Cephalopod Sex Determination and its Ancient Evolutionary Origin.

Octopuses, squids, and cuttlefishes - the coleoid cephalopods - are a remarkable branch in the tree of life whose members exhibit a repertoire of sophisticated behaviors (Hanlon and Messenger, 2018). As a clade, coleoids harbor an incredible variety of novel traits including the most complex nervous system among invertebrates, derived camera-type eyes, and rapid adaptive camouflage abilities (Young, 1971; Hanlon, 2007). The burst of evolutionary novelty that distinguishes cephalopods is even more striking in a phylogenetic context; cephalopods are a deeply diverged lineage that last share a common ancestor with other extant molluscs in the Cambrian period, roughly 550 million years ago (Ponder and Lindberg, 2008; Huang et al.

Cell types and molecular architecture of the Octopus bimaculoides visual system.

Cephalopods have a remarkable visual system, with a camera-type eye and high acuity vision that they use for a wide range of sophisticated visually driven behaviors. However, the cephalopod brain is organized dramatically differently from that of vertebrates and invertebrates, and beyond neuroanatomical descriptions, little is known regarding the cell types and molecular determinants of their visual system organization. Here, we present a comprehensive single-cell molecular atlas of the octopus optic lobe, which is the primary visual processing structure in the cephalopod brain.

Cortical signatures of wakeful somatosensory processing.

Sensory inputs carry critical information for the survival of an organism. In mice, tactile information conveyed by the whiskers is of high behavioural relevance, and is broadcasted across cortical areas beyond the primary somatosensory cortex. Mesoscopic voltage sensitive dye imaging (VSDI) of cortical population response to whisker stimulations has shown that seemingly 'simple' sensory stimuli can have extended impact on cortical circuit dynamics.

Changes in white matter in mice resulting from low-frequency brain stimulation.

Recent reports have begun to elucidate mechanisms by which learning and experience produce white matter changes in the brain. We previously reported changes in white matter surrounding the anterior cingulate cortex in humans after 2-4 weeks of meditation training. We further found that low-frequency optogenetic stimulation of the anterior cingulate in mice increased time spent in the light in a light/dark box paradigm, suggesting decreased anxiety similar to what is observed following meditation training.

Rhythmic brain stimulation reduces anxiety-related behavior in a mouse model based on meditation training.

Meditation training induces changes at both the behavioral and neural levels. A month of meditation training can reduce self-reported anxiety and other dimensions of negative affect. It also can change white matter as measured by diffusion tensor imaging and increase resting-state midline frontal theta activity.

Visual Processing: Hungry Like the Mouse.

In this issue of Neuron, Burgess et al. (2016) explore how motivational state interacts with visual processing, by examining hunger modulation of food-associated visual responses in postrhinal cortical neurons and their inputs from amygdala.

Large-scale imaging of cortical dynamics during sensory perception and behavior.

Sensory-driven behaviors engage a cascade of cortical regions to process sensory input and generate motor output. To investigate the temporal dynamics of neural activity at this global scale, we have improved and integrated tools to perform functional imaging across large areas of cortex using a transgenic mouse expressing the genetically encoded calcium sensor GCaMP6s, together with a head-fixed visual discrimination behavior. This technique allows imaging of activity across the dorsal surface of cortex, with spatial resolution adequate to detect differential activity in local regions at least as small as 100 μm.

Brief cognitive training interventions in young adulthood promote long-term resilience to drug-seeking behavior.

Environmental stress and deprivation increase vulnerability to substance use disorders in humans and promote drug-seeking behavior in animal models. In contrast, experiences of mastery and stability may shape neural circuitry in ways that build resilience to future challenges. Cognitive training offers a potential intervention for reducing vulnerability in the face of environmental stress or deprivation.

Diverse visual features encoded in mouse lateral geniculate nucleus.

The thalamus is crucial in determining the sensory information conveyed to cortex. In the visual system, the thalamic lateral geniculate nucleus (LGN) is generally thought to encode simple center-surround receptive fields, which are combined into more sophisticated features in cortex, such as orientation and direction selectivity. However, recent evidence suggests that a more diverse set of retinal ganglion cells projects to the LGN.

Identification of the GATA factor TRPS1 as a repressor of the osteocalcin promoter.

A proteomic analysis of proteins bound to the osteocalcin OSE2 sequence of the mouse osteocalcin promoter identified TRPS1 as a regulator of osteocalcin transcription. Mutations in the TRPS1 gene are responsible for human tricho-rhino-phalangeal syndrome, which is characterized by skeletal and craniofacial abnormalities. TRPS1 has been shown to bind regulatory promoter sequences containing GATA consensus binding sites and to repress transcription of genes involved in chondrocyte differentiation.

A role for the cyclin box in the ubiquitin-mediated degradation of cyclin G1.

Cyclin G1 was identified as a transcriptional target of p53 that encodes a protein with strong homology to the cyclin family of cell cycle regulators. We show that either ectopically expressed or endogenous cyclin G1 protein is very unstable, undergoes modification with ubiquitin, and is likely degraded by the proteasome. Ectopic cyclin G1 protein stability is increased by cyclin box mutation or by association with inactive cyclin-dependent kinase (CDK) subunits, suggesting that a function of cyclin G1 as a CDK regulator may be required for its rapid turnover.

Terminal osteoblast differentiation, mediated by runx2 and p27KIP1, is disrupted in osteosarcoma.

The molecular basis for the inverse relationship between differentiation and tumorigenesis is unknown. The function of runx2, a master regulator of osteoblast differentiation belonging to the runt family of tumor suppressor genes, is consistently disrupted in osteosarcoma cell lines. Ectopic expression of runx2 induces p27KIP1, thereby inhibiting the activity of S-phase cyclin complexes and leading to the dephosphorylation of the retinoblastoma tumor suppressor protein (pRb) and a G1 cell cycle arrest.