The interpolated contrast discrimination functions gave the thres

The interpolated contrast discrimination functions gave the threshold buy TSA HDAC contrast, Δc, for any contrast, c, for a behavioral sensitivity of d′ = 1 (see above, Psychophysical Contrast-Discrimination Functions), thus: equation(6) R(c+Δc)=R(c)+σ.R(c+Δc)=R(c)+σ.

To compute the next point on the contrast-response function, we thus applied Equation 6, for c = 0 and Δc as estimated from the interpolated contrast discrimination function, i.e., R(Δc) = b + σ. Subsequent values of R were computed by repeated application of Equation 6 in which each new c was set to c+Δc from the previous iteration and Δc for that new contrast c, was retrieved from the interpolated contrast discrimination function (see Supplemental Experimental Procedures, for more details on the fitting procedure). σ and b were adjusted to produce the best fit of the contrast-response functions in the least-squares sense. The contrast-discrimination functions were fit (nonlinear least-squares) by the selection model, using (1) and (3). To perform Decitabine ic50 the fit, the contrast discrimination performance of the selection model (percent [%] correct) was computed by simulating synthetic trials based on

responses computed from the measured contrast-response functions. Contrast-response functions were interpolated with a simplified version of Equation 3 (a Naka-Rushton type equation), which lacked the exponent s. The exact form of the interpolation function was not essential (see Supplemental Experimental Procedures).

For any fixed value of k ( Equation 1) and value of the sensory noise (σ), the selection model performance (percent [%] correct) was computed as follows. For each pedestal contrast, Gaussian response distributions were computed for each stimulus location and each ever interval of the task ( Figure 7A). The mean of each response distribution was determined according to the interpolated contrast-response functions. The standard deviations of the Gaussian response distributions were set to the σ parameter. Responses were then combined into “readout” distributions using the max-pooling rule ( Equation 1) and the parameter k ( Figure 7B). On each of 10,000 simulated trials, a response was taken from the readout distribution for each interval. If the larger of these two responses was in the same interval as the increment in contrast, the trial was marked as correct. The Δc that produced 76% correct values using this procedure was taken as the discrimination threshold. Values of k and σ were adjusted to produce the best fit of the contrast discrimination functions in the least-squares sense. We also computed two variations of the aforementioned model (see Figure 8). One variation included two σ values (σf and σd), one for the focal cue and one for the distributed cue trials.

Single Boltzmanns were used here so that x0 corresponded to the h

Single Boltzmanns were used here so that x0 corresponded to the half activation. I-X plots at −84 mV and +76 mV for different internal and external Ca2+ conditions were generated as above, but fit to a double Boltzmann equation (Equation 2) as: equation(Equation 2) y=Imax1+eZ1(x0−x)(1+eZ2(x0−x))where Z1 and Z2 are the slope factors and x0 represents

the operating point. Throughout the manuscript, Z2 is presented mTOR inhibitor as the slope. I-X plots were generated for +76 mV potentials by zeroing the MET traces prior to mechanical stimulus onset except when noted. For steps, adaptation time constant fits were obtained at ∼50% peak current using a double exponential decay (Equation 3): equation(Equation 3) y=y0+A1e−(x−x0)/τ1+A2e−(x−x0)/τ2y=y0+A1e−(x−x0)/τ1+A2e−(x−x0)/τ2where τ1 and τ2 are the reported decay constants and A1 and A2 are the amplitudes of respective decay components. Where needed adaptation time constants were fit with a triple exponential decay (Equation 4): equation(Equation 4) y=y0+A1e−(x−x0)/τ1+A2e−(x−x0)/τ2+A3e−(x−x0)/τ3y=y0+A1e−(x−x0)/τ1+A2e−(x−x0)/τ2+A3e−(x−x0)/τ3where KPT-330 clinical trial τ1, τ2, and τ3 are the reported decay constants and A1, A2,

and A3 are the amplitudes of respective decay components. τ3 values were limited to a maximum of 50 ms. Percent adaptation was calculated as (1− Isteady state/Ipeak) ∗ 100. Data were analyzed using jClamp and graphs created using Origin 8.6 and Adobe Illustrator. Statistical analysis used two-tailed Student’s t tests with Excel (Microsoft). All p values presented used paired t tests with comparisons within a cell, and unpaired unequal variance tests across cell conditions. Significance (p values) are ∗ p < 0.05, ∗∗ p < 0.01, ∗∗∗ p < 0.005. Data are presented as mean ± SD. This work was supported by NRSA F32 DC109752 and K99 DC013299 to AWP, by DAAD (German academic exchange service) to

T.E., and by RO1 DC003896 from NIDCD to A.J.R. as well as core grant P30-44992. The authors are grateful to Benjamin Chui, who helped with the design and fabrication of silicon devices. Thanks to Gregory Frolenkov for use of his pressure clamp system. “
“Temporal coding within oscillating aminophylline neuronal networks is an important organizational principle (Buzsáki, 2006 and Schnitzler and Gross, 2005). The suprachiasmatic nucleus (SCN) is a neuronal network that controls daily rhythms in mammalian behavior and physiology (Mohawk and Takahashi, 2011). Individual SCN neurons display self-sufficient rhythms in gene expression and electrical activity (Welsh et al., 2010) generated at the molecular level by interacting feedback loops involving the transcription and translation of clock genes (e.g., period2) ( Takahashi et al., 2008). The network-level properties of the SCN sustain robust and coherent oscillations at the population level ( Welsh et al., 2010), and intercellular interactions appear to be absent in most non-SCN tissues ( Stratmann and Schibler, 2006).

, 2012) Although it has also become clear that the effect of OT

, 2012). Although it has also become clear that the effect of OT on social behavior is highly dependent on individual differences and context, the topic remains a rich future area of study linking pharmacological, ecological, and psychiatric approaches. Another major achievement of social neuroscience has been the linking of social and physical health (Eisenberger and Cole, 2012 and Eisenberger, 2012). Early work identifying the neural correlates

of social pain (e.g., from exclusion or rejection by others) found a remarkable overlap with systems involved in physical pain and linked individual differences in physical and social pain sensitivity. Perhaps even more telling was that experiences that increased social pain also strongly influenced physical pain, and vice versa (Eisenberger, 2012). On the flip side, social support has been shown to reduce both subjective

reports and Selleck MS-275 neural responses related to physical pain, while taking Tylenol reduces not only physical pain but also hurt feelings and neural responses to social exclusion (Dewall et al., 2010). Far from simply justifying the shared (though often underappreciated) sense that social pain is as real as physical pain, the establishment of this link between the two has opened up a broad range of new studies, emphasizing the highly interactive nature of social cognition and behavior (a topic to which we will return below). Perhaps in part as a consequence of the inherent attraction selleck of the questions investigated by social neuroscience, the field has received considerable attention from the media and

hence also the general public. This has not always been a good thing. Some overpromotion of early findings in the field resulted in a subsequent backlash against Dichloromethane dehalogenase social neuroscience for its failure to deliver on those earlier promises. Particularly acute was a recent episode highlighting the difficulty of supporting many claims drawn from statistical analyses of neuroimaging data (Vul et al., 2009), an issue that pertains to both cognitive neuroscience and social psychology more broadly, but that came to a head at the intersection of these two fields. Social neuroscience, as well as the neuroimaging and psychology fields in general, has been considerably sensitized to these issues, with the overall result that statistical inferences are applied more cautiously by authors and better scrutinized by journal reviewers, publication biases are being exposed in the literature, and increased value has been assigned to replication (Francis, 2012, Green et al., 2008, Kriegeskorte et al., 2010 and Poldrack, 2011). However, given the complexity of the phenomena studied by social neuroscience, these issues will continue to demand attention.

Extracellular polarization of the hair cells produced a transvers

Extracellular polarization of the hair cells produced a transverse motion of the

tectorial membrane toward the neural limb (Figures 7B and 7C). PARP inhibitor A mean negative displacement of beads of 24 ± 16 nm (range 10 to 56 nm; d = 0.36–0.51) was achieved in eight preparations using 100 μA current flowing from the abneural to neural electrodes. These measurements were made on beads located above SHCs and, by focusing through the tectorial membrane, it was possible also to image the bundles ( Figures 7A and 7B). Comparison of the relative displacement of the hair bundle to that of beads lying directly above the bundle indicated that the bundle moved slightly more than the LBH589 purchase bead ( Figure 7B). The ratio of the bundle to bead displacement for the same polarization was 1.45 ± 1.1 (n = 5), though this is not significantly different from 1 (two-tailed Students t test, p = 0.2), suggesting a tight coupling of the bundles to the tectorial membrane. Tectorial membrane

motion in response to extracellular stimulation was also monitored over the THCs, the mean negative displacement being 25 ± 22 nm (n = 4). The displacements obtained by extracellular polarization were similar to those elicited from individual SHCs in that they were reversibly blocked by 10 mM Na+ salicylate (Figure 7C). This reversible block, shown in four preparations, makes it unlikely that lateral movements produced by extracellular currents stemmed from a direct electrophoretic motion of the tectorial membrane. The dose-response relationship for the action of salicylate on the voltage-evoked movements (Figures 7D and 7E) was fit with a Hill equation with a half-blocking concentration of 3.6 mM, similar to that in OHCs (Tunstall et al., 1995).

In order to ascertain whether the bundle movements were elicited over the same range of membrane potentials as those seen in individual SHCs, we estimated the membrane depolarization evoked by extracellular polarization. To do this, SHCs were patch clamped in a preparation in which the 17-DMAG (Alvespimycin) HCl tectorial membrane had been removed but which was stimulated by extracellular current polarization (Figure 7F). The change in membrane potential increased with the current polarization, as did the size of the hair bundle movement. In multiple SHC recordings, the depolarization (measured in current clamp) was proportional to the magnitude of the external current from 40 to 100 μA, with a proportionality constant of 0.74 mV/μA. If extracellular current stimuli are as effective in the presence of the tectorial membrane, the 100 μA polarization routinely used would depolarize the SHCs to ∼20 mV assuming they have a resting potential of about −55 mV in perilymph (Tan et al., 2013).

Dendritic spikes consist of

Dendritic spikes consist of PD-0332991 clinical trial an initial fast, followed by a slower component (Figure 7G, upper traces), as described previously (Losonczy and Magee, 2006 and Remy et al., 2009). The initial fast component of the dendritic spike was particularly apparent as a marked increase

in the first derivative of the somatic voltage trace (Figure 7G inset, Figure 7I, δV/δt). Dendritic spikes could never be elicited by synchronous uncaging in dentate granule cells (n = 47 dendrites). Thus, CA1 dendrites are capable both of linear and supralinear integration via dendritic spikes. Dentate granule cells, in contrast, invariably exhibit linear integration, but with a variable gain. The observation that the relationship of measured versus expected gluEPSPs was linear over a wide range of input strengths was surprising, since we expected that the loss of local driving force at the dendritic stimulation site would lead to a saturation of the local EPSP size with increasing stimulation

strength (for estimation of the magnitude of this effect see Experimental Procedures). These data suggested the presence of a voltage-dependent Talazoparib datasheet boosting mechanism that normalizes EPSPs for the loss of driving force and causes a linear gain. Because synaptically elicited perforant path EPSCs had a substantial NMDA component (NMDA/AMPA peak current ratio 1.08 ± 0.12, n = 9, Figure S3, see also Keller et al., 1991), we explored how these receptors impact processing of synchronous

input. In the presence of the NMDA receptor blocker D-APV, the ratio of measured versus expected gluEPSPs declined when the number of synchronously stimulated spines was increased (Figures 8A and 8B, n = 14 branches). Application of TTX (1 μM, n = 23 branches, PDK4 Figures 8C and 8D) or Ni2+ (1 mM, n = 17 branches, Figures 8E and 8F) also decreased the ratio of measured versus expected gluEPSPs (see Figure 8G for summary, Dunnett test, p < 0.0001, p = 0.004, p = 0.02, respectively), but not as strongly as the application of D-APV. These data indicate that linear integration in granule cells requires NMDA receptors, and—to a lesser extent—voltage-gated Na+ and Ca2+ channels. It should be noted that the NMDA/AMPA ratio could be enhanced in uncaging experiments, because it cannot be excluded that photoliberated glutamate gains access to perisynaptic NMDA receptors. We explored this effect in the computational model. We stimulated up to 13 synapses on the dendritic tree of a model granule cell, with synapses exhibiting the experimentally determined NMDA/AMPA ratio of 1.08, while recording voltage from the dendritic stimulation site and the soma. We first stimulated an individual synaptic spine alone (•), then 12 further spines (∑○), and finally all 13 spines (∑○+ •, Figure 9A, upper traces) in a comparable manner as during uncaging experiments.

Estimates put the proportion of inhibitory neurons in layer

Estimates put the proportion of inhibitory neurons in layer

4 at 25%. Inhibition and excitation share selectivity: those stimuli that elicit excitation also elicit inhibition onto cortical neurons (Douglas et al., 1988 and Ferster, 1986). One possible PD0332991 function of such shared selectivity is to maintain the stability of the cortical circuitry. Inhibition allows a circuit to have strong excitatory recurrent connections to amplify small signals without risking runaway feedback in the excitatory network (Douglas and Martin, 1991). Strong excitatory recurrence in turn increases the dynamic range of cortical neurons, increases their information-carrying capacity, increases the ability of the cortex to perform complex computations (Hansel and Sompolinsky, 1996 and Latham and Nirenberg, 2004; Tsodyks et al., 1997 and van Vreeswijk and Sompolinsky, 1998), and may underlie surround suppression (Ozeki et al., 2009). Surround suppression is one receptive field property that probably requires strong lateral inhibition (Figure 8, black dot in column

1). But here, the underlying inhibition has the same preferred orientation as excitation: surround suppression is greatly reduced when the surround stimulus SKI-606 manufacturer is presented at the cross-orientation (Hubel and Wiesel, 1965 and DeAngelis et al., 1994). Thus, the inhibition is “”lateral”" in the spatial domain, rather than in the orientation domain. The effects of even this inhibition, however, may be weak in simple cells. Among simple cells that are dominated by excitation from the LGN, few exhibit strong surround suppression (Ozeki et al., 2009). Much effort has been directed recently into uncovering the mechanisms underlying orientation selectivity in rodents. The mouse provides opportunities to exploit recent advances in genetic labeling of specific neuronal subsets, in optogenetics, and in imaging. These techniques promise an even more detailed and fine-grained understanding

of the cortical circuit than has so far been possible in the cat. Reports that inhibitory neurons are more broadly orientation selective than excitatory neurons (Kerlin et al., 2010 and Runyan et al., 2010) and that the tuning width of inhibition recorded intracellularly is broader than that for excitation (Atallah Olopatadine et al., 2012 and Li et al., 2012) raise the possibility of cross-orientation inhibition in the mouse. Not all results are in agreement, however (Tan et al., 2011), and some experiments suggest that threshold is as important or more so in shaping neuronal responses (Jia et al., 2010). Whether or not mouse V1 uses identical mechanisms to cat V1, the following differences exist between the two in overall organization: mouse receptive fields are almost ten times larger than those in the cat, as is preferred stimulus size; mice have no orientation columns; it appears that the cortico-cortical excitatory inputs in the mouse come from cells of widely different orientation preference (Jia et al., 2010 and Ko et al.

, 2005) T3 was completed with 81 4% of the original number of pa

, 2005). T3 was completed with 81.4% of the original number of participants (N = 1816, mean age = 16.27 years, SD 0.73, 52.3% girls). Before each assessment wave, informed consent was obtained from all adolescents and their guardian(s) after the nature of the study had been fully explained. Furthermore, all of the TRAILS study procedures were approved by the International ethical committee

‘Central Committee on Research Involving Human Subjects (CCMO)’ in the Netherlands. For the INK 128 manufacturer analyses of the present study, only Dutch subjects with complete data on predictors and outcome were included in the analyses. Of the fourteen pairs of siblings within the TRAILS-sample, one of the siblings was randomly excluded. This resulted in a final sample of n = 1192. Included participants were this website equally likely to be male/female (χ2 (1 df, N = 2230) = 3.67, p > .05), more likely to have a higher socioeconomic status (χ2 (2 df, N = 2230) = 107.55, p < .001), had a higher intelligence (t = 10.02, 2169 df, p < .001), and were less likely to have initiated cannabis use at the second assessment of TRAILS (mean age 13.56 years; SD 0.53) (χ2 (1 df, N = 2230) = 6.60, p < .05) when compared

to the excluded participants. Alcohol and cannabis use: Frequency of alcohol and cannabis use was assessed at T3 by self-report questionnaires filled out at school, supervised by TRAILS assistants. Confidentiality of the study was emphasized so that adolescents were reassured that their parents or teachers would CYTH4 not have access to the information they provided. Among other questions, participants were asked to report the frequency of cannabis and alcohol use ever, in the past year, and in the past four weeks. Response options ranged from 0 to

13, with 0–10 corresponding to the equivalent number of times, and 11, 12 and 13 corresponding to, respectively, 11–19, 20–39, and at least 40 times. In order to create comparable measures of regular alcohol and cannabis use, both were defined according to the number of occasions of use. Regular alcohol consumption was defined as drinking on 10 or more occasions in the past four weeks ( Andersson et al., 2007 and Hibell et al., 2009). Regular cannabis use was defined as the use of cannabis on at least four occasions in the past four weeks. When averaged, this reflects weekly or more frequent than weekly use of cannabis. In order to minimize the possibility of including substance-related phenotypes in the comparison groups, regular users were compared to abstainers. For cannabis use, abstainers were those that reported never to have used cannabis. Because hardly any adolescents reported no alcohol consumption ever, alcohol abstainers were those that reported no consumption of alcohol in the past year. In addition, to make sure that the addressed associations were specific for regular use, rather than for substance use in general, regular users were also compared to experimental users.

Conditioned tone responses were calculated by normalizing firing

Conditioned tone responses were calculated by normalizing firing rate (z scores) during the tone relative to pretone activity (Burgos-Robles et al., 2009). In brief, we divided the 30 s tone into 10 3 s bins. A z score for each of these bins was calculated, relative to 10 pretone bins of equal duration. Neurons were considered tone responsive if the first 3 s bin following tone onset exceeded a z score of > 2.58 (p <

0.01, two tails). BGB324 datasheet Only excitatory conditioned tone responses were included. Tone responses represent the average of two trials during fear expression test after conditioning or extinction. For analysis of successive inactivations of vHPC and BLA in the same PL neuron, we used repeated-measures ANOVA followed by Tukey post hoc analysis (STATISTICA; Statsoft, Tulsa, OK). Upon completion of all experiments, rats were transcardially perfused with 0.9% saline solution followed by 10% buffered formalin.

To assist with localization of electrode placement, a microlesion was made by passing anodal current (20 μA for 20 s) through the wires to deposit iron in the tissue. Brains were extracted and fixed in a 30% sucrose/ 10% formalin solution, and 6% of ferrocyanide to stain the iron deposits. Injector’s cannula and electrode placements were verified by cutting coronal sections 40 μm thick, mounted on slides and staining for Nissl bodies with cresyl violet. Location of the tips of the injectors and electrode marking microlesions were reconstructed onto atlas coronal templates. We thank C. Bravo-Rivera and K. Quiñones-Laracuente for technical Ibrutinib cell line assistance. We also thank. M.R. Milad, D. Paré, and J.P. Johansen for helpful comments on the manuscript. This work was supported by National Institutes of Health grants (R01-MH058883 and R01-MH081975) to G.J.Q., by National Center for Research Resources award (U54 RR026139), and by

the National Institute on Minority Health and Health Disparities award (8U54MD 007587-03), Consejo Nacional de Ciencia y Tecnología fellowship to F.S.-B., APA Diversity Program in Neuroscience fellowship and R36-MH089296 to D.S.-M., and COR program (T34-MH19134) to E.P.-D. “
“An essential component of decision-making is the retrieval of values associated with stimuli and utilization of this information Oxalosuccinic acid to select responses. Value is the net payoff, or outcome, that is predicted to occur in the future given a stimulus or state. Recent studies have shed light on the neuronal correlates of value representations in the brain and how stimulus-outcome associations are updated when task contingencies are changed (e.g., Padoa-Schioppa and Assad, 2006; Platt and Glimcher, 1999; Sugrue et al., 2005). Across several species, the OFC has been consistently implicated in coding and utilizing such representations during decision making. Stimuli elicit responses in orbitofrontal neurons that are sensitive to future outcome (Hikosaka and Watanabe, 2000; Padoa-Schioppa and Assad, 2006; Schoenbaum et al.

Here, we show that greater hippocampal activation in aMCI relativ

Here, we show that greater hippocampal activation in aMCI relative to the control group was isolated to the DG/CA3 region consistent with earlier studies. Treatment with low-dose levetiracetam significantly reduced that excess activity, such

that hippocampal activation in patients on drug did not differ from age-matched control subjects. Additionally, drug treatment significantly improved three-choice recognition performance. Selleckchem Decitabine Memory errors attributable to DG/CA3 dysfunction, which differed between the groups when aMCI subjects were on placebo, were significantly reduced by levetiracetam treatment. Diagnosis of aMCI was based on criteria proposed by Petersen et al. (1999). Patients with aMCI had a global clinical dementia rating (CDR; Morris, 1993) of 0.5 with a sum of boxes score not exceeding 2.5, scored at least 1.5 standard deviations below the HDAC activation norm on neuropsychological assessments of memory function, and reported a decline of memory confirmed by an informant. These aMCI subjects showed impairments in both single and multiple domains (All neuropsychological test data acquired at baseline are shown in Table S1, available online). Healthy control subjects

had a global CDR of 0 and scored within 1 standard deviation of the norm on neuropsychological testing. Group demographics and baseline data are shown in Table 1. At the end of each treatment phase, participants completed a high-resolution fMRI scan while performing a memory task designed to assess the function of the DG/CA3 network (Bakker et al., 2008 and Lacy et al., 2011). Subjects were presented with a series of pictures of everyday objects and asked to determine for each object if the item was “new,” “old,” or “similar.” As in typical 2-judgment recognition memory tests, an item was correctly

judged “new” if it was seen for the first time in the context of the task and “old” if the item was repeated. The third option of “similar” was the correct judgment when an object only resembled an item previously seen in the task (Figure 1A). These “similar lures” were the critical trials for assessment of DG/CA3 contribution to memory performance. Correct identification of “similar” items should next depend on DG-mediated pattern separation, referring to the ability to encode inputs with some degree of overlapping information into distinctive representations. The CA3 and its strong autoassociative network mediates a complementary function of pattern completion, in which retrieval of previously stored information is based on commonalities between current input and prior experience (Figure 1B). These functions of the DG/CA3 network are supported by behavioral and neurophysiological data obtained in animal studies (Leutgeb et al., 2004, Leutgeb and Leutgeb, 2007 and McHugh et al.

During the “early phase” of the response (40–140 ms after stimulu

During the “early phase” of the response (40–140 ms after stimulus onset), the population-response (Figures 2A and 2B) and activation maps (Figure 2C) were similar among the contour and noncontour trials. Maps measured from both conditions showed clear activation patches

corresponding to the individual Gabor elements comprising the stimuli. That is, the population response in the early phase appeared to encode mainly the representation of individual Gabor elements without any obvious circle/background segregation (see also Figures S1A–S1D available online). To further analyze this, we made a scatterplot of the population response in individual V1 pixels for the two conditions (Figure 2D). The red lines depict the activity differences EGFR inhibitor between contour and noncontour trials before stimulus onset, i.e., the 1% and 99% percentile of the differences histogram (these values were then extrapolated to later times of stimulus presentation). Most pixels in the circle and background areas showed similar response amplitude and therefore lie within the red boundaries (Figure 2D). The pixel differences DAPT cost histograms (contour-noncontour; Figure 2E) are centered on zero (d′ = 0.04 between circle and background histograms. This is not significantly different from d′ computed for trials with shuffled labels,

mean d′ = 0.04, p = 0.53, 100 iterations). This means that from 60 to 80 ms the population response in V1 pixels did not differ between the contour and noncontour conditions. This situation changed completely in the “late phase” of the response (150–250 ms after stimulus onset). Whereas the population response in the circle area was only slightly higher for the contour condition (Figure 2A, late phase), the time course of the population response in the background area showed suppression (Figure 2B). This suppression was prominent in the contour condition, starting∼140 ms after stimulus onset and reaching minimal amplitude at

∼250 ms after stimulus onset. Remarkably, the neural activation Bay 11-7085 map of the late phase in the contour condition showed a clear amplitude segregation of the circle contour from the background (Figure 2F), with the high activation in the circle area simply “popping out” from the suppressed activation in the background area (see also Figure S1E, available online, for similar results in monkey S). To further analyze this, we made a scatterplot of the population response of individual V1 pixels for the two conditions (Figure 2G; red lines as in 2D). Fifty percent of V1 pixels lie above the upper boundary in the circle area (Figure 2G, left; cf. early phase Figure 2D, left). In the background area, 66% of the pixels lie below the lower boundary (Figure 2G, right cf. early phase Figure 2D, right). The pixel differences histograms (contour-noncontour; Figure 2H) are shifted from zero (d′ = 2.02 between circle and background histograms.