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Cereb Cortex. 2018 Jan 1;28(1):116-130. doi: 10.1093/cercor/bhw356.

Low-Beta Oscillations Turn Up the Gain During Category Judgments.

Author information

1
Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA.
2
Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
3
Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA.

Abstract

Synchrony between local field potential (LFP) rhythms is thought to boost the signal of attended sensory inputs. Other cognitive functions could benefit from such gain control. One is categorization where decisions can be difficult if categories differ in subtle ways. Monkeys were trained to flexibly categorize smoothly varying morphed stimuli, using orthogonal boundaries to carve up the same stimulus space in 2 different ways. We found evidence for category-specific patterns of low-beta (16-20 Hz) synchrony in the lateral prefrontal cortex (PFC). This synchrony was stronger when a given category scheme was relevant. We also observed an overall increase in low-beta LFP synchrony for stimuli that were near the category boundary and thus more difficult to categorize. Beta category selectivity was evident in partial field-field coherence measurements, which measure local synchrony, but the boundary enhancement was not. Thus, it seemed that category selectivity relied on local interactions while boundary enhancement was a more global effect. The results suggest that beta synchrony helps form category ensembles and may reflect recruitment of additional cortical resources for categorizing challenging stimuli, thus serving as a form of gain control.

KEYWORDS:

categorization; oscillations; prefrontal cortex; synchrony

PMID:
29253255
PMCID:
PMC6248822
DOI:
10.1093/cercor/bhw356
[Indexed for MEDLINE]
Free PMC Article

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