Research in my laboratory uses neurophysiological and behavioural approaches to study perception and memory. We are interested in how neural populations are recruited and shaped during perception. Faces and vocalizations are used as stimuli to shed light on possible underlying neural specializations for these social signals. We then study how perception of social signals leads to memory formation, and how memories and past experiences shape perception. We also examine the influences of emotional state, expectation, and eye movements on perception. See lab website for more details.
- Processing of social signals (faces, voices, body parts, and gestures)
- Functional organization of the temporal lobe
- Neural ensemble changes with learning
- The role of sleep oscillations in memory consolidation
- Relation between ongoing brain states and stimulus-driven activity
- Influences of emotional states, memory, and saccadic eye movements on perception
Our overarching goal is to understand how cell assemblies are created, maintained, and modified in the neocortical mantle. This pursuit has pushed us towards the use of ethologically relevant stimuli and testing paradigms, since we would like to tap into what brains are doing and not just what they can do. We also contrast stimulus-driven neural responses (reflecting a neural representation of objects in the environment) with internally-generated responses (like memory traces), which involves recording spontaneous activity and activity during sleep. While this places our research in fields as diverse as face perception, learning and plasticity, neural population coding, and sleep, the projects listed above are interrelated and often are conducted within the same behavioral or electrophysiological recording sessions.
Hoffman KL, Ghazanfar AA, Gauthier I, Logothetis NK (in press) Category-specific responses to faces and objects in primate auditory cortex. Frontiers in Systems Neuroscience.
Hoffman KL, Battaglia FP, Harris K, MacLean J, Marshall L, Mehta M (2007) The upshot of upstates in the neocortex: from slow oscillations to memory formation. Journal of Neuroscience 27(44):11838-11841.
Dahl CD, Logothetis NK, Hoffman KL (2007) Individuation and holistic processing of faces in rhesus monkeys. Proceedings of the Royal Society of London B: Biological Sciences 274: 2069-2076.
Hoffman KL, Gothard KM, Schmid MC, Logothetis NK. (2007) Facial-expression and gaze-selective responses in the monkey amygdala. Current Biology 17: 1–7.>/p>
Ghazanfar AA, Maier JX, Hoffman KL, Logothetis NK (2005) Multisensory integration of dynamic faces and voices in rhesus monkey auditory cortex. Journal of Neuroscience 25: 5004-5012.
Hoffman KL, McNaughton BL (2002) Coordinated reactivation of distributed memory traces in primate neocortex. Science 297:2070-3.
Hoffman KL, McNaughton BL (2002) Sleep on it: cortical reorganization after-the-fact. Trends in Neuroscience. 25(1):1-2.