User:Kdp8y/Draft:Sonja Hofer

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Dr. Sonja Hofer is a German neuroscientist studying sensations and plasticity. Her research focuses on how brain circuits related to sensations, especially visual processing, are organized, and how their plasticity enables them to change to encode new information as we learn and encounter new experiences. She received her undergraduate degree from the Technical University of Munich, received her PhD at the Max Planck Institute of Neurobiology in Martinsried, Germany, and completed a post doctorate at the University College London. After being an Assistant Professor at the Biozentrum University of Basel in Switzerland for five years, she has now returned to London as a group leader and professor in the Sainsbury Wellcome Center for Neural Circuits and Behavior, where she has her own research lab.^[1]

Dr. Hofer was born close to Munich, Germany. She received her primary education at Gymnasium, a state school.^[2]

Dr. Hofer began her undergraduate career in Munich at the Technical University studying biology with a specialization in zoology^[1]. Later, Dr. Hofer worked with Starlings, studying their auditory system^[1]. By recording spike activity action potentials from neurons in their brains, she studied how the brain detects important signals from background noise^[3].

During her PhD at Max Planck Institute of Neurobiology, Martinsried, Germany, Dr. Sonja Hofer researched visual processing and plasticity in the primary visual cortex in mice^[4]. There she worked on monocular deprivation and used mice as a model for plasticity and learning in cortical circuits in order to better understand the ability to learn in adult humans.

Her work showed plasticity in the neocortical circuits of adult mice. Specifically, if mice have experienced an event earlier in life that causes a change in the neocortical circuits, it may allow them to have faster plasticity later in life^[5].

In the late stages of her PhD, Dr. Hofer used dendritic spine imaging and two photon laser scanning microscopy.^[1] She observed that when rodents undergo a novel experience, new dendritic spines grow. After the experience is forgotten, the connections become weaker. However, if the mouse undergoes the same experience, it can learn faster because the connection is already there. Ultimately, she showed the neural correlate that relearning is faster than learning.^[6]

She also used high level imaging techniques to record the structure of neurons, record their function, and observe action potentials firing. Dr Hofer also used calcium indicators. She observed that when the fluorescence of the dyes changed, the calcium concentration became higher, which is highly correlated to the action potential firing.^[1] She used this observation to measure responses of neurons in the living brain. Dr. Hofer was one of the first to use this method to look at sensory processing and to measure response and to visual stimuli in the primary visual cortex in mice.^[7]

Dr. Hofer completed her post-doctorate at the University College London from 2006 to 2012.^[1] Through her postdoctoral work she intended to move away from a reductionist paradigm of molecule deprivation and transition into learning and specifically what occurs in the brain as we learn new information. She investigated how the layers of cortical circuits communicate with each other and focused on connectivity between functionally different neurons, their emergence during development, and the overall functional specificity within circuits. She developed a novel technique that combined in vivo two-photon calcium imaging with in vitro whole-cell recordings in order to take detailed images at different depths of the cortex in vivo^[8]. By looking at slices of the same tissue, her lab was able to identify in vitro and match neural landmarks and patterns in order to find the likeliness of their connections and functions. Her findings supported clear functional organization within the subnetworks in the visual cortex.^[9][10]

Dr. Hofer studied behaviour in animals, shifting away from reductionist paradigms to monitoring behaviour in awake animals to investigate how the brain processes visual information within the visual world and how this information changes with learning. ^[11]Dr. Hofer’s lab began looking at local circuits within the primary visual cortex ^[12]and how the local cells are connected. Her lab research then shifted to focus on circuit neuroscience which looks at the communication between areas of the cortex and the neocortex and how the areas of the cortex communicate with each other such as how the processor visual stimulus reached the cortex and then how the cortex talks with the thalamus. Her lab focused on investigating these different and separate circuits and how they talk to each other and communicate to make different functions arise as well as how these circuits interact with the midbrain to generate movement of intrinsic behavior. This is what caused her lab to shift its focus from vision to behaviour focusing on how visual information is processed and how it influences decision making. The thalamus was a point of interest as the gateway to the cortex as almost all information that goes to the cortex passes through the thalamus.^[13] The thalamus possesses nuclei like the lateral geniculate nucleus (LGN) that brings information from the eye to the cortex.^[14] However, not only these kinds of primary sensory cortical areas received semantic input^[1] rather it is all the areas of the cortex but these complex and prominent interactions are still unclear. Her lab believes that these circuits and loops may be important for the integration of sensory information with the cortex. Research topics to come out of Dr. Hofer’s lab include determining how learning modified neuronal representation in the primary visual cortex (V1) during acquisition of a visually gauged behavioral task.^[15][16] In this experiment, mice were learning to discriminate between two visual patterns where one was rewarded. Through the measurement of neuronal ensemble with two-photon microscopy, Dr. Hofer was able to closely associate the improvements in behaviour with increasingly distinguished population-level of task-relevant stimuli. In addition to this Dr. Hofer's lab has researched the ventral lateral geniculate nucleus (vLGN) which is an inhibitory prethalamic area as a critical point of control of visual evoked defense responses in mice.^[17][18][19]

• Eric Kandel Young Neuroscientists Prize, presented on September 27, 2013^[20][21][22]
• ERC Starting Grant 2013^[23]
• Wellcome Trust Research Career Development Fellowship and Wellcome-Beit Prize^[24][25]