Direction- and velocity-specific responses from beyond the classical receptive field in the middle temporal visual area (MT)

The true receptive field of more than 90% of neurons in the middle temporal visual area (MT) extends well beyond the classical receptive field (crf), as mapped with conventional bar or spot stimuli, and includes a surrounding region that is 50 to 100 times the area of the crf. These extensive surrounds are demonstrated by simultaneously stimulating the crf and the surround with moving stimuli. The surrounds commonly have directional and velocity-selective influences that are antagonistic to the response from the crf. The crfs of MT neurons are organized in a topographic representation of the visual field. Thus MT neurons are embedded in an orderly visuotopic array, but are capable of integrating local stimulus conditions within a global context. The extensive surrounds of MT neurons may be involved in figure-ground discrimination, preattentive vision, perceptual constancies, and depth perception through motion cues.     

Intuition and autism: a possible role for Von Economo neurons

Von Economo neurons (VENs) are a recently evolved cell type which may be involved in the fast intuitive assessment of complex situations. As such, they could be part of the circuitry supporting human social networks. We propose that the VENs relay an output of fronto-insular and anterior cingulate cortex to the parts of frontal and temporal cortex associated with theory-of-mind, where fast intuitions are melded with slower, deliberative judgments. The VENs emerge mainly after birth and increase in number until age 4 yrs. We propose that in autism spectrum disorders the VENs fail to develop normally, and that this failure might be partially responsible for the associated social disabilities that result from faulty intuition.     

Associative change in the representations acquired during conditional discriminations: further analysis of the nature of conditional learning

Three experiments with rats investigated how the associative strengths of the representations that underlie conditional learning change when they are conditioned in compound. The results of each experiment suggest that the representation whose associative strength is most discrepant from the asymptote supported by the outcome of the trial undergoes the greatest change in associative strength. These results parallel those from simple Pavlovian conditioning (e.g., R. A. Rescorla, 2000). are inconsistent with unique-cue and configural accounts of conditional learning, and support a connectionist analysis of learning in which a "winner-takes-all" rule applies to the hidden units that can be activated and acquire associative strength at a given point in time.     

Neuropsychological sequelae following pediatric stroke: A nonlinear model of age at lesion effects

Aim: The distribution and quality of brain recovery following pediatric arterial ischemic stroke remains controversial. The literature suggests that age at stroke may be an important modulator of neuropsychological outcome, with reports inferring either greater vulnerability or plasticity in the nascent brain. Our aim was to investigate neuropsychological outcomes following pediatric stroke in a clinical sample with reference to age at lesion, lesion laterality, elapsed time from stroke to assessment, and persistent neurological sequelae.

Methods: Using comprehensive neuropsychological assessment batteries, we investigated retrospectively a large (n?=?44) and evenly distributed group of children who had ischemic stroke during “infancy” (1 month to 1 year), “early childhood” (1 to 6 years), and “late childhood” (6 to 16 years).

Results: Children who suffered a stroke performed significantly worse on a range of neuropsychological measures when compared to a normative sample. However, children who suffered a stroke between 1 and 6 years old demonstrated better preserved neuropsychological profiles than either the earlier (before age 1) or later (after age 6) age groups. In addition, those children suffering a left hemisphere lesion performed more poorly on a range of neuropsychological measures than did children with right hemisphere lesions.

Interpretation: Age at stroke is an important determinant of recovery following insult and may modulate neuropsychological and cognitive outcome.     

Time flies when you're having fun: temporal estimation and the experience of boredom

Boredom is a common experience in healthy individuals and may be elevated in various neurological or psychiatric conditions. As yet, very little is known about the cognitive or neural bases of the subjective experience of boredom. We examined temporal perception and the temporal allocation of attention in healthy individuals reporting high- or low-levels of boredom. We found no difference in high- or low-boredom-prone individuals in the temporal allocation of attention, while individuals who experienced low-levels of boredom tended to underestimate time more so than high-boredom-prone individuals. Furthermore, high-boredom-prone individuals demonstrated higher error values when estimating time indicating that the subjective perception of the passage of time may be a critical component to the experience of boredom.     

Rapid long lasting learning in a collinear edge-detection task

We have developed a detection task in which subjects identify a pair of collinear edges in a field of polygons. Five of our six subjects showed significant, rapid learning at this task. Four showed evidence of retention a day and a week later. In several transfer tests, we found that disruption of the distractors produced a significant drop-off in performance. These results are consistent with a model in which collinear targets initially produce a salience signal too weak to be reliably detected over the noise of the distractors. As the experiment proceeds, the visual system learns to dampen the distractor signals, allowing for more reliable detection.     

The end-of-session message in systemic family therapy: a descriptive study

A retrospective case note review was conducted with the aim of describing the end-of-session messages conveyed during Milan-style systemic family therapy. Fifty consecutive families treated in an adult family clinic were included. A classification of messages was developed; for each type of message the mean number per therapy session was calculated and the rates compared both within and between four systemic categories of family. 'Supportive/engaging' messages were given more frequently than 'hypothesis-related' messages in each systemic category and this difference was most marked in families with grief as the central issue. More 'acknowledgement' messages were used in the 'grief' group than in the 'separation/individuation' group. 'Hypothesis-related' messages were used more often in the 'separation/individuation' group than in the 'grief' group. We discuss possible reasons for the observed patterns and compare different ways in which the message can be conceived and implemented.     

Transfer of configural learning between the components of a preexposed stimulus compound: implications for elemental and configural models of learning

In 2 experiments, rats received preexposure to 2 compound contexts: AB and CD for the congruent group and AC and BD for the incongruent group. Subsequently, all rats received a configural discrimination in which separate placement in contexts A or B indicated that presentations of stimulus X would be followed by food and presentations of Y would not, and separate placement in contexts C and D indicated that Y would be followed by food and X would not. In both experiments, rats in the congruent group acquired the conditional discrimination more rapidly than those in the incongruent group. These results are inconsistent with conventional associative accounts of either stimulus preexposure effects or configural learning and instead provide support for a connectionist account.