Place cells may simply be memory cells: Memory compression leads to spatial tuning and history dependence

The observation of place cells has suggested that the hippocampus plays a special role in encoding spatial information. However, place cell responses are modulated by several nonspatial variables and reported to be rather unstable. Here, we propose a memory model of the hippocampus that provides an interpretation of place cells consistent with these observations. We hypothesize that the hippocampus is a memory device that takes advantage of the correlations between sensory experiences to generate compressed representations of the episodes that are stored in memory. A simple neural network model that can efficiently compress information naturally produces place cells that are similar to those observed in experiments. It predicts that the activity of these cells is variable and that the fluctuations of the place fields encode information about the recent history of sensory experiences. Place cells may simply be a consequence of a memory compression process implemented in the hippocampus.

A survey on GAN acceleration using memory compression techniques

Since its invention, generative adversarial networks (GANs) have shown outstanding results in many applications. GANs are powerful, yet resource-hungry deep learning models. The main difference between GANs and ordinary deep learning models is the nature of their output and training instability. For example, GANs output can be a whole image versus other models detecting objects or classifying images. Thus, the architecture and numeric precision of the network affect the quality and speed of the solution. Hence, accelerating GANs is pivotal. Data transfer is considered the main source of energy consumption, that is why memory compression is a very efficient technique to accelerate and optimize GANs. Two main types of memory compression exist: lossless and lossy ones. Lossless compression techniques are general among all models; thus, we will focus in this paper on lossy techniques. Lossy compression techniques are further classified into (a) pruning, (b) knowledge distillation, (c) low-rank factorization, (d) lowering numeric precision, and (e) encoding. In this paper, we survey lossy compression techniques for CNN-based GANs. Our findings showed the superiority of knowledge distillation over pruning alone and the gaps in the research field that needs to be explored like encoding and different combination of compression techniques.

Biomechanical Comparison of a New Memory Compression Alloy Plate versus Traditional Titanium Plate for Anterior Cervical Discectomy and Fusion: A Finite Element Analysis

Objective. To compare the biomechanical properties of a new memory compression alloy plate and traditional titanium plate after anterior cervical discectomy and fusion (ACDF). Methods. A finite element model of the C3-7 segments was developed and validated. The C5-6 disc was removed, and an intervertebral cage made of peek material was implanted. Then, a new memory compression alloy plate composed of Ti-Ni memory alloy and a traditional titanium plate were integrated at the C5-6 segment. All models were subjected to a load of 73.6 N to simulate the head weight and 1 Nm of flexion-extension, lateral bending, and axial rotation. The range of segmental motion (ROM) and stress on the prostheses, adjacent discs, and endplates were analyzed. Results. Compared with intact status, ACDF with the new prothesis and traditional titanium plate reduced the ROM of C5-6 in six directions by 95.2%-100% and increased that of adjacent discs (C4-5 and C6-7) by 4.8%-112.5%. Adjacent disc stress peaks were higher for the traditional titanium plate (0.7-4.2 MPa) than for the new prosthesis (0.6-4.1 MPa). Endplate stress peaks were the highest in ACDF with the new prosthesis (15.6-53.3 MPa), followed by ACDF with traditional titanium plate (5.0-29.4 MPa). Stress peaks were significantly lower for the new prothesis (12.8-52.3 MPa) than for the traditional titanium plate (397.0-666.1 MPa). Conclusions. The new prosthesis improved the immediate stability of the surgical site and had an elastic modulus that was smaller than that of traditional titanium plate, making it conducive to reducing stress shielding and the impact on the adjacent intervertebral disc.