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Theories of human behavior from Plato to Freud have repeatedly emphasized links between emotion and reason, a relationship now commonly attributed to pathways connecting phylogenetically "old" and "new" brain regions. Expanding on this theory, this study examined functional interactions between specific limbic and neocortical regions accompanying normal and disease-associated shifts in negative mood state.Regions of concordant functional change accompanying provocation of transient sadness in healthy volunteers and resolution of chronic dysphoric symptoms in depressed patients were examined with two positron emission tomography techniques: [15O]water and [18F]fluorodeoxyglucose, respectively.With sadness, increases in limbic-paralimbic blood flow (subgenual cingulate, anterior insula) and decreases in neocortical regions (right dorsolateral prefrontal, inferior parietal) were identified. With recovery from depression, the reverse pattern, involving the same regions, was seen--limbic metabolic decreases and neocortical increases. A significant inverse correlation between subgenual cingulate and right dorsolateral prefrontal activity was also demonstrated in both conditions.Reciprocal changes involving subgenual cingulate and right prefrontal cortex occur with both transient and chronic changes in negative mood. The presence and maintenance of functional reciprocity between these regions with shifts in mood in either direction suggests that these regional interactions are obligatory and probably mediate the well-recognized relationships between mood and attention seen in both normal and pathological conditions. The bidirectional nature of this limbic-cortical reciprocity provides additional evidence of potential mechanisms mediating cognitive ("top-down"), pharmacological (mixed), and surgical ("bottom-up") treatments of mood disorders such as depression.

There has been a recent surge of research on the topic of poor-pitch singing. However, this research has not addressed an important distinction in measurement: that between accuracy and precision. With respect to singing, accuracy refers to the average difference between sung and target pitches. Precision, by contrast, refers to the consistency of repeated attempts to produce a pitch. A group of 45 non-musician participants was asked to vocally imitate unfamiliar 5-note melodies, as well as to sing a series of familiar melodies from memory (e.g., Happy Birthday). The results showed that singers were more accurate than they were precise, and that a majority of participants could justifiably be categorized as imprecise singers. Accuracy and precision measures were correlated with one another, and conditional-probability analyses suggested that accuracy predicted precision more so than the converse. Finally, performance differences across groups of singers were greater for the imitation of unfamiliar tone sequences than for the recall of familiar melodies.

Ambient vision comprises the visual functions that are associated with the maintenance of spatial orientation and that depend on peripheral, preconscious visual inputs. Although a limited number of brain areas appear to be activated by coherent wide-field-of-view (WFOV) motion in more than one axis, a diffuse pattern of lateralized brain activity occurs in response to clockwise or counterclockwise ambient visual roll motion. In the present study involving positron emission tomography (PET), a similar finding was shown for rightward versus leftward yaw stimulation. A total of 18 PET scans were obtained from six subjects in response to either leftward or rightward WFOV motion in a collimated display subtending100 degrees horizontally. Rightward stimulation elicited mainly activation throughout the right hemisphere, whereas leftward stimulation elicited mainly activation throughout the left hemisphere. These findings provide further evidence that the ambient vision signal is either processed or transmitted throughout the entire brain, as befits a visual function that is fundamental to all other perceptual systems.

Functional reorganization of auditory attention was studied in 12 congenitally blind subjects and 12 controls using high-density event-related potentials during a highly focused dichotic listening task. Reaction times for the attend-ear intensity-deviant targets were markedly faster for the blind. Brain activity associated with sustained attention (N1 effect, Nd), and with the automatic detection of deviants in an unattended channel (MMN), did not exhibit reorganization. In contrast, marked plasticity changes were reflected in late auditory attentional processing (attend-ear targets), in the form of a prolonged negativity (200-450 ms post-stimulus) that was absent in the sighted subjects. The plasticity changes in the blind had a time course indicating progressive recruitment of parietal and then occipital regions, providing new evidence for cross-modal sensory reorganization in the blind.

Positron emission tomography (PET) provides an unprecedented opportunity to study the organization of cognitive functions in the working brain of normal individuals. A number of PET experiments, based on well-established paradigms derived from cognitive psychology, have investigated several aspects of language processing. These studies show that word processing is carried out by a distributed network of cortical areas with functional specificity. Results of this research sometimes confirm--sometimes clearly contradict--classic axioms of language organization. This article illustrates some of the methodological issues in PET research, then provides an overview of the most relevant studies using PET. Integrated with other functional imaging methodologies and with behavioral data from cognitive psychology and lesion studies, PET will certainly continue to represent a precious tool to enhance our knowledge of the functional organization of language.

The neural substrates of affective prosody are beginning to be understood. However, temporal processing and differences between emotions have yet to be established. High-density brain electrical activity was recorded while twenty healthy females heard and categorized semantically neutral sentences presented in five emotional prosodies (happy, sad, angry, fearful, and neutral). Accuracy was comparable between emotions, but reaction time was significantly different. Event-related potentials (ERPs) revealed an overall effect of prosody, with a main component peaking at 1 sec, localized in anterior temporal cortex (right greater than left). Main differences between emotions included an early effect peaking at 450 ms with increased activity in response to fear and localized in right dorsal premotor cortex. A later effect, peaking at 950 ms, showed sad-specific activity localized to left inferior premotor cortex. These results suggest that different emotions recruit distinct premotor regions during affective prosody recognition.

Exaggerated cognitive bias is observed in affective disorder patients, and is often probed using the Emotional Stroop (eStroop) task. Few studies of the eStroop have employed Event-Related Potentials (ERPs). Here, High-density ERPs were recorded while healthy subjects with and without sub-syndromal Depression and Seasonal Affective Disorder (SAD) performed eStroop variations containing disorder-congruent words. RTs did not reliably differentiate between groups. Emotional relative to neutral words elicited either a P1 or a new component with anterior frontal topography, the Early Anterior Positivity (EAP), maximal 200-400ms post-onset. In study 1, an EAP was elicited by depression words in subjects with and without depression, while amplitude of the Late Posterior Positivity (LPP) was greater in the depression group. In study 2, an EAP to winter-related words was observed in SAD participants during the winter, while only a P1 occurred in the summer. The EAP may index automatic processing of aversive self-relevant stimuli.

Previous research suggests that adults more accurately identify faces in Low Spatial Frequency (LSF), which is supported by holistic processing, compared to High SF, supported by localized processing. The current study used magnetoencephalography to record the face-specific neuromagnetic M170 response to faces and butterflies presented in LSF, Broad SF and HSF. Child, adolescent and adult participants made face/object discriminations. Sensors of interest over left and right occipito-temporal scalp regions were grand-averaged over the 6 conditions. Results indicated that the peak M170 neuromagnetic response was greater and occurred earlier with increasing age. In adults, LSF faces elicited an earlier peak response compared to HSF faces. Similarly, in adolescents LSF faces elicited an earlier peak M170 response than HSF faces; however, in children there was no effect of SF on the latency of the peak M170 response. Results suggest an advantage of holistic face processing in adolescents and adults, but not children.