Involvement of the Superior Temporal Cortex and the Occipital Cortex in Spatial Hearing: Evidence from Repetitive Transcranial Magnetic Stimulation

The processing of auditory spatial information in cortical areas of the human brain outside of the primary auditory cortex remains poorly understood. Here we investigated the role of the superior temporal gyrus (STG) and the occipital cortex (OC) in spatial hearing using repetitive transcranial magnetic stimulation (rTMS). The right STG is known to be of crucial importance for visual spatial awareness, and has been suggested to be involved in auditory spatial perception. We found that rTMS of the right STG induced a systematic error in the perception of interaural time differences (a primary cue for sound localization in the azimuthal plane). This is in accordance with the recent view, based on both neurophysiological data obtained in monkeys and human neuroimaging studies, that information on sound location is processed within a dorsolateral "where" stream including the caudal STG. A similar, but opposite, auditory shift was obtained after rTMS of secondary visual areas of the right OC. Processing of auditory information in the OC has previously been shown to exist only in blind persons. Thus, the latter finding provides the first evidence of an involvement of the visual cortex in spatial hearing in sighted human subjects, and suggests a close interconnection of the neural representation of auditory and visual space. Because rTMS induced systematic shifts in auditory lateralization, but not a general deterioration, we propose that rTMS of STG or OC specifically affected neuronal circuits transforming auditory spatial coordinates in order to maintain alignment with vision.

Lewald, Jorg, Meister, Ingo G., Weidemann, Jurgen, Topper, Rudolf
Involvement of the Superior Temporal Cortex and the Occipital Cortex in Spatial Hearing: Evidence from Repetitive Transcranial Magnetic Stimulation
J. Cogn. Neurosci. 2004 16: 828-838

http://jocn.mitpress.org/cgi/citmgr?gca=jocn;16/5/828

Social concepts are represented in the superior anterior temporal cortex

Social concepts such as "tactless" or "honorable" enable us to describe our own as well as others' social behaviors. The prevailing view is that this abstract social semantic knowledge is mainly subserved by the same medial prefrontal regions that are considered essential for mental state attribution and self-reflection. Nevertheless, neurodegeneration of the anterior temporal cortex typically leads to impairments of social behavior as well as general conceptual knowledge. By using functional MRI, we demonstrate that the anterior temporal lobe represents abstract social semantic knowledge in agreement with this patient evidence. The bilateral superior anterior temporal lobes (Brodmann's area 38) are selectively activated when participants judge the meaning relatedness of social concepts (e.g., honor–brave) as compared with concepts describing general animal functions (e.g., nutritious–useful). Remarkably, only activity in the superior anterior temporal cortex, but not the medial prefrontal cortex, correlates with the richness of detail with which social concepts describe social behavior. Furthermore, this anterior temporal lobe activation is independent of emotional valence, whereas medial prefrontal regions show enhanced activation for positive social concepts. Our results demonstrate that the superior anterior temporal cortex plays a key role in social cognition by providing abstract conceptual knowledge of social behaviors. We further speculate that these abstract conceptual representations can be associated with different contexts of social actions and emotions through integration with frontolimbic circuits to enable flexible evaluations of social behavior.

Roland Zahn, Jorge Moll, Frank Krueger, Edward D. Huey, Griselda Garrido, and Jordan Grafman
Social concepts are represented in the superior anterior temporal cortex
Proceedings of the National Academy of Sciences 104: 6430-6435; published online before print as 10.1073/pnas.0607061104

http://www.pnas.org/cgi/content/full/104/15/6430

Neural connections of the posteromedial cortex in the macaque

The posterior cingulate and the medial parietal cortices constitute an ensemble known as the posteromedial cortex (PMC), which consists of Brodmann areas 23, 29, 30, 31, and 7m. To understand the neural relationship of the PMC with the rest of the brain, we injected its component areas with four different anterograde and retrograde tracers in the cynomolgus monkey and found that all PMC areas are interconnected with each other and with the anterior cingulate, the mid-dorsolateral prefrontal, the lateral parietal cortices, and area TPO, as well as the thalamus, where projections from some of the PMC areas traverse in an uninterrupted bar-like manner, the dorsum of this structure from the posteriormost nuclei to its rostralmost tip. All PMC regions also receive projections from the claustrum and the basal forebrain and project to the caudate, the basis pontis, and the zona incerta. Moreover, the posterior cingulate areas are interconnected with the parahippocampal regions, whereas the medial parietal cortex projects only sparsely to the presubiculum. Although local interconnections and shared remote connections of all PMC components suggest a functional relationship among them, the distinct connections of each area with different neural structures suggests that distinct functional modules may be operating within the PMC. Our study provides a large-scale map of the PMC connections with the rest of the brain, which may serve as a useful tool for future studies of this cortical region and may contribute to elucidating its intriguing pattern of activity seen in recent functional imaging studies.

Josef Parvizi, Gary W. Van Hoesen, Joseph Buckwalter, and Antonio Damasio
Neural connections of the posteromedial cortex in the macaque Proceedings of the National Academy of Sciences 103: 1563-1568; published online before print as 10.1073/pnas.0507729103


ttp://www.pnas.org/cgi/content/full/103/5/1563

Amygdala contribution to selective dimensions of emotion

The amygdala has been implicated in emotional processes, although the precise nature of the emotional deficits following amygdala lesions remains to be fully elucidated. Cognitive disturbances in the perception, recognition or memory of emotional stimuli have been suggested by some, whereas others have proposed changes in emotional arousal. To address this issue, measures of emotional arousal and valence (positivity and negativity) to a graded series of emotional pictures were obtained from patients with lesions of the amygdala and from a clinical contrast group with lesions that spared this structure. Relative to the contrast group, patients with damage to the amygdala evidenced a complete lack of an arousal gradient across negative stimuli, although they displayed a typical arousal gradient to positive stimuli. These results were not attributable to the inability of amygdala patients to process the hostile or hospitable nature of the stimuli, as the amygdala group accurately recognized and categorized both positive and negative features of the stimuli. The relative lack of emotional arousal to negative stimuli may account for many of the clinical features of amygdala lesions.

Gary G. Berntson , Antoine Bechara , Hanna Damasio , Daniel Tranel , and John T. Cacioppo
Amygdala contribution to selective dimensions of emotion Social Cognitive and Affective Neuroscience Advance Access published on June 1, 2007, DOI 10.1093/scan/nsm008.Soc Cogn Affect Neurosci 2: 123-129.

http://scan.oxfordjournals.org/cgi/content/abstract/2/2/123

Cingulate cortex: a closer look at its gut-related functional topography

Earlier studies have documented activation of the cingulate cortex during gut related sensory-motor function. However, topography of the cingulate cortex in relationship to various levels of visceromotor sensory stimuli and gender is not completely elucidated. The aim was to characterize and compare the activation topography of the cingulate cortex in response to 1) subliminal, 2) perceived rectal distensions, and 3) external anal sphincter contraction (EASC) in males and females. We studied 18 healthy volunteers (ages 18–35 yr; 10 women, 8 men) using functional MRI blood-oxygenation-level-dependent technique. We obtained 11 axial slices (voxel vol. 2.5–6.0 x 2.5 x 2.5 mm3) through the cingulate cortex during barostat-controlled subliminal, liminal, and supraliminal nonpainful rectal distensions as well as EASC. Overall, for viscerosensation, the anterior cingulate cortex exhibited significantly more numbers of activated cortical voxels for all levels of stimulations compared with the posterior cingulate cortex (P < 0.05). In contrast, during EASC, activity in the posterior cingulate was larger than in the anterior cingulate cortex (P < 0.05). Cingulate activation was similar during EASC in males and females (P = 0.58), whereas there was a gender difference in anterior cingulate activation during liminal and supraliminal stimulations (P < 0.05). In females, viscerosensory cortical activity response was stimulus-intensity dependent. Intestinal viscerosensation and EASC induce different patterns of cingulate cortical activation. There may be gender differences in cingulate cortical activation during viscerosensation. In contrast to male subjects, females exhibit increased activity in response to liminal nonpainful stimulation compared with subliminal stimulation suggesting differences in cognition-related recruitment.
functional magnetic resonance imaging; rectal distension; external anal sphincter contraction.

Adeyemi Lawal, Mark Kern, Arthi Sanjeevi, Candy Hofmann, and Reza Shaker
Cingulate cortex: a closer look at its gut-related functional topography Am J Physiol Gastrointest Liver Physiol 289: G722-G730, 2005.

http://ajpgi.physiology.org/cgi/content/full/289/4/G722

Dissociating medial frontal and posterior cingulate activity during self-reflection

Motivationally significant agendas guide perception, thought and behaviour, helping one to define a ‘self’ and to regulate interactions with the environment. To investigate neural correlates of thinking about such agendas, we asked participants to think about their hopes and aspirations (promotion focus) or their duties and obligations (prevention focus) during functional magnetic resonance imaging and compared these self-reflection conditions with a distraction condition in which participants thought about non-self-relevant items. Self-reflection resulted in greater activity than distraction in dorsomedial frontal/anterior cingulate cortex and posterior cingulate cortex/precuneus, consistent with previous findings of activity in these areas during self-relevant thought. For additional medial areas, we report new evidence of a double dissociation of function between medial prefrontal/anterior cingulate cortex, which showed relatively greater activity to thinking about hopes and aspirations, and posterior cingulate cortex/precuneus, which showed relatively greater activity to thinking about duties and obligations. One possibility is that activity in medial prefrontal cortex is associated with instrumental or agentic self-reflection, whereas posterior medial cortex is associated with experiential self-reflection. Another, not necessarily mutually exclusive, possibility is that medial prefrontal cortex is associated with a more inward-directed focus, while posterior cingulate is associated with a more outward-directed, social or contextual focus.

Marcia K. Johnson , Carol L. Raye , Karen J. Mitchell , Sharon R. Touryan , Erich J. Greene , and Susan Nolen-Hoeksema
Dissociating medial frontal and posterior cingulate activity during self-reflection Soc Cogn Affect Neurosci 1: 56-64.

http://scan.oxfordjournals.org/cgi/content/full/1/1/56