Analysis of brain activity during local hot-cold stimulus using near-infrared spectroscopy (Analysis of brain activity during pain stimulus by cold stimulus)

Abstract

Methods such as the Predicted Mean Vote and Standard New Effective Temperature were developed to evaluate thermal comfort. However, radiation and convection of heat due to factors such as sunlight or air cycle are strong in indoor environments. Moreover, the thermal environment in such indoor environment is non-uniform and locally inhomogeneous, which makes evaluation thermal comfort difficult. We aim to evaluate the local thermal environment by analyzing brain activity. The final goal is to develop an air conditioning control system in non-uniform and locally inhomogeneous thermal environment by brain activity. In this paper, we describe analysis of brain activity during local cold stimulation. We measured oxyhemoglobin (oxyHb) levels in the prefrontal cortex and the primary somatosensory cortex while subjects touched aluminum plates that were cooled or heated to different temperatures. The results show that oxyHb changes in the prefrontal cortex vary according to the temperature of the aluminum plates.

Central Nervous System Responses to Comfortable Thermal Stimuli to the Soles of the Feet with Simultaneous Presentation of Other Sensory Stimuli

“…Moreover, the researchers reported that cold water significantly decreased activity in the θ (4.0 -8.0 Hz) and α1 bands after presentation, compared with warm water [7]. Regarding the relationship between cerebral blood flow and thermal stimulation, Hou et al [8] reported that cerebral blood flow in the frontal lobe during the presentation of local hot-cold stimuli to the hand using an aluminum plate exhibited increased or decreased oxy-Hb under specific temperature conditions. With hot stimulation, oxy-Hb decreased at 39 °C and increased at 45 °C [8].…”

“…Regarding the relationship between cerebral blood flow and thermal stimulation, Hou et al [8] reported that cerebral blood flow in the frontal lobe during the presentation of local hot-cold stimuli to the hand using an aluminum plate exhibited increased or decreased oxy-Hb under specific temperature conditions. With hot stimulation, oxy-Hb decreased at 39 °C and increased at 45 °C [8]. Taken together, the studies described above suggest that brain activity varies depending on the presentation temperature.…”

“…Music stimuli, movie stimuli, illumination stimuli, odor stimuli and vibration stimuli (applied to the trunk) were presented. Previous studies evaluated participants' brain activity when presenting stimuli to a single sensory modality, based on physiological responses of the central nervous system [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. However, few studies have examined the combination thermal stimuli with stimulation of other sensory modalities.…”