section_path: Science/Neuroscience
section_name: Neuroscience
paragraph_text: Neuroscience
  
  As an interdisciplinary field and its branch of cognitive neuroscience particularly, neuroscience operates under the ontological assumption of physicalism. In other words, it assumes that only the fundamental phenomena studied by physics exist. Thus, neuroscience seeks to understand mental phenomena within the framework according to which human thought and behavior are caused solely by physical processes taking place inside the brain, and it operates by the way of reductionism by seeking an explanation for the mind in terms of brain activity.
  
  To study the mind in terms of the brain, several methods of functional neuroimaging are used to study the neuroanatomical correlates of various cognitive processes that constitute the mind. The evidence from brain-imaging indicates that all processes of the mind have physical correlates in brain function; however, such correlational studies cannot determine whether neural activity plays a causal role in the occurrence of these cognitive processes (correlation does not imply causation) and they cannot determine if the neural activity is either necessary or sufficient for such processes to occur. Identification of causation, and of necessary and sufficient conditions, requires explicit experimental manipulation of that activity. If manipulation of brain activity changes consciousness, then a causal role for that brain activity can be inferred.
  
  Two of the most common types of manipulation experiments are loss-of-function and gain-of-function experiments. In a loss-of-function (also called "necessity") experiment, a part of the nervous system is diminished or removed in an attempt to determine if it is necessary for a certain process to occur, and in a gain-of-function (also called "sufficiency") experiment, an aspect of the nervous system is increased relative to normal. Manipulations of brain activity can be performed with direct electrical brain stimulation, magnetic brain stimulation using transcranial magnetic stimulation, psychopharmacological manipulation, optogenetic manipulation, and by studying the symptoms of brain damage (case studies) and lesions. In addition, neuroscientists are also investigating how the mind develops with the development of the brain.