Frontoparietal cortex: The immune system of the mind

The frontoparietal control system is to the mind what the immune system is to the body. It may oversimplify the situation, but we’re finding it’s a useful metaphor nonetheless. Indeed, we’ve just published a new theory paper explaining that there is already an avalanche of evidence supporting this metaphor. Even though much work is left …

Cingulate Cortex and the Evolution of Human Uniqueness

Figuring out how the brain decides between two options is difficult. This is especially true for the human brain, whose activity is typically accessible only via the small and occasionally distorted window provided by new imaging technologies (such as functional MRI (fMRI)). In contrast, it is typically more accurate to observe monkey brains since the …

Levels of Analysis and Emergence: The Neural Basis of Memory

Cognitive neuroscience constantly works to find the appropriate level of description (or, in the case of computational modeling, implementation) for the topic being studied.  The goal of this post is to elaborate on this point a bit and then illustrate it with an interesting recent example from neurophysiology. As neuroscientists, we can often  choose to …

Grand Challenges of Neuroscience: Day 4

After a bit of a hiatus, I’m back with the last three installments of “Grand Challenges in Neuroscience”. Topic 4: Time Cognitive Science programs typically require students to take courses in Linguistics (as well as in the philiosphy of language).  Besides the obvious application of studying how the mind creates and uses language, an important …

Grand Challenges of Neuroscience: Day 3

Topic 3: Spatial Knowledge Animal studies have shown that the hippocampus contains special cells called “place cells”.  These place cells are interesting because their activity seems to indicate not what the animal sees, but rather where the animal is in space as it runs around in a box or in a maze. (See the four …

Grand Challenges of Neuroscience: Day 1

Following up on MC's posts about the significant insights in the history of neuroscience, I'll now take Neurevolution for a short jaunt into neuroscience's potential future. In light of recent advances in technologies and methodologies applicable to neuroscience research, the National Science Foundation last summer released a document on the "Grand Challenges of Neuroscience".  These …

History’s Top Brain Computation Insights: Day 25

25) The dopamine system implements a reward prediction error algorithm (Schultz – 1996, Sutton – 1988) It used to be that the main thing anyone "knew" about the dopamine system was that it is important for motor control.   Parkinson's disease, which visibly manifests itself as motor tremors, is caused by disruption of the dopamine …

History’s Top Brain Computation Insights: Day 24

24) Cognitive control processes are distributed within a network of distinct regions (Goldman-Rakic – 1988, Posner – 1990, Wager & Smith 2004, Cole & Schneider – 2007) Researchers investigating eye movements and attention recorded from different parts of the primate brain and found several regions showing very similar neural activity. Goldman-Rakic proposed the existence of …

History’s Top Brain Computation Insights: Day 23

23) Motor cortex is organized by movement direction (Schwartz  & Georgopoulos – 1986, Schwartz – 2001) Penfield had shown that motor cortex is organized in a somatotopic map. However, it was unclear how individual neurons are organized. What does each neuron’s activity represent? The final location of a movement, or the direction of that movement? …

History’s Top Brain Computation Insights: Day 20

20) Spike-timing dependent plasticity: Getting the brain from correlation to causation (Levy – 1983, Sakmann – 1994, Bi & Poo – 1998, Dan – 2002) Hebb's original proposal was worded as such: "When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, …

History’s Top Brain Computation Insights: Day 19

19) Neural networks can self-organize via competition (Grossberg – 1978, Kohonen – 1981) Hubel and Wiesel's work with the development  of cortical columns (see previous post) hinted at it, but it wasn't until Grossberg and Kohonen built computational architectures explicitly exploring competition that its importance was made clear. Grossberg was the first to illustrate the …

History’s Top Brain Computation Insights: Day 14

14) Neocortex is composed of columnar functional units (Mountcastle – 1957, Hubel & Wiesel – 1962) Mountcastle found that nearby neurons in monkey somatosensory cortex tend to activate for similar sensory experiences. For example, a neuron might respond best to a vibration of the right index finger tip, while a neuron slightly deeper in might …

History’s Top Brain Computation Insights: Day 13

13) Larger cortical space is correlated with greater representational resolution; memories are stored in cortex (Penfield – 1957) Prior to performing surgery, Wilder Penfield electrically stimulated epileptic patients' brains while they were awake. He found the motor and somatosensory strips along the central sulcus, just as was found in dogs by Fitsch & Hitzig (see …

History’s Top Brain Computation Insights: Day 11

11) Action potentials, the electrical events underlying brain communication, are governed by ion concentrations and voltage differences mediated by ion channels (Hodgkin & Huxley – 1952) Hodgkin & Huxley developed the voltage clamp, which allows ion concentrations in a neuron to be measured with the voltage constant. Using this device, they demonstrated changes in ion …

History’s Top Brain Computation Insights: Day 10

10) The Hebbian learning rule: 'Neurons that fire together wire together' [plus corollaries] (Hebb – 1949) D. O. Hebb's most famous idea, that neurons with correlated activity increase their synaptic connection strength, was based on the more general concept of association of correlated ideas by philosopher David Hume (1739) and others. Hebb expanded on this …