Imaging the neural circuitry and chemical control of aggressive motivation.

Background: With the advent of functional magnetic resonance imaging (fMRI) in awake animals it is possible to resolve patterns of neuronal activity across the entire brain with high spatial and temporal resolution. Synchronized changes in neuronal activity across multiple brain areas can be viewed as functional neuroanatomical circuits coordinating the thoughts, memories and emotions for particular behaviors. To this end, fMRI in conscious rats combined with 3D computational analysis was used to identifying the putative distributed neural circuit involved in aggressive motivation and how this circuit is affected by drugs that block aggressive behavior.

Neural effects of MDMA as determined by functional magnetic resonance imaging and magnetic resonance spectroscopy in awake marmoset monkeys.

We used functional magnetic resonance imaging (fMRI) to investigate the acute effects of a recreational dose (1 mg/kg p.o.) of 3,4-methylenedioxymethamphetamine (MDMA) on regional brain activity in awake, restrained marmoset monkeys.

Imaging brain activity in conscious monkeys following oral MDMA ("ecstasy").

Recreational use of 3,4-methylenedioxymethamphetamine (MDMA;"ecstasy") poses worldwide potential health problems. Clinical studies show that repeated exposure to low oral doses of MDMA has toxic effects on the brain, altering cognitive and psychosocial behavior. Functional magnetic resonance imaging in conscious marmoset monkeys was used to evaluate the sensitivity of the brain to an oral dose of MDMA (1 mg/kg).

Imaging the neural substrates involved in the genesis of pentylenetetrazol-induced seizures.

Purpose: Functional imaging of animal models makes it possible to map the functional neuroanatomy contributing to the genesis of seizures. Pentylenetetrazol (PTZ)-induced seizure in rats, a relevant model of human absence and of generalized tonic-clonic epilepsy, was used to stimulate seizure activity within 30 s of administration while collecting continuous, high-resolution, multislice images at subsecond intervals.

Methods: Pilot studies were conducted to establish a quick and effective PTZ model for the imaging experiments.

Procedure for minimizing stress for fMRI studies in conscious rats.

Functional magnetic resonance imaging (fMRI) in conscious animals is evolving as a critical tool for neuroscientists. The present study explored the effectiveness of an acclimation procedure in minimizing the stress experienced by the animal as assessed by alterations in physiological parameters including heart rate, respiratory rate, and serum corticosterone levels. Results confirm that as the stress of the protocol is minimized, there is a significant decrease in head movements and enhancement in data quality.

Imaging cocaine-induced changes in the mesocorticolimbic dopaminergic system of conscious rats.

Functional magnetic resonance imaging (fMRI) was used to assess the effects of cocaine on brain activation in fully conscious rats. Methods were developed to image cocaine-induced changes in blood-oxygen-level-dependent (BOLD) signal without the peripheral cardiac and respiratory complications associated with psychostimulant administration. Using spin echo planar imaging (EPI), conscious rats were imaged in a 4.

Changes in MRI signal intensity during hypercapnic challenge under conscious and anesthetized conditions.

Most functional magnetic resonance imaging (fMRI) studies in animals are conducted under anesthesia to minimize motion artifacts. However, methods and techniques have been developed recently for imaging fully conscious rats. Functional MRI studies on conscious animals report enhanced BOLD signal changes as compared to the anesthetized condition.

Regional cerebral blood flow and BOLD responses in conscious and anesthetized rats under basal and hypercapnic conditions: implications for functional MRI studies.

Anesthetics, widely used in magnetic resonance imaging (MRI) studies to avoid movement artifacts, could have profound effects on cerebral blood flow (CBF) and cerebrovascular coupling relative to the awake condition. Quantitative CBF and tissue oxygenation (blood oxygen level-dependent [BOLD]) were measured, using the continuous arterial-spin-labeling technique with echo-planar-imaging acquisition, in awake and anesthetized (2% isoflurane) rats under basal and hypercapnic conditions. All basal blood gases were within physiologic ranges.

The macrosphere model: evaluation of a new stroke model for permanent middle cerebral artery occlusion in rats.

Background And Purpose: The suture middle cerebral artery occlusion (MCAO) model is widely used for the simulation of focal cerebral ischemia in rats. This technique causes hypothalamic injury resulting in hyperthermia, which can worsen outcome and obscure neuroprotective effects. Herein, we introduce a new MCAO model that avoids these disadvantages.