Daniel Justin Powell

Bowdoin College · Program in Neuroscience

Changes in ambient temperature affect all biological processes. However, these effects are process specific and often vary non-linearly. It is thus a non-trivial problem for neuronal circuits to maintain coordinated, functional output across a range of temperatures. The cardiac nervous systems in two species of decapod crustaceans, Homarus american...

A fundamental question in neuroscience is whether neuronal circuits with variable circuit parameters that produce similar outputs respond comparably to equivalent perturbations.1, 2, 3, 4 Work on the pyloric rhythm of the crustacean stomatogastric ganglion (STG) showed that highly variable sets of intrinsic and synaptic conductances can generate si...

Coupled oscillatory circuits are ubiquitous in nervous systems. Given that most biological processes are temperature sensitive, it is remarkable that the neuronal circuits of poikilothermic animals can maintain coupling across a wide range of temperatures. Within the stomatogastric ganglion (STG) of the crab, Cancer borealis , the fast pyloric rhyt...

Neuronal responses to peptide signaling are determined by the specific binding of a peptide to its receptor(s). For example, isoforms of the same peptide family can drive distinct responses in the same circuit by having different affinities for the same receptor, by having each isoform bind to a different receptor, or by a combination of these scen...

There is considerable flexibility embedded within neural circuits. For example, separate modulatory inputs can differently configure the same underlying circuit but these different configurations generate comparable, or degenerate, activity patterns. However, little is known about whether these mechanistically different circuits in turn exhibit deg...

Coupled oscillatory circuits are ubiquitous in nervous systems. Given that most biological processes are temperature sensitive, it is remarkable that the neuronal circuits of poikilothermic animals can maintain coupling across a wide range of temperatures. Within the stomatogastric ganglion (STG) of the crab Cancer borealis, the fast pyloric rhythm...

Elevated [K⁺] is often used to alter excitability in neurons and networks by shifting the potassium equilibrium potential (EK) and, consequently, the resting membrane potential. We studied the effects of increased extracellular [K⁺] on the well-described pyloric circuit of the crab, Cancer borealis. A 2.5-fold increase in extracellular [K⁺] (2.5x[K...

Elevated [K ⁺ ] is often used to alter excitability in neurons and networks by shifting the potassium equilibrium potential (E K ) and, consequently, the resting membrane potential. We studied the effects of increased extracellular [K ⁺ ] on the well-described pyloric circuit of the crab, Cancer borealis. A 2.5-fold increase in extracellular [K ⁺ ]...

When presented with a light cue followed by food, some rats simply approach the foodcup (Nonorienters), while others first orient to the light in addition to displaying the food-cup approach behavior (Orienters). Cue-directed orienting may reflect enhanced attentional and/or emotional processing of the cue, suggesting divergent natures of cue-infor...

The amygdala is important for reward-associated learning, but how distinct cell groups within this heterogeneous structure are recruited during appetitive learning is unclear. Here we used Fos induction to map the functional amygdalar circuitry recruited during early and late training sessions of Pavlovian appetitive conditioning. We found that a n...

The aim of this study was to examine the involvement of the hypothalamic neuropeptide orexin in the acquisition and expression of Pavlovian appetitive conditioning. Food deprived male rats received either a tone which co-terminated with delivery of food pellets distinct from their regular chow diet, or presentations of the tone alone in the conditi...