A genetic link between discriminative fear coding by the lateral amygdala, dopamine, and fear generalization.

The lateral amygdala (LA) acquires differential coding of predictive and non-predictive fear stimuli that is critical for proper fear memory assignment. The neurotransmitter dopamine is an important modulator of LA activity and facilitates fear memory formation, but whether dopamine neurons aid in the establishment of discriminative fear coding by the LA is unknown. NMDA-type glutamate receptors in dopamine neurons are critical for the prevention of generalized fear following an aversive experience, suggesting a potential link between a cell autonomous function of NMDAR in dopamine neurons and fear coding by the LA.

Synaptic regulation of microtubule dynamics in dendritic spines by calcium, F-actin, and drebrin.

Dendritic spines are actin-rich compartments that protrude from the microtubule-rich dendritic shafts of principal neurons. Spines contain receptors and postsynaptic machinery for receiving the majority of glutamatergic inputs. Recent studies have shown that microtubules polymerize from dendritic shafts into spines and that signaling through synaptic NMDA receptors regulates this process.

Dynamic microtubules promote synaptic NMDA receptor-dependent spine enlargement.

Most excitatory synaptic terminals in the brain impinge on dendritic spines. We and others have recently shown that dynamic microtubules (MTs) enter spines from the dendritic shaft. However, a direct role for MTs in long-lasting spine plasticity has yet to be demonstrated and it remains unclear whether MT-spine invasions are directly influenced by synaptic activity.

BDNF-induced increase of PSD-95 in dendritic spines requires dynamic microtubule invasions.

Microtubules (MTs) are capable of entering dendritic spines in mature hippocampal neurons through dynamic polymerization. Although these MT invasions are directly associated with neuronal activity, their function remains unknown. Here we demonstrate in mouse hippocampal neurons that MT entries into spines regulate the increase in postsynaptic density-95 (PSD-95) protein after brain-derived neurotrophic factor (BDNF) treatment.

The dynamic cytoskeleton: backbone of dendritic spine plasticity.

Dendritic spines are small actin-rich protrusions on the surface of dendrites whose morphological and molecular plasticity play key roles in learning and memory. Both the form and function of spines are critically dependent on the actin cytoskeleton. However, new research, using electron microscopy and live-cell super-resolution microscopy indicates that the actin cytoskeleton is more complex and dynamic than originally thought.

Activity-dependent dynamic microtubule invasion of dendritic spines.

Dendritic spines are the primary sites of contact with presynaptic axons on excitatory hippocampal and cortical neurons. During development and plasticity spines undergo marked changes in structure that directly affect the functional communication between neurons. Elucidating the cytoskeletal events that induce these structural changes is fundamental to understanding synaptic biology.

Bistable network behavior of layer I interneurons in auditory cortex.

GABAergic interneurons in many areas of the neocortex are mutually connected via chemical and electrical synapses. Previous computational studies have explored how these coupling parameters influence the firing patterns of interneuronal networks. These models have predicted that the stable states of such interneuronal networks will be either synchrony (near zero phase lag) or antisynchrony (phase lag near one-half of the interspike interval), depending on network connectivity and firing rates.

Modulation of gamma-aminobutyric acid type A receptor-mediated spontaneous inhibitory postsynaptic currents in auditory cortex by midazolam and isoflurane.

Background: Anesthetic agents that target gamma-aminobutyric acid type A (GABA(A)) receptors modulate cortical auditory evoked responses in vivo, but the cellular targets involved are unidentified. Also, for agents with multiple protein targets, the relative contribution of modulation of GABA(A) receptors to effects on cortical physiology is unclear. The authors compared effects of the GABA(A) receptor-specific drug midazolam with the volatile anesthetic isoflurane on spontaneous inhibitory postsynaptic currents (sIPSCs) in pyramidal cells of auditory cortex.