Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA.
Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Cereb Cortex. 2018 Jan 1;28(1):116-130. doi: 10.1093/cercor/bhw356.
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.
局部场电位 (LFP) 节律的同步被认为可以增强被注意的感觉输入的信号。其他认知功能也可以从这种增益控制中受益。一种是分类，当类别以微妙的方式不同时，决策可能会很困难。猴子被训练使用正交边界以两种不同的方式来灵活地对平滑变化的变形刺激进行分类，从而将相同的刺激空间分割成不同的类别。我们发现了外侧前额叶皮层 (PFC) 中特定于类别的低β（16-20 Hz）同步的证据。当给定的类别方案相关时，这种同步更强。我们还观察到，对于接近类别边界且因此更难分类的刺激，低β LFPs 同步总体上增加。β 类别选择性在局部场-场相干性测量中是明显的，该测量测量局部同步，但边界增强则不是。因此，似乎类别选择性依赖于局部相互作用，而边界增强是一种更全局的影响。结果表明，β 同步有助于形成类别集合，并可能反映了为分类具有挑战性的刺激而招募额外的皮质资源，因此它是一种增益控制形式。
