Betsy Murray and crew find evidence to resolve two different views of the function of the orbitofrontal cortex (OFC). One view is that the OFC provides inhibitory control and emotion regulation. The other view is that processes the value of things. They show that damage limited to the OFC does not affect inhibitory or emotional control, but damage to nearby fiber tracts do. There you go.
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Pannunzi et al propose a model of visual category learning in which bottom-up sensory inputs to the inferior temporal cortex are sculpted by top-down inputs from the prefrontal cortex (PFC). The PFC improves signal to noise by enhancing the category-relevant features of the stimuli.
Miller Lab work cited:
Freedman, D.J., Riesenhuber, M., Poggio, T., and Miller, E.K. (2001) Categorical representation of visual stimuli in the primate prefrontal cortex. Science, 291:312-316. View PDF »Freedman, D.J., Riesenhuber, M., Poggio, T., and Miller, E.K (2003) A comparison of primate prefrontal and inferior temporal cortices during visual categorization. Journal of Neuroscience, 23(12):5235-5246. View PDF »
Meyers, E.M., Freedman, D.J., Kreiman, G., Miller, E.K., and Poggio, T. (2008) Dynamic population coding of category information in the inferior temporal cortex and prefrontal cortex. Journal of Neurophysiology. 100:1407-1419. View PDF »
Muhammad, R., Wallis, J.D., and Miller, E.K. (2006) A comparison of abstract rules in the prefrontal cortex, premotor cortex, the inferior temporal cortex and the striatum. Journal of Cognitive Neuroscience, 18: 974-989. View PDF »
Seger, C.A. and Miller, E.K. (2010) Category learning in the brain. Annual Review of Neuroscience, Vol. 33: 203-219. View PDF »
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Ekstrom and Watrous review the role of low frequency oscillatory coupling in cognition. The propose that different resonant frequencies within the same networks support movement vs memory related functions. They provide further evidence and argument for a role for oscillatory coupling in multiplexing of function. In other words, different frequency coupling can allow the same networks to have different roles by allowing them to communicate different messages to different targets.
Miller Lab work on oscillatory coupling and multiplexing:
Buschman, T.J. and Miller, E.K. (2007) Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices. Science. 315: 1860-1862 View PDF »Miller, E.K. and Buschman, T.J. (2013) Cortical circuits for the control of attention. Current Opinion in Neurobiology. 23:216–222 View PDF »
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Miller Lab alumnus, Andreas Nieder, shows number tuned neurons in pefrontal and parietal cortices of naive (untrained) subjects.
Viswanathan and Nieder 2013Andreas Nieder’s Miller Lab work on the neural substrates for numerosity:
Nieder, A., Freedman, D.J., and Miller, E.K. (2002) Representation of the quantity of visual items in the primate prefrontal cortex. Science. 297:1708-1711. View PDF »
Nieder, A. and Miller, E.K. (2003) Coding of cognitive magnitude: Compressed scaling of numerical information in the primate prefrontal cortex. Neuron. 37:149-157. View PDF »
Nieder, A. and Miller, E.K. (2004) A parieto-frontal network for visual numerical information in the monkey. Proceedings of the National Academy of Sciences, 101:7457-7462. View PDF »
Nieder, A. and Miller, E.K. (2004) Analog numerical representations in rhesus monkeys: Evidence for parallel processing. Journal of Cognitive Neuroscience. 16:889-901. View PDF »
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DIY attempts at electrical brain stimulation to improve cognition are to get easier. Nature editorial.
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Kometer et al show that psilocybin decreased spontaneous alpha oscillations which precluded the usual decrease in alpha when a visual stimulus is presented. Psilocybin may result in a brain state in which normal stimulus-driven cortical excitation is overwhelmed by spontaneous neuronal excitation resulting in altered perception and hallucinations.
We recently found evidence that alpha oscillations are useful for clearing out unwanted thoughts (neural ensembles) that could interfere with the current cognitive demands:
- Buschman, T.J., Denovellis, E.L., Diogo, C., Bullock, D. and Miller, E.K. (2012) Synchronous oscillatory neural ensembles for rules in the prefrontal cortex. Neuron, 76: 838-846. View PDF
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Soltani et al (2013) explored the role of D1 and D2 dopamine receptors in saccade target selection. They find evidence that D1 receptors modulate the strength of inputs to the frontal eye fields and recurrent connectivity whereas D2 may modulate the output of the FEF. This may be because D1 seems to reduce LTP and LTD, which is consistent with observations that D1 receptors contribute to associative learning (Puig and Miller, 2012). Like Puig and Miller (2012), they also found that D1 blockade increases response perseveration.
Further reading:
Puig, M.V. and Miller, E.K. (2012) The role of prefrontal dopamine D1 receptors in the neural mechanisms of associative learning. Neuron. 74: 874-886. View PDF » -
Matt Chafee and crew show that monkeys under the influence of ketamine show similar deficits as human schizophrenia patients on a test of context processing.
Blackman et al 2013 -
Attentional blink is decreased attention to a second stimulus if it quickly follows (200-500 ms) another stimulus. Maloney et al find that neural information in area LIP tracks attentional blink.
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More evidence for a role for beta coherence in cognition.
Lipsman et al find that an increase in beta coherence in human VM prefrontal cortex just before humans subjectively evaluated faces as “sad” but not before “happy” judgments, especially true when the faces were more ambiguous and thus more difficult to judge.Miller Lab work on beta coherence and cognition:
- Miller, E.K. and Buschman, T.J. (2013) Cortical circuits for the control of attention. Current Opinion in Neurobiology. 23:216–222 View PDF »
- Buschman, T.J., Denovellis, E.L., Diogo, C., Bullock, D. and Miller, E.K. (2012) Synchronous oscillatory neural ensembles for rules in the prefrontal cortex. Neuron, 76: 838-846. View PDF
- Buschman, T.J. and Miller, E.K. (2009) Serial, covert, shifts of attention during visual search are reflected by the frontal eye fields and correlated with population oscillations. Neuron, 63: 386-396. View PDF »
- Buschman, T.J. and Miller, E.K. (2007) Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices. Science. 315: 1860-1862 View PDF »