Distinct temporal lobe projections to auditory and visual regions in the ventral prefrontal cortex support face and vocalization processing.
Maria M Diehl, Jennifer Bartlow-Kang, Tadashi Sugihara, Lizabeth M Romanski
Talk
Time: 2009-06-30 02:00 PM – 02:15 PM
Last modified: 2009-06-04
Abstract
The integration of face and voice information is required for communication in human and non-human primates. The purpose of this study was to examine connections between the auditory and visual responsive regions in the ventrolateral prefrontal cortex (VLPFC) and specific regions of the temporal lobe. Previous studies have shown that neurons within area 45 of the VLPFC are responsive to pictures of complex visual stimuli, including faces, while adjacent area 12/47 contains cells that are responsive to complex auditory stimuli including species-specific vocalizations. Furthermore, when face and vocalization stimuli are presented simultaneously, multisensory, audiovisual responses can be elicited from some VLPFC neurons within these same regions. We asked whether these different physiologically responsive regions of prefrontal cortex might also receive a different complement of afferent input from the temporal lobe which would convey the different selectivity to audio-visual stimuli.
We recorded auditory, visual, and multisensory responsive neurons from VLPFC. After determining the boundaries of the auditory, visual, and multisensory-responsive regions, we placed distinct anatomical tracers into each location. This would allow us to determine the different patterns of afferent and efferent connections of each of these functionally distinct VLPFC regions. Our results demonstrate that prefrontal auditory neurons receive the densest input from superior temporal gyrus (STG) areas TAa, the anterior parabelt, and to a lesser extent area TPO. In contrast, visually responsive neurons in VLPFC receive afferent projections from a number of inferotemporal cortex areas including TE, IPa, PGA and TPO. Injections placed into regions where neurons responded to both auditory and visual stimuli resulted in labeling mainly in TPO and to a lesser degree areas TAa, IPa, and TE. Finally, all of our injections resulted in retrograde labeling of the amygdala and anterograde labeling of the striatum. By investigating the anatomical connections of the VLPFC, we hope to better understand how auditory and visual information reaches the frontal lobes. The information gained from our tracing studies may provide clues about the neural circuit that underlies integration and processing of communication information.
We recorded auditory, visual, and multisensory responsive neurons from VLPFC. After determining the boundaries of the auditory, visual, and multisensory-responsive regions, we placed distinct anatomical tracers into each location. This would allow us to determine the different patterns of afferent and efferent connections of each of these functionally distinct VLPFC regions. Our results demonstrate that prefrontal auditory neurons receive the densest input from superior temporal gyrus (STG) areas TAa, the anterior parabelt, and to a lesser extent area TPO. In contrast, visually responsive neurons in VLPFC receive afferent projections from a number of inferotemporal cortex areas including TE, IPa, PGA and TPO. Injections placed into regions where neurons responded to both auditory and visual stimuli resulted in labeling mainly in TPO and to a lesser degree areas TAa, IPa, and TE. Finally, all of our injections resulted in retrograde labeling of the amygdala and anterograde labeling of the striatum. By investigating the anatomical connections of the VLPFC, we hope to better understand how auditory and visual information reaches the frontal lobes. The information gained from our tracing studies may provide clues about the neural circuit that underlies integration and processing of communication information.