Transcranial infrared laser stimulation improves rule-based, but not information-integration, category learning in humans

Nathaniel J Blanco; Celeste L Saucedo; F Gonzalez-Lima

doi:10.1016/j.nlm.2016.12.016

Transcranial infrared laser stimulation improves rule-based, but not information-integration, category learning in humans

Neurobiol Learn Mem. 2017 Mar:139:69-75. doi: 10.1016/j.nlm.2016.12.016. Epub 2016 Dec 27.

Authors

Nathaniel J Blanco¹, Celeste L Saucedo², F Gonzalez-Lima³

Affiliations

¹ Department of Psychology and Institute for Neuroscience, University of Texas at Austin, TX 78712, USA; Department of Psychology, The Ohio State University, Columbus, OH 43210, USA. Electronic address: nathanblanco@gmail.com.
² Department of Psychology and Institute for Neuroscience, University of Texas at Austin, TX 78712, USA. Electronic address: celestesaucedo@utexas.edu.
³ Department of Psychology and Institute for Neuroscience, University of Texas at Austin, TX 78712, USA. Electronic address: gonzalezlima@utexas.edu.

PMID: 28039085
DOI: 10.1016/j.nlm.2016.12.016

Abstract

This is the first randomized, controlled study comparing the cognitive effects of transcranial laser stimulation on category learning tasks. Transcranial infrared laser stimulation is a new non-invasive form of brain stimulation that shows promise for wide-ranging experimental and neuropsychological applications. It involves using infrared laser to enhance cerebral oxygenation and energy metabolism through upregulation of the respiratory enzyme cytochrome oxidase, the primary infrared photon acceptor in cells. Previous research found that transcranial infrared laser stimulation aimed at the prefrontal cortex can improve sustained attention, short-term memory, and executive function. In this study, we directly investigated the influence of transcranial infrared laser stimulation on two neurobiologically dissociable systems of category learning: a prefrontal cortex mediated reflective system that learns categories using explicit rules, and a striatally mediated reflexive learning system that forms gradual stimulus-response associations. Participants (n=118) received either active infrared laser to the lateral prefrontal cortex or sham (placebo) stimulation, and then learned one of two category structures-a rule-based structure optimally learned by the reflective system, or an information-integration structure optimally learned by the reflexive system. We found that prefrontal rule-based learning was substantially improved following transcranial infrared laser stimulation as compared to placebo (treatment X block interaction: F(1, 298)=5.117, p=0.024), while information-integration learning did not show significant group differences (treatment X block interaction: F(1, 288)=1.633, p=0.202). These results highlight the exciting potential of transcranial infrared laser stimulation for cognitive enhancement and provide insight into the neurobiological underpinnings of category learning.

Keywords: Category learning; Cognitive enhancement; Low-level laser therapy; Neuromodulation; Photobiomodulation; Transcranial laser stimulation.

Publication types

Randomized Controlled Trial

MeSH terms

Adolescent
Adult
Female
Humans
Infrared Rays*
Learning / radiation effects*
Low-Level Light Therapy*
Male
Neuropsychological Tests
Young Adult