In the Briggs laboratory, we are interested in understanding how specific and identified cortical circuits encode information about the visual world. We also examine how attention impacts the way in which visual information is encoded by neurons and circuits. We use a variety of technical approaches including multi-electrode array recordings in subjects trained on attention-demanding tasks and combination of multi-electrode array recordings with optogenetics to record and manipulate the activity of select neuronal populations in vivo. In order to match neurophysiological recordings to identified neurons and circuits, we perform histology and reconstruct the anatomical structure of recorded and labeled neurons.
The following rotation projects are available in my laboratory:
- Functional role of corticogeniculate feedback in vision: We use optogenetic techniques to manipulate corticogeniculate neurons in vivo to examine the function of corticogeniculate feedback in visual processing. Project involves surgical injection of virus to drive expression of optogenetic proteins in target neurons followed by neurophysiological recording experiments. New experiments will include behavioral training and circuit manipulation during behavior. Histological processing of tissue is the final experimental step. Data analysis involves spike sorting and generating tuning curves for recorded neurons. Additional data analysis includes morphological reconstruction of virus-labeled neurons located in various cortical and subcortical regions that project to the visual thalamus (see Circuit tracing).
- Neuronal mechanisms of attention: We use multi-electrode array recordings in the visual thalamus and primary visual cortex of subjects performing attention-demanding tasks. Project involves daily behavioral training and recordings from arrays inserted or chronically implanted. Data analysis involves spike sorting and analysis of tuning and attentional modulation of recorded neurons. Local field potentials are also recorded in multiple brain structures and signal processing techniques are utilized to analyze amplitude and phase relationships between simultaneously recorded signals.
- The role of visual thalamus in residual vision following loss of retinal or cortical inputs: We perform surgical manipulations to remove retinal projection neurons or neurons in primary visual cortex and perform follow-up behavioral and neurophysiological recordings to explore changes in visual response properties of neurons in the visual thalamus following loss of retinal or cortical inputs. Project involves daily behavioral training and recording from implanted multi-electrode arrays, surgical injections of chemical agents to remove cell populations, and neurophysiological recording experiments. Histological processing of retinal and brain tissue is the final experimental step. Data analyses include spike sorting, generating tuning curves and other response metrics, and morphological analyses of retinal and brain tissue.
- Visual processing in natural settings: We use multi-electrode array recordings in the visual cortex while subjects freely navigate and explore a naturalistic environment. Project involves daily behavioral monitoring using head-mounted eye tracking cameras, motion capture systems, and neurophysiological recordings. Data analyses include generating movies of visual perception during free navigation and analyzing neurophysiological data as described in other projects.