Patterns Of Functional Organization Research Articles

Olov Oscarsson (1931-1996) of Lund University, a Pioneer in Cerebellar Neurobiology.

The present Cerebellar Classic highlights the experimental work of the Swedish neurophysiologist Olov Oscarsson (1931-1996) on the afferent innervation of the cerebellum by axons emanating from neurons in the spinal cord and the inferior olive. Historically, the schemes of cerebellar division had been principally based on the external morphology of lobules and fissures. However, the macroscopic anatomical division of the cerebellum does not coincide with its pattern of functional organization. By defining a system of longitudinal somatotopy, Oscarsson contributed to the much needed plan of cerebellar division that correlates experimental information on axonal connections with physiology. His contribution has ultimately led to the currently accepted microzonal modular scheme of cerebellar corticonuclear microcomplexes.

21813 Changes in Electrophysiologic Activity in the Rat Visual Cortex following Traumatic Brain Injury (TBI)

ABSTRACT IMPACT: This research aims to identify changes in visual network function after TBI as a way to define potential therapeutic targets for neuromodulation or neural tissue substrates. OBJECTIVES/GOALS: The objectives of this study are to compare neural activity in the visual cortex following TBI with cortical activity in the uninjured brain. This study aims to characterize functional changes in single neuron activity, spike-field relationships and oscillatory activity. METHODS/STUDY POPULATION: The effects of TBI will be studied by comparing electrophysiologic recordings from Long-Evans rats with a fluid percussion injury (FPI) to rats with a sham injury. Four days after the injury or sham procedure, a laminar probe with multiple electrode contacts will be chronically implanted in the ipsilesional primary visual cortex (V1). Afterwards, rats will be anesthetized weekly for 3 weeks (up to 4 weeks post-injury) to assess visual processing in response to drifting grating visual stimulation. To assess behavioral correlates, neural activity will also be recorded while rats perform a visual discrimination task in an operant, touchscreen chamber twice weekly. Recordings will be analyzed for visually evoked units, unit entrainment to local field potentials (LFPs) and evoked oscillatory activity. RESULTS/ANTICIPATED RESULTS: Consistent with other studies, our preliminary evidence from V1 recordings in naive rats has shown that individual neurons are responsive to visual stimuli, visual stimuli are associated with evoked oscillations and unit activity is correlated with LFPs. While activity of individual V1 neurons in injured animals is expected to recover to resemble activity in uninjured animals over time, patterns of functional organization in the two groups are expected to diverge over time. We anticipate that TBI-associated axonal damage, neuronal loss and changes in synaptic weights will lead to disruptions in the timing of neural activity in V1. These perturbations of neural communication within the visual system are expected to be associated with behavioral deficits in the awake, visual discrimination task. DISCUSSION/SIGNIFICANCE OF FINDINGS: This study helps define how cortical network disruption after TBI. These changes are potential targets for novel TBI therapeutics, including neuromodulation and neural tissue transplantation. Thus, this work lays the groundwork for future studies aimed at mitigating the effects of TBI with rationally designed experimental therapeutics.

Randomly connected networks generate emergent selectivity and predict decoding properties of large populations of neurons.

Modern recording methods enable sampling of thousands of neurons during the performance of behavioral tasks, raising the question of how recorded activity relates to theoretical models. In the context of decision making, functional connectivity between choice-selective cortical neurons was recently reported. The straightforward interpretation of these data suggests the existence of selective pools of inhibitory and excitatory neurons. Computationally investigating an alternative mechanism for these experimental observations, we find that a randomly connected network of excitatory and inhibitory neurons generates single-cell selectivity, patterns of pairwise correlations, and the same ability of excitatory and inhibitory populations to predict choice, as in experimental observations. Further, we predict that, for this task, there are no anatomically defined subpopulations of neurons representing choice, and that choice preference of a particular neuron changes with the details of the task. We suggest that distributed stimulus selectivity and functional organization in population codes could be emergent properties of randomly connected networks.

Altered resting-state functional network connectivity is associated with suicide attempt in young depressed patients

The purpose of this study was to investigate the changes in resting-state brain functional network connectivity (FNC) in young depressed patients with and without suicidal behavior, and the relationship between FNC and suicidal attempts in depressed youths using resting-state fMRI (RS-fMRI). We conducted independent component analysis (ICA) to identify intrinsically connected neural networks and analyze the alterations of intra- and inter-network connectivity using FNC analysis in 35 depressed youth with suicidal attempts (SU group), 18 patients without suicidal attempts (NSU group) and 47 healthy controls (HC), and investigate brain-behavior associations between the FNC coefficients and clinical behavior in the SU group. SU group showed significantly decreased internetwork connectivity between anterior default mode network (aDMN) and salience network (SN), as well as the right frontal-parietal network (rFPN). However, the internetwork connectivity between the SN and rFPN in SU group was higher than that in NSU group. Moreover, decreased aDMN-rFPN connectivity was negatively correlated with BHS scores, and the differences in SN-rFPN and aDMN-pDMN connectivity were negatively associated with the HAMD score in the SU group. Our findings may provide new insights into the patterns of functional organization in the brain of suicidal depressed patients.

Patterns of Covariant Power and Coherent Eeg Activity During Rest in Young Adults

Functional cortical organization is not dependent on cognition only, but also reflects basic intrinsic individual characteristics stable over time and across physiological conditions that suggest the existence of self-organization patterns operating even during rest. The aim of the present study was to investigate the pattern of functional organization of EEG broad bands and coherent activity during rest by means of Principal Component Analysis (PCA) with closed and open eyes of 28 men and women. PCA revealed patterns of covariant oscillatory activity and functionally related regions with covariant coherent activity present during resting conditions, different for open and closed eyes. Different patterns of covariant oscillations within alpha frequencies were identified consistent with current notions on overlapping frequencies with different origin and behavioral context. Covariant coherent cortical networks were revealed congruent with functional systems described during cognitive processes; one, linking regions involved in visuo-motor coordination, another in language, and a third one in visuo-spatial processes suggesting that strong functional links are present during rest.

Mapping cerebral blood flow during speech production in hereditary ataxia

Dysarthria is a significant feature of the dominantly inherited spinocerebellar ataxias (SCA), but little is known about the patterns of brain activity associated with this disorder of motor speech control. Positron emission tomography (PET) was used to study regional cerebral blood flow during speech and rest in a group of 24 subjects with hereditary ataxia with mild-to-moderate dysarthria. These data were compared to the results obtained from a group of 13 age-matched, normal speakers. In the ataxic subjects, speech rates during scanning were significantly slowed compared to normal speakers. Significant reductions in mean regional blood flow were found in the cerebellum but not in supratentorial regions in the ataxic subjects. Multiple linear regression was used to model speech rate from regional blood flow. Four regions were identified as having significant relationships with speech rate in the model: the left inferior frontal and transverse temporal regions, and the right inferior cerebellar region and caudate nucleus. The relationship between flow and rate was positive in the inferior frontal and cerebellar regions and negative in the caudate and the transverse temporal region. The ataxic model represents an elaboration of the relationship previously reported for normal speakers, likely reflecting both the effects of, and compensation for, cerebellar degeneration in motor speech control. Although the mean regional blood flow values presented a pattern of functional organization for motor speech control at odds with lesion data, the performance-based model was in agreement with clinical experience. Incorporating performance data in functional image analysis may be more revealing of system characteristics than simply examining mean blood flow values.

Patterns of functional brain organization and migraine.

The purpose of this study was to examine the relationship between the patterns of functional organization of the brain, as evaluated by the number of anomalous brain conditions or phenomena (ABCP), and the prevalence of migraine in a group of 434 women with lifetime major depressive disorder. ABCP are conditions or phenomena which are clearly related to brain function whose prevalence significantly deviates from the statistical mean for the general population. Eighteen ABCP (e.g. mixed or left handedness, enuresis after age 5, learning and speech disorders) were used in this study as 'markers' for their associated patterns of functional brain organization. The relationship between the number of ABCP and the prevalence of migraine was highly significant. The correlation between the number of ABCP and the prevalence of migraine was 0.36 (P < 0.0001, confidence interval 0.26, 0.43). The prevalence of migraine in patients with no ABCP (n = 11) was 9%, while that of those with eight or more ABCP (n = 40) was 85%. This supports the hypothesis that there is a relationship between patterns of functional brain organization and migraine prevalence.