PROJECTS
- Neuromodulation in the Auditory Cortex
- Modeling of Cortical Networks
- Effects of Norepinephrine on Neocortical Circuitry
- Modulation of Transmitter Release by Serotonin
- Effect of Cholinergic and Adrenergic Modulation on Electrophysiological Auditory Responses on Anesthetized and Behaving Rats
- Role of the Cholinergic and the Adrenergics Systems in Rodent Models of Attention
1. Neuromodulation in the Auditory Cortex
Humberto Salgado, Justin Nichols, Lu Dinh, Mary Lee
The auditory cortex receives a strong cholinergic projection whose repeated activation induces long-lasting physiological changes. Aims of this project are:
a) identify and describe short-term effects of acetylcholine at glutamatergic and GABAergic synapses (TB, HS, JN, NG)
b) identify the effect of cholinergic agonists on the firing pattern of glutamatergic and GABAergic cells in the auditory cortex (RB)
c) study and identification of the dendritic and axonal morphology of the cells studied electrophysiologically (MB, BR, AY, CJ, AL)
d) localization of cholinergic receptors and cellular subtypes in the auditory cortex (LM, RB)
e) effect of monoamines in the modulation of cell and synaptic properties (HS)
f) interaction between cholinergic and monoaminergic second-messenger cascades in the modulation of cellular and synaptic properties (HS, RB)
2. Modeling of Cortical Networks
Lu Dinh, Nikki Nguyen, Humberto Salgado, Justin Nichols
We are developing a software for the simulation of small cortical networks. Aims of this project are:
a) developing a realistic model of single pyramidal cell (LD)
b) developing a realistic model of fast-spiking and regular-spiking GABAergic neurons (LD)
c) simulate short-term properties of cortical synaptic release (LD)
d) generate a model of electrically and synaptically coupled GABAergic neurons (LD, NN)
e) generate experimental data for optimizing the simulation parameters (HS, JN)
f) use the model for determining basic small cortical circuit properties (LD, NN, JN)
3. Effects of Norepinephrine on Neocortical Circuitry
Lu Dinh, Humberto Salgado, Justin Nichols, Francisco Garcia, Mary Lee
Among several parameters, norepinpehrine affects the release of executive neurotransmitters (GABA and Glutamate). Our preliminary results revealed that Norepinephrine differentially modulates two inhibitory circuits in supragranular cortical layers (layer I vs. layer II/III). We believe that the adrenergic modulation of layer I might be specific for emotional auditory inputs while adrenergic modulation of lower layers might improve processing of specific tonotopic input.
4. Modulation of Transmitter Release by Serotonin
Francisco Garcia, Lu Dinh, Humberto Salgado, Mary Lee
The Raphe nucleus projects dense innervation to all the neocortex, including the auditory cortex. Scant information is available on its physiological effects. Our preliminary results show that Serotonin strongly and reversibly effects the amplitude of synaptic responses in the supragranular layers of the auidtory cortex. Our laboratory is commited to understanding whether this effect might be asssociated with a gain adjustment during intense or stressful activitiy.
5. Effect of Cholinergic and Adrenergic Modulation on Electrophysiological Auditory Responses on Anesthetized and Behaving Rats
Justin Nichols, Alexandra Beckett, Lu Dinh, Humberto Salgado, Behzad Karimi
We are studying the effect of local pressure in the Iontophoretic application of Cholinergic and Adrenergic drugs on the firing patterns evoked by auditory stimulation in the rat auditory cortex. We compare results from anesthtized versus behaving animals.
6. Role of the Cholinergic and the Adranergics Systems in Rodent Models of Attention
Dewey Clay Brown II , Swagada Roychowdhury, Narendrakumar Ravi Varadharajulu, Lu Dinh, Humberto Salgado, Justin Nichols, Melina Bloomfield, Jason Tam, Amulya Ydlapalli
We developed two automated systems for monitoring the performnace of rats during tasks with various attentive demands. We are focusing on tasks challenging sustained attention in the attentional shifts. We are currently using these systems to determine the efect of Cholinergic and Adrenergic drugs on sustained attention and attentional shifts.
7. Morphology of neocortical neurons
Swagata Roychowdhury, Nicole Jones, Myriam Danyali, Bejoy Thomas, Amulya Ydlapalli
Patch-clamped neurons from brain slices are injected with 0.5% biocytin solution. Slices are fixed for developing the neurons injected with biocytin for post-hoc recognition and other types of morphological analysis. A camera lucida system is used for neuron tracing and drawing.
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