Biomedical subjects

N A Blum

Publications and source records attributed to N A Blum.

3 recordsLinked to original sources

PubMed1995

Investigating thought disorder in schizophrenia with the lexical decision task.

Prior work has found evidence of hyperpriming in schizophrenics, which has been related to a persistence of associational activation in thought disorder. We extended this work by administering a lateralized version of the lexical decision task to 10 thought-disordered schizophrenics (TD), 10 non-thought-disordered schizophrenics (NTD), and 11 control subjects to localize the patterns of priming. All subjects were right-handed males. Associated, unassociated, and neutral prime-target pairs were displayed across seven stimulus location combinations: prime and target both presented to the center, left visual field (LVF), or right visual field (RVF); prime presented to the center with target presented to the LVF or RVF; and prime and target presented contralaterally. TD schizophrenics exhibited priming effects comparable to those of the other subject groups, suggesting intact semantic memory structures and memory processes that may be unimpaired under the conditions studied. It is believed that the associative process mediating priming effects found in schizophrenia are later in the sequence than those examined in this study.

Adolescent↗

PubMed1991

Multisite microprobes for neural recordings.

Multisite, passive microprobes have been developed to allow simultaneous recording of action potential activity from multiple neurons at different locations in the brain. The microprobes were fabricated using standard integrated circuit techniques. The probe is a planar structure that consists of gold electrodes sandwiched between two polyimide dielectric layers and bonded to a molybdenum structural support. Windows in the top dielectric layer expose the electrode sites and bonding pads. In two distinct versions of the probe four or six recordings sites, respectively, of approximately 25 microns 2 are arranged on a dagger-shaped structure which can penetrate the pia. The bonding pads and interconnect wires at the probe head are entirely encapsulated in a tubular fixture that is packed with silicone RTV and sealed with epoxy to protect the interconnections from contact with body fluids. The site impedances at 1 kHz are typically between 2 and 4 M omega. Probe lifetimes for continuous immersion in physiological saline solution, as measured by impedance, have exceeded 750 h. The failure mechanism is believed to be due to moisture and ion absorption in the top dielectric layer. In acute neurophysiological experiments using the four site probes, action potential activity was recorded from physiologically identified neurons in the dorsal column nuclei of anesthetized rat.

Action Potentials↗

PubMed1984

Cognitive vulnerability to auditory hallucination. Impaired perception of meaning.

Forty-four psychiatric patients were separated into four groups on the basis of presence/absence of hallucinations and reactive/process status. Reactive hallucinators were found to be singularly impaired in two aspects of cognitive processing: (1) tolerance of ambiguity; and (2) availability of alternative meanings. The perceptual errors produced by premature judgment and limited consideration of alternative meanings for misperceptions are discussed as factors predisposing to auditory hallucination.

Adult↗