Neural dynamics in the orbitofrontal cortex reveal cognitive strategies.

Behavior is sloppy: a multitude of cognitive strategies can produce similar behavioral read-outs. An underutilized approach is to combine multifaceted behavioral analyses with neural recordings to resolve cognitive strategies. Here we show that rats performing a decision-making task exhibit distinct strategies over training, and these cognitive strategies are decipherable from orbitofrontal cortex (OFC) neural dynamics.

Combining Old and New Tricks: The Study of Genes, Neurons, and Behavior in Crayfish.

For over a century the nervous system of decapod crustaceans has been a workhorse for the neurobiology community. Many fundamental discoveries including the identification of electrical and inhibitory synapses, lateral and pre-synaptic inhibition, and the Na/K-pump were made using lobsters, crabs, or crayfish. Key among many advantages of crustaceans for neurobiological research is the unique access to large, accessible, and identifiable neurons, and the many distinct and complex behaviors that can be observed in lab settings.

The dynamic range of voltage-dependent gap junction signaling is maintained by -induced membrane potential depolarization.

Like their chemical counterparts, electrical synapses show complex dynamics such as rectification and voltage dependence that interact with other electrical processes in neurons. The consequences arising from these interactions for the electrical behavior of the synapse, and the dynamics they create, remain largely unexplored. Using a voltage-dependent electrical synapse between a descending modulatory projection neuron (MCN1) and a motor neuron (LG) in the crustacean stomatogastric ganglion, we find that the influence of the hyperpolarization-activated inward current () is critical to the function of the electrical synapse.

Neuropeptide Modulation Increases Dendritic Electrical Spread to Restore Neuronal Activity Disrupted by Temperature.

Peptide neuromodulation has been implicated to shield neuronal activity from acute temperature changes that can otherwise lead to loss of motor control or failure of vital behaviors. However, the cellular actions neuropeptides elicit to support temperature-robust activity remain unknown. Here, we find that peptide neuromodulation restores rhythmic bursting in temperature-compromised central pattern generator (CPG) neurons by counteracting membrane shunt and increasing dendritic electrical spread.

Physiologists turned Geneticists: Identifying transcripts and genes for neuronal function in the Marbled Crayfish, .

The number of undergraduate researchers interested in pursuing neurophysiological research exceeds the research laboratory positions and hands-on course experiences available because these types of experiments often require extensive experience or expensive equipment. In contrast, genetic and molecular tools can more easily incorporate undergraduates with less time or training. With the explosion of newly sequenced genomes and transcriptomes, there is a large pool of untapped molecular and genetic information which would greatly inform neurophysiological processes.

Temperature-robust activity patterns arise from coordinated axonal Sodium channel properties.

Action potentials are a key component of neuronal communication and their precise timing is critical for processes like learning, memory, and complex behaviors. Action potentials propagate through long axons to their postsynaptic partners, which requires axons not only to faithfully transfer action potentials to distant synaptic regions but also to maintain their timing. This is particularly challenging when axons differ in their morphological and physiological properties, as timing is predicted to diverge between these axons when extrinsic conditions change.

State-Dependent Modification of Sensory Sensitivity via Modulation of Backpropagating Action Potentials.

Neuromodulators play a critical role in sensorimotor processing via various actions, including pre- and postsynaptic signal modulation and direct modulation of signal encoding in peripheral dendrites. Here, we present a new mechanism that allows state-dependent modulation of signal encoding in sensory dendrites by neuromodulatory projection neurons. We studied the impact of antidromic action potentials (APs) on stimulus encoding using the anterior gastric receptor (AGR) neuron in the heavily modulated crustacean stomatogastric ganglion (STG).

Axonal Conduction Velocity Measurement.

Action potential conduction velocity is the speed at which an action potential (AP) propagates along an axon. Measuring AP conduction velocity is instrumental in determining neuron health, function, and computational capability, as well as in determining short-term dynamics of neuronal communication and AP initiation (Ballo and Bucher, 2009; Bullock, 1951; Meeks and Mennerick, 2007; Rosenthal and Bezanilla, 2000; Städele and Stein, 2016; Swadlow and Waxman, 1976). Conduction velocity can be measured using extracellular recordings along the nerve through which the axon projects.

Extracellular Axon Stimulation.

This is a detailed protocol explaining how to perform extracellular axon stimulations as described in Städele and Stein, 2016. The ability to stimulate and record action potentials is essential to electrophysiological examinations of neuronal function. Extracellular stimulation of axons traveling in fiber bundles (nerves) is a classical technique in brain research and a fundamental tool in neurophysiology (Abbas and Miller, 2004; Barry, 2015; Basser and Roth, 2000; Cogan, 2008).

Changes in Dorsal Root Ganglion Gene Expression in Response to Spinal Cord Stimulation.

Background And Objectives: Spinal cord stimulation (SCS) has been shown to influence pain-related genes in the spinal cord directly under the stimulating electrodes. There is limited information regarding changes occurring at the dorsal root ganglion (DRG). This study evaluates gene expression in the DRG in response to SCS therapy.

Genomics of the Effect of Spinal Cord Stimulation on an Animal Model of Neuropathic Pain.

Background: Few studies have evaluated single-gene changes modulated by spinal cord stimulation (SCS), providing a narrow understanding of molecular changes. Genomics allows for a robust analysis of holistic gene changes in response to stimulation.

Methods: Rats were randomized into six groups to determine the effect of continuous SCS in uninjured and spared-nerve injury (SNI) animals.

Serum prolactin, gonadotropins, and estradiol in menstruating and amenorrheic mothers during two years' lactation.

Serum prolactin, LH, FSH, and estradiol were measured in single blood samples collected from 465 nursing mothers in Central Africa (Kivu, Zaïre) during the first 2 postpartum years. Lactating mothers were hyperprolactinemic during 15 to 18 postpartum months. Both serum prolactin and FSH were higher in amenorrheic than in menstruating nursing mothers; the difference was more apparent during the first than during the second year.