Information about the visual world is transmitted to the brain in sequences of action potentials in retinal ganglion cell axons that make up the optic nerve. In vivo recordings of ganglion cell spike trains in several animal models have revealed much of what is known about how the early visual system processes and encodes visual information. However, such recordings have been rare in one of the...

In vivo and in vitro evidence from animals suggesting that gap junctions (GJs) play a role in the spreading of epileptiform activity. We have examined the influence of the gap junction opener trimethylamine (TMA) and the connexin 36 (Cx36) gap junctional blocker, quinine, on epileptiform activity induced by 4-aminopyridine (4-AP) in the rat entorhinal cortex (EC) and the CA1 hippocampal region....

The nature of the synaptic connection from the auditory nerve onto the cochlear nucleus neurons has a profound impact on how sound information is transmitted. Short-term synaptic plasticity, by dynamically modulating synaptic strength, filters information contained in the firing patterns. In the sound-localization circuits of the brain stem, the synapses of the timing pathway are characterized ...

Synaptic short-term plasticity is a key regulator of neuronal communication and is controlled via various mechanisms. A well established property of mossy fiber to CA3 pyramidal cell synapses is the extensive short-term facilitation during high-frequency bursts. We investigated the mechanisms governing facilitation using a combination of whole-cell electrophysiological recordings, electrical mi...

The brain stem nucleus locus coeruleus (LC) is thought to modulate cortical excitability by norepinephrine (NE) release in LC forebrain targets. The effects of LC burst discharge, typically evoked by a strong excitatory input, on cortical ongoing activity are poorly understood. To address this question, we combined direct electrical stimulation of LC (LC-DES) with extracellular recording in LC ...

Neurons compute mainly with action potentials or “spikes”, which are stereotypical electrical impulses. Over the last century, the operating function of neurons has been mainly described in terms of firing rates, with the timing of spikes bearing little information. More recently, experimental evidence and theoretical studies have shown that the relative spike timing of inputs has an important ...

Jie Wu Shailendra Dubhashi Gary H. Bernstein University of Notre Dame Department of Electrical Engineering Notre Dame, Indiana 46556 Abstract. Inductive links are widely used for implanted biomedical applications, and with amplitude modulation their use can be expanded to the transmission of pulse trains for deep brain stimulation (DBS). Using a passive envelope detector and an integrated coil,...

This study has characterized constrictions of small cutaneous arteries in the guinea pig ear in response to electrical stimulation of the cervical sympathetic nerve (SNS) in vivo. Video microscopy and on-line image analysis were used to examine diameter changes of ear arteries (80-140 μm resting diameter) in anesthetized guinea pigs. Trains of 50-300 impulses, but not single pulses or short tra...

Current clinical practice in programming a cochlear implant (CI) for individuals with single-sided deafness (SSD) is to maximize the transmission of speech information via the implant, with the implicit assumption that this will also result in improved spatial-hearing abilities. However, binaural sensitivity is reduced by interaural place-of-stimulation mismatch, a likely occurrence with a stan...

In somatosensory cortex (S1) tactile stimulation activates specific regions. The borders between representations of different body parts constrain the spread of excitation and inhibition: connections that cross from one representation to another (cross-border, CB) are weaker than those remaining within the representation (noncross border, NCB). Thus, physiological properties of CB and NCB synap...