subcortical arousal in perceptual awareness

Conditions: Epilepsy

Summary: the study is a multi-site study and will be conducted at up to 11 investigative sites in the united states. the study will investigate subcortical arousal circuits in visual perception using techniques with complementary strengths based on promising initial studies.

the study will investigate subcortical arousal circuits in visual perception using techniques with complementary strengths based on promising initial studies. this study is expected to shed important light on the precise relationship between transient increases in subcortical arousal and perceptual awareness, generalizable across the visual modality. this research will therefore provide important general potential benefits, including 1. identification of subcortical arousal systems in perception, which can benefit treatment of many disorders where perceptual deficits are common, e.g. traumatic brain injury, alzheimer's disease, stroke, developmental disorders, schizophrenia, epilepsy and others. 2. understanding the role of specific subcortical arousal circuits in perception may help target improved treatments, including transient thalamic stimulation like that planned for the present investigations, or less invasive treatments (tms, tdcs, designer drugs) to improve function of these circuits. 3. the planned no-report paradigms may detect perceptual awareness in severe brain damage and anesthesia, where people are unable to overtly respond. the main hypotheses are that 1. the thalamic awareness potential (tap) will be associated with visual perception independent of report, and 2. thalamic intralaminar stimulation at the time of stimulus presentation will augment the probability of perceptual awareness.

Eligibility criteria:
the following are the inclusion/exclusion criteria for epilepsy patients with thalamic electrodes age 13 years and up (aim 1): inclusion criteria: * normal vision with or without the use of corrective lenses * normal hearing not needing an assistive hearing device exclusion criteria: * severe vision impairment even with correction preventing ability to see stimuli (prevents accurate pupil and eye gaze measurements) * unable to perform the perception task due to cognitive impairment other than due to the participant's epilepsy. all participants must be capable of consenting for themselves. the following are the inclusion/exclusion criteria for epilepsy patients with thalamic electrodes age 18 years and up (aim 2): inclusion criteria: * normal vision with or without the use of corrective lenses * normal hearing not needing an assistive hearing device * a female subject must have a negative pregnancy test and if sexually active, must be using a reliable form of birth control for the duration of the trial, be surgically sterile, or be at least two years post-menopausal. exclusion criteria: * severe vision impairment even with correction preventing ability to see stimuli (prevents accurate pupil and eye gaze measurements) * unable to perform the perception task due to cognitive impairment other than due to participant's epilepsy. all participants must be capable of consenting for themselves. * pregnancy