Table 2.

Summary of brain areas, functions associated with and symptoms related to weightless/space conditions.

Brain Area (*)	Function	Symptom
Primary somatosensory cortex (1, 2, 3)	Proprioception Somatic sensations	Somatosensory problems, self-position accuracy problems
Parietal cortex, somatosensory association cortex (5, 7)
Primary and association visual cortex (17, 18)	Visual perception	Color perception problems, loss of acuity
Auditory association cortex (22)	Hearing and auditory perception	Sound localization in binaural hearing
Prefrontal cortex and premotor cortex (11, 47, 6)	Problem solving, executive functions, working memory, task management, inhibitory control, decision making and attention	Executive problems: decision-making errors, attention problems, spatial working memory, concentration problems
Primary motor cortex (4)	Voluntary motor initiation, especially in the distal extremities and facial and oral musculature	Difficulty acquiring targets in voluntary movements, transient effects during first month
Frontal eye field (8)	Non-tracking voluntary eye movements, visual attention	Visual attention problems
Cerebellum	Motor control	Motor coordination and movement-timing problems
Entorhinal cortex, olfactory cortex, insula (34)	Olfaction, taste and memory	Perceived changes in taste and smell of food
Vestibular system and cortex	Gravity-sensing, 3D positioning in space, and sensory orientation-integration.	Space motion sickness, malaise, headache, vomiting, lack of motivation and dizziness
Limbic system	Emotions, social behavior, attention, memory, motivation, olfaction, learning, decision-making and reward sensitiveness	Diminished social interaction, irritability, concentration problems, lack of motivation, memory problems, depression, anxiety and mood problems
Brainstem	Sleep cycle and arousal	Sleep problems

* Numbers indicate Brodmann’s area codes (see Figure 1).