Humans rely on precise proprioceptive feedback from our muscles to perform daily activities, which is important in both the acquisition and execution of movements. Somatosensory input from the body shapes motor learning through central processes, as demonstrated for tasks using the arm, under active (self-generated) and passive conditions. Presently, we investigated whether passive movement training of the ankle increased proprioceptive acuity (psychophysical experiment) and whether it changed the peripheral proprioceptive afferent signal (microneurography experiment). In the psychophysical experiment, the ankle of 32 healthy human participants was moved passively using pairs of ramp-and-hold movements in different directions. In a pre-training test, participants made judgements about the movement direction in a two-alternative forced choice paradigm. Participants then underwent passive movement training, but only half were cued for learning, where a reference position was signaled by a sound and the parti...

Proper somatosensory circuit assembly is critical for processing somatosensory stimuli and for responding accordingly. In comparison to other sensory circuits (e.g., olfactory and visual), somatosensory circuits have unique anatomy and function. However, understanding of somatosensory circuit development lags far behind that of other sensory systems. For example, there are few identified transcription factors required for integration of interneurons into functional somatosensory circuits. Here, as a model, we examine one type of somatosensory interneuron, Even-skipped expressing Laterally placed interneurons (ELs) of the Drosophila larval nerve cord. Even-skipped (Eve) is a highly conserved, homeodomain transcription factor known to play a role in cell fate specification and neuronal axon guidance. Because marker genes are often functionally important in the cell types they define, we deleted eve specifically from EL interneurons. On the cell biological level, using single neuron labeling, we find eve play...

Oxytocin (Oxt) controls reproductive physiology and various kinds of social behaviors, but the exact contribution of Oxt to different components of parental care still needs to be determined. Here we illustrate the neuroanatomical relations of the parental nurturing-induced neuronal activation with magnocellular oxytocin neurons and fibers in the medial preoptic area (MPOA), the brain region critical for parental and alloparental behaviors. We utilized genetically-targeted mouse lines for Oxt , oxytocin receptor (Oxtr) , vasopressin receptor 1a (Avpr1a) , vasopressin receptor 1b (Avpr1b), and thyrotropin-releasing hormone (Trh) to systematically examine the role of Oxt-related signaling in pup-directed behaviors. The Oxtr - Avpr1a - Avpr1b triple knockout (TKO), and Oxt - Trh - Avpr1a - Avpr1b quadruple KO (QKO) mice were grossly healthy and fertile, except for their complete deficiency in milk ejection and modest deficiency in parturition secondary to maternal loss of the Oxt or Oxtr genes. In our minimal...

With increasing life span and prevalence of dementia, it is important to understand the mechanisms of cognitive aging. Here, we focus on a subgroup of the population we term “cognitively frail,” defined by reduced cognitive function in the absence of subjective memory complaints, or a clinical diagnosis of dementia. Cognitive frailty is distinct from cognitive impairment caused by physical frailty. It has been proposed to be a precursor to Alzheimer’s disease, but may alternatively represent one end of a nonpathologic spectrum of cognitive aging. We test these hypotheses in humans of both sexes, by comparing the structural and neurophysiological properties of a community-based cohort of cognitive frail adults, to people presenting clinically with diagnoses of Alzheimer’s disease or mild cognitive impairment, and community-based cognitively typical older adults. Cognitive performance of the cognitively frail was similar to those with mild cognitive impairment. We used a novel cross-modal paired-associates t...

Sarael Alcauter is an assistant professor in the department of behavioral and cognitive neurobiology at the Institute of Neurobiology, National Autonomous University of Mexico (UNAM).

Sergei Kirov is a professor in the department of neurosurgery and brain and the Behavior Discovery Institute at the Medical College of Georgia.

Sheena Josselyn is a senior scientist in The Hospital for Sick Children’s Neurosciences and Mental Health Program.

Sho Aoki is a postdoctoral scholar at the Okinawa Institute of Science and Technology.

Silke Nuber and coworkers generated and deeply characterized numerous transgenic rodent models to study PD and related disorders, including the first inducible α-synuclein (αS) transgenic mice, humanized BAC-wildtype human αS tg rat models.

Sridevi Venkatesan is a graduate of the Indian Institute of Science, Bangalore, in India, and is currently a third-year PhD student in the department of physiology at the University of Toronto.