21 research outputs found
Visual discomfort from flash afterimages of riloid patterns
Op-art-based stimuli have been shown to be uncomfortable, possibly due to a combination of fixational eye movements (microsaccades) and excessive cortical responses. Efforts have been made to measure illusory phenomena arising from these stimuli in the absence of microsaccades, but there has been no attempt thus far to decouple the effects of the cortical response from the effect of fixational eye movements. This study uses flash afterimages to stablise the image on the retina and thus reduce the systematic effect of eye movements, in order to investigate the role of the brain in discomfort from op-art-based stimuli. There was a relationship between spatial frequency and the magnitude of the P300 response, showing a similar pattern to that of discomfort judgements, which suggests there might be a role of discomfort and excessive neural responses independently from the effects of microsaccades
Visual discomfort from flash afterimages of riloid patterns
Op-art-based stimuli have been shown to be uncomfortable, possibly due to a combination of fixational eye movements (microsaccades) and excessive cortical responses. Efforts have been made to measure illusory phenomena arising from these stimuli in the absence of microsaccades, but there has been no attempt thus far to decouple the effects of the cortical response from the effect of fixational eye movements. This study uses flash afterimages to stabilise the image on the retina and thus reduce the systematic effect of eye movements, in order to investigate the role of the brain in discomfort from op-art-based stimuli. There was a relationship between spatial frequency and the magnitude of the P300 response, showing a similar pattern to that of discomfort judgements, which suggests that there might be a role of discomfort and excessive neural responses independently from the effects of microsaccades
Studying the effects of thalamic interneurons in a thalamocortical neural mass model
Neural mass models of the thalamocortical circuitry are
often used to mimic brain activity during sleep and
wakefulness as observed in scalp electroencephalogram
(EEG) signals [1]. It is understood that alpha rhythms
(8-13 Hz) dominate the EEG power-spectra in the resting-state
[2] as well as the period immediately before
sleep [3]. Literature review shows that the thalamic
interneurons (IN) are often ignored in thalamocortical
population models; the emphasis is on the connections
between the thalamo cortical relay (TCR) and the thalamic
reticular nucleus (TRN). In this work, we look into
the effects of the IN cell population on the behaviour of
an existing thalamocortical model containing the TCR
and TRN cell populations [4]. A schematic of the
extended model used in this work is shown in Fig.1.
The model equations are solved in Matlab using the
Runge-Kutta method of the 4th/5th order. The model
shows high sensitivity to the forward and reverse rates
of reactions during synaptic transmission as well as on
the membrane conductance of the cell populations. The
input to the model is a white noise signal simulating
conditions of resting state with eyes closed, a condition
well known to be associated with dominant alpha band
oscillations in EEG e.g. [5]. Thus, the model parameters
are calibrated to obtain a set of basal parameter values
when the model oscillates with a dominant frequency
within the alpha band. The time series plots and the
power spectra of the model output are compared with
those when the IN cell population is disconnected from
the circuit (by setting the inhibitory connectivity parameter
from the IN to the TCR to zero). We observe
(Fig. 2 inset) a significant difference in time series output
of the TRN cell population with and without the IN
cell population in the model; this in spite of the IN
having no direct connectivity to and from the TRN cell
population (Fig. 1). A comparison of the power spectra
behaviour of the model output within the delta
(1-3.5Hz), theta (3.75-7.5Hz), alpha (7.75-13.5Hz) and
beta (13.75-30.5Hz) bands is shown in Fig. 2. Disconnecting
the IN cell population shows a significant drop in the
alpha band power and the dominant frequency of oscillation
now lies within the theta band. An overall ‘slowing’
(left-side shift) of the power spectra is observed with an
increase within the delta and theta bands and a decrease
in the alpha and beta bands. Such a slowing of EEG is a
signature of slow wave sleep in healthy individuals, and
this suggests that the IN cell population may be centrally
involved in the phase transition to slow wave sleep [6]. It
is also characteristic of the waking EEG in Alzheimer’s
disease, and may help us to understand the role of the IN
cell population in modulating TCR and TRN cell behaviour
in pathological brain conditions
Effect of within-session breaks in play on responsible gambling behaviour during sustained monetary losses
Rapid, continuous gambling formats are associated with higher risks for gambling-related harm in terms of excessive monetary and time expenditure. The current study investigated the effect on gambling response latency and persistence, of a new form of within-game intervention that required players to actively engage in response inhibition via monitoring for stop signals. Seventy-four experienced electronic gaming machine gamblers, with a mean age of 35.28 years, were recruited to participate in a rapid, continuous gambling task where real money could be won and lost. Participants were randomly allocated to either the control condition where no intervention was presented, or either a condition with a passive three minute break in play or a condition with a three minute intervention that required participants to engage in response inhibition. Although there was no main effect for experimental condition on gambling persistence, both interventions were effective in elevating response latency during a period of sustained losses. It was concluded that within-game interventions that create an enforced break in play are effective in increasing response latency between bets during periods of sustained losses. Furthermore, within-game interventions that require active involvement appear to be more effective in increasing response latency than standard, passive breaks in play
2. London-Havana Diary: Art Publishing, Sustainability, Free Speech and Free Papers
May 2018, London I’ve been prompted to sign off the essay about art publishing in Havana that I wrote for this anthology over two years ago, but I can’t bear to do it. In part because the world seems so changed, and changing, in part because I am. I read in the essay a false confidence. Not that my report was proved incorrect, but that in attempting an overview, the writing failed to address its own relationship to the issues — of self-censorship, institutional power, and control of access to..
Individual correlations between discomfort judgements and VEP amplitude.
<p>Correlations between discomfort judgements and VEP amplitude for each of the nine stimuli (each stimulus represented by one point), plotted individually.</p
Time series of EEG.
<p>Mean EEG amplitude time series for three levels of spatial frequency (<i>λ</i>), for leftmost plot waviness (<i>μ</i>) = 100 (waviest lines) through to rightmost plot waviness (<i>μ</i>) = inf (straight lines). Top row = O1, bottom row O2.</p
Discomfort judgements (left) and VEP amplitude (right).
<p>Left Mean discomfort judgements against spatial frequency (<i>λ</i>) for three levels of line waviness (<i>μ</i>). <i>μ</i> = 100 are the waviest, <i>μ</i> = inf are the straight lines. Error bars are one standard error. Right Mean VEP amplitude against spatial frequency (<i>λ</i>), for three levels of waviness (<i>μ</i>). <i>μ</i> = 100 are the waviest, waviness <i>μ</i> = inf are the straight lines. Error bars are one standard error.</p