Motor signatures of emotional reactivity in frontotemporal dementia

Automatic motor mimicry is essential to the normal processing of perceived emotion, and disrupted automatic imitation might underpin socio-emotional deficits in neurodegenerative diseases, particularly the frontotemporal dementias. However, the pathophysiology of emotional reactivity in these diseases has not been elucidated. We studied facial electromyographic responses during emotion identification on viewing videos of dynamic facial expressions in 37 patients representing canonical frontotemporal dementia syndromes versus 21 healthy older individuals. Neuroanatomical associations of emotional expression identification accuracy and facial muscle reactivity were assessed using voxel-based morphometry. Controls showed characteristic profiles of automatic imitation, and this response predicted correct emotion identification. Automatic imitation was reduced in the behavioural and right temporal variant groups, while the normal coupling between imitation and correct identification was lost in the right temporal and semantic variant groups. Grey matter correlates of emotion identification and imitation were delineated within a distributed network including primary visual and motor, prefrontal, insular, anterior temporal and temporo-occipital junctional areas, with common involvement of supplementary motor cortex across syndromes. Impaired emotional mimesis may be a core mechanism of disordered emotional signal understanding and reactivity in frontotemporal dementia, with implications for the development of novel physiological biomarkers of socio-emotional dysfunction in these diseases

Neural bases of autobiographical support for episodic recollection of faces.

Incidental retrieval of autobiographical knowledge can provide rich contextual support for episodic recollection of a recent event. We examined the neural bases of these two processes by performing fMRI scanning during a recognition memory test for faces that were unfamiliar, famous, or personally known. The presence of pre-experimental knowledge of a face was incidental to the task, but nonetheless resulted in improved performance. Two distinct networks of activation were associated with correct recollection of a face's prior presentation (recollection hits vs. correct rejections) on one hand, and with pre-experimental knowledge about it (famous or personally known vs. unfamiliar faces) on the other. The former included mid/posterior cingulate cortex, precuneus, and ventral striatum. The latter included bilateral hippocampus, retrosplenial, and ventromedial prefrontal cortices. Anterior and medial thalamic activations showed an interaction between both effects, driven by increased activation for recollection of unfamiliar faces. When recollecting the presentation of a famous or personally known face, hippocampal activation increased with participants' ratings of how well they felt they knew the person shown. Ventromedial prefrontal cortex showed significantly greater activation for personally known than famous faces. Our results indicate a dissociation between the involvement of retrosplenial vs. mid/posterior cingulate and precuneus in memory tasks. They also indicate that, during recognition memory experiments, the hippocampus supports incidental retrieval of pre-experimental knowledge about the stimuli presented. This type of knowledge likely underlies the additional recollection found for prior presentation of well known stimuli compared with novel ones and may link hippocampal activation at encoding to subsequent memory performance more generally

The impairment of emotion recognition in Huntington’s disease extends to positive emotions

Patients with Huntington’s Disease are impaired in the recognition of emotional signals. However, the nature and extent of the impairment is controversial: It has variously been argued to be disgust-specific (Sprengelmeyer et al., 1996; 1997), general for negative emotions (Snowden, et al., 2008), or a consequence of item difficulty (Milders, Crawford, Lamb, & Simpson, 2003). Yet no study to date has included more than one positive stimulus category in emotion recognition tasks. We present a study of 14 Huntington’s patients and 15 control participants performing a forced-choice task with a range of negative and positive non-verbal emotional vocalizations. Participants were found to be impaired in emotion recognition across the emotion categories, including positive emotions such as amusement and sensual pleasure, and negative emotions, such as anger, disgust, and fear. These data complement previous work by demonstrating that impairments are found in the recognition of positive, as well as negative, emotions in Huntington’s disease. Our results point to a global deficit in the recognition of emotional signals in Huntington’s Disease

Luminescence of AlN:Mn2+ materials: Properties and mechanisms

Luminescence processes resulting in 600 nm emission of Mn2+ ions in AlN:Mn ceramics were studied based on investigations of photoluminescence and its excitation spectra, luminescence kinetics and long-lasting luminescence (PersL) properties. For AlN:Mn2+ nanopowders, the photoluminescence spectra and PersL were studied. Luminescence properties were examined and compared after the samples were irradiated with 520 nm light, resulting in direct excitation of Mn2+ ions, thus causing the intra-center luminescence, or with 263 nm light. As known, in the last case, the oxygen-related defects are primarily excited with the following energy transfer to Mn2+ ions and 600 nm emission, thus forming the recombination luminescence (RecL). Two types of excitations of the 600 nm RecL were used. In the first case, the luminescence response was detected during the sample irradiation with 263 nm light. It was found that at RT, the decay of the RecL is fast and its decay constant τ = 1.2 ms coincides with the value obtained for the intra-center luminescence. A time-dependent rise of the 600 nm luminescence intensity under 263 nm excitation was observed. In the other case, the 600 nm RecL was detected when irradiation of the sample with 263 nm light was ceased, and spectra and decay of PersL were studied. It was found that the decay of 600 nm PersL spectra could be described using three exponential functions, thus manifesting a variety of luminescence processes. The results allow tracing of the luminescence processes and proposal of the mechanisms resulting in the 600 nm light emission of Mn2+ ions. An energy level scheme of AlN:Mn2+ was constructed to elucidate of the luminescence processes and mechanisms