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Minimally invasive pediatric epilepsy surgery (MIPES) is a rising technique in the management of focal-onset drug-refractory epilepsy. Minimally invasive surgical techniques are based on small, focal interventions (such as parenchymal ablation or localized neuromodulation) leading to elimination of the seizure onset zone or interruption of the larger epileptic network. Precise localization of the seizure onset zone, demarcation of eloquent cortex, and mapping of the network leading to seizure propagation are required to achieve optimal outcomes. The toolbox for presurgical, noninvasive evaluation of focal epilepsy continues to expand rapidly, with a variety of options based on advanced imaging and electrophysiology. In this article, we will examine several of these diagnostic modalities from the standpoint of MIPES and discuss how each can contribute to the development of a localization-based hypothesis for potential surgical targets.

Highlights • Photophobia is a common, disabling symptom observed in patients with Progressive Supranuclear Palsy (PSP). • We assessed the functional impacts of photophobia in PSP, and find that bright light is painful. • Symptoms limit participation in activities of daily living, reducing time spent outside the house., Objective To determine the impact of photophobia on persons with Progressive Supranuclear Palsy (pwPSP) by determining the functional impact of light sensitivity using methods established in migraine research. Methods All 60 participants (pwPSP = 15, persons with Parkinson Disease (pwPD) = 15, Older adults = 30) completed a series of questionnaires designed to assess the impact of photophobia on activities of daily living. Group comparisons were controlled for multiple comparisons using a false discovery rate of 0.05. Results Most (14/15) pwPSP participants noted that bright light hurt their eyes, and this proportion was significantly greater than pwPD (6/15; p = 0.03, corrected). PSP participants reported statistically significantly more severe light sensitivity on a subjective 0–100 scale (p = 0.003, corrected), and noted reduced time spent in both indoor and outdoor activities. Some PSP participants (n = 3) noted that they needed to wear sunglasses indoors, but most noted a reluctance to leave their house during the day due to photophobia. PwPSP indicated that they require more help from others to complete daily tasks that require them to be outside during daylight hours. Conclusions Overall, we note a significant debility due to photophobia in PSP, and this impacts outdoor more than indoor activities. The functional disability in PSP caused by photophobia appears to cause a substantive reduction in quality of life. Future studies could consider incorporating specific metrics to evaluate measurable differences with photophobia onset and worsening severity.

A common technique used to study the response selectivity of neurons is to measure the relationship between sensory stimulation and action potential responses. Action potentials, however, are only indirectly related to the synaptic inputs that determine the underlying, subthreshold, response selectivity. We present a method to predict membrane potential, the measurable result of the convergence of synaptic inputs, based on spike rate alone and then test its utility by comparing predictions to actual membrane potential recordings from simple cells in primary visual cortex. Using a noise stimulus, we found that spike rate receptive fields were in precise correspondence with membrane potential receptive fields ( R2 = 0.74). On average, spike rate alone could predict 44% of membrane potential fluctuations to dynamic noise stimuli, demonstrating the utility of this method to extract estimates of subthreshold responses. We also found that the nonlinear relationship between membrane potential and spike rate could also be extracted from spike rate data alone by comparing predictions from the noise stimulus with the actual spike rate. Our analysis reveals that linear receptive field models extracted from noise stimuli accurately reflect the underlying membrane potential selectivity and thus represent a method to generate estimates of the underlying average membrane potential from spike rate data alone.

Primary visual cortex (V1) is the site at which orientation selectivity emerges in mammals: visual thalamus afferents to V1 respond equally to all stimulus orientations, whereas their target V1 neurons respond selectively to stimulus orientation. The emergence of orientation selectivity in V1 has long served as a model for investigating cortical computation. Recent evidence for orientation selectivity in mouse V1 opens cortical computation to dissection by genetic and imaging tools, but also raises two essential questions: (1) How does orientation selectivity in mouse V1 neurons compare with that in previously described species? (2) What is the synaptic basis for orientation selectivity in mouse V1? A comparison of orientation selectivity in mouse and in cat, where such measures have traditionally been made, reveals that orientation selectivity in mouse V1 is weaker than in cat V1, but that spike threshold plays a similar role in narrowing selectivity between membrane potential and spike rate. To uncover the synaptic basis for orientation selectivity, we made whole-cell recordingsin vivofrom mouse V1 neurons, comparing neuronal input selectivity—based on membrane potential, synaptic excitation, and synaptic inhibition—to output selectivity based on spiking. We found that a neuron's excitatory and inhibitory inputs are selective for the same stimulus orientations as is its membrane potential response, and that inhibitory selectivity is not broader than excitatory selectivity. Inhibition has different dynamics than excitation, adapting more rapidly. In neurons with temporally modulated responses, the timing of excitation and inhibition was different in mice and cats.

As their power and utility increase, genome-wide association (GWA) studies are poised to become an important element of the neurosurgeon's toolkit for diagnosing and treating disease. In this paper, the authors review recent findings and discuss issues associated with gathering and analyzing GWA data for the study of neurological diseases and disorders, including those of neurosurgical importance. Their goal is to provide neurosurgeons and other clinicians with a better understanding of the practical and theoretical issues associated with this line of research. A modern GWA study involves testing hundreds of thousands of genetic markers across an entire genome, often in thousands of individuals, for any significant association with a particular disease. The number of markers assayed in a study presents several practical and theoretical issues that must be considered when planning the study. Genome-wide association studies show great promise in our understanding of the genes underlying common neurological diseases and disorders, as well as in leading to a new generation of genetic tests for clinicians.