Biomedical subjects

Allan Snyder

Publications and source records attributed to Allan Snyder.

4 recordsLinked to original sources

PubMed2006

Savant-like numerosity skills revealed in normal people by magnetic pulses.

Oliver Sacks observed autistic twins who instantly guessed the exact number of matchsticks that had just fallen on the floor, saying in unison "111". To test the suggestion that normal individuals have the capacity for savant numerosity, we temporarily simulated the savant condition in normal people by inhibiting the left anterior temporal lobe of twelve participants with repetitive transcranial magnetic stimulation (rTMS). This site has been implicated in the savant condition. Ten participants improved their ability to accurately guess the number of discrete items immediately following rTMS and, of these, eight became worse at guessing as the effects of the pulses receded. The probability of as many as eight out of twelve people doing best just after rTMS and not after sham stimulation by chance alone is less than one in one thousand.

Adult↗

PubMed2006

Are angry male and female faces represented in opposite hemispheres of the female brain? A study using repetitive transcranial magnetic stimulation (rTMS).

The universality across cultures for recognizing the facial expression of anger suggests an evolved mechanism for dealing with threat. Using low frequency repetitive transcranial magnetic stimulation (rTMS) and a paradigm involving color-naming latencies for angry, fearful and neutral faces, and for emotional and neutral words respectively, we found evidence for a hemispheric specialization according to the sex and emotional content of faces in female subjects. Participants showed increased attention specifically to male angry faces after stimulation of the right superior temporal lobe, whereas they showed increased attention to angry female faces after left temporal stimulation. No effect was detected regarding the processing of fearful faces or emotional words. This result suggests differential processing of sex-specific threat-related stimuli specifically involving both hemispheres, i.e., that male and female faces are processed in opposite hemispheres, which might reflect the divergent adaptive significance of male and female threat for young females.

Adolescent↗

PubMed2004

Concept formation: 'object' attributes dynamically inhibited from conscious awareness.

We advance a dominant neural strategy for facilitating conceptual thought. Concepts are groupings of "object" attributes. Once the brain learns such critical groupings, the "object" attributes are inhibited from conscious awareness. We see the whole, not the parts. The details are inhibited when the concept network is activated, ie. the inhibition is dynamic and can be switched on and off. Autism is suggested to be the state of retarded concept formation. Our model predicts the possibility of accessing nonconscious information by artificially disinhibiting (turning off) the inhibiting networks associated with concept formation, using transcranial magnetic brain stimulation (TMS). For example, this opens the door for the restoration of perfect pitch, for recalling detail, for acquiring accent-free second languages beyond puberty, and even for enhancing creativity. The model further shows how unusual autistic savant skills as well as certain psychopathologies can be due respectively to privileged or inadvertent access to information that is normally inhibited from conscious awareness.

Adult↗

PubMed2004

Nonconscious idea generation.

The recognition of the correct solution to a problem after a period when one is not actively searching for an answer is well documented. However, previous research has focused on problems an individual has not yet resolved. We presented a scenario in which 125 participants believed that they had completed a task and so had no reason to seek further solutions. To their surprise, after a period of distraction, we resumed the testing session. This novel method was combined with accurate recording of both response content and timing. The results from the second session a remarkable similarity n initial burst to those from the first, including a ideas, allowing the inference that, even in the absence of a reason to seek solutions, a process of nonconscious idea generation might be operating.

Adolescent↗