No abstract

Examined the representation of real-world events in memory as a function of orientation toward a videotaped sequence in which 2 people play a board game. In 4 experiments, analyzed subjects' segmentation of the videotaped sequence into events, using a technique developed by Newtson (1973). A comparison of segmentation patterns with performance on recognition, recall, and cued-recall tasks indicated that recall of events changed as a function of subjects' orientation toward the videotape, whereas recognition of events did not. The authors conclude that orientation toward an episodic sequence affects how rather than what events are represented in memory. An account of how orientation might affect the encoding and the representation of events is offered.

Autism and schizophrenia share overlapping genetic etiology, common changes in brain structure and common cognitive deficits. A number of studies using resting state fMRI have shown that machine learning algorithms can distinguish between healthy controls and individuals diagnosed with either autism spectrum disorder or schizophrenia. However, it has not yet been determined whether machine learning algorithms can be used to distinguish between the two disorders. Using a linear support vector machine, we identify features that are most diagnostic for each disorder and successfully use them to classify an independent cohort of subjects. We find both common and divergent connectivity differences largely in the default mode network as well as in salience, and motor networks. Using divergent connectivity differences, we are able to distinguish autistic subjects from those with schizophrenia. Understanding the common and divergent connectivity changes associated with these disorders may provide a framework for understanding their shared cognitive deficits.

1. The spatial patterns of activation in the rat cerebellar cortex evoked by peripheral stimulation were studied in vivo using optical imaging techniques. 2. Crus I and Crus II were stained with the pH sensitive dye, neutral red. Electrical stimulation of the vibrissae area of the ipsilateral face evoked optical responses consisting of parasagittal bands. The bands were 100-300 microns in width, elongated in the anterior-posterior direction, commonly extended across at least two folia, and varied in number from 1 to 7. 3. The optical responses were dependent on activation of postsynaptic elements since they were decreased substantially by the non-N-methyl-D-aspartate antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione. The optical bands were shown to correspond anatomically with the parasagittal compartments revealed by immunostaining with anti-zebrin II. 4. The present study demonstrates that functional parasagittal compartments exist in the rat cerebellar cortex and suggests that zebrin-positive Purkinje cell subgroups are anatomically related to this functional organization.

No abstract

The cues associated with drugs of abuse have an essential role in perpetuating problematic use, yet effective connectivity or the causal interaction between brain regions mediating the processing of drug cues has not been defined. The aim of this fMRI study was to model the causal interaction between brain regions within the drug-cue processing network in chronic cocaine smokers and matched control participants during a cocaine-cue exposure task. Specifically, cocaine-smoking (15M; 5F) and healthy control (13M; 4F) participants viewed cocaine and neutral cues while in the scanner (a Siemens 3 T magnet). We examined whole brain activation, including activation related to drug-cue processing. Time series data extracted from ROIs determined through our General Linear Model (GLM) analysis and prior publications were used as input to IMaGES, a computationally powerful Bayesian search algorithm. During cocaine-cue exposure, cocaine users showed a particular feed-forward effective connectivity pattern between the ROIs of the drug-cue processing network (amygdala → hippocampus → dorsal striatum → insula → medial frontal cortex, dorsolateral prefrontal cortex, anterior cingulate cortex) that was not present when the controls viewed the cocaine cues. Cocaine craving ratings positively correlated with the strength of the causal influence of the insula on the dorsolateral prefrontal cortex in cocaine users. This study is the first demonstration of a causal interaction between ROIs within the drug-cue processing network in cocaine users. This study provides insight into the mechanism underlying continued substance use and has implications for monitoring treatment response.

A novel form of spreading acidification and depression in the rat cerebellar cortex was imaged in vivo using the pH-sensitive dye, Neutral red. Surface stimulation evoked an initial beam of increased fluorescence (i.e., decreased pH) that spread rostrally and caudally across the folium and into neighboring folia. A transient but marked suppression in the excitability of the parallel fiber-Purkinje cell circuitry accompanied the spread. Characteristics differentiating this phenomenon from the spreading depression of Leao include: high speed of propagation on the surface (average of 450 microm/s), stable extracellular DC potential, no change in blood vessel diameter, and repeatability at short intervals. This propagating acidification constitutes a previously unknown class of neuronal processing in the cerebellar cortex.

Failing to engage in joint attention is a strong marker of impaired social cognition associated with autism spectrum disorder (ASD). The goal of this study was to localize the source of impaired joint attention in individuals with ASD by examining both behavioral and fMRI data collected during various tasks involving eye gaze, directional cuing, and face processing. The tasks were designed to engage three brain networks associated with social cognition [face processing, theory of mind (TOM), and action understanding]. The behavioral results indicate that even high-functioning individuals with ASD perform less accurately and more slowly than neurotypical (NT) controls when processing eyes, but not when processing a directional cue (an arrow) that did not involve eyes. Behavioral differences between the NT and ASD groups were consistent with differences in the effective connectivity of FACE, TOM, and ACTION networks. An independent multiple-sample greedy equivalence search was used to examine these social brain networks and found that whereas NTs produced stable patterns of response across tasks designed to engage a given brain network, ASD participants did not. Moreover, ASD participants recruited all three networks in a manner highly dissimilar to that of NTs. These results extend a growing literature that describes disruptions in general brain connectivity in individuals with autism by targeting specific networks hypothesized to underlie the social cognitive impairments observed in these individuals.