Mechanisms Underlying Network Oscillations
Oscillations are ubiquitous in the central nervous system. Our research focuses on the cellular and synaptic mechanisms that underlie the generation and modification of oscillations in neural networks. Network oscillations arise as coordinated activity among populations of neurons and their abnormalities are implicated in various cognitive impairments.
The role of neuronal circuits in the generation of oscillations is perhaps best studied in central pattern generators (CPGs), networks responsible for rhythmic motor activity. Given the significant role of oscillations in a multitude of behaviors and pathological conditions, it is necessary to understand how oscillations are generated in the nervous system, what controls their frequency and how oscillatory components are coordinated to produce synchronous activity. The pyloric central pattern generator (CPG) in the STG is an excellent system to address these issues. The pyloric network produces rhythms in a range of frequencies (0.5-2 Hz), controlling rhythmic contractions of striated muscles in the pylorus, a section of the foregut responsible for the filtering of masticated food. There are 11 to14 pyloric neurons located in the STG. Most of these are identified individuals with known synaptic connectivity.
We study the ionic mechanisms (e.g., voltage-gated ion channels) underlying the highly nonlinear membrane behavior in these neurons, and the short-term synaptic dynamics of their connections to understand the generation of the specific electrical network activity patterns. Model networks in invertebrates have been used for decades to extract principles that were later shown to apply in mammalian networks. General principles obtained from studying the functions of synaptic dynamics in the generation and coordination of pyloric oscillations may potentially apply to other oscillatory networks that show activity-dependent changes in synaptic efficacy.
Understanding these cellular and synaptic mechanisms provides important insight into the generation of self-organized oscillations of the brain, such as the multiple rhythms observed during sleep cycles or in structures involved in learning and memory formation and often affected in pathological conditions including epilepsy, depression and schizophrenia.
The STG contains only about 30 neurons (depending on species and inter-individual variability). Their cell bodies sit around the synaptic neuropil that is made up of fine branches from both intrinsic neurons and terminals of descending axons. The known synaptic connections consist of graded inhibitory chemical synapses and electrical coupling. The gastric mill circuit and the pyloric circuit are multiply interconnected. Shown here are the core pyloric neurons in their connectivity, and the spontaneous triphasic rhythmic activity they produce in vitro.
Farzan Nadim
Office: 973-596-8453
Lab: 973-596-8290
Jorge Golowasch
Office: 973-596-8444
Lab: 973-596-8290
Dirk Bucher
Office: 973-596-8469
Lab: 973-596-6274