127
Static, Low-Frequency, and Pulsed Magnetic Fields
with cytoskeletal filaments and thermal fluctuations to derive constraints for possible
transduction mechanisms involving mechanosensory elements such as ion channels.
Nishimura et al. (2010) investigated the behavioral responses of a diurnal agamid
lizard (Pogona vitticeps) to a sinusoidal extremely low frequency electric and magnetic
field (ELF-EMF; 6 and 8 Hz, 2.6 μT, 10 V/m). Lizards in the EMF group were exposed
to ELF-EMF for 12 hours a day (during the daytime). The number of tail lifts was monitored beginning 3 days before exposure and ending after 5 days of exposure. The average
number of tail lifts per individual per day was found to be greater in the EMF group
than in the control group. The authors confirmed the reproducibility of this response
by a crossover trial. These results suggest that at least some lizards are able to perceive
ELF-EMF. Furthermore, when the parietal eye of the lizards was covered with a small
round aluminum cap, which could block light, the tail-lifting response to ELF-EMF
disappeared. These experiments suggest that lizards can perceive EMF and the parietal
eye may be involved in light-dependent magnetoreceptive responses.
3.3.1.2 Behavior and Recognition
Scientific interest in behavioral changes in organisms has led to the development of
a psychology of learning that studies the effects of various external stimuli in living
organisms. Several investigations have been conducted for studying the effects of magnetic fields on behavior and the central nervous system of organisms using techniques
developed specifically in these research fields. Behavioral research directed toward the
effects of magnetic exposure on living organisms mainly addresses two questions: (1)
whether magnetic fields are sensed and avoided and (2) whether magnetic fields have
any influence on the functions of learning and memory. Magnetic field experiments
addressing both the questions have been conducted using several indicators, such as
open-field behavior, operant behavior, and spontaneous motor activity, as tools of observation and measurement. This section focuses on recent advances and new aspects in
magnetic field effects and mechanisms on biological systems (see also Section 3.3.1.1).
Regarding SMF effects on the functions of learning and memory, Ammari et al.
(2008) investigated the behavioral effects of an SMF (128 mT, 1 h/day for 5 days) in male
rats. The authors concluded that SMF exposure altered emotional behaviors in the plus
maze and led to cognitive impairments, or at least substantial attention disorders, in the
Morris water maze.
Fu et al. (2008) investigated the short- and long-term effects of ELF-EMF on spatial
recognition memory in mice by using a two-trial recognition Y-maze that is based on
the innate tendency of rodents to explore novel environments. Mice were exposed to an
EMF (25 Hz, 0.6 mT; or 50 Hz, 1.1 mT) for either 7 days (short term) or 25 days (long
term) and then tested in the Y-maze. The results indicated that neither short- nor longterm exposures to EMF affected the locomotor activity of mice in the Y-maze. However,
long-term exposure to a 50 Hz EMF reduced recognition of the novel arm. These findings
suggest that ELF-EMF impairs spatial recognition memory in the Y-maze depending on
the field strength or the duration of exposure or both.
In contrast, Liu et al. (2008) suggested that ELF-EMF (50 Hz, 2 mT) improves learning and memory function. In this study, authors examined the changes in spatial learning and memory in rats using the Morris water maze test after 4 weeks of daily exposure
Static, Low-Frequency, and Pulsed Magnetic Fields
with cytoskeletal filaments and thermal fluctuations to derive constraints for possible
transduction mechanisms involving mechanosensory elements such as ion channels.
Nishimura et al. (2010) investigated the behavioral responses of a diurnal agamid
lizard (Pogona vitticeps) to a sinusoidal extremely low frequency electric and magnetic
field (ELF-EMF; 6 and 8 Hz, 2.6 μT, 10 V/m). Lizards in the EMF group were exposed
to ELF-EMF for 12 hours a day (during the daytime). The number of tail lifts was monitored beginning 3 days before exposure and ending after 5 days of exposure. The average
number of tail lifts per individual per day was found to be greater in the EMF group
than in the control group. The authors confirmed the reproducibility of this response
by a crossover trial. These results suggest that at least some lizards are able to perceive
ELF-EMF. Furthermore, when the parietal eye of the lizards was covered with a small
round aluminum cap, which could block light, the tail-lifting response to ELF-EMF
disappeared. These experiments suggest that lizards can perceive EMF and the parietal
eye may be involved in light-dependent magnetoreceptive responses.
3.3.1.2 Behavior and Recognition
Scientific interest in behavioral changes in organisms has led to the development of
a psychology of learning that studies the effects of various external stimuli in living
organisms. Several investigations have been conducted for studying the effects of magnetic fields on behavior and the central nervous system of organisms using techniques
developed specifically in these research fields. Behavioral research directed toward the
effects of magnetic exposure on living organisms mainly addresses two questions: (1)
whether magnetic fields are sensed and avoided and (2) whether magnetic fields have
any influence on the functions of learning and memory. Magnetic field experiments
addressing both the questions have been conducted using several indicators, such as
open-field behavior, operant behavior, and spontaneous motor activity, as tools of observation and measurement. This section focuses on recent advances and new aspects in
magnetic field effects and mechanisms on biological systems (see also Section 3.3.1.1).
Regarding SMF effects on the functions of learning and memory, Ammari et al.
(2008) investigated the behavioral effects of an SMF (128 mT, 1 h/day for 5 days) in male
rats. The authors concluded that SMF exposure altered emotional behaviors in the plus
maze and led to cognitive impairments, or at least substantial attention disorders, in the
Morris water maze.
Fu et al. (2008) investigated the short- and long-term effects of ELF-EMF on spatial
recognition memory in mice by using a two-trial recognition Y-maze that is based on
the innate tendency of rodents to explore novel environments. Mice were exposed to an
EMF (25 Hz, 0.6 mT; or 50 Hz, 1.1 mT) for either 7 days (short term) or 25 days (long
term) and then tested in the Y-maze. The results indicated that neither short- nor longterm exposures to EMF affected the locomotor activity of mice in the Y-maze. However,
long-term exposure to a 50 Hz EMF reduced recognition of the novel arm. These findings
suggest that ELF-EMF impairs spatial recognition memory in the Y-maze depending on
the field strength or the duration of exposure or both.
In contrast, Liu et al. (2008) suggested that ELF-EMF (50 Hz, 2 mT) improves learning and memory function. In this study, authors examined the changes in spatial learning and memory in rats using the Morris water maze test after 4 weeks of daily exposure