Journal of neurophysiology
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Recent theoretical models of primary visual cortex predict a relationship between receptive field properties and the location of the neuron within the orientation maps. Testing these predictions requires the development of new methods that allow the recording of single units at various locations across the orientation map. Here we present a novel technique for the precise alignment of functional maps and array recordings. ⋯ Experimental results of the alignment procedure from two implementations in monkey V1 are presented. The estimated accuracy of the procedure is evaluated using computer simulations. The methodology should prove useful in studying how signals from the local neighborhood of a neuron, thought to provide a dominant feedback signal, shape the receptive field properties in V1.
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Experimental and clinical evidence indicates that pain can affect cognitive processes, but the cortical networks involved in pain-cognition interactions are unclear. In this study, we determined the effect of pain on the activity of cortical areas involved in cognition acting as a whole (i.e., a network). Subjects underwent functional magnetic resonance imaging (fMRI) while engaged in an attention-demanding cognitive task (multisource interference task) of varying difficulty and simultaneously receiving painful stimuli at varying intensities. ⋯ We suggest this attention-specific network balances the needs of general self-referential and environmental awareness versus focused attention to salient information. We postulate that pain affects cognitive ability by its reliance on this common attention-specific network. These data provide evidence that pain can modulate a network presumed to be involved in focused attention, suggesting a mechanism for the interference of pain on cognitive ability by the consumption of attentional resources.
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Recent studies have shown that the local field potential (LFP) can provide a simple method for obtaining an accurate measure of reaching and saccade behaviors. However, it is not clear whether this signal is equally informative with respect to more complex movements. Here we recorded LFPs and single units (SUs) from different areas in the posterior parietal cortex of macaques during a prehension task and compared LFP selectivity with SU selectivity. ⋯ Significant relations with target parameters were found for all tested bands of LFP, but effects in the fast (gamma) band exhibited properties that were consistent with contamination of the LFP by residual spiking activity. Taken together, our results suggest that the LFP provides a simple method for extracting ample movement-related information. However, some of its properties make it less adequate for predicting rapidly changing movements.
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The cholinergic innervation of the prefrontal cortex (PFC) plays a pivotal role in regulating executive functions. Muscarinic receptors activated by acetylcholine depolarize pyramidal neurons in the rodent PFC homologue, but the mechanisms mediating this modulation are controversial. To address this question, we studied the responses of layer V rat pre- and infralimbic cortex pyramidal neurons to muscarinic receptor stimulation. ⋯ Reduction of Kir2 channel currents by M(1) receptor stimulation significantly increased the temporal summation of excitatory synaptic potentials (EPSPs) evoked by repetitive stimulation of layer I. This action was complimented by M(2/4) receptor mediated presynaptic inhibition of the same terminals. As a consequence of this dual modulation, the responses to a single, isolated afferent volley was reduced, but the response to a high-frequency afferent burst was potentiated.