This experiment examined whether or not aggression in the lizard Anolis (suborder Lacertilia, family Iguanidae) is lateralized. Five pair of adult Anolis were subjected to several 20 min behavioral trials, during which one animal was placed in the cage of the other. Behaviors were captured on video and coded according t o eye preference, motor activity, posture, and color. Analysis of the data found that the most aggressive behaviors, including biting, threatened biting, and aggressive movements, were done under the guidance of the left eye. Both left and right eyes were used with equal frequency during non-aggressive movements. Most of these aggressive episodes were done while the animals were "lightly" colored, Because of a n almost complete crossingover of the optic tract in Anolis, along with the absence of a corpus callosum, it is likely that most,if not all, of the information in the left eye was processed by the right hemisphere. These results suggest that the lizard Anolis, like humans, rats, and chicks, may mediate aggressive responses predominantly through right-hemispheric brain mechanisms, o 1996 Wiley-Liss, Inc.
Nitric oxide (NO) is a biologically active inorganic molecule produced when the semiessential amino acid l-arginine is converted to l-citrulline and NO via the enzyme nitric oxide synthase (NOS). NO is known to be involved in the regulation of many physiological processes, such as control of blood flow, platelet adhesion, endocrine function, neurotransmission, neuromodulation, and inflammation, to name only a few. During neuropathological conditions, the production of NO can be either protective or toxic, dependent on the stage of the disease, the isoforms of NOS involved, and the initial pathological event. This paper reviews the properties of NO and NOS and the pathophysiology of Huntington's disease (HD). It discusses ways in which NO and NOS may interact with the protein product of HD and reviews data implicating NOS in the neuropathology of HD. This is followed by a synthesis of current information regarding how NO/NOS may contribute to HD-related pathology and identification of areas for potential future research. J. Neurosci. Res. 64:99 -107, 2001.
Patients diagnosed with Huntington's Disease (HD) commonly show a denial of symptoms and an unawareness of the motoric, cognitive, and emotional changes that accompany this disease. To examine if this denial has a neurological component to it, 19 patients who received a positive diagnosis of HD from the presymptomatic HD clinic at the University of Connecticut Medical School, and 14 consecutive patients referred for neuropsychological testing with nonHD diagnoses, were administered a simple, eight-item self-report test that asked them to rate their cognitive and motoric abilities. Two staff members, both of whom met with the patients and were familiar with the neuropsychological test results, similarly rated the patients' deficits. HD patients were then divided into "high" (HA) vs. "low" (LA) anosognosia groups based on differences between their self-ratings and staff ratings, and given a neuropsychological battery. Correlation's between the two investigators found that the eight-item scale was highly reliable across investigators (R =.89). HD patients were significantly different from controls in their self-rating of their own capabilities in comparison to staff ratings (p <.05). ANOVA found the HA HD patients to be impaired relative to the LA HD group on a number of neuropsychological measures, including the Wisconsin Card Sorting Test and various measures pertaining to visual-spatial ability on the Wechsler Adult Intelligence Scale-Revised. These findings suggest that a component of the "illness denial" that HD patients exhibit, and that traditionally have been attributed to "psychodynamic" factors, likely have a neurological component to them. Implications of these findings for teams who are preparing to provide anosognostic HD patients with positive results regarding their HD workup is discussed.
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