The relationship between cardiac dosimetry and tumour quadrant location in left sided whole breast and chest wall adjuvant radiotherapy.

BACKGROUND: Radiotherapy after breast surgery decreases locoregional recurrence and improves survival. This is not without risks from radiation exposure and could have implications in clinical practice. Our study investigates the correlation between tumour location and radiation dose to the heart. METHODS: Left-sided breast cancer patients who had radiotherapy at Aberdeen Royal Infirmary in 2010 were identified. Tumour location was established from notes and imaging. Radiotherapy planning scans were reviewed, and cardiac doses calculated. The mean cardiac dose, maximum dose and volume of the heart in the field, along with V5-V40, were determined. RESULTS: 40 patients had mastectomies and 118 breast conserving surgery. The median percentage of the heart in the field and the Interquartile Range was 0.59% (0.03-1.74) for all patients, with the highest for lower inner quadrant (LIQ) tumours 1.20% (0.29-2.40), followed by mastectomy 0.94% (0.02-1.82). The mean heart dose showed a higher median for mastectomies 1.59 Gy (1.00-1.94), followed by LIQ tumours 1.58 Gy (1.31-2.28), with an overall median of 1.42 Gy (1.13-1.95). The median percentage of the heart in the field, the mean cardiac dose and V5-V30 did not reach statistical significance, however, V40 and the maximum dose did. CONCLUSIONS: The benefits of radiotherapy after breast cancer surgery are established, but with potential harm from cardiac exposure. Our cohort showed higher radiation exposure to the heart in patients with LIQ tumours and mastectomies but reached significance only for V40 and maximum dose. This highlights tumour location as a potentially important risk factor for cardiac exposure with breast radiotherapy.

The ideation of movement is supported by fronto-temporal cortical regions involved in the retrieval of semantic knowledge.

BACKGROUND AND AIM OF THE WORK: The neurofunctional correlates of movement ideation, which should be distinguished from motor imagery, have not been fully investigated. This functional Magnetic Resonance Imaging (fMRI) experiment revealed the brain activation patterns associated with different motor processes, including ideation. METHODS: Fifteen healthy participants underwent fMRI and performed three tasks using the right index finger: 1. execution of a simple prespecified movement; 2. execution of a simple voluntary movement; 3. ideation of a simple voluntary movement without execution. A number of t-test comparisons across conditions were carried out. RESULTS: The execution ofa simple prespecified finger movement activated the right inferior parietal cortex and substantia nigra, the left middle frontal gyrus, and thalamus, and bilaterally the post-central gyri, the superior parietal lobule and the cerebellum. Execution of a simple voluntary movement activated the left anterior cingulate cortex. The ideation of a voluntary simple movement activated the left inferior, middle and superior temporal gyri and the inferior frontal gyri bilaterally. CONCLUSIONS: The execution of a prespecified action involves structures within the somatosensory cortex, such as the post-central gyrus. The execution of a voluntary action is achieved with the support of the anterior cingulate cortex, a structure active when resolution of conflict is required. The ideation of a voluntary action requires the contribution of associative areas of the left frontal and temporal lobes, which support the retrieval of semantic knowledge necessary in the planning of a voluntary act.

The neural mechanisms of reciprocal communication.

Imitation in humans has been attributed to increased activation of the mirror neuron system, but there is no neural model to explain reciprocal communication. In this study, we investigated whether reciprocal, communicative, imitative exchanges activate the same neural system as imitation of simple movements, and whether the neural network subserving communication is lateralized. Fifteen participants were tested using functional magnetic resonance imaging with an online interactive-imitative paradigm while they performed finger movements for three different purposes: (1) to imitate the experimenter, (2) to elicit an imitation from the experimenter, and (3) to simply perform the movement. Subtraction analysis (imitation > movement, initiation > movement) revealed the activation of a strongly lateralized network, where the infra-parietal lobule (IPL) activation was lateralized to the left, while the infero-frontal gyrus (IFG) activation was to the right. It is concluded that imitation in a communicative paradigm recruits a lateralized network, with left fronto- and right parietal activation, that overlaps with a network that subserves understanding of an Other's intentions in relation to the Self. This finding lends plausibility to the suggestion that the neural network for imitation evolved to support interpersonal communication.

Different neuronal pathways support the generation of general and specific mental images.

The aim of this functional magnetic resonance imaging (fMRI) study was to investigate the neural correlates associated with the generation of general (i.e., prototypical) and specific (i.e., exemplar) visual mental images from concrete nouns. The fMRI paradigm included a non-imagery baseline, and two activation conditions requiring the generation of either general or specific images. Image generation times and brain activation were recorded. Analysis of the behavioral results showed that generating general images took less than the specific ones. The comparison of each activation condition with the baseline showed significant increase in brain activation in left frontal areas in both kinds of images, with the additional involvement of the posterior cingulate cortex during the generation of specific images. When the two activation conditions were contrasted with each other and masked for their respective comparison with baseline, significant activation was found in right frontal areas for general mental images, whereas a significant increase in activation in the left superior frontal region and the right thalamus was detected during the generation of specific mental images. These findings suggest that general and specific mental images are generated with the support of two different neural pathways. The generation of general images seems to involve brain areas associated with the formation of global gestalt-like images (areas in the right hemisphere), while the generation of specific mental images appears to require additional support from areas involved in the retrieval of visual details (i.e., the right thalamus).