Temporal Cognition in Children with Autistic Spectrum Disorders: Tests of Diachronic Thinking

Impaired diachronic thinking-(the propensity and capacity to think about events spreading across time)-was demonstrated in a 2-Phase study in which children with autism were compared with age and ability matched controls. Identical tests of diachronic thinking were administered in both phases of the study, but to different participant groups, with the same results. The marked impairments shown are therefore robust. Various non-temporal explanations of the findings were eliminated by the results of control tasks in Phase 2. Diachronic thinking did not correlate with verbal or non-verbal ability, age, or mentalising ability, consistent with other evidence of the specificity of diachronic thinking ability. Possible causes of impaired diachronic thinking in autism are discussed.

Concept-matching in the brain depends on serotonin and gamma-frequency shifts

A Eureka moment has three components--puzzle, solution and hedonic response (elation etc.). Puzzle and solution come together in the association cortex and are immensely variable from instance to instance. By contrast, the hedonic response is subcortical and almost one-dimensional; how is it triggered? It is triggered by the relation between puzzle and solution, a good fit or good match, like the relation between two words that rhyme. In 1999 J.W. Fost proposed that serotonin is a crucial agent; here it is proposed that a frequency-jump initiates the serotonin causal chain, as energy shifts from 20 to 40 Hz or some such jump. The hypothesis assumes that any discrete idea is embodied in a time-course of electrical and chemical changes in a network of neurons, and that keeping the idea in mind involves repeating more or less the same time-course over and over. If observed frequencies in the gamma range result from such repetition, the period for running the time-course once is of the order of 25 ms. Also accepted is the suggestion that, although the brain runs many processes simultaneously, in the conscious mind attention focuses on only one idea at a time; an attempt to "think of two things at once" actually results only in giving them attention alternately, with a repeat-time of the order of 50 ms and frequency 20 Hz. Only if the two time-courses have certain elements in common will there be any repetition at 40 Hz. Now suppose a thinker takes up a problem and makes a succession of attempts at solution. As long as he thinks of wrong answers, he generates activity only at 20 Hz, but when he hits upon the right answer, activity at 40 Hz shows up. This is a highly oversimplified scenario but its essential features might carry over to the vastly more complicated workings of a real brain. The virtue of the proposed mechanism is its generality. Under the proposal, any ideas in mind that do not match give no result but as soon as two ideas match, results ensue. This behavior in the model, wholly general except in one specific respect, is needed for conformity with real human brains' behavior. In normal people, production of this "link-joy" is an important reward mechanism and malfunction of this system may contribute to Capgras syndrome and some varieties of autism.

Cooperation of the basal ganglia, cerebellum, sensory cerebrum and hippocampus: possible implications for cognition, consciousness, intelligence and creativity

It is suggested that the anatomical structures which mediate consciousness evolved as decisive embellishments to a (non-conscious) design strategy present even in the simplest unicellular organisms. Consciousness is thus not the pinnacle of a hierarchy whose base is the primitive reflex, because reflexes require a nervous system, which the single-celled creature does not possess. By postulating that consciousness is intimately connected to self-paced probing of the environment, also prominent in prokaryotic behavior, one can make mammalian neuroanatomy amenable to dramatically straightforward rationalization. Muscular contraction is the nervous system's only externally directed product, and the signaling routes which pass through the various brain components must ultimately converge on the motor areas. The function of several components is still debatable, so it might seem premature to analyze the global operation of the circuit these routes constitute. But such analysis produces a remarkably simple picture, and it sheds new light on the roles of the individual components. The underlying principle is conditionally permitted movement, some components being able to veto muscular contraction by denying the motor areas sufficient activation. This is true of the basal ganglia (BG) and the cerebellum (Cb), which act in tandem with the sensory cerebrum, and which can prevent the latter's signals to the motor areas from exceeding the threshold for overt movement. It is also true of the anterior cingulate, which appears to play a major role in directing attention. In mammals, the result can be mere thought, provided that a second lower threshold is exceeded. The veto functions of the BG and the Cb stem from inhibition, but the countermanding disinhibition develops at markedly different rates in those two key components. It develops rapidly in the BG, control being exercised by the amygdala, which itself is governed by various other brain regions. It develops over time in the Cb, thereby permitting previously executed movements that have proved advantageous. If cognition is linked to overt or covert movement, intelligence becomes the ability to consolidate individual motor elements into more complex patterns, and creativity is the outcome of a race-to-threshold process which centers on the motor areas. Amongst the ramifications of these ideas are aspects of cortical oscillations, phantom limb sensations, amyotrophic lateral sclerosis (ALS) the difficulty of self-tickling and mirror neurons.