Animals, including humans, explore the environment using active strategies that involve moving their sensors (fingers, eyes). An excellent example of this type of behavior is active whisking in rodents. During active whisking, rats move their whiskers in stereotyped ways making contact with objects (active touch) to identify them and to explore the environment. An important problem is that sensory systems in the brain must detect the neural activity related to active touch by distinguishing it from the activity caused by moving the whiskers. The whiskers transmit this sensory information through primary sensory relay cells in the trigeminal complex, which produce two major ascending and contralateral pathways. One innervates the thalamus, leading primarily to the neocortex in the forebrain (trigeminothalamic), and the other innervates the deep layers of the superior colliculus in the midbrain tectum (trigeminotectal). The role of these two ascending pathways in the detection of active touch signals during exploratory whisking is poorly understood. We propose that the superior colliculus is a major sensory relay that serves to detect touch signals during exploratory behavior by differentiating movement-related and contact-related activity. Therefore, in agreement with its well-known role in orienting to novel stimuli, the superior colliculus is an essential component of the sensory circuitry responsible for the detection of sensory stimuli during active exploration. There are three goals in this project. The first goal is to determine the response properties of superior colliculus cells during whisking movement and touch. The second goal is to determine the role of superior colliculus afferents in driving and/or modulating the whisking responses. The third goal is to characterize the activity and response properties of superior colliculus cells as animals actively move their whiskers and detect behaviorally relevant sensory stimuli during exploratory behavior. The long term goal of this research project is to reveal the neural substrates of sensory detection and processing, which has direct relevance to many neurological disorders.

Public Health Relevance

This goal of this research is to determine the role of the superior colliculus, and other brain structures, in the detection and processing of sensory (tactile) stimuli during exploratory behavior. Such basic knowledge is vital to understand how the brain mediates normal behavior and has direct relevance to many neurological and psychiatric disorders, such as sensory neglect syndromes, learning disabilities, autism, anxiety disorders, and others.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Sensorimotor Integration Study Section (SMI)
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Gnadt, James W
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Drexel University
Anatomy/Cell Biology
Schools of Medicine
United States
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Castro-Alamancos, Manuel A; Favero, Morgana (2015) NMDA receptors are the basis for persistent network activity in neocortex slices. J Neurophysiol 113:3816-26
Castro-Alamancos, Manuel A; Bezdudnaya, Tatiana (2015) Modulation of artificial whisking related signals in barrel cortex. J Neurophysiol 113:1287-301
Castro-Alamancos, Manuel A; Gulati, Tanuj (2014) Neuromodulators produce distinct activated states in neocortex. J Neurosci 34:12353-67
Bezdudnaya, Tatiana; Castro-Alamancos, Manuel A (2014) Neuromodulation of whisking related neural activity in superior colliculus. J Neurosci 34:7683-95
Castro-Alamancos, Manuel A (2013) The motor cortex: a network tuned to 7-14 Hz. Front Neural Circuits 7:21
Favero, Morgana; Castro-Alamancos, Manuel A (2013) Synaptic cooperativity regulates persistent network activity in neocortex. J Neurosci 33:3151-63
Favero, Morgana; Varghese, Gladis; Castro-Alamancos, Manuel A (2012) The state of somatosensory cortex during neuromodulation. J Neurophysiol 108:1010-24
Bezdudnaya, Tatiana; Castro-Alamancos, Manuel A (2011) Superior colliculus cells sensitive to active touch and texture during whisking. J Neurophysiol 106:332-46
Hirata, Akio; Castro-Alamancos, Manuel A (2011) Effects of cortical activation on sensory responses in barrel cortex. J Neurophysiol 105:1495-505
Hirata, Akio; Castro-Alamancos, Manuel A (2010) Neocortex network activation and deactivation states controlled by the thalamus. J Neurophysiol 103:1147-57

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