NB-IoT Devices in Reverberation Chambers: A Comprehensive Uncertainty Analysis.

New protocols related to internet-of-things applications may introduce previously unnoticed measurement effects in reverberation chambers due to the narrowband nature of these protocols. Such technologies also require less loading to meet the coherence-bandwidth conditions, which may lead to higher variations, hence uncertainties, across the channel. In this work, we extend a previous study of uncertainty in NB-IoT and CAT-M1 device measurements in reverberation chambers by providing, for the first time, a comprehensive uncertainty analysis of the components related to the reference and DUT measurements. By use of a significance test, we show that certain components of uncertainty become more dominant for such narrowband protocols, and cannot be considered as negligible, as in current standardized test methods. We show that the uncertainty, if not accounted for by using the extended formulation, will be greatly overestimated and could lead to non-compliance to standards.

"Frontal lobe syndrome"? Subtypes of acquired personality disturbances in patients with focal brain damage.

Conceptualizations of the nature of acquired personality disturbances after brain damage, especially to prefrontal cortex, have progressed from clinical observations of a large, disparate set of disturbances to theories concerning neuroanatomically-based subgroups with prefrontal damage. However, hypothesized subtypes have not yet been studied systematically. Based on our previous investigations of acquired personality disturbances, we hypothesized five subtypes of acquired personality disturbances: Executive Disturbances, Disturbed Social Behavior, Emotional Dysregulation, Hypo-emotionality/De-Energization, and Distress, as well as an undisturbed group. Subtypes were investigated in 194 adults with chronic, stable, focal lesions located in various aspects of prefrontal lobes and elsewhere in the brain, using two different cluster analysis techniques applied to ratings on the Iowa Scales of Personality Change. One technique was a hypothesis-driven approach; the other was a set of strictly empirical analyses to assess the robustness of clusters found in the first analysis. The hypothesis-driven analysis largely supported the hypothesized set of subtypes. However, in contrast to the hypothesis, it suggested that disturbed social behavior and emotional dysregulation are not two distinct subtypes, but two aspects of one multifaceted type of disturbance. Additionally, the so-labeled "executive disturbances" group also showed disturbances in other domains. Results from the second (empirical) set of cluster analyses were consistent with findings from the hypothesis-driven cluster analysis. Overall, findings across the two cluster analyses indicated four subtypes of acquired personality disturbances: (1) executive disturbances in association with generalized disturbance, (2) dysregulation of emotions and behavior, (3) hypo-emotionality and de-energization, and (4) distress/anxiety. These findings show strong correspondence with subtypes suggested by prominent models of prefrontal systems based on neuroanatomically-defined circuits. Clarification of distinctive subtypes of acquired personality disturbances is a step toward enhancing our ability to tailor rehabilitative interventions for patients with prefrontal brain injuries.

Case report: stimulation of the right amygdala induces transient changes in affective bias.

BACKGROUND: Sensitive outcome measures are needed to quantify the effects of neuromodulation in mood disorders. OBJECTIVE: This study examined the utility of a novel affective bias (AB) task in identifying transient mood changes induced by amygdala stimulation in a single rare participant. METHODS: Localized, pulsed electrical stimulation was delivered for 8 min during measures of AB and self-reported mood. Responses were compared with those gathered without stimulation on the same day in the same setting, using paired t-tests. RESULTS: Stimulation of the basolateral nucleus of the right amygdala at 50 Hz, 15 V, and 200 µs pulse-width produced a significant positive shift in AB (t = -2.864, df = 53, P = .006), despite equivocal findings on self-reported mood (t = -.184, df = 12, P = .857). CONCLUSION: Affective bias may be more sensitive to stimulation-induced fluctuations in mood than subjective report, suggesting utility as an outcome measure in neuromodulation studies.

Spectral organization of the human lateral superior temporal gyrus revealed by intracranial recordings.

The place of the posterolateral superior temporal (PLST) gyrus within the hierarchical organization of the human auditory cortex is unknown. Understanding how PLST processes spectral information is imperative for its functional characterization. Pure-tone stimuli were presented to subjects undergoing invasive monitoring for refractory epilepsy. Recordings were made using high-density subdural grid electrodes. Pure tones elicited robust high gamma event-related band power responses along a portion of PLST adjacent to the transverse temporal sulcus (TTS). Responses were frequency selective, though typically broadly tuned. In several subjects, mirror-image response patterns around a low-frequency center were observed, but typically, more complex and distributed patterns were seen. Frequency selectivity was greatest early in the response. Classification analysis using a sparse logistic regression algorithm yielded above-chance accuracy in all subjects. Classifier performance typically peaked at 100-150 ms after stimulus onset, was comparable for the left and right hemisphere cases, and was stable across stimulus intensities. Results demonstrate that representations of spectral information within PLST are temporally dynamic and contain sufficient information for accurate discrimination of tone frequencies. PLST adjacent to the TTS appears to be an early stage in the hierarchy of cortical auditory processing. Pure-tone response patterns may aid auditory field identification.

Recognition without awareness in a patient with simultanagnosia.

We report a psychophysiological study of "recognition without awareness" in patient 2354, who had severe but circumscribed atrophy in the occipitoparietal region bilaterally (caused by visual-variant Alzheimer's disease, documented by structural and functional neuroimaging) and an accompanying Balint syndrome that prevented her from recognizing the emotional valence of many highly charged negative visual scenes (e.g., a burned body). Despite this lack of overt recognition, patient 2354 nonetheless generated large amplitude skin conductance responses to highly charged negative pictures, demonstrating the same kind of recognition without awareness that has been reported previously in patients with bilateral occipitotemporal dysfunction and prosopagnosia [e.g., Tranel, D., & Damasio, A. R. (1985). Knowledge without awareness: an autonomic index of facial recognition by prosopagnosics. Science, 228, 1453-1454.]. Our case complements both previous evidence of covert, nonconscious recognition in patients with prosopagnosia, and previous behavioral studies of patients with Balint syndrome that have shown evidence of "preattentive" visual processing. The findings add to the small but important set of empirical observations regarding nonconscious visual processing in neurological patients, and indicate that recognition without awareness can occur in the setting of dorsal visual stream dysfunction and Balint syndrome. The findings in our patient suggest that she has patent pathways from higher-order visual cortices to autonomic effectors in the amygdala or hypothalamus, even though the results of such information processing are not made available to conscious awareness.

Comparative proteomic analysis reveals differential expression of Hsp25 following the directed differentiation of mouse embryonic stem cells.

Murine embryonic stem (ES) cells can be committed to neural differentiation with high efficiency in culture through the use of feeder- and serum-free media. This system is proving to be an excellent model to study processes involved in ES cell commitment to neural cell fate. We used this approach to generate neurogenic embryoid bodies (NEBs) in a serum-free culture system to perform proteomic analysis of soluble fractions and identify early changes in protein expression as ES cells differentiate. Ten candidate proteins were altered significantly in expression levels. One of the most significant alterations was for the small heat shock protein Hsp25. Three species of Hsp25 are detected in ES cells, and this expression pattern changes during the first 24 h of differentiation until expression is decreased to levels that are barely detectable at 4 days following differentiation. We used immunofluorescence studies to confirm that following ES cell differentiation, expression of Hsp25 becomes excluded from neural precursors as well as other differentiating cells, making it a potentially useful marker of early ES cell differentiation.

Knowing "what" and knowing "when".

The ability to situate autobiographical memories accurately in the "time-line" of one's own life is a particular aspect of retrograde memory that has received little attention in well-controlled, systematic studies. Here, we addressed this issue by testing the hypothesis that patients with basal forebrain damage would be impaired in their ability to place various autobiographical memories accurately on a 'time-line' of their life. Seven such subjects were contrasted with 11 medial temporal lobe subjects, 8 brain-damaged comparison subjects, and 18 normal comparison subjects, using a procedure in which subjects placed autobiographical events on a time-line of their life. The basal forebrain group was very impaired in this task, relative to the other groups, and on average, misplaced events by more than five years. Although the basal forebrain group was also impaired in retrieving the contents of autobiographical memory, they did not differ statistically from the medial temporal lobe group in this regard (and the medial temporal lobe group did not have impaired time placement of memories). The results indicate an intriguing dissociation between "knowing what" and "knowing when," and suggest that the basal forebrain contains structures that are especially important for "knowing when." Our findings are compatible with the view that the basal forebrain participates critically in retrieval strategies important for memory chronology, which contrasts with the medial temporal lobe's critical role in relational memory per se.