Huntington’s disease (HD) is characterized by striatal atrophy that begins long before the onset of motor symptoms. Clinical diagnosis of HD is based on the unequivocal presence of otherwise unexplained extrapyramidal movement disorder. However, structu...

E. P. became profoundly amnesic in 1992 after viral encephalitis, which damaged his medial temporal lobe bilaterally. Because of the rarity of such patients, we have performed a detailed neuroanatomical analysis of E. P.'s lesion using magnetic resonance imaging, and we have assessed his cognitive abilities with a wide range of neuropsychological tests. Finally, we have compared and contrasted the findings for E. P. with the noted amnesic patient H.M, whose surgical lesion is strikingly similar to E. P.'s lesion.

The re-emergence of task-related activation patterns during awake rest has been reported to play a role in memory consolidation and perceptual learning. This study aimed to test whether such reactivation occurs in the primary sensorimotor cortex following a visuomotor task. During functional magnetic resonance imaging (fMRI) scanning, 42 healthy participants (13 women and 29 men) learned visuomotor tracking, while a rotational perturbation was introduced between the cursor position and joystick angle. This visuomotor task block was interleaved with a control block, during which participants passively viewed a replay of their previously performed cursor movements. Half of the participants used their right hand, whereas the other half used their left hand to control the joystick. Resting-state scans were acquired before and after the visuomotor task sessions. A multivariate pattern classifier was trained to classify task and control blocks and was then tested on resting-state scans collected before and after...

While the pathological changes induced by the loss of dopamine innervation in the basal ganglia by Parkinson's disease are well studied, little is known about functional changes in the neural circuitry of this area during normal aging. Accordingly we have analyzed age-associated changes in the basal ganglia of behaviorally characterized, awake rhesus monkeys, using pharmacological MRI to map responses to dopaminergic stimulation. Apomorphine, a mixed D1/D2 dopamine receptor agonist, significantly reduced neural activity in the substantia nigra (SN) of young adult rhesus monkeys, while evoking little change in aged animals. Compared to young animals, both apomorphine and amphetamine (an indirect D1/D2 dopamine receptor agonist) significantly increased activation of the aged rhesus globus pallidus externa (GPe). In addition, the aged animals showed decreased activity in the putamen in response to amphetamine administration. The changes in SN, GPe and putamen activation are consistent with the concept that ba...

Postmortem studies indicate a temporal sequence of primary allocortical and secondary neocortical degeneration during Alzheimer disease (AD) progression. Hippocampus (HC) atrophy correlates with allocortical neuronal degeneration and atrophy of the corpus callosum (CC) reflects loss of intracortical projecting pyramidal neurons in neocortex. First, we wanted to determine the temporal sequence and rate of degeneration of HC and CC in AD. Second, to answer the question, whether rates of atrophy were correlated with rates of cognitive decline and third, whether both markers could be proposed as potential morphological parameters for mapping drug effects on brain structure in longitudinally studied AD patients and healthy control subjects. MRI-derived measures of CC and HC were compared between 27 clinically diagnosed AD patients and 28 age- and gender-matched healthy control subjects. Rates of CC and HC atrophy were determined in 21 AD patients and 10 control subjects studied longitudinally. We found mean rel...

Associative learning is a dynamic process that allows us to incorporate new knowledge within existing semantic networks. Even after years, a seemingly stable association can be altered by a single significant experience. Here, we investigate whether the acquisition of new associations affects the neural representation of stimuli and how the brain categorizes stimuli according to preexisting and emerging associations. Functional MRI data were collected during a differential fear conditioning procedure and at test (4–5 weeks later). Two pictures of faces and two pictures of houses served as stimuli. One of each pair coterminated with a shock in half of the trials (partial reinforcement). Applying Multivoxel Pattern Analysis (MVPA) in a trial-by-trial manner, we quantified changes in the similarity of neural representations of stimuli over the course of conditioning. Our findings show an increase in similarity of neural patterns throughout the cortex on consecutive trials of the reinforced stimuli. Furthermor...

Emotion regulation (ER) can modulate both immediate (emotional experience) and long-term (episodic memory) effects of emotion. Previous studies have mainly focused on reappraisal and suppression, strategies known to engage extensive cognitive resources....

Spatial normalization is fundamental to multi-subject fMRI experiments as it facilitates a common space in which group analyses are performed. Commonly, experimental data is aligned to either a group template (e.g. MNI-152) or to an individual template ...

Tic disorders (TD) are characterized by the presence of motor and/or vocal tics. Common neurophysiological frameworks suggest dysregulations of the cortico-striatal-thalamo-cortical (CSTC) brain circuit that controls movement execution. Besides common tics, there are other “non-tic” symptoms that are primarily related to sensory perception, sensorimotor integration, attention, and social cognition. The existence of these symptoms, the sensory tic triggers, and the modifying effect of attention and cognitive control mechanisms on tics may indicate the salience network's (SN) involvement in the neurophysiology of TD. Resting-state functional MRI measurements were performed in 26 participants with TD and 25 healthy controls (HC). The group differences in resting-state functional connectivity patterns were measured based on seed-to-voxel connectivity analyses. Compared to HC, patients with TD exhibited altered connectivity between the core regions of the SN (insula, anterior cingulate cortex, and temporopariet...

Linguistic processing is a complex skill with several dissociable components, including semantic, phonological, and syntactic processing. The goal of the present study was to compare and contrast the patterns of cortical activity associated with each of these processes. Twelve healthy young adults were scanned while performing match-to-sample tasks meant to elicit three different types of language processing. The semantic task required choosing a synonym, the phonological task required choosing a rhyme from among two words ending with the same sequence of letters, and the syntactic task required choosing a verb to agree in number with a singular or plural noun. Each of these tasks was compared to a control task of choosing an identical match in an alternating block sequence. Thus the format of the stimulus and the format of the response remained constant across all conditions, and only the linguistic basis of the decision varied. Imaging was performed using a 1.5 T whole-body MRI scanner with a full head c...