@article {88, title = {Fast Readout of Object Identity from Macaque Inferior Temporal Cortex}, journal = {Science}, volume = {310}, year = {2005}, month = {04/2005}, pages = {863 - 866}, abstract = {

Understanding the brain computations leading to object recognition requires quantitative characterization of the information represented in inferior temporal (IT) cortex. We used a biologically plausible, classifier-based readout technique to investigate the neural coding of selectivity and invariance at the IT population level. The activity of small neuronal populations (approximately 100 randomly selected cells) over very short time intervals (as small as 12.5 milliseconds) contained unexpectedly accurate and robust information about both object \"identity\" and \"category.\" This information generalized over a range of object positions and scales, even for novel objects. Coarse information about position and scale could also be read out from the same population.

}, keywords = {Action Potentials, Animals, Brain Mapping, Macaca mulatta, Neurons, Psychology, Psychomotor Performance, Recognition, Temporal Lobe, Time Factors, Visual Perception}, issn = {0036-8075}, doi = {10.1126/science.1117593}, url = {https://www.sciencemag.org/lookup/doi/10.1126/science.1117593}, author = {Hung, Chou P. and Kreiman, Gabriel and Poggio, Tomaso and DiCarlo, James J.} } @article {87, title = {Multiple Object Response Normalization in Monkey Inferotemporal Cortex}, journal = {Journal of Neuroscience}, volume = {25}, year = {2005}, month = {07/2005}, pages = {8150 - 8164}, abstract = {

The highest stages of the visual ventral pathway are commonly assumed to provide robust representation of object identity by disregarding confounding factors such as object position, size, illumination, and the presence of other objects (clutter). However, whereas neuronal responses in monkey inferotemporal cortex (IT) can show robust tolerance to position and size changes, previous work shows that responses to preferred objects are usually reduced by the presence of nonpreferred objects. More broadly, we do not yet understand multiple object representation in IT. In this study, we systematically examined IT responses to pairs and triplets of objects in three passively viewing monkeys across a broad range of object effectiveness. We found that, at least under these limited clutter conditions, a large fraction of the response of each IT neuron to multiple objects is reliably predicted as the average of its responses to the constituent objects in isolation. That is, multiple object responses depend primarily on the relative effectiveness of the constituent objects, regardless of object identity. This average effect becomes virtually perfect when populations of IT neurons are pooled. Furthermore, the average effect cannot simply be explained by attentional shifts but behaves as a primarily feedforward response property. Together, our observations are most consistent with mechanistic models in which IT neuronal outputs are normalized by summed synaptic drive into IT or spiking activity within IT and suggest that normalization mechanisms previously revealed at earlier visual areas are operating throughout the ventral visual stream.

}, keywords = {Animals, Brain Mapping, Macaca mulatta, Male, Photic Stimulation, Posture, Psychology, Recognition, Temporal Lobe, Visual Pathways, Visual Perception}, issn = {0270-6474}, doi = {10.1523/JNEUROSCI.2058-05.2005}, url = {http://www.jneurosci.org/cgi/doi/10.1523/JNEUROSCI.2058-05.2005}, author = {Zoccolan, D. and Cox, David D. and DiCarlo, James J.} } @article {107, title = {Velocity Invariance of Receptive Field Structure in Somatosensory Cortical Area 3b of the Alert Monkey}, journal = {The Journal of Neuroscience}, volume = {19}, year = {1999}, month = {01/1999}, pages = {401 - 419}, abstract = {

This is the second in a series of studies of the neural representation of tactile spatial form in cortical area 3b of the alert monkey. We previously studied the spatial structure of 330 area 3b neuronal receptive fields (RFs) on the fingerpad with random dot patterns scanned at one velocity (40 mm/sec;\ DiCarlo et al., 1998). Here, we analyze the temporal structure of 84 neuronal RFs by studying their spatial structure at three scanning velocities (20, 40, and 80 mm/sec). As in the previous study, most RFs contained a single, central, excitatory region and one or more surrounding or flanking inhibitory regions. The mean time delay between skin stimulation and its excitatory effect was 15.5 msec. Except for differences in mean rate, each neuron\’s response and the spatial structure of its RF were essentially unaffected by scanning velocity. This is the expected outcome when excitatory and inhibitory effects are brief and synchronous. However, that interpretation is consistent neither with the reported timing of excitation and inhibition in somatosensory cortex nor with the third study in this series, which investigates the effect of scanning direction and shows that one component of inhibition lags behind excitation. We reconcile these observations by showing that overlapping (in-field) inhibition delayed relative to excitation can produce RF spatial structure that is unaffected by changes in scanning velocity. Regardless of the mechanisms, the velocity invariance of area 3b RF structure is consistent with the velocity invariance of tactile spatial perception (e.g., roughness estimation and form recognition).

}, keywords = {Adaptation, Animals, Brain Mapping, Cortical Synchronization, Evoked Potentials, Female, Macaca mulatta, Male, Neural Inhibition, Physiological, Somatosensory Cortex, Visual Fields}, issn = {0270-6474}, doi = {10.1523/JNEUROSCI.19-01-00401.1999}, url = {http://www.jneurosci.org/lookup/doi/10.1523/JNEUROSCI.19-01-00401.1999}, author = {DiCarlo, James J. and Johnson, Kenneth O.} } @article {119, title = {Stimulus configuration, classical conditioning, and hippocampal function.}, journal = {Psychological Review}, volume = {99}, year = {1992}, month = {04/1992}, pages = {268 - 305}, abstract = {

Hippocampal participation in classical conditioning is described in terms of a multilayer network that portrays stimulus configuration. The network (a) describes behavior in real time, (b) incorporates a layer of \"hidden\" units positioned between input and output units, (c) includes inputs that are connected to the output directly as well as indirectly through the hidden-unit layer, and (d) uses a biologically plausible backpropagation procedure to train the hidden-unit layer. Nodes and connections in the neural network are mapped onto regional cerebellar, cortical, and hippocampal circuits, and the effect of lesions of different brain regions is formally studied. Computer simulations of the following classical conditioning paradigms are presented: acquisition of delay and trace conditioning, extinction, acquisition-extinction series of delay conditioning, blocking, over-shadowing, discrimination acquisition, discrimination reversal, feature-positive discrimination, conditioned inhibition, negative patterning, positive patterning, and generalization. The model correctly describes the effect of hippocampal and cortical lesions in many of these paradigms, as well as neural activity in hippocampus and medial septum during classical conditioning. Some of these results might be extended to the description of anterograde amnesia in human patients.

}, keywords = {Animals, Association Learning, Brain Mapping, Cerebellum, Cerebral Cortex, Classical, Computer Simulation, Conditioning, Hippocampus, Humans, Models, Neural Pathways, Neurological}, issn = {0033-295X}, doi = {10.1037/0033-295X.99.2.268}, url = {http://doi.apa.org/getdoi.cfm?doi=10.1037/0033-295X.99.2.268}, author = {Schmajuk, Nestor A. and DiCarlo, James J.} }