How the mind sharpens the senses
Zen meditation improves sense of touch
Mental states induce neuroplasticity and learning
Participants of the study use a special meditation technique
The participants were all Zen-scholars with many years of meditation practice. They were scientifically escorted during a four-day Zen-retreat in the spiritual center “Benediktushof”, Germany. The retreat was held in complete silence, with at least eight hours of meditation per day. All participants practiced their familiar meditation, which is characterized by a non-specific monitoring of thoughts and surroundings. Additionally, some participants applied a special finger-meditation for two hours per day, during which they were asked to specifically focus on their right index finger and become aware of spontaneously arising sensory percepts in this finger. Subsequent assessment of the group that practiced finger-meditation showed a significant improvement in the tactile acuity of the right index and middle finger. A control group that had maintained their familiar meditation practice for the whole time, showed no changes in tactile acuity.
Data show significant improvement of the sense of touch
In order to assess the sense of touch quantitatively, researchers measured the so-called “two-point discrimination threshold”. This marker indicates how far apart two stimuli need to be, in order to be discriminated as two separate sensations. After the finger meditation, the performance improved on average by 17 percent. By comparison, tactile acuity of the visually impaired is 15 to 25 percent above that of typical sighted individuals, because their sense of touch is used so intensively to make up for the reduced visual information. Hence, the changes induced by meditation are comparable to those achieved by intense long-term training.
Meditation induces plasticity and learning processes as active training or physical stimulation
It is known for long that extensive training induces neuroplasticity, which denotes the ability of the brain to adapt and restructure itself, thereby improving perception and behavior. Recently, the group of neuroscientists of the Neural Plasticity Lab headed by Hubert Dinse has shown that these processes can be initiated even without training by mere exposure to passive stimulation, which was translated only recently into a stimulating glove, which is used as therapeutical intervention in stroke patients. The fact that merely mental states without any physical stimulation can improve perception has now been shown for the first time. “The results of our study challenge what we know about learning mechanisms in the brain. Our concept of neuroplasticity must be extended, because mental activity seems to induce learning effects similar to active stimulation and physical training,” Dinse suggests.
The study was funded by the German Research Foundation (DFG, SFB 874), the BMBF, Bernstein Focus State Dependencies of Learning and supported by the Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, and the Willigis-Jäger Stiftung West-Östliche Weisheit.
Philipp ST, Kalisch T, Wachtler T, Dinse HR (2015) Enhanced tactile acuity through mental states. Sci. Rep. 5,13549; doi: 10.1038/srep13549