Altered basal ganglia output during self-restraint.

Suppressing actions is essential for flexible behavior. Multiple neural circuits involved in behavioral inhibition converge upon a key basal ganglia output nucleus, the substantia nigra pars reticulata (SNr). To examine how changes in basal ganglia output contribute to self-restraint, we recorded SNr neurons during a proactive behavioral inhibition task.

Improved inference in coupling, encoding, and decoding models and its consequence for neuroscientific interpretation.

Background: A central goal of systems neuroscience is to understand the relationships amongst constituent units in neural populations, and their modulation by external factors, using high-dimensional and stochastic neural recordings. Parametric statistical models (e.g.

Globus pallidus dynamics reveal covert strategies for behavioral inhibition.

Flexible behavior requires restraint of actions that are no longer appropriate. This behavioral inhibition critically relies on frontal cortex - basal ganglia circuits. Within the basal ganglia, the globus pallidus pars externa (GPe) has been hypothesized to mediate selective proactive inhibition: being prepared to stop a specific action, if needed.

The Persistence of Memory: How the Brain Encodes Time in Memory.

Time and memory are inextricably linked, but it is far from clear how event durations and temporal sequences are encoded in memory. In this review, we focus on resource allocation models of working memory which suggest that memory resources can be flexibly distributed amongst several items such that the precision of working memory decreases with the number of items to be encoded. This type of model is consistent with human performance in working memory tasks based on visual, auditory as well as temporal stimulus patterns.

Oscillation patterns of local field potentials in the dorsal striatum and sensorimotor cortex during the encoding, maintenance, and decision stages for the ordinal comparison of sub- and supra-second signal durations.

Ordinal comparison of successively presented signal durations requires (a) the encoding of the first signal duration (standard), (b) maintenance of temporal information specific to the standard duration in memory, and (c) timing of the second signal duration (comparison) during which a comparison is made of the first and second durations. Rats were first trained to make ordinal comparisons of signal durations within three time ranges using 0.5, 1.

Oscillatory multiplexing of neural population codes for interval timing and working memory.

Interval timing and working memory are critical components of cognition that are supported by neural oscillations in prefrontal-striatal-hippocampal circuits. In this review, the properties of interval timing and working memory are explored in terms of behavioral, anatomical, pharmacological, and neurophysiological findings. We then describe the various neurobiological theories that have been developed to explain these cognitive processes - largely independent of each other.

Dedicated clock/timing-circuit theories of time perception and timed performance.

Scalar Timing Theory (an information-processing version of Scalar Expectancy Theory) and its evolution into the neurobiologically plausible Striatal Beat-Frequency (SBF) theory of interval timing are reviewed. These pacemaker/accumulator or oscillation/coincidence detection models are then integrated with the Adaptive Control of Thought-Rational (ACT-R) cognitive architecture as dedicated timing modules that are able to make use of the memory and decision-making mechanisms contained in ACT-R. The different predictions made by the incorporation of these timing modules into ACT-R are discussed as well as the potential limitations.

Altered brain activation in ventral frontal-striatal regions following a 16-week pharmacotherapy in unmedicated obsessive-compulsive disorder.

Recent studies have reported that cognitive inflexibility associated with impairments in a frontal-striatal circuit and parietal region is a core cognitive deficit of obsessive-compulsive disorder (OCD). However, few studies have examined progressive changes in these regions following clinical improvement in obsessive-compulsive symptoms. To determine if treatment changes the aberrant activation pattern associated with task switching in OCD, we examined the activation patterns in brain areas after treatment.

Multi-level comparison of empathy in schizophrenia: an fMRI study of a cartoon task.

Empathy deficits might play a role in social dysfunction in schizophrenia. However, few studies have investigated the neuroanatomical underpinnings of the subcomponents of empathy in schizophrenia. This study investigated the hemodynamic responses to three subcomponents of empathy in patients with schizophrenia (N=15) and healthy volunteers (N=18), performing an empathy cartoon task during functional magnetic resonance imaging.

Structural abnormalities of the right inferior colliculus in schizophrenia.

Although structural and functional neuroimaging studies of schizophrenia have suggested that impaired connectivity in the extensive network of cortical and subcortical areas is involved in its pathophysiology, there were no studies have investigated the structural integrity of the lower sensory brain areas including the inferior (IC) and the superior (SC) colliculus. The IC plays an important role in mediating auditory gating processes and inhibitory neural transmission, while the SC is a key structure in a distributed network mediating saccadic eye movements and shifts of attention, both of which have been linked to the pathophysiology of schizophrenia. We compared the morphologies of the IC and SC, which are involved in the early stage processing of visual and auditory stimuli, in patients with schizophrenia (N=28) and healthy controls (N=34) using high-resolution magnetic resonance imaging.

Integration of cross-modal emotional information in the human brain: an fMRI study.

The interaction of information derived from the voice and facial expression of a speaker contributes to the interpretation of the emotional state of the speaker and to the formation of inferences about information that may have been merely implied in the verbal communication. Therefore, we investigated the brain processes responsible for the integration of emotional information originating from different sources. Although several studies have reported possible sites for integration, further investigation using a neutral emotional condition is required to locate emotion-specific networks.

BOLD response during visual perception of biological motion in obsessive-compulsive disorder : an fMRI study using the dynamic point-light animation paradigm.

Objective: Although research has shown that deficits in various cognitive functions may underlie obsessive-compulsive disorder (OCD), studies have not yet clarified the specificity and etiology of perception processing, particularly the perception of biological motion that is correlated with social cognition. We used functional magnetic resonance imaging (fMRI) to investigate neural activity associated with the perception of biological motion in OCD patients.

Methods: The subjects were 15 patients with OCD and 15 age- and IQ-matched healthy volunteers.

Objects and their icons in the brain: the neural correlates of visual concept formation.

We are constantly exposed to symbols such as traffic signs, emoticons in internet communication, or other abstract representations of objects as well as, of course, the written words. However, aside from the word reading, little is known about the way our brain responds when we read non-lexical iconic symbols. By using functional MRI, we found that the watching of icons recruited manifold brain areas including frontal and parietal cortices in addition to the temporo-occipital junction in the ventral pathway.

Artificial shifting of fMRI activation localized by volume- and surface-based analyses.

Spatial smoothing is an important post-processing procedure that is used to increase the signal-to-noise ratio (SNR) of blood oxygenation level-dependent signals (BOLD) in common functional magnetic resonance imaging (fMRI) applications. However, recent studies have shown that smoothing artificially shifts probabilistic local maxima of fMRI activations. In this study, we show shifting of the localization of functional centers in hand motor areas of the cerebral cortex by three-dimensional isotropic Gaussian kernel smoothing or two-dimensional heat kernel smoothing in volume- and surface-based fMRI analyses.

Neural correlates of cognitive inflexibility during task-switching in obsessive-compulsive disorder.

A deficit in cognitive flexibility is acknowledged as a cognitive trait for obsessive-compulsive disorder (OCD). However, no investigations to date have used a cognitive activation paradigm to specify the neural correlates of this deficit in OCD. The objective of this study was to clarify how abnormal brain activities relate to cognitive inflexibility in OCD, using a task-switching paradigm.