June 24, 2015

Deep learning in the neocortex

Deep learning is an approach to artificial intelligence (AI) that loosely mimics how the brain works. By mimicking the operations of the brain, deep learning can rival, or even outperform, human beings in a number of functions, such as image recognition [1], motor control [2], and speech recognition [3]. Moreover, deep networks can develop representations that are a better match to recordings in the neocortex of humans or non-human primates than existing models in neuroscience [4,5]. This suggests that deep learning captures something important about how our own brains work. The key to “deep” learning (as opposed to “shallow” learning) […]
June 24, 2015

Multiple memory systems for enhanced reinforcement learning

Not all of our memories are stored in the same way. We have multiple memory systems that can provide different types of information [1,2]. Some of our memories are very detailed, giving us the ability to recall specific events and remember what it felt like when we were living it [3]. Our recent memories are stored in this way, as are some of the more emotionally salient events from our life. For example, you might be able to recall exactly what you had for breakfast yesterday or the song that was playing during your first kiss. In contrast, many of […]
June 24, 2015

Yiu AP, Mercaldo V, Yan C, Richards BA, Rashid AJ, Hsiang HL, Pressey J, Mahadevan V, Tran MM, Kushner SA, Woodin MA, Frankland PW and Josselyn SA, “Neurons are recruited to a memory trace based on relative neuronal excitability at the time of training”, Neuron, 83(3), 722-735

Memories are thought to be sparsely encoded in neuronal networks, but little is known about why a given neuron is recruited or allocated to a particular memory trace. Previous research shows that in the lateral amygdala (LA), neurons with increased CREB are selectively recruited to a fear memory trace. CREB is a ubiquitous transcription factor implicated in many cellular processes. Which process mediates neuronal memory allocation? One hypothesis is that CREB increases neuronal excitability to bias neuronal recruitment, although this has not been shown experimentally. Here we use several methods to increase neuronal excitability and show this both biases recruitment into […]
June 24, 2015

Muldal AM, Lillicrap TP, Richards BA and Akerman CJ, “Clonal relationships impact neuronal tuning within a phylogenetically ancient vertebrate brain structure”, Current Biology, 24(16), 1929-1933

Understanding how neurons acquire specific response properties is a major goal in neuroscience. Recent studies in mouse neocortex have shown that “sister neurons” derived from the same cortical progenitor cell have a greater probability of forming synaptic connections with one another [1 and 2] and are biased to respond to similar sensory stimuli [3 and 4]. However, it is unknown whether such lineage-based rules contribute to functional circuit organization across different species and brain regions [5]. To address this question, we examined the influence of lineage on the response properties of neurons within the optic tectum, a visual brain area found in all vertebrates [6]. […]