I review the contributions of brain imaging toward the characterization of attentional control in the human brain.The majority of experiments to date have investigated visual spatial orienting. A consistent pattern of brain areas has been revealed, comprising most notably the posterior parietal cortex around the intraparietal sulcus and frontal regions including the frontal eye fields. The brain areas implicated in the control of visual spatial attention were noted to resemble those involved in the control of eye movements, and direct experimental comparisons supported a tight link between the two systems. The findings suggested a sensible view of the attentional 'homunculus' as a distributed neural system related to the control of eye movements. Eye movements form perhaps the most basic orienting response, and can be shifted rapidly and efficiently based on multiple frames of reference. Some attention experiments using objects and features instead of spatial locations as the target of selection also obtained similar patterns of parietal-frontal activations, rendering further support to this view of the attentional control system.Some recent experiments, however, have cautioned against a premature conclusion regarding the ubiquity of the attentional control system revealed by studies of visual spatial attention. Different parietal and frontal regions become engaged when attention is shifted along non-spatial dimensions, such as when attention is directed toward a particular motor act or toward a specific point in time. In these cases, the neural system resembles those involved in the control of limb movements. The attentional homunculus thus begins to dissolve. The alternative view suggested is that attentional control may be a property of specialized parietal-frontal systems that transform perception into action. Future studies will be needed to validate this view of attention, or to provide a more mature understanding of its true nature.     

Now you see it, now you don't: on turning semantic interference into facilitation in a Stroop-like task

We use a masked priming procedure to test two accounts of the picture-word interference (PWI) effect: the lexical selection by competition account (Levelt et al., 1999; Roelofs, 1992) and the response selection account (Lupker, 1979; Miozzo and Caramazza, 2003). In the visible (standard) condition, we replicated the often-observed semantic interference effect. In the masked condition, we observed semantic facilitation. We take the polarity shift as a function of masking to mean that the semantic interference and semantic facilitation in the PWI task should be attributed to two qualitatively different processes. We argue that this conclusion follows naturally from the response selection account, but only with great difficulty from the lexical selection by competition account.     

Now you see me,now you don't: addressing bisexual invisibility in relationship therapy

ABSTRACT

In our Western world where sexual identity is typically seen as binary (homosexual or heterosexual), those of us who fall outside of such a narrow parameter are rendered invisible. This can be echoed not only in the relationships bisexual clients have with monosexual partners, but also with their therapists. If their therapist lacks an understanding of biphobia and bisexual identity they run the risk of reinforcing a bisexual client's sense of invisibility.

My paper seeks to address bisexual invisibility by describing biphobia and highlighting the common dilemmas bisexual clients might face in their relationships with gay or straight partners. I use the term bi-aware therapy, to emphasise what is required for a relationship therapist of any modality to work effectively and sensitively with bisexual clients.     

Priming deficits in amnesia: now you see them, now you don't.

The rate with which perceptual information becomes available was manipulated in 2 word naming experiments. Word priming effects, in terms of reduced naming latencies for repeated items, and recognition memory measures were obtained with matched groups of amnesic patients and control participants. In both experiments, the amnesic patients evidenced significantly reduced priming effects compared to control participants under difficult task conditions. Under easy task conditions the baseline naming latencies of the amnesics were significantly longer than those of controls, but the difference in priming effects failed to reach significance. The findings are consistent with the Information Availability model of priming positing that both priming and explicit memory are mediated by episodic information from a study or information processing episode. It is argued that word priming does not represent a memory function that is spared in amnesia.     

Now you see it,now you don't: Testing environments modulate the association between hippocampal volume and cortisol levels in young and older adults

The hypothalamic pituitary adrenal axis production of the stress hormone cortisol interacts with the hippocampal formation and impacts memory function. A growing interest is to determine whether hippocampal volume (HV) predicts basal and/or reactive cortisol levels in young and older adults. Recent evidence shows that contextual features in testing environments might be stressful and inadvertently induce a stress response in young and/or older populations. This latter result suggests that variations in testing environments might influence associations between HV and cortisol levels in young and older adults. To this end, we investigated 28 healthy young adults (ages 18–35) and 32 healthy older adults (ages 60–75) in two different environments constructed to be more or less stressful for each age group (Favoring‐Young versus Favoring‐Old conditions). Cortisol levels were repeatedly assessed in each environment, and young and older participants underwent an anatomical magnetic resonance imaging scan for subsequent assessment of HV. Results in both age groups showed that HV was significantly associated with cortisol levels only in the unfavorable stressful testing conditions specific for each age group. This association was absent when testing environments were designed to decrease stress for each age group. These findings are fundamental in showing that unless the nature of the testing environment is taken into consideration, detected associations between HV and cortisol levels in both young and older populations might be confounded by environmental stress. © 2014 Wiley Periodicals, Inc.     

"If you love someone, you don't hurt them": a comprehensive process analysis of a weeping event in therapy.

Early theorists described physical diseases (e.g., asthma, ulcers) thought to be associated with the inhibition of weeping (e.g., Alexander 1950), and catharsis theories (Breuer and Freud 1895/1955; Koestler 1964) postulated that unexpressed emotion accumulated as in a tank, and then overflowed as tears when a threshold level was exceeded. From a more biological perspective, it has been suggested that stress produces toxic chemicals in the body that become concentrated in the lacrimal gland and are released through weeping, restoring homeostasis (Frey 1985). As a result of these theories, psychotherapists tend to believe weeping is healthy for clients and that it serves to decrease depression (Trezza et al. 1988). While laboratory studies have typically not supported these ideas (e.g., Labott and Martin 1987, 1988), no studies have been performed on weeping specifically in the context of psychotherapy.