Opposing effects on muscarinic acetylcholine receptors in the piriform cortex of odor-trained rats

We combined pharmacological studies and electrophysiological recordings to investigate modifications in muscarinic acetylcholine (ACh) receptors (mAChR) in the rat olfactory (piriform) cortex, following odor-discrimination rule learning. Rats were trained to discriminate between positive and negative cues in pairs of odors, until they reached a phase of high capability to learn unfamiliar odors, using the same paradigm (“rule learning”). It has been reported that at 1–3 d after the acquisition of odor-discrimination rule learning, pyramidal neurons in the rat piriform cortex show enhanced excitability, due to a reduction in the spike-activated potassium current I_AHP, which is modulated by ACh. Further, ACh and its analog, carbachol (CCh), lost the ability to reduce the I_AHP in neurons from trained rats. Here we show that the reduced sensitivity to CCh in the piriform cortex results from a decrease in the number of mAChRs, as well as a reduction in the affinity of the receptors to CCh. Also, it has been reported that 3–8 d after the acquisition of odor-discrimination rule learning, synaptic transmission in the piriform cortex is enhanced, and paired-pulse facilitation (PPF) in response to twin stimulations is reduced. Here, intracellular recordings from pyramidal neurons show that CCh increases PPF in the piriform cortex from odor-trained rats more than in control rats, suggesting enhanced effect of ACh in inhibiting presynaptic glutamate release after odor training.     

How to keep a reversible figure from reversing: teasing out top-down and bottom-up processes

The nature of processes underlying our perception of reversible figures was examined through two experiments investigating the effects of prior exposure conditions on an observer's report of figural reversal. In experiment 1, observers were adapted over several minutes to an unambiguous version of a rotating Necker cube prior to the presentation of the standard ambiguous figure. Results indicated that adaptation produced an immediate bias to perceive the ambiguous figure in the opposite configuration (ie reverse bias) and to reduce reports of reversal over the test period. The introduction of a brief delay between the adaptation and test periods revealed that this bias is a highly transient effect and is only clearly evident when the adaptation and test figures are matched in size. In experiment 2, observers were primed with an unambiguous figure for a few seconds prior to the presentation of the standard ambiguous figure. In this case, the obtained bias strongly favored the observer's reporting the ambiguous figure to be in the same configuration as the adapting figure (ie positive bias); and neither introducing a delay period nor changing figure size had any effect. We conclude that these experiments reveal the distinct roles of transient, retinally localized neural processes as well as more stable, global processes under specifiable conditions.     

Attachment style, ethnicity and help-seeking attitudes among adolescent pupils

The present study set out to explore influences on help-seeking attitudes among adolescents. The roles of attachment style, ethnicity and symptomatology were examined, as previous research (predominantly from outside the UK) has shown they have an influence on help-seeking. A self-report questionnaire survey of help-seeking attitudes was carried out among 112 Asian, black and white UK pupils (age 15 years). Teachers were identified as the most frequently used source of previous professional help. Greater intentions to seek help were associated with being female, having a secure attachment style and having had previous experience of obtaining professional psychological help, but ethnicity and level of emotional and behavioural difficulties did not predict. Results are discussed in terms of implications for enhancing adolescent help-seeking.     

Consumer Preference Programs for Individuals Who Are Homeless and Have Psychiatric Disabilities: A Drop-In Center and a Supported Housing Program

We illustrate Fairweather's approach to Experimental Social Innovation and Dissemination with two experimental studies of programs to reduce homelessness for 168 and 225 people with mental illness and often substance abuse. Literally homeless participants were randomly assigned to programs that emphasized consumer choice or to the usual continuum of care, in which housing and services are contingent on sobriety and progress in treatment. A drop-in center that eliminated barriers to access to services was more successful than control programs in reducing homelessness, but after 24 months only 38% of participants had moved to community housing. A subsequent apartment program, in which individuals in the experimental condition moved to subsidized apartments directly from the street, with services under their control, had 79% in stable housing (compared to 27% in the control group) at the end of 6 months. Groups in this study did not differ on substance abuse or psychosocial outcomes.     

The relationship between depressive symptoms and error monitoring during response switching

Heightened sensitivity to failure and negative information is thought to be an important maintenance mechanism for symptoms of depression. However, the specific neural and behavioral correlates of the abnormal reactions to errors associated with depression are not yet well understood. The present study was designed to shed new light on this issue by examining how depressive symptoms relate to error monitoring in the context of different task demands. We used a modified flanker task in which the stimulus–response (S–R) mappings were reversed between blocks, differentiating relatively easy nonreversal blocks from the more-demanding S–R reversal blocks. Undergraduates performed this task and then completed a self-report measure of anhedonic depression. The results revealed that depressive symptoms were related to poorer posterror accuracy in the more-difficult S–R reversal blocks, but not in the easier nonreversal blocks. Event-related brain potentials (ERPs) within a subsample of these participants further indicated that depressive symptoms were associated with reduced error positivity (Pe) amplitudes in both block types, suggesting that depressive symptoms were related to reduced attention allocation to errors across the easy and hard blocks. Finally, brain–behavior correlations indicated that highly depressed individuals failed to display a relationship between Pe amplitude and posterror accuracy in the S–R reversal blocks, a relationship that was intact in the low-depression group. Together, these results suggest that task demands play a critical role in the emergence of error-monitoring abnormalities in depression.     

The Effect of Education on Age-Related Functional Activation During Working Memory

Education has been suggested to play a protective role against the development of age-related dementias. Accordingly, we examined modulation of functional activation during working memory by age and education. Eight older individuals with a college education, six older individuals with a high school education, and eight younger individuals with a college education performed a working memory task during O¹⁵ [water] PET scanning. In a voxel-by-voxel whole brain search, older participants with less education demonstrated greater left frontal activation relative to older participants with more education. Older participants with more education demonstrated greater right precuneus activation relative to older participants with less education. This suggests that older less educated participants may have used additional frontal resources to compensate for dysfunctional parietal cortex. These results occurred in the context of similar activation in well-educated younger and older participants. Younger participants had one unique area of activation in the left posterior parietal cortex and no differences in frontal activation were observed between these two groups. The results of this study indicate the need to consider education in age-related neuroimaging studies.     

Intentionality: Some Lessons from the History of the Problem from Brentano to the Present

Abstract

Intentionality (‘directedness’, ‘aboutness’) is both a central topic in contemporary philosophy of mind, phenomenology and the cognitive sciences, and one of the themes with which both analytic and Continental philosophers have separately engaged starting from Brentano and Edmund Husserl’s ground-breaking Logical Investigations (1901) through Roderick M. Chisholm, Daniel C. Dennett’s The Intentional Stance, John Searle’s Intentionality, to the recent work of Tim Crane, Robert Brandom, Shaun Gallagher and Dan Zahavi, among many others. In this paper, I shall review recent discussions of intentionality, including some recent explorations of the history of the concept (paying particular attention to Anselm), and suggest some ways the phenomenological approach of Husserl and Heidegger can still offer insights for contemporary philosophy of mind and consciousness.