Encoding of Temporal Sound Features in the Rodent Superior Paraolivary Nucleus

The superior paraolivary nucleus (SPON) is a prominent cell group in the mammalian brainstem. SPON neurons are part of a monaural circuit that encodes temporal sound features in the ascending auditory pathway. Such attributes of acoustic signals are critical for speech perception in humans and likely equally as important in animal communication. While basic properties of SPON neurons have been characterized in some detail, a comprehensive examination of mechanisms that underlie their ability to precisely represent temporal information is lacking. Furthermore, little is known of how the SPON impacts its primary target, the inferior colliculus. Combinations of electrophysiological, pharmacological and histological techniques were used to investigate SPON neuronal responses to stimuli whose temporal parameters were systematically varied. In addition, properties of neurons in the inferior colliculus were examined before and after reversible inactivation of the SPON in order to explore its functional role in hearing. An after-hyperpolarization rebound mechanism was shown to generate the hallmark offset response of SPON neurons in vitro. Single-cell labeling techniques provided a detailed morphological description of cell bodies and dendrites and revealed a homogeneous population of neurons. Moreover, subthreshold ionic currents and synaptic neurotransmitter receptor systems were shown to mediate the precision of responses to temporal features of sound in vivo. It was also demonstrated that input from the SPON shapes response properties of inferior colliculus neurons to both periodic and singular temporal stimulus features. Taken together, these results suggest the SPON likely has a substantial role in temporal processing that has not been taken into account in the current understanding of the central auditory system. Demonstrating a functional role for the SPON in hearing will expand our knowledge of neuronal circuits responsible for representing biologically important sounds in both normal hearing and hearing impaired states

Positive Portrayal of Women in African Prose: A Cursory Look at Sembène Ousmane’s God’s Bits of Wood and Ama Ata Aidoo’s Changes.

African novelists have long been seen as biased in their portrayal of female characters. This practice is condemned by many feminist writers as perpetuating male dominance and subjugating against women. However, Sembène Ousmane and Ama Ata Aidoo gave a different account of women characters in their works by assigning them positive roles. This paper asserts that the action of these two Anglophone and Francophone writers marks a shift from the status quo and is indicative of their stance as committed feminist writers. The paper further establishes that their stance offers the needed pretext to make a case for social and economic advancement of women in the two works. Finally, the paper concludes that characterization of women in these works by the two novelists helps to create an awareness of the power of the female species as an equal force in national development. Key words: Feminism, Marxism, domination, positive portrayal, liberation, progress

Acute tryptophan depletion attenuates conscious appraisal of social emotional signals in healthy female volunteers

Rationale: Acute tryptophan depletion (ATD) decreases levels of central serotonin. ATD thus enables the cognitive effects of serotonin to be studied, with implications for the understanding of psychiatric conditions, including depression. Objective: To determine the role of serotonin in conscious (explicit) and unconscious/incidental processing of emotional information. Materials and methods: A randomized, double-blind, cross-over design was used with 15 healthy female participants. Subjective mood was recorded at baseline and after 4 h, when participants performed an explicit emotional face processing task, and a task eliciting unconscious processing of emotionally aversive and neutral images presented subliminally using backward masking. Results: ATD was associated with a robust reduction in plasma tryptophan at 4 h but had no effect on mood or autonomic physiology. ATD was associated with significantly lower attractiveness ratings for happy faces and attenuation of intensity/arousal ratings of angry faces. ATD also reduced overall reaction times on the unconscious perception task, but there was no interaction with emotional content of masked stimuli. ATD did not affect breakthrough perception (accuracy in identification) of masked images. Conclusions: ATD attenuates the attractiveness of positive faces and the negative intensity of threatening faces, suggesting that serotonin contributes specifically to the appraisal of the social salience of both positive and negative salient social emotional cues. We found no evidence that serotonin affects unconscious processing of negative emotional stimuli. These novel findings implicate serotonin in conscious aspects of active social and behavioural engagement and extend knowledge regarding the effects of ATD on emotional perception

The Game Development Process: Hands-On

Understanding the game development process is integral to achieving success in the game industry. Although informative, the attempts made to make people more knowledgeable on the matter may not reflect current industry practices. The information unarticulated by these mediums could be important for job placements or advancements in the industry. In order to gain a better understanding of the game development process, we assimilated with the development studio GDX to help develop a game for the Wii console. Our tasks involved developing several of the mini-games within the game. As a result of our work, we gained invaluable insight on various aspects of the game development process and experienced the delights and disappointments that are associated with this fast-growing industry

Recognition of nectin-2 by the natural killer cell receptor T cell immunoglobulin and ITIM domain (TIGIT)

T cell immunoglobulin and ITIM domain (TIGIT) is an inhibitory receptor expressed on the surface of natural killer (NK) cells. TIGIT recognizes nectin and nectin-like adhesion molecules and thus plays a critical role in the innate immune response to malignant transformation. Although the TIGIT nectin-like protein-5 (necl-5) interaction is well understood, how TIGIT engages nectin-2, a receptor that is broadly over-expressed in breast and ovarian cancer, remains unknown. Here, we show that TIGIT bound to the immunoglobulin domain of nectin-2 that is most distal from the membrane with an affinity of 6 μm, which was moderately lower than the affinity observed for the TIGIT/necl-5 interaction (3.2 μm). The TIGIT/nectin-2 binding disrupted pre-assembled nectin-2 oligomers, suggesting that receptor-ligand and ligand-ligand associations are mutually exclusive events. Indeed, the crystal structure of TIGIT bound to the first immunoglobulin domain of nectin-2 indicated that the receptor and ligand dock using the same molecular surface and a conserved “lock and key” binding motifs previously observed to mediate nectin/nectin homotypic interactions as well as TIGIT/necl-5 recognition. Using a mutagenesis approach, we dissected the energetic basis for the TIGIT/nectin-2 interaction and revealed that an “aromatic key” of nectin-2 is critical for this interaction, whereas variations in the lock were tolerated. Moreover, we found that the C-C′ loop of the ligand dictates the TIGIT binding hierarchy. Altogether, these findings broaden our understanding of nectin/nectin receptor interactions and have implications for better understanding the molecular basis for autoimmune disease and cancer