Biomedical Engineering Reference
In-Depth Information
(i.e., single blinks) has a relatively high baseline frequency. However, when the base-
line frequency of single blinks is low, this form of response might be targeted without
foreseeable difficulties. In line with this view, Lancioni et al. (2009b) used a single-blink
response with a man of 26 years of age who had suffered severe brain injury and coma
after a road accident and had a diagnosis of a minimally conscious state with pervasive
neuromotor disabilities. The microswitch was an adapted version of the optic sensor
described above (Lancioni et al. 2005a, 2006f). The performance of single blink responses
allowed the man to access brief periods of preferred stimulation during the intervention
phases. The response frequencies during those phases increased rapidly and remained
high.
Lancioni et al. (2007b) investigated the possibility of using small upward or downward
movements of the forehead skin as the response through which participants of 6 and
14 years of age could control relevant stimulation. The microswitch consisted of an optic
sensor (barcode reader) with an electronic regulation unit and a small tag with horizontal
bars that was kept on the participants' forehead. The optic sensor was held in front of the
tag. During the intervention, small movements of the tag (consequent to small upward or
downward movements of the forehead skin) triggered the microswitch system and caused
brief periods of preferred stimulation. Both participants had a clear response increase dur-
ing the intervention phases of the study.
Lancioni et al. (2007c) reported the use of small hand-closure movements as the response
with two participants of 5 and 21 years of age. The response consisted of the participants'
fingers touching or pressing on a microswitch fixed to the palm of their hand. The micro-
switch involved a two-membrane thin device. The outer membrane (i.e., the one directly
exposed to the participants' fingers) was a touch-sensitive sensor and was activated by
contact with any of their fingers. The inner membrane was activated if the participants
applied a pressure of approximately 20 g. Data showed that both participants success-
fully learned to use the microswitch as a way to access preferred stimulation during the
intervention.
Lancioni et al. (2009a) investigated the use of eyebrow lifting as the target response with
a 68-year-old man with a diagnosis of minimally conscious state and pervasive neuromo-
tor disabilities after traumatic brain injury and coma. The microswitch adopted for this
response was a modified version of the optic sensor used in the studies targeting eyelid
closures and eyelid upward movements (see above). Eyebrow lifting was instrumental to
allow the man brief access to preferred visual stimuli (i.e., video-clips with sport events
and comic sketches) during the intervention periods of the study. Data showed that the
response frequency increased largely during the intervention as compared with the base-
line period.
Lancioni et al. (2010a) reported new research efforts aimed at building alternatives to
the aforementioned experimental microswitches. These alternatives were to overcome
a perceived limit of the aforementioned microswitches, specifically, their need to be
held close to the part of the body producing the response (e.g., eyelids, lips, and fore-
head) through support frames (e.g., eyeglasses). Those support frames may be viewed
as slightly invasive (not always pleasant) for the participant and not always practical or
reliable for staff personnel responsible of their use within the programs. In fact, they
may be difficult to place/maintain whenever the participant has dystonic movements
or a head posture unsuitable to the stability of the frame. The alternatives investigated
involved camera-based technology. This technology was used to monitor eyelid-closure
responses by a man of 25 years of age. The man's left eyelid was provided with a green
color spot greater than 1.5 cm
2
. The spot would be minimally visible when the eye was
