Molecular mechanisms controlling synaptic recruitment of GluA4 subunit-containing AMPAreceptors

Synaptic recruitment of AMPA receptors (AMPARs) represents a key postsynaptic mechanism driving functional development and maturation of glutamatergic synapses. At immature hippocampal synapses, PKA-driven synaptic insertion of GluA4 is the predominant mechanism for synaptic reinforcement. However, the physiological significance and molecular determinants of this developmentally restricted form of plasticity are not known. Here we show that PKA activation leads to insertion of GluA4 to synaptic sites with initially weak or silent AMPAR-mediated transmission. This effect depends on a novel mechanism involving the extreme C-terminal end of GluA4, which interacts with the membrane proximal region of the C-terminal domain to control GluA4 trafficking. In the absence of GluA4, strengthening of AMPAR-mediated transmission during postnatal development was significantly delayed. These data suggest that the GluA4-mediated activation of silent synapses is a critical mechanism facilitating the functional maturation of glutamatergic circuitry during the critical period of experience-dependent fine-tuning.

Developmental switch in the kinase dependency of long-term potentiation depends on expression of GluA4 subunit-containing AMPA receptors

The AMPA-receptor subunit GluA4 is expressed transiently in CA1 pyramidal neurons at the time synaptic connectivity is forming, but its physiological significance is unknown. Here we show that GluA4 expression is sufficient to alter the signaling requirements of long-term potentiation (LTP) and can fully explain the switch in the LTP kinase dependency from PKA to Ca2(+)/calmodulin-dependent protein kinase II during synapse maturation. At immature synapses, activation of PKA leads to a robust potentiation of AMPA-receptor function via the mobilization of GluA4. Analysis of GluA4-deficient mice indicates that this mechanism is critical for neonatal PKA-dependent LTP. Furthermore, lentiviral expression of GluA4 in CA1 neurons conferred a PKA-dependent synaptic potentiation and LTP regardless of the developmental stage. Thus, GluA4 defines the signaling requirements for LTP and silent synapse activation during a critical period of synapse development.

Book review: New perspectives on the Irish abroad: the silent people?

Review of Mícheál Ó hAodha and Máirtín Ó Catháin eds., New perspectives on the Irish Abroad: The silent people? Lanham, Md.; Toronto: Lexington Books, 2014,166 pages. ISBN-13: 978-0739183717

Beacon

BEACON continuously relays live web searches as they are being made around the world presenting them back in series and at regular intervals as an endless concrete poetry. The beacon has been instigated to act as a silent witness: a feedback loop providing a global snapshot of ourselves to ourselves in real-time.

Hollywood and world cinema influences: tracing intertextuality in the works of two contemporary filmmakers from Francophone Africa; Mahamat Saleh Haroun and Abderrahmane Sissako

Don’t tell me the moon is shining; show me the glint of light on broken glass Anton Chekhov Representations of Africa in cinema are almost as old as cinema itself and date back to Hollywood’s silent era. Most early examples feature the continent as a mere exotic backdrop and include The Sheik (Melford 1921), soon followed, in 1926, by George Fitzmaurice’s Son of the Sheik starring Rudolph Valentino. The next decade brought Van Dyke’s Tarzan movies, Robert Stevenson’s King Solomon’s Mines (1937), and, on the European side, Duvivier’s Pépé le Moko (1936). For representations of Francophone Africa by Africans themselves, the viewing public more or less had to wait, however, until decolonisation in the 1960s (with, for example, Sembene Ousmane’s Borom Sarret and La Noire de…, both released in 1966 and, in 1968, Mandabi). Since then Francophone African cinema has come a long way and has diversified into various strands. Between Borom Sarret and Mahamat-Saleh Haroun’s 2006 Daratt, Saison sèche - or the same director’s Un homme qui crie, almost half a century has elapsed. Over this period, films inevitably have addressed a spectrum of visual, ideological and political tropes. They range from unadorned depictions of the newly independent states and their societies to highly aestheticised productions, not to mention surreal and poetic visions as displayed for instance in Djibril Diop Mambéty’s Touki Bouki (1973). Most of the early films send an overt socio-political message which is a clear and explicit denunciation of a corrupt state of affairs (Souleymane Cissé’s Baara, 1977). They aim to trigger strong emotional and political responses from the viewer, in unambiguous support for the film-maker’s stand. Sembene himself declared: “I consider cinema a means of political action” (Murphy 2000: 221). Similarly, the Mauritanian director Med Hondo wishes to “take up this technical medium and to make it a mouthpiece on behalf of [his] fellow Africans and Arabs” (Jeffries 2002: 11). All this echoes the claims of the Fédération Panafricaine des Cinéastes (FEPACI, founded in 1969), an organisation “dedicated to the liberation of Africa”. In sharp contrast to the incipient momentum given Francophonie by Bourguiba, the Nigerien Hamani Diori and the Senegalese Senghor, who invoked a worldwide communauté organique francophone, FEPACI called for “the creation of an aesthetics of disalienation… [using] didactic... forms to denounce the alienation of countries that were politically independent but culturally and economically dependent on the West” (Diawara 1996: 40). Sembene’s Xala (1974) became the blueprint for this, to this day the best-known vein of Francophone African cinema. Thus considered, this pedigree seems a million miles from mainstream global cinema with its overriding mission to entertain. A question therefore arises: to what extent can a cinema that sprang from such beginnings be seen to interface in any meaningful way with a global film industry that, overwhelmingly and for a century, has indeed entertained the world – with Hollywood at its centre?

The Triveneto transhumance: law, land, movement

North Italy's nomadic shepherds are a phenomenon unique in the world. Their nomadic nature is taken to the extreme since they move constantly rather than solely in the winter or the summer, as in the usual nomadism. Their home is on wheels and their territory is the tightly regulated yet sprawling Triveneto area. The Triveneto transhumance moves beyond private/public property divides, and indeed beyond lawful/unlawful distinctions, giving rise to what I have called an animal normativity. Relying on Valentina De Marchi's text 'Fame d'Erba' on the Triveneto transhumance, I show how territory becomes a question of animal hunger, and movement becomes an atmospheric, silent and imperceptible affect that crosses private property boundaries, state law limitations, reservation areas and road networks. This way of being, beyond the usual distinctions, offers an example of an alternative political and legal organisation that brings forth the continuum between the human, the natural and the legal/political.

Interrupting the courtroom organism: screaming bodies, material affects and the theatre of cruelty

This article offers a method of reading the courtroom which produces an alternative mapping of the space. My method combines a reading of Antonin Artaud’s Theatre of Cruelty with a Deleuzian theoretical analysis. I suggest that this is a useful method since it allows examination of the spatial praxes of the courtroom which pulsate with a power to organize, terrorize and to judge. This method is also able to conceptualize the presence of ‘‘screaming’’ bodies and living matter which are appropriated to build, as well as feed the presence and functioning of the courtroom space, or organism. By using a method that articulates the cry of these bodies in the shadow of the organism, it becomes clear that this cry is both unwelcome and suppressed by the courtroom. The howl of anxious bodies enduring the process and space of the law can be materialized through interruptions to the courtroom, such as when bodies stand when they should not and when they speak when they should be silent. These vociferous actualizations of the scream serve only to feed the organism they seek to disturb, yet if the scream is listened to before it disrupts, the interruption becomes-imperceptible to the courtroom. Through my Artaudian/Deleuzian reading, I give a voice to the corporeal gasp that lingers before the cry, which is embedded within the embodied multiplicity from which it is possible to draw a creative line of flight. The creative momentum of this line of flight produces a sustainable interruption to the courtroom process, which instead of being consumed by the system, has the potential to produce new courtroom alignments. My text therefore offers an alternative reading of the courtroom, and in doing so also offers a refined understanding of how to productively ‘‘interrupt’’ the courtroom process.